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      1. Disease management of Agricultural Crops  
        2. Disease Management of Horticultural Crops 
         
        2. Disease Management of Horticultural Crops 
        
         
        Fruit Crops 
        Diseases  of Mango 
          Anthracnose  (Colletotrichum  gloeosporioides) 
        Symptoms  
        
          
            - Produces       leaf spots, blossom blight, wither tip, twigs blight and fruit rot.
 
            - Small       blister like spots develop on the leaves and twigs. Young leaves  wither        and dry  Tender twigs wither       and die back  symptom appears. 
 
            - Affected       branches ultimately dry up. Black spots appear on fruits.
 
            - The fruit       pulp becomes hard, crack and decay at ripening. Infected fruits drop 
 
           
            
        Mode  of survival and spread 
        
          
            - on dried leaves, defoliated branches mummified  flowers and flower brackets. 
 
            - Contact with diseased fruit during transport and  storage. The secondary spread is through  airborne conidia 
 
           
        Favourable  conditions  
        
          
            - Temperature of 25°C and Relative Humidity 95-97% 
 
           
        Management 
        
          
            - Before storage, treat with hot water, (50-55°C)  for 15 minutes 
 
           
          Mango malformation  (Fusarium moliliforme var. subglutinans) 
        Symptoms  
        
          
            -  Three types  of symptoms: bunchy top phase, floral malformation and vegetative malformation. 
 
            - In bunchy top phase in nursery bunch of  thickened small shoots, bearing small rudimentary leaves.  Shoots  remain short and stunted giving a bunchy top appearance. 
 
            - In vegetative malformation, excessive vegetative  branches of limited growth in seedlings.  They are swollen with short internodes  forming a bunches of various size and the top of the seedlings shows bunchy top  appearance. 
 
            - In malformation of inflorescens, shows variation  in the panicle.  Malformed  head dries up in black massesa  and  persist for long time. 
 
            - Secondary branches are transformed into number  of small leaves giving a witches broome appearance. 
 
           
            
        Mode  of spread 
        
          
            - Diseased propagatives materials. 
 
           
        Management  
        
          
            - Diseased plants should be destroyed 
 
            - Use of disease free planting material 
 
            - Pruning of diseased parts along the basal 15-20  cm apparently healthy portions. 
 
           
          Grey  Blight (Pestalotia mangiferae)
        Symptoms 
        
          
            - Brown spots develop on the margin and at the tip  of the leaf lamina.  They increase in size and become dark  brown. Black dots appear on the spots which are acervali of the fungus. 
 
           
        Mode  of survival and spread 
        
          
            - Survive on mango leaves for over a year. Spreads  through wind borne conidia. 
 
           
        Favourable  conditions 
        
          
            - Heavy infection is noticed during the monsoon  when the temperature is 20-25oC.and high humidity. 
 
           
        Management 
        
          
            - Remove and destroy infected plant parts. 
 
           
          Sooty mould (Capnodium mangiferae)
         Symptoms 
        
          
            - The fungi produce mycelium which is superficial  and dank.They row on  sugary secretions of the plant hoppers.  Black encrustation is formed which  affect the photosynthetic activity.
 
           
        Favourable  conditions 
        
          
            - The fungus grows on the leaf surface on the  sugary substances secreted by Jassids,Aphids and scale insects. 
 
           
        Management 
        
          
            - Management should be done for insects and sooty  moulds simultaneously.  
 
            - Starch dries and forms a flake which are removed  along with the fungus. 
 
           
         
        
         
        Diseases  of Citrus 
          Gummosis  (Phytophthora parasitica, P. palmivora, P. citrophthora) 
        Symptoms 
        
          
            - First symptoms are dark staining of bark       which progresses into the wood.
 
            - Bark at the base is destroyed resulting       in girdling and finally death of the tree.
 
            - Bark in such parts dries, shrinks and       cracks and shreds in lengthwise vertical strips.
 
            - Later profuse exudation of gum from the       bark of the trunk.
 
            - Infection extends to crown roots.
 
           
            
         
        Favourable  conditions 
        
          
            - Prolonged contact of trunk with water as       in flood irrigation; water logged areas and heavy soils.
 
           
        Mode  of spread and survival 
        
          
            - Soil inhabitants.
 
            - Sporangia spread by splashing rain       water, irrigation water and wind.
 
            - Irrigation water and wind.
 
           
        Management 
        
          
            - Injuries to crown roots or base of stem       during cultural operations should be  avoided.
 
           
          
            - If lesion has girdled less than ½ the       girth, remove the diseased bark with a   knife along with ½” of uninvaded bark.
 
           
          Canker  (Xanthomonas campestris pv citri)
        Symptoms 
        
          
            - Acid lime, lemon and grapefruit are       affected. Rare on sweet oranges and mandarins.
 
            - Affects leaf, twig and fruits. In       canker, leaves are not distorted.
 
            - Lesions are typically circular with       yellow coloured; appear on both sides of leaf, severe in acid lime (difference       from scab) When lesions are produced on twigs, they are girdled and die. 
 
            - On fruits, canker lesions reduce market       value.
 
           
             
        Favourable  conditions 
        
          
            - At 20-30°C,free of moisture.
 
           
        Mode  of survival and spread 
        
          
            - Wind and rain splashes.
 
            - Survives in infected leaves for 6       months.
 
            - Injury caused by leaf miner helps the       entry of the bacterium.
 
           
        Management 
        
          
            - Control leaf miner when young flush is       produced.
 
            - Prune badly infected twigs before the       onset of monsoon.
 
           
          Tristeza or quick decline (Virus)
        Symptoms 
        
          
            - Lime is susceptible both as seedling or       buddling on any root stock.
 
            - But mandarin and sweet orange seedlings       or on rough lemon, trifoliate orange, citrange; Rangpur lime root stocks       tolerant; susceptible root stocks are grapefruit and sour orange.
 
            - In sweet orange or mandarin on       susceptible root stocks, leaves develop deficiency symptoms and absise.
 
            - Roots decay, twigs die back. Fruit set       diminishes; only skeleton remains.
 
            - Fine pitting of inner face of bark of       sour orange stock.
 
            - Grapefruit and acid lime are susceptible       irrespective of root stock.
 
            - Tree stunted and dies yield very much       reduced. Fruits are small in size.
 
           
        Mode  of spread 
        
          
            - Use of infected bud wood Toxoptera citricida (aphid) is the       important vector.
 
           
        Management 
        
          
            - For sweet orange and mandarin. Avoid       susceptible root stocks.
 
            - For acid lime, use seedling preimmunised       with mild strain of tristeza.
 
           
          Greening  (Liberobactor asiaticum) (Phloem limited Bactria- like- organism)
        Symptoms 
        
          
            - This disease affects almost all citrus       varieties irrespective of root stock.
 
            - Stunting of leaf, sparse foliation, twig       die back, poor crop of predominantly greened, worthless fruits.
 
            - Sometimes only a portion of tree is       affected.A diversity of foliar chlorosis.
 
            - A type of mottling resembling zinc       deficiency often predominates.
 
            - Young leaves appear normal but soon       assume on outright position, become leathery and develop prominant veins       and dull olive green colour. Green circular dots on leaves.
 
            - Many twigs become upright and produce       smaller leaves.
 
            - Fruits small, lopsided with curved       columella. The side exposed to direct sunlight develops full orange colour       but the other side remain dull olive green.
 
            - Low in juice and soluble solids, high in       acid. Worthless either as fresh fruit or for processing. Seeds poorly       developed, dark coloured, aborted.
 
           
        Mode  of spread 
        
          
            - Infected budwood; psyllid vector-Diaphorina       citri
 
           
        Management 
        
          
            - Control psyllids with insecticides.
 
            - Use pathogen free bud wood for       propagation.
 
           
         
        
         
        Diseases  of Guava 
        Anthracnose (Colletotrichum  gloeosporioides) 
        Symptoms 
        
          
            - Symptoms  of this disease are observed on mature fruits on the tree. 
 
            - The  characteristic symptoms consist of sunken, dark colored, necrotic lesions.  Under humid conditions, the necrotic lesions become covered with pinkish spore  masses. 
 
            - As the  disease progresses, the small sunken lesions coalesce to form large necrotic  patches affecting the flesh of the    fruit 
 
           
        Management 
        
          
            - Control measures are needed in       commercial guava production. 
 
            - The use of resistant cultivars provides       the most efficient tactic in disease management. 
 
           
          Guava Rust (Puccinia psidii)
        Symptoms 
        
          
            - The pathogen can affect foliage, young       shoots, inflorescences and fruit of guava.
 
            - Typical symptoms associated with this       disease include distortion, defoliation, reduced growth and if severe,       mortality. 
 
            - On fully expanded leaves, dark bordered,       roughly circular brown lesions with yellow halos develop
 
           
        Management 
        
          
            - Control of guava rust is based on the       use of fungicides. 
 
            - Scouting fields for onset of disease or       during the times of year when environmental conditions are favorable for       pathogen infection are recommended so that proper and timely fungicide       applications can be made. 
 
            - In addition, proper cultural tactics       such as proper fertilization, irrigation, pruning and sanitation aide in       achieving a healthy, vigorously growing tree less vulnerable to disease       pressures. 
 
           
          Guava  Diseases Caused by Nonfungal Agents (Cephaleuros virescens)
          Algal  Leaf Spot
        Symptoms 
        
          
            - Disease symptoms are exhibited on both       abaxial and adaxial leaf surfaces as orange, rust-colored, dense silky       tufts ranging from 5 to 8 mm in diameter. 
 
            - Upon scraping away these spots, a thin,       grayish white to dark-colored, necrotic crust remains on the leaf.
 
            - These spots usually come together to       form large irregular patches on a leaf. As the spots mature they take on a       dull, grayish green color.
 
            - Twigs and branches are also affected       causing the bark to crack due to the growth and expansion of the pathogens       filaments into the cortical tissues of the host.
 
           
          Management
         
        
          
            - Algal  leaf spot can be reduced by maintaining tree vigor with cultural techniques  such as proper fertilization and irrigation, proper pruning to enhance air  circulation within the canopy and sunlight penetration, managing weeds and  wider tree spacing. Managing insect, mite and other foliar diseases increases  tree vigor and lessens susceptibility to this disease.
 
           
         
        
         
        Diseases  of Apple 
          Scab   (Venturia inaequalis) 
        Symptoms 
        
          
            - Symptom       appears on leaves and fruits. 
 
            - On lower       side of the leaf lesion appear as olivaceous spots   which turn dark brown to black and       become velvety. 
 
            - On young       foliage, the spots have a radiating appearance with a feathery edge. 
 
            - On older       leaves the lesions are more definite in outline. 
 
            - The       lesion may form a convex surface with corresponding concave area on the       opposite side.
 
            -  In severe infection leaf blade curved,       dwarfed and distorted. 
 
            - Fruits       show small, rough, black circular lesions.
 
            - The       centre of the spots become corky and on mature fruits, yellow halo is  seen around the lesions.
 
           
             
         
        Mode  of spread and survival 
        
          
            - Primary       spread through ascospores and secondary spread by air borne conidia.
 
            - Favourable       conditim
 
            - Cool and       moist conditions due to rain or show at higher elevation and shady       portion.
 
           
          Management
                     Clean cultivation, collection and  destruction of fallen leaves  
         Fire  blight (Erwinia amylovora) 
        
          
            - The       initial symptom usually occurs on flowers, which become water soaked, then       shrivel turn brownish to black in colour and fall or remain hanging in       tree. 
 
            - The       symptom spread to leaves twigs. Terminal twigs wilt from hip to downward       and also spread to branches fruits becomes water soaked, turns brown,       shrivels and findly becomes black. 
 
            - Oozing       may be seen in the affected area. 
 
           
        Survival  and spread 
        
          
            - The bacterium survives in infected branches and  twigs. Secondary spread by insects and rain splash.
 
           
        Favourable  condition 
        
          
            - Temperature above 24ºC and heavy rain.
 
           
        Management 
        
          
            - Removal and destruction of affected parts.
 
            - cutting of blighted twigs and root sprouts in  summer 
 
           
          Soft  rot  (Penicillium expansum)
        Symptom 
        
          
            - Young       spots starts from stem end of the fruit as light brown watery rot. As the       fruit ripens  area of the rotting       increases, 
 
            - skin       becomes wrinkled.
 
            - A       peculiar musty odour is emitted
 
            - Under       humid condition a bluish green sprorulating growth appears.
 
           
        Mode  of spread and survival 
        
          
            - Infection       take place by wounds in the skin caused by insects and during handing in       storage and transport.
 
           
        Management 
        
          
            - Careful       handling of fruits without causing any wounds.
 
           
          
         
         
        Vegetable Crops 
        Diseases of Tomato 
        Damping Off (Pythium  aphanidermatum) 
        Symptom 
        
          
            - This is one of the worst       diseases of tomato occurring in the nursery. 
 
      - Damping off of tomato occurs       in two stages, i.e. the pre-emergence and the post-emergence phase. 
 
      - In the pre-emergence the       phase the seedlings are killed just before they reach the soil surface. 
 
      - The young radicle and the       plumule are killed and there is complete rotting of the seedlings. 
 
      - The post-emergence phase is       characterized by the infection of the young, juvenile tissues of the       collar at the ground level.
 
      - The infected tissues become       soft and water soaked. The seedlings topple over or collapse.
 
       
       
         
        Control  
        
          
            - Seed treatment with fungal       culture Trichoderma viride (4 g/kg of seed) 
 
     
    Early Blight (Alternaria  solani)
        Symptom 
        
          
            - This is a common disease of       tomato occurring on the foliage at any stage of the growth.
 
      - The fungus attacks the       foliage causing characteristic leaf spots and blight. Early blight is       first observed on the plants as small, black lesions mostly on the older       foliage. 
 
      - Spots enlarge, and by the       time they are one-fourth inch in diameter or larger, concentric rings in a       bull's eye pattern can be seen in the center of the diseased area. 
 
      - Tissue surrounding the spots       may turn yellow. If high temperature and humidity occur at this time, much       of the foliage is killed.
 
      - Lesions on the stems are       similar to those on leaves, sometimes girdling the plant if they occur       near the soil line.
 
      - Transplants showing       infection by the late blight fungus often die when set in the field. The       fungus also infects the fruit, generally through the calyx or stem       attachment. 
 
     
  Control 
        
          
            - Removal and destruction of       the affected plant parts. Practicing crop rotation helps to minimize the       disease incidence. 
 
     
    Fusarium Wilt (Fusarium  oxysporum f. sp. Lycopersici)
        Symptom 
        
          
            - This is one of the worst       diseases of tomato occurring mostly in the nurseries. The first symptoms       of the disease are clearing of the veinlets and chlorosis of the leaves. 
 
      - The younger leaves may die       in succession and the entire may wilt and die in a course of few days.       Soon the petiole and the leaves droop and wilt.
 
      - In young plants, symptom       consists of clearing of veinlet and dropping of petioles. In field,       yellowing of the lower leaves first and affected leaflets wilt and die. 
 
      - The symptoms continue in       subsequent leaves. At later stage, browning of vascular system occurs.       Plants become stunted and die.
 
       
       
         
        Control 
        
          
            - The nursery should be regularly       inspected for wilt infected plants. 
 
      - The affected plants should       be removed and destroyed. 
 
      - Prior to planting the beds       should be drenched with Carbendazim (0.1%) and the seeds should be treated       with the Thiram (2.5 kg/ha). 
 
      - Crop rotation with a non-host       crop such as cereals helps to reduce the disease inoculum.
 
     
    Septoria Leaf Spot (Septoria lycopersici)
        Symptom 
        
          
            - The plant may be attacked at       any stage of its growth. The disease is characterized by numerous, small,       grey, circular leaf spots having dark border.
 
     
  Control 
        
          
            - Removal and destruction of       the affected plant parts. 
 
     
    Bacterial Wilt  (Pseudomonas solanacearum)
        Symptom 
        
          
            - This is one of the most       serious diseases of tomato crop. Relatively high soil moisture and soil       temperature favour disease development. 
 
      - Characteristic symptoms of       bacterial wilt are the rapid and complete wilting of normal grown up       plants.
 
      - Lower leaves may drop before       wilting. Pathogen is mostly confined to vascular region; in advantage       cases, it may invade the cortex and pith and cause yellowbrown       discolouration of tissues. 
 
      - Infected plant parts when cut       and immersed in clear water, a white streak of bacterial ooze is seen       coming out from cut ends.
 
     
  Control 
        
          
            - Crop rotations, viz.,       cowpea-maize-cabbage, okra-cowpea-maize, maize- cowpea-maize and finger       millet-egg plant are reported effective in reducing bacterial wilt of       tomato.
 
      - Seedling treatment with       Streptocycline (1 g/40 litres of water) for 30 min protects the seedlings       in the initial stages of growth.
 
     
    Bacterial Leaf Spot (Xanthomonas campestris  pv. Vesicatoria)
        Symptom 
        
          
            - Moist weather and splattering       rains are conducive to disease development. Most outbreaks of the disease       can be traced back to heavy rainstorms that occur in the area.
 
      - Infected leaves show small,       brown, water soaked, circular spots surrounded with yellowish halo. 
 
      - On older plants the leaflet       infection is mostly on older leaves and may cause serious defoliation.
 
      - The most striking symptoms       are on the green fruit. Small, water-soaked spots first appear which later       become raised and enlarge until they are one-eighth to one-fourth inch in       diameter. 
 
      - Centers of these lesions       become irregular, light brown and slightly sunken with a rough, scabby       surface. 
 
      - Ripe fruits are not       susceptible to the disease. Surface of the seed becomes contaminated with       the bacteria, remaining on the seed surface for some time. 
 
      - The organism survives in       alternatehosts, on volunteer tomato plants and on infected plant debris.
 
     
  Control 
        
          
            - Bacterial spot is difficult       to control once it appears inthe field. 
 
      - Disease-free seed and       seedlings should always be used and the crop should be rotated with       non-host crops so as to avoid last years crop residue. 
 
      - Spraying with Agrimycin-100       (100 ppm) thrice at 10 days intervals effectively controls the disease.
 
     
    Tomato Mosaic Virus  (TMV)
        Symptom 
        
          
            - The disease is characterized       by light and dark green mottling on the leaves often accompanied by wilting       of young leaves in sunny days when plants first become infected.
 
      - The leaflets of affected       leaves are usually distorted, puckered and smaller than normal. Sometimes       the leaflets become indented resulting in "fern leaf" symptoms. 
 
      - The affected plant appears       stunted, pale green and spindly. 
 
      - The virus is spread by       contact with clothes, hand of working labour, touching of infected plants with       healthy ones, plant debris and implements. 
 
     
  Control 
        
          
            - Seeds from disease free       healthy plants should be selected for sowing. The seeds should be       thoroughly rinsed and dried in shade. 
 
      - In the nursery all the       infected plants should be removed carefully and destroyed. Seedlings with       infected with the viral disease should not be used for transplanting. 
 
      - Crop rotation with crops       other than tobacco, potato, chilli, capsicum, brinjal, etc. should be       undertaken.
 
     
    Tomato Leaf Curl Virus  (TLCV)
        Symptom 
        
          
            - This disease is transmitted       by whitefly (Bemisia tabaci). It is one of the most devastating diseases       of tomato. 
 
      - Leaf curl disease is       characterized by severe stunting of the plants with downward rolling and       crinkling of the leaves. The newly emerging leaves exhibit slight yellow       colouration and later they also show curling symptoms. 
 
      - Older leaves become leathery       and brittle. The nodes and internodes are significantly reduced in size.
 
      - The infected plants look       pale and produce more lateral branches giving a bushy appearance. The       infected plants remain stunted. 
 
     
  Control 
        
          
            - The affected plants should       be removed and destroyed. Alternate or collateral hosts harboring the       virus causing this disease is removed at the time of weeding or earthing       up operations to minimize the spread of the disease. 
 
      - Checking the white fly       population can reduce the disease incidence. 
 
     
    Tomato Spotted Wilt  Virus (TSWV)
        Symptom 
        
          
            - The spotted wilt virus is       transmitted through thrips (Thrips tabaci, Frankliniella schultzi and F. occidentalis). 
 
      - This disease is similar to       streak in that it causes streaking of the leaves, stems and fruits.       Numerous small, dark, circular spots appear on younger leaves. 
 
      - Leaves may have a bronzed       appearance and later turn dark brown and wither. 
 
      - Fruits show numerous spots       about one-half inch in diameter withconcentric, circular markings. On ripe       fruit, these markings are alternate bands of red and yellow.
 
       
      
         
        Control 
        
          
            - The affected plants should       be removed and destroyed. 
 
      - Alternate or collateral       hosts harboring the virus causing this disease is removed at the time of       weeding or earthing up operations to minimize the spread of the disease. 
 
     
    
    Diseases of Brinjal 
    Bacterial  Wilt (Pseudomonas solanacearum)  
      Symptoms 
    
      - Bacterial wilt symptoms on       leaf surface Wilting, stunting, yellowing of the foliage and finally       collapse of the entire plant are the characteristic symptoms of the       disease. 
 
      - Lower leaves may droop first       before wilting occurs. 
 
      - The vascular system becomes       brown. 
 
      - Bacterial ooze comes out from       the affected parts. 
 
      - Plant show wilting symptoms       at noontime will recover at nights, but die soon. 
 
     
    Control 
    
      - Pant samrat variety is       tolerant. 
 
      - Crop rotation with       cruciferous vegetables such as cauliflower help in reducing the disease       incidence. 
 
      - Fields should be kept clean       and effected parts are to be collected and burnt. 
 
      - The disease is more prevalent       in the presence of root knot Nematodes, so control of these nematodes will       suppress the disease spread. 
 
     
    Cercospora Leaf Spot (Cercospora solani -melongenae, C. Solani)  
      Symptoms       
      Leaf spot  symptoms   
    
      - The leaf spots are       characterized by chlorotic lesions, angular to irregular in shape, later       turn grayish-brown with profuse sporulation at the centre of the spot. 
 
      - Severely infected leaves drop       off prematurely, resulting in reduced fruit yield. 
 
     
    Control 
    
      - Pant Samrat variety is       resistant to both the leaf spots. 
 
      - Diseases can be managed by       growing resistant varieties. 
 
     
    Tobacco mosaic virus  (TMV) 
      Symptoms 
       
    
      - Mosaic       mottling of leaves and stunting of plants are the characteristic symptoms       of potato virus Y Mosaic symptoms are mild in early stages but later       become severe. 
 
     
    
      - Infected       leaves are deformed, small and leathery. Very few fruits are produced on       infected plants. 
 
      - The       important symptom produced by tobacco mosaic virus is conspicuous mottling       of leaves. 
 
      - Leaves       also develop blisters in advanced cases. Severely infected leaves become       small and misshapen. Plants infected early remain stunted. 
 
      - PVY       is easily sap transmitted. 
 
      - It       is transmitted in the field through aphids, Aphis gossypii and Myzus       persicae and perpetuates on weed hosts like Solanum nigrum and S.xanthocarpum. 
 
      - TMV       is transmitted by sap, contaminated implements and clothes, soil debris       and hands of labour. 
 
      - It       can perpetuate on many cultivated plants like cucurbits, legumes, pepper,       tobacco, tomato and weed hosts. The virus survives in plant debris in       soil. 
 
     
  Control 
    
      - Destroy all weeds and avoid       planting cucumber, pepper, tobacco, tomato near brinjal seed beds and       field. 
 
      - Wash hands with soap and       water before working in seed beds. 
 
      - Prohibit smoking or chewing       of tobacco who are handling brinjal seedlings. 
 
       
    Collar  Rot (Sclerotium rolfsii)  
    
      - The disease occasionally       occurs in serious form. 
 
     
    Symptoms 
    
      - The lower portion of the stem       is affected from the soil borne inoculum (sclerotia). 
 
      - Decortication is the main       symptom. 
 
      - Exposure and necrosis of       underlying tissues may lead to collapse of the plant. 
 
      - Near the ground surface on       the stem may be seen the mycelia and sclerotia. 
 
      - Lack of plant vigour,       accumulation of water around the stem, and mechanical injuries help in       development of this disease. 
 
     
    Control 
    
      - Seed treatment with 4 g of Trichoderma       viride formulation per kg seed will help in reducing the disease. 
 
      - Collection and destruction of       diseased parts and portions of the plant. 
 
     
    
      
       
      Diseases of Cucurbits 
      Fusarium wilt of water melon  (Fusarium  oxysporum f. sp. Niveum),  Muskmelon – F. o. fsp. Melonis          
        Symptoms 
      
        
          - The disease attack the plant at all stages of  plant growth. 
 
          - When young seedlings are infected they damp off  and die. 
 
          - In older plants the plant wilt and die within 10  days. 
 
          - Vascular discolaration can be seen. In wet  weather, pinkish or whitish fungal growth can be seen on dead stems.
 
         
        Mangement 
      
        
          - Collection and burning of       infected plant.
 
          - Seed treatment and soil       application with T. Viride or P.       fluorescens
 
          - Use of disease free seeds.
 
         
        Root rot of muskmelon (Pythium  aphendermatum)
         Root  rot of pumpkin and squash (Fusarium  solani f.sp. cucurbitae)
         Root rot of watermelon, cucumber  (Pythium irregulare and P.ultimum)
        Symptoms 
      
        
          - The roots of the affected plants appear water  soaked with sunken darkened lesions. The crown of the plants is girdled and  entire plant is collapsed. Fruits become rotted by the fungus.
 
         
        Management 
      
        
          - As like wilt the management practice should be  followed.
 
         
        Verticillium wilt  (Verticillium  albo-atrum)
        Symptoms 
      
        
          - The leaves of the plant become yellow from base  of the plant upwards and the whole plant wilts. If the stem is cut open, brown  discoloration can be seen.
 
         
        Anthracnose (Collectorichum lagenarium)
        Symptoms 
      
        
          - Small yellowish or water soaked areas appears on  leaves which enlarge rapidly and turn brown in most cucurbits but black in  water melon. The affected bark break and fall of or the whole leaf dries. When  the infection occurs in stem, the whole vine is killed. When infection occurs  in fruit pedicle, the young fruit may be darken, shrivel and dry. Circular  black  cankers appear on fruits. The  spots may be up to 5 cm dia based on the host and environment. In the sunken  black spots salmon coloured spores can be seen.
 
         
        Management 
      
        
          - Collection and destruction of infected plant.
 
           
        Alternaria leaf spot/ target  leaf spot / Macrosporium blight (Alternaria  cucumerina, Macrosporium cucumerinum)
        Symptoms 
      
        
          - Small, circular spots appear on leaves. As the  spot enlarges concentric rings can be seen on infected area. The fungus also  causes fruit rot
 
         
        Management 
      
        
          - Use of disease free seeds.
 
         
        Cercospora leaf spot (Cercospora citrullina)
        Symptoms 
      
        
          - Small black circular spots with grey centre  appear on leaves. Severely infected leaves fall off. The fruit size is reduced.
 
         
        Management 
      
        
          - Collection and burning of       infected leaf.
 
          - Crop rotation.
 
           
        Downy mildew (Pseudoperonospora  cubensis)
        Symptoms 
      
        
          - Symptoms resembling mosaic viz, pale green areas  separated by dark green areas appear on upper surface of leaf. During wet  season, corresponding lower surface is covered with faint purplish fungal  growth. The entire leaf dries up quickly.
 
         
        Management 
      
        
          - Use of bed system with wide spacing with good  drainage and air movement and exposure to sun help to check the disease  development.
 
         
        Angular leaf spot (Pseudomonas  syringae pv.lachrymans)
        Symptoms 
      
        
          - Water soaked lesions appear on leaves which are  confined to veins. Then turn grey to tan and form an exudates in the lower  surface. The spots loosen and fall out. Infected fruits develop a brown,  circular, superficial, firm rot which causes rapid detorition. The rot may  extend into flesh.
 
         
        Management 
      
        
          - Use of disease free seed and crop rotation.
 
         
        Fruit rot (Pythium aphenidermatum)
        Symptoms 
      
        
          - Initially the skin of the fruit shows soft, dark  green water soaked lesions which gradually develop into a watery soft rot.  Cottony mycelium develop on the affected portions. The fruit in contact with  the soil is attacked easily.
 
         
        Management 
      
        
          - Keep fruits not in touch with soil
 
         
        Other fruit rots of watermelon 
      
        
          - Aspergillus fruit rot – Aspergillus flavus
 
          - Curvularia fruit rot – Curvularia ovoidae
 
          - Myrothecium fruit rot – Myrothecium roridum
 
          - Rhizopus fruit rot – Rhizopus oryzae
 
          - Diplodia fruit rot – Diplodia natalensis (also affects       cucumber)
 
         
        Viral disease 
      
        
          - Cucumber mosaic virus – Vector-       aphids (A. craccivora M.persicae)
 
         
        Symptoms 
      
        
          - Mosaic mottling, leaf distortion, stunting of  the plants, shortened internode and petoles. Infected plants bear only very few  flowers. In fruits mottled yellowish green areas can be seen.
 
         
        Management 
      
        
          
            - Removal and burning of infected plants.
 
            - Eradication weeds hosts
 
           
         
       
      Other viral diseases 
      
        
          - Watermelon mosaic virus –       watermelon and muskmelon
 
          - Squash mosaic – Squash and       pumpkin
 
          - Mosaic disease – Bottle       gourd, snake gourd, squash, ribbed gourd
 
         
       
      Management 
      
        
          - Removal and burning of infected plants.
 
          - Eradication weeds hosts
 
         
        Phyllody – Phytoplasma (Vector – leaf hopper) 
      
        
          - It affects bitter gourd, bottle gourd, cucumber,  ridge gourd and snake gourd. The symptoms are shortening of internodes and  phyllody of normal flowers. Corolla, androecium and gynecium are transferred  into green leaf like structures.
 
         
        Management 
      
        
          - Removal of infected plants.
 
          - Clean cultivation without       weed host.
            
            
          
 
         
         
        Diseases of French bean 
        Anthracnose 
          Symptoms: Brown canker on  pods. 
          Management 
       
      
        
        Angular leaf spot
        Symptoms: On the leaves  there are angular red brown spots
         Management  
      
        
          - Use healthy seeds. 
 
          - Adopt 2 year crop rotation in       infected field. 
 
         
        Common Mosaic
        Symptoms: Leaf turned  curved due to etiolation and dry down near veins. There is less number of pods  and seeds.
         Management 
      
        
          - Grow resistant varieties e.g.       contender 
            
          
 
         
         
        Diseases of Carrot 
                Black Root Rot  (Thielaviopsis basicola) 
        
          - This can be a problem disease on carrots grown  on muck or high organic soils. 
 
          - Washed carrots may show black scattered lesions  when stored in polythene bags.
 
         
        Management  
        
          - Avoid root damage
 
          - Do not store in high  temperature.
 
         
        Cavity Spot (Pythium spp.) 
          Symptom 
        
          - Cavity spot occurs on both parsnips and carrots. 
 
          - Tonnage of the crop is not reduced but the  cavities make the roots unmarketable.
 
          - The disease occurs on carrots grown on mineral  or peat (muck) soils.
 
         
        Management  
        
          - No control for this disease is known other than  growing carrots on new land free of this problem disease.
 
         
        Common Scab (Streptomyces  scabies) 
          Symptom 
        
          - This is the same scab that attacks potatoes and  other root crops. 
 
          - Alkaline soils and dryish high organic soils are  conducive to the development of the superficial disease.
 
          - Scab lesions on the carrot surface.
 
         
        Management 
        
          - Avoid potato fields and lower the soil pH if  above 7 or more.
 
         
        Cercospora Leaf Spot  (Cercospora carotae)  
          Symptom 
        
          - This disease can be as destructive as Alternaria  leaf blight. 
 
          - Again the disease is both seed- and  residue-borne. 
 
          - Younger leaves are more susceptible than older  leaves.
 
         
        Management  
        
          - Ploughing under crop residues, crop rotation and  foliar fungicides are all control recommendations.
 
         
        Sclerotinia Rot - White  Mould (Sclerotinia sclerotiorum)  
          Symptom 
        
          
            - The infectious ascospores of this fungus are  abundant as a consequence of the build-up of the disease on millions of acres  of canola and bean crops. 
 
            - Carrots may show little or no damage incidence  in the field but following washing and storage white mold outbreaks often occur  on the stored roots. 
 
            - Only a small percentage of the roots may be  initially infected but the fungus mycelium can move very rapidly from carrot to  carrot.
 
            - In a matter of weeks the whole storage container  may become a mass of white mold and black sclerotia surrounding each and every  carrot.
 
           
          Management  
        
          - Frequent inspection in storage, low  temperatures, aeration. 
 
         
        Bacterial Leaf Blight  (Xanthomonos campistris pv.carotae) 
        
          - A seed-borne bacterial disease that causes leaf  spotting similar to Cerospora or Alternaria blights.      
 
         
        
        Diseases of Crucifers 
            Cabbage, cauliflower, turnip,  broccoli are some of the important cruciferous crops 
        Club root (Plasmodiophora brassicae) 
      
        
          - The       above ground symptoms are, yellowing of leaves, stunting and later the       diseased plant die. 
 
          - Young       plants die with in a short time while older plants fail to produce       marketable heads. 
 
          - On       roots and root lets, spindle shaped with thick centre and tapered ends       giving a club shaped malformation is developed. 
 
          - The       club shaped structered  cells are       invaded by the secondary,weakly parasitic organisms and the cells are       disintegrated which produce toxins and the plants are killed.
 
         
        Management 
      
        
        Black rot (Xanthomonas  campestris pv.campestris) 
      
        
          - On leaves ‘V’ shaped chlorotic to yellow lesions  develop from the leaf margins. 
 
          - They become black later. The veins and veinlets  become black.Systemic infection spreads to the root.
 
          - The vascular bundle in the stem becomes black  followed by integration of fleshy stalk.
 
          - The attack of soft rot organisms cause further  detoriation. 
 
          - The cabbage heads and cauliflower curds are  invaded and become discolored.
 
         
        Management 
      
        
          - Use of healthy seed
 
          - Spraying with Agrimycin 200 ppm            
 
         
        Alternaria leaf spot/ Black spot/ Brown spot (Alternaria brassicicola) 
      
        
          - Small       dark coloured lesions up to 1.0 cm in dia appear on leaves.
 
          -  In humid condition conidiophores appear       on the lesion in concentric rings.
 
          - Linear       spots also appear on petioles, stems and seed pods. 
 
          - On       cauliflower curds brown discoloration occurs. 
 
          - In       case of A.brassicae the spots are smaller in dia and lighter in       colour.
 
         
        Favourable condition 
      
        
          - Hot       moist weather, temperature 26°
            C. Dew or rain for 9 hrs is essential for       infection.
 
         
        Management 
      
        
          - Hot       water treatment of seeds at 500C for 30 minutes.
 
          - Crop       rotation, avoiding overhead irrigation.
 
         
        Wire Stem 
      
        
          - Wire       stem gets its name from symptoms that occur on the stem at the soil level.       A dark, watersoaked lesion initially appears on the stem. 
 
          - Later       stems become wiry and slender at the point of the lesion. 
 
          - Diseased       crucifer plants transplanted to the field grow poorly, are stunted, and       may eventually die, especially if there is inadequate moisture shortly       after transplanting. 
 
          - If       infected plants remain alive, the stem becomes tough and woody.       Plants that survive usually mature late and fail to produce a marketable       head. 
 
         
        Bottom Rot 
      
        
          - Bottom       rot is a disease of mature cabbage.
 
          -  After cabbage transplants become large       enough to begin to shade the ground, the disease appears on the lower side       of the head leaves that are in contact with the soil. 
 
          - The       midrib is often the first part of the leaf attacked.
 
          -  Resulting lesions are sunken, black, and       sharply elliptical with the long side of the lesion parallel to the side       of the midrib.
 
          -  Lesions may dry out and become papery       brown in appearance if the weather becomes dry. 
 
          - The       surface of the lesion may be covered with a sparse, weblike mycelium. 
 
          - Eventually       a general black decay occurs at the base of the leaf.
 
          -  The tip of the leaf then turns yellow and       then the entire leaf wilts.
 
          -  Infected leaves are shed and only a naked       stalk, capped with a small head, remains.
 
          -  Bottom rot becomes a head rot if       temperatures are warm and the relative humidity is high.
 
          -  A weblike mycelium develops between       diseased leaves.
 
          -  Infected leaves are eventually covered       with small, brown, fungal structures called sclerotia, which can persist       on plant debris in the soil for long periods of time. 
 
          - The       stem remains unaffected, thus, the head remains upright. 
 
         
        Cultural Control 
      
        
          - Choose       a fertile, well-drained site for the plant bed. Poor drainage favors       seedling disease. 
 
          - Avoid       excessive amounts of nitrogen fertilizer. Succulent plants are more       susceptible to infection. 
 
          - Seed       crucifers when the soil temperature reaches 69°F (21°C) and seed as       shallowly as possible so that germination and emergence are rapid. 
 
          - Discard       transplant seedlings that show symptoms of wire stem. 
 
          - Avoid       banking or throwing soil up around plants during field cultivation. 
 
          - Harvest       cabbage heads early. Cabbage leaves become more susceptible the longer       they stand in the field. 
 
         
        Survival 
      
        
          -  Sources of the fungus include       infested seeds, cruciferous weeds, and residues of cruciferous crops       remaining in or on the soil
 
          - Survival       in crop residues in soil for 3 years.
 
         
        Management 
      
        
          - Use of       disease free seed
 
          - Rotation       with non  cruciferous crops for  4 years where the disease is severe
 
          - Providing       adequate drainage facility.
 
          - Soil       fumigation with chloropicrin etc.
 
         
        Cabbage yellows / Fusarium wilt of cabbage (F.  Oxysporum  conglutians) 
      
        
          - The       plant  become yellow in colour.
 
          -  The wilting of leaves may be more       prominent on one side of plant that the other.
 
          -  Leaves dries up. When the infected stem       is cut open brown discoloration will be seen.
 
           
        Management 
      
        
          - Use of       disease free seed.Crop rotation, field sanitation .
 
          - Use of       resistant varieties.
 
         
        Ring spot of cabbage (Mycosphaerella brassicicola) 
      
        
          - Outer       leaves are severely affected.
 
          -  Brown to tan spots of 1-2 cm dia. appear       on leaves.
 
          - Central       portions are grey in colour with numerous fruiting bodies appear in  concenric rings.
 
          -  The spots are surrounded by a green band       which remains great even after the whole leaves turn yellow.
 
          -  Diseased        leaves fall off. When the spot affects head, marked value is       reduced.
 
         
        Management 
      
        
          - Collection       and destruction of plant debris
 
          - Hot       water treatment of seeds 45°
            C for 20 min
 
         
        Stalk rot (Sclerotinia sclerotiarum) 
      
        
          - In       cabbage water soaked  spots appear       on stem and leaves near the ground level. 
 
          - The       leaves wilt and plant collapses with in 10-15 days. When head is infected       cottony white fungal growth is seen with numerous hard black sclerotia.
 
          - In       cauliflower yellowing starts from tip of the leaves to down wards till the       entire leaves are covered.
 
          -  The leaves shed prematurely. 
 
          - The       rotting progress to stem and the stem girdles and the stem rots upto the       curd region. 
 
          - Curd       are also affected. White fluffy mycelial        growth with numerous sclerotia in the affected portions can be       seen..
 
         
        Management 
      
      
       
      Disease of Onion 
      Basal Rot (Fusarium  oxysporum f. cepae) 
         
        This disease is worldwide and again caused by a specialized form of Fusarium.  
      
        
          - This disease can begin in the field and continue on       in storage. 
 
         
        Pink Root (Pyrenochaeta terrestris, Fusarium spp.) 
        
        Management 
        Infection is usually spread by onion sets. No other control procedures are  known.
        
         Rot (Penicillium spp.)
        
        Management  
      
        
          - Several fungal and bacterial diseases are capable of       causing storage rots in onions, particularly if the crop is inadequately       or poorly cured following harvest. 
 
          - Adequate ventilation must also be supplied during       storage.
            
          
 
         
         
        Disease of Garlic 
      Macrophomina rot (Macrophomina  phasoolina) 
      Garlic types 1069-9,1069-5,1069-6,1075-6,were resistant and  1029,1037,1040, 1073 -3, 073-5, 1073-7, 1073-9, 1073-10, 1073-14 and 1073-17  were moderately resistant. 
      Pink root (Pyrenochaeta tattestris)  
      Pink root of garlics is caused by the fungus. (Hansen)  Gorenz, walker and Larson Pehoma terrestris (Hanson) it has been  reported from all the garlic growing areas. 
      Symptoms 
      
        - The fungus attacks onion from the seedling  stage onwards.
 
        - The roots are affected and they turn pink  or reddish and sometimes darken to a red or purple colour black spores form on  the diseased roots which eventually shrivel and die. 
 
        - Diseased plants can be easily pulled. The  above ground symptoms are shunting and yellowing tip burn and die back of the  leaves.
 
        - Affected seedlings may be killed. Older  plants are not normally killed but bulb formation is affected and yields are  low. 
 
        - Bulbs are not attacked although the outer  scales may be penetrated. 
 
        - New roots are formed throughout the season  and these may be infected and killed successively.
 
       
      Spread of the disease 
      The  pathogen is soil borne and infection is mostly from mycelia in the soil.  Optimum soil temperatures for disease development are 24-28° C. 
  Management 
      Long  rotations should be practiced to prevent build up of inoculum in the soil. 
      
      
       
      Diseases of Cassava 
      
        Indian Cassava  Mosaic Virus Disease (ICMV)   
          Symptoms 
        
          - Mosaic       symptom, reduction in leaf size, misshapened twisted leaves.
 
          -  The affected plants stunted, tuber       splitting and yield reduction.
 
         
        Management 
        
          - Selection       of setts from healthy plants
 
          - Use of       resistant varieties like MnGa-1
 
         
        Sett rot / stem rot – Diplodia natalensis (Botryodiplodia  theobromae) 
        
          - It is       found in stored setts and new planting in dry areas. 
 
          - Vascular       strands show black discoloration and necrosis radiating from wounds. 
 
          - Epidermel       blisters are produced under which the infected dark brown or black tissues       can be seen. 
 
          - Masses       of black pycnidia can be seen when the blister rupture.
 
         
        Management 
        
          - Selection of healthy setts    
 
         
       
      
      
      
        Black Rot (Ceratocystis fimbriata)  
        Symptoms            
       
      
        - Small, circular, slightly sunken, dark brown  spots are the initial symptoms of black rot.
 
        - Spots enlarge and appear greenish black to black  when wet and grayish black when dry. Within the spots are small, black fungal  structures (perithecia) with long necks which appear to the naked eye as dark  bristles. The rot usually remains firm and shallow. 
 
        - If secondary fungi or bacteria invade the tissue  however, the flesh beneath the spot turns black, and this blackened area may extend  to the center of the root.
 
        - Tissue near the discolored area may have a  bitter taste. Eventually, the entire root may rot. Roots may appear healthy at  harvest but rot in storage, during transit, or in the market. 
 
       
      Management  
      
        - 
          
Control black rot with  crop rotation, since most crops are unaffected by the disease.  
         
        - 
          
            Disinfect seedbeds if a  clean site is unavailable.  
         
        - 
          
            Propagate plants from  healthy stem cuttings.  
         
        - 
          
            Cure roots immediately  after harvest. (Cure roots at 85 to 95 ° F and 85 to 90 percent relative  humidity for 5 to 10 days). 
         
        - 
          
            Do not wash and package  roots showing symptoms of black rot.  
         
        - 
          
            Decontaminate equipment  that comes into contact with an infected crop. 
         
       
      Rhizopus Soft Rot (Rhizopus  stolonifer)  
        Symptom       
      
        - Infection and decay commonly occur at one or  both ends of the root, although infection occasionally begins elsewhere. 
 
        - Rotting may be inhibited under dry conditions,  but under humid conditions the affected sweet potatoes become soft and watery,  and the entire root rots within a few days. 
 
        - If the humidity is high, the sweet potatoes  become heavily "whiskered" with a grayish black fungal growth. This  feature distinguishes Rhizopus soft rot from other storage rots.
 
        - The color of the root is not significantly  altered, but an odor is produced that attracts fruit flies to the area.
 
        - Infection is especially likely if the relative  humidity is between 75 and 85 percent during storage or transport. Also, the  longer roots are stored, the more susceptible they become. 
 
        - Chilling and heat damage also predispose sweet  potatoes to infection. Soft rot is very destructive when sweet potatoes are  washed, packed, or shipped to market during cold weather.
 
       
      Management       
      
        - Carefully handle sweet       potatoes during harvest to prevent unnecessary wounding. This is the most       important control method for soft rot. 
 
        - Properly cure roots       immediately after harvest. 
 
        - Store roots at 55 to 60       degrees F. 
 
        - Avoid handling stored roots       because handling can create new wounds. Recuring is one possible solution       to this problem. 
 
        - Apply a recommended fungicide       after harvest. 
 
        - Do not allow sweet potatoes       to be exposed to sunlight for extended periods (to prevent heat damage) or       to be chilled in the field. 
 
       
      Bacterial Soft Rot (Erwinia chrysanthemi)       
      Symptoms 
      
        - Roots are affected in the field, or more  commonly in storage, by a soft rot that turns diseased tissue light brown and  watery . 
 
        - Lesions on storage roots often have a dark brown  margin. Some storage roots appear healthy from the outside but are decayed  internally. 
 
        - Infected roots show black streaks in the  vascular tissue and eventually undergo a soft, moist decay.
 
        - Mother roots often decay in plant beds. In the  field, brown to black, water-soaked lesions appear on stems and petioles.  Eventually, the stem may become watery and collapse, causing the ends of vines  to wilt. 
 
        - Usually, one or two vines may collapse, but  occasionally the entire plant dies.
 
       
      Management       
      
        - Carefully handle sweet       potatoes during all stages of production. This is the most important       control method for bacterial soft rot. 
 
        - Select mother roots from       fields free of the disease. 
 
        - Cull roots infected during       storage. 
 
        - Use vines cut above the soil       surface for transplanting. 
 
        - Use a handling system that       does not involve immersion of sweet potatoes in water. 
 
       
      Charcoal Rot (Macrophomina phaseoli) 
      Symptoms       
      
        - In the field, brown to black, water-soaked  lesions appear on stems and petioles. Eventually, the stem may become watery  and collapse, causing the ends of vines to wilt. 
 
        - Usually, one or two vines may collapse, but  occasionally the entire plant dies.
 
        - Charcoal rot, caused by the fungus, can  cause losses of sweet potatoes in storage, but serious losses seldom occur. The  disease is sometimes confused with black rot and Java black rot.
 
        - Symptoms in storage begin as a reddish brown to  brown, firm, moist rot, initially restricted to the area just beneath the sweet  potato skin. 
 
        - As the decay progresses, the pathogen moves  toward the center of the sweet potato, causing further rot. Two distinct zones  become apparent within the infected tissue. 
 
        - The leading edge continues as a reddish brown  decay, and a zone of black develops behind the zone of active decay. 
 
        - Although the lesions are sometimes restricted,  charcoal rot usually consumes the entire root, which eventually dries, becoming  hard and mummified.
 
       
      Management 
      
        - Properly cure sweet potatoes       immediately after harvest to reduce the incidence of charcoal rot. 
 
       
      
       
      Spice Crops     
      
      
      
     
         
        Diseases of Pepper 
        
          - Phytophthora foot rot / quick wilt  (Phytopthora capsici)
 
         
        Symptoms 
              Four  types of symptoms can be seen 
        
          - Leaf infection
 
         
        Water soaked  lesions with fimbriate margin develop from margins of leaves or in the centre  of the leaf. The defoliation occurs in severe infection. 
        
          - Die back
 
         
        The aerial  branches get infected at any point. At the site of infection of branch, the  discoloration occurs and rotting progress upwards and downwards resulting in  die-back symptoms. The lateral branches of the affected vines break off at the  nodes and fall off. 
        
          - Foot rot or Collar rot
 
         
        The stem near  the ground level get infected and the rotting and death of vine occurs with in  2-3 weeks. The affected portion emits bad odour. The necrosis progress down  wards to the underground stem and to the root system. 
        
          - Root rot
 
         
        The infection starts at main root  or at feeder root. The leaves become yellow and defoliate. 
         
        Management 
        
          - Selection       of healthy nursery material.
 
    - Provide       good drainage.
 
    - The       tender runner shoots and leaves in the ground should be pruned off to       avoid direct contract to the soil.
 
    - Application       of neem cake and Trichoderma viride       or P. fluorescens.
 
         
        
         
        Diseases of  Cardamom 
        Damping off / rhizome rot / clamp rot (Pythium  vexans, Fusarium oxyoporum, Rhizoctonia solani) 
          Symptoms 
              Infected  leaves become pale, yellow and ultimately the young leaves die. Older leaves  die prematurely and new shoots that arise are weak, decay and the rhizomes rot  at the base of the stem. The diseased shoot can be pulled out easily. The  disease can be spoiled stem long distance by the presence of fallen shoots. 
        Management 
        
          - Destruction       of diseased clumps.
 
    - Providing       proper drainage
 
    - Changing       the nursery site
 
         
        Azhukal       disease / capsule rot / fruit rot – ( Phytophthora parasitica       car. Nicotincanae, Phytophthora palmivora, P.meadii, Pythium vexans) 
        Symptoms 
                  Symptoms can  appear on tender and matured leaves. Large circular, irregular, water soaked  spots with black colour appear on leaves. The exposed portion of the unopened  leaves may rot. Grey patches of irregular spots with brown margin are formed at  the base of the leaf sheath. The  basal  portion rots and the pseudo stem break away at the collar region. The infection  spreads to the underground plants and the rhizomes become rots. Small light  brown lesions appear in the green tender fruits which fall of in 3-6 days  leaving the small fruit stalk. The tip of inflorescence also rot. 
        Management 
        
          - Removal       and burning of infected particles and rhizomes.
 
    - Avoid       moving of rhizomes sum diseased areas to healthy area for planting
 
    - Provide       proper drainage
 
         
        Symptoms 
                General  chlorosis of young leaves – parallel streaks of pale green tissues running  along the veins from midrib to the margins. Leaf sheath also shows stich  stripes. In advanced stage the whole plant shows mosaic symptom clumps  destoriates rapidly and plants are started. Rhizome shrivels and plants dies.  If young clumps are attached they die before flowering. 
         
        Management 
        
          - Collection       and removal of infected clumps along with rhizomes and burning.
 
    - Raising       of nursery in diseases free areas.
 
         
        4. Chenthal disease / leaf blight (Colletotrichum  gloeosporioides) 
         
        Symptom 
          Elongated, water soaked lesions of varying size appear on  the upper surface of the leaf. The spots becomes brown to dark with pale yellow  halo. Leaves wither and pseudo stem wilts. New shoots which develop are reduced  in size. Flowers fail to develop. The inflorescence dry up stating from tip  downwards. The affected gardens shows burnt appearance. 
         
        Management 
        
          
            - Removal        and destruction of affected leaves
 
     
         
        5. Nilgiris  necrosis (Nilgiris necoros virus)  
         
        Symptoms 
                On  leaves alternate light green to yellow patches or streaks appear parallel to  the veins. A number of discontinuous spots appear on other areas of leaves. The  virus spreads systemically in all the tillers. The leaves become small,  stunted. The mature leaves tear off along the necrotic spots and shown shredded appearance  leaves malformed. 
         
        Management 
        
          - Use healthy rhizomes for planting
 
    - Rogue the infected plants.
 
         
        
         
        Diseases of Ginger 
        Soft  rot or rhizome rot 
        Soft rot is the most destructive disease of  ginger which results in total loss of affected clumps. The disease is  soil-borne and is caused by Pythium aphanidermatum. P. vexans and P. myriotylum are also reported to be associated with the disease. The fungus multiplies with  build up of soil moisture with the onset of south west monsoon.Younger sprouts  are the most susceptible to the pathogen.  
         
        Symptoms 
        
          
            - The  infection starts at the collar region of the pseudostems and progresses upwards  as well as downwards. The collar region of the affected pseudostem becomes  water soaked and the rotting spreads to the rhizome resulting in soft rot. 
 
      - At a  later stage root infection is also noticed. 
 
      - Foliar  symptoms appear as light yellowing of the tips of lower leaves which gradually  spreads to the leaf blades. 
 
      - In  early stages of the disease, the middle portion of the leaves remain green  while the margins become yellow. The yellowing spreads to all leaves of the  plant from the lower region upwards and is followed by drooping, withering and  drying of pseudostems. 
 
     
  Management 
        
          
            - Cultural  practices such as selection of well drained soils for planting is important for  managing the disease, since stagnation of water predisposes the plant to  infection. 
 
      - Seed  rhizomes are to be selected from disease free gardens, since the disease is  also seed borne. 
 
      - Application  of Trichoderma harzionum along with neem cake @ 1kg/bed helps in  preventing the disease. 
 
     
         
        
         
        Plantation Crops 
        Diseases of Areca nut 
        Foot rot or       Anabe roga (Ganoderma lucidum) 
        Symptoms 
              The leaf lets in the outer wholes of  leaves become yellow and spreads to the whole leaf and the leaves drooping down  covering the stem. Later, the inner whole leaves  also become yellow. Subsequently all the  leaves droop, dry up and fall off, leaving the stem alone. Then the stem also  become brittle and easily broken by heavy wind. The base of the stem shows brown  discoloration and oozing of dark fluid. Bracket shaped fustification of the  fungus called ‘anabe’ appears at the base of the trunk. Roots become  discoloured, brittle and dried. When infected trunk is cut brown discoloration  can be seen up to one metre from ground level. 
        Management 
        
          - Clean cultivation.
 
    - Destruction of infected trees.
 
    - Maintaining optimal plant population without over       crowding.
 
    - Providing good drainage facility and fertilizers and       manures.
 
         
        Yellow leaf       disease (Phytoplama) 
        Symptom 
              Yellowing of tips of leaflets in 2 or 3  leaves of outermost whorl. Brown necrotic streaks run parallel to veins in  unfolded leaves. The yellowing extends to the middle of the lamina.Tips of the  chlorotic leaves dry up. In advanced stage all the leaves become yellow.  Finally the crown leaves fall off leaving of a bare trunk. Root tips turn black  and gradually rot. 
        Management 
        
          - Growing resistant varieties like true mangala and south  kanara.
 
    - Application of potassium and magnesium more than the  recommended level.
 
         
        Mahali / kolerogo/  fruit rot (Phyhophthora arecae) 
        Symptoms 
                 Rotting and excessive shedding of  immature nuts from the trees. The water soaked spots initially develop at the  base of the nut. Fruit stalks and rachis of inflorescence are also affected.  Nuts show large vacuoles and dark brown radial strands. Very often the top of  the affected trees dries up resulting in withering of leaves and bunches.  Affected nuts fall off and show the white mycelial growth of the fungus. 
         
        Management 
        
          
            - Clean  cultivation
 
      - Destruction  of affected trees.
 
      - Collection  and burning of fallen nuts.
 
     
         
        4. Bud rot (Phytophthora arecae) 
         The first symptom is the change  of spindle leaf colour from green to yellow and then brown. The leaves rot and  the growing bud rots causing death of the palm. The affected young leaf whorl  can be easily pulled off. The outer leaves also become yellow and droop  off  one by one leaving a bare stem. 
        Management 
                      Destruction and removal of dead palms and  bunches affected by makali disease.   
        
         
        Flower Crops 
        Disease of Rose 
         
        Black spot (Diplocarbon  rosae)  
        Symptoms 
        
          - Black lesions with feathery margins surrounded  by yellow tissue are found on the leaves. Infected leaves drop prematurely. 
 
    - Purple/red bumpy areas on first year canes may  be evident. 
 
    - Plants may be weakened due to defoliation and  reduced flower production may be observed.
 
         
          
        Management 
        
          - 
            
Use of Resistant Varieties. 
     
    - 
      
Cultural-Roses should be planted where the sun  can quickly dry the night's dew.  
     
    - 
      
Space roses far enough apart for good air  circulation Avoid overhead watering and keep foliage as dry as possible. 
     
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Sanitation-Remove infected canes and burn  diseased leaves. 
     
         
        2. Powdery mildew (Sphaerotheca pannosa) 
         
        Symptoms 
        
          - 
            
The symptom appears as grayish-white powdery  substance on the surfaces of young leaves, shoots and buds. 
     
    - 
      
Infected leaves may be distorted, and some leaf  drop may occur.  
     
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Flower buds may fail to open, and those that do  may produce poor-quality flowers. 
     
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It can occur almost anytime during the growing  season when temperatures are mild (70 to 80 °F), and the relative humidity is  high at night and low during the day.  
     
    - 
      
It is most severe in shady areas and during  cooler periods 
     
         
          
        Management 
        
          
            - Collection and burning of fallen leaves.
 
     
    3. Die back (Diplodia  rosarum)
          
        Symptoms 
        
          
            - Drying of twigs from tip down wards.
 
      - Blackening of the twigs. 
 
      - The disease spreads to root and causes complete  killing of the plants.
 
     
  Management 
        
          - Pruning       should be done so that lesions on the young shoots will be eliminated.       Apply chaubatia pastic in the pruned area.
 
         
        4. Rust (Phragmidum mucronatum) 
         
        Symptoms 
        
          - 
            
Damage to lemon yellow pustules appear on lower  surface of the leaves and stems. Then the colour changes to blackish red.  
     
    - 
      
The affected leaves turn yellow deformed and  fall prematurely.  
     
    - 
      
Die back symptom also appear due to weakening of  the plant.  
     
         
        Management 
        
          
            - Collection       and burning of fallen leaves.
 
     
         
        
        
         
        Disease of Jasmine 
        Phyllody 
        Symptoms 
              Leaves become small malformed and bushy.  In the place of flowers green leaf like malformed flowers are formed. 
         
        Management 
        
          - Selection of cuttings from healthy plants.
 
         
        
        
        
         
        Disease of Chrysanthemum 
        Rust (Puccinia crysanthemi) 
           
Rust  is a serious disease especially in the early spring.  
        
          - The disease symptoms are in the form of brown blister-like  swellings, which appear on the undersides of leaves. 
 
    - These burst open releasing masses of brown, powdery spores.  Severely infected plants become very weak and fail to bloom properly.
 
         
           
        Management 
        
          - Early removal of infected leaves/plants helps to prevent the  further spread of the disease. 
 
         
        Septoria Leaf Spot (Sepotria chrysanthemella) 
           
        Leaf spots occur during cool-wet periods of the rainy season.  
        
          - Since the pathogens are spread through rain splashes the  lowermost leaves get infected  first. 
 
    - Serious infection may result in premature withering of the  leaves; the dead leaves hang to the stem for some time. 
 
    - When flowering starts the infection occurs on flower buds,  which rot completely.
 
         
          
        Management 
        
          - Destruction of disease debris and avoiding excessive  irrigation is recommended.
 
         
        Powdery Mildew (Oidium chrysanthemi) 
           
        Infection is  more severe in older plants under humid conditions.  
        
          
            - The growth of the fungus on the leaves appears as powdery  coating. Infected leaves turn yellow and dry out.
 
      - Infected plants remains stunted and fail to flower.
 
     
         
          
        Management 
        
        
        
        
         
        Diseases of Carnation 
        1. Fusarium wilt (Fusarium  oxysporum f.sp. dianthi) 
         
        Symptoms 
          In young plants, the first sign of  the disease is fading or graying of the normal colour of the leaves with  wilting of the leaves and young stems.  It is followed by eventual collapse of the whole plant. When older plants are infected, similar  symptoms are produced but the older leaves may show chlorosis followed by an  indistinct purple-red discoloration. The  vascular tissues of infected stems is stained dark brown. Mature plants show wilt symptoms over a  period of several months before they die and eventually become straw coloured. 
          Fungus : 
           
          Management  
          The diseased plants should be  removed immediately after noticing the disease.  Complete root system and surrounding soil should be dug out and disposed  off carefully. Soil solarization using  clear transparent polyethylene film (0.1 mm thick) for 30 days gives  satisfactory control. Grafting of  susceptible cultivars like A 
          lice, Fulvio Rosa, Gus Royalette and Johy, on to resistant rootstocks i.e.  Arancio 25D, Exquisite, Heidi and May Britt and growing in soil naturally  infested with fungus was also found to reduce the incidence of disease. 
         
        2. Alternaria leaf spot (Alternaria  dianthi) 
        Symptoms 
        The chief symptom is blight or rot  at leaf bases and around nodes, which are girdled. Spots on leaves are ashy white.  The centre of old spots are covered with dark  brown to black fungal growth. Leaves may  be constricted and twisted and the tip may be killed. Branches die-back at the girdled area and  black crusts of conidia are formed on the cankers. 
           
          Management  
          To reduce the disease incidence,  humidity may be kept low by providing proper air circulation. Disease-free planting material should be  used.   
         
        3. Bacterial  wilt (Burkholderia caryophylli) 
         
        Symptoms 
                  The upper parts of established  plants turn pale and wilt.The stem  develops elongated discolored stripes and split open which is characteristic of  the disease.The roots are rotted  partially and the cortical tissues become sticky and shows discoloration, a  tendency to straighten out instead of remaining curled. The leaves are twisted.  The roots are generally lacking on one side  and remain discolored. The base of the  cutting is discolored, with an elongated brown area extending upwards.The bacteria invade xylem vessels and spread  to infect the young shoots. The vessels  are disrupted and the host plant produces meristematic tissues. This new tissue causes an uneven development  of cortex which splits open longitudinally. Carnation wilt, a vascular disease may be induced by mechanical  plugging, a toxin or a combination of factors.  Carnation cuttings wilted when placed in a filtrate of a bacterial  suspension of B. caryophylli. In  the naturally infected carnation plants the xylem vessels are found partly  plugged. Lysis of xylem vessels,  is also observed. Infection is carried  to upper portions of the branch into the leaves.  Bacteria are not found in parenchyma  tissues. Carnation cuttings suspended in  bacterial filtrates in which proteins and other large molecular compounds are  removed did not wilting symptoms. 
           
        Management  
                  Use of cuttings taken from upper  parts of the healthy stock plants are less liable for infection and hence  advocated as a control measure. Diseased  plant debris should be collected and burnt. Overhead watering and splash watering should be avoided. Disease-free planting materials are to be  used. Role cultivars viz., Elegance,  Northland and Starlite are less susceptible to bacterial wilt. 
        
        
        
         
        Diseases of Gerbera (Gerbera asplenifolia, G.  aurantiaca, G. jamesonii (Barbeton daisy), G. Kunzeane and G.viridfolla) 
        1. Root rot (Rhizoctonia solani Kuhn and Pythium irregualsre)   
        The infection result in stunted  growth. Ultimately the entire plant dry. Rhizoctonia solani causes more losses and can attack older plants.  Soil sterilization controls the diseases. 
         
        2. Foot rot  and root rot (Phytophthora cryptogeas) 
        The short stems blacken and rot.  The leaves and flower die. Soil  sterilization with vampam at 100 ml/square meter is very effective. Warming of soil (26° C) reduces the incidence  of the disease.   
         
        3. Blight /  Grey mould (Botrytis cinera Pers) 
         The fungus kills young growing tissues. The flower heads of the Gerbera growing  in humid conditions show small, black spots on the ray florets. Deep planting, poor drainage and poor  ventilation predispose the plants to infection.  The disease can be reduced when the infected parts are removed and  destroyed.   
         
        4. Powdery  mildew (Erysiphe chichoracearum DC and Oidium erysiphoides f.sp. gerbera) 
        The fungus forms white  powdery coating on the foliage. Spraying  with wettabel sulphur controls E. Chichoracearum. Diseased leaves should  be removed and destroyed. 
         
        5.  Anthracnose (Colletotrichum  gloeosporiodes Penz)   
        On Gerbera  jamesonii  Bolus ex. Hook.f.  It has been reported from Karnataka and Maharashtra. The  disease appears as circular, scattered, reddish brown spots. They coalesce with one another during moist  weather involving large area and resulting in withering, rolling and drying of  leaves. Excessive watering and crowding  of plants should be avoided. Diseased  leaves should be collected and burnt.   
         
        8. Blossom  blight asnd stalk rot (Phytophythora palmivoras Butler)  
         It was reported from Maharashtra  during 1971 and Karnataka. The disease  appears as light brown, irregular, water soaked spots on flower stalks and  petals.  The spots increase rapidly and  coalesce with one another and form distinct depressed lesions. Under humid conditions the infections become  severe involving the entire flower head and resulting in blossom blight and  stalk rot. The disease is favoured by  drizzling rains and cool moist weather.   The fungus is soil-borne and the infection starts from the base touching  the soil.  Use of disease free soil for  cultivation reduces the disease incidence. Affected flowers should be collected and destroyed. Excessive watering should be avoided 
         
        9. Tobacco  rattle  (Tobacco rattle  virus) 
        Yellow or black annulated  ring spots asre observed on the foliage.   Soil steaming before each crop destroys the nematode vector, Trichodorus spp. and prevents the disease. 
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