Temperate Vegetables (1+1)

DISEASES

DISEASES
Damping-off of seedling
Pathogen: Phytophthora spp., Pythium spp., Fusarium spp. and Rhizoctonia solani

• Seedlings are killed both at pre and post-emergence stages.
• Infected seedlings topple down to the ground.

Control measures:

• Treat the nursery beds with formalin (1part formalin: 7parts water) and cover the treated beds with polythene sheets for 15-20 days before sowing.
• The seeds should be sown only when the soil becomes completely free from formalin vapours.
• Drench the nursery beds with a mixture of mancozeb (0.25%) and carbendazim 50WP (0.05%) at the initiation of post emergence damping–off symptoms.
• Always sow hot water-streptocycline treated seeds in nursery beds.

Black leg (Phoma lingam)

• It occurs in areas with rainfall during the growing period.
• Seed borne and hence occurs from the early stage.
• Stem of affected plant when split vertically shows severe black discolouration of sap stream.
• Whole root system decays from bottom upwards.
• Often, the affected plants fall over in the field

Control measures:

• Hot water treatment is effective. Also spray the seed crop with copper oxychloride or with an organomercuric compound
  
• Pusa Drum Head variety of cabbage is tolerant under field condition.

Curd rot/Black spot
Pathogen: Fusarium spp., Sclerotinia sclerotiorum, Alternaria brassicae, A. brassicicola, Botrytis cinerea, Erwinia carotovora and Bacillus polymixa

• Curds start rotting from any portion.
• The rotting usually starts after some injury.

Control measures:

• Protective spray with a mixture of mancozeb (0.25%) and Streoptocycline (0.01%) is given to the curds particularly if there is a likelihood of frost.
• Repeat same after 8-10days interval.
• Small rotten areas on the curds may be cut with a knife and painted with Bordeaux mixture (Copper sulphate 800g + lime 800g + water 200L) or copper oxychloride (0.3%).

Stalk rot/Watery soft rot
Pathogen: Sclerotinia sclerotiorum

• Leaves lose their shine and droop down.
• Stalks rot from inside, become hollow and filled with black sclerotia.
• Curds lose compactness followed by development of characteristic soaked white rot.
• Water soaked lesions also appear on bolting shoots later exhibiting white silvery appearance followed by complete wilting.
• There is no pod formation in diseased plants.

Control measures:

• Follow cauliflower- paddy rotation.
• Pick out diseased leaves and destroy them.
• Spray the crop at 10-15day interval with carbendazim 50WP (0.05%) and mancozeb (0.25%) starting from earthing up stage at 10-15 days interval till bolting stage.

Downy mildew
Pathogen: Peronospora parasitica

• White mildew growth underside leaves followed by yellowing on corresponding upper side.

Control measures:

• Spray the crop with mancozeb (0.25%) at the appearance of the disease and repeat after 10-15days interval.
• Give a spray of metalaxyl + mancozeb (0.25%) in the nursery at the appearance of the disease.

Black rot
Pathogen: Xanthomonas compestris pv. compestris

• At the point of infection on the leaves, tissues turn yellow and chlorosis progresses towards centre forming “V’ shaped lesions with the base towards the mid-rib.
• The veins and veinlets of the chlorotic tissues become dark.
• The infection on head results in brown to black discoloration of the surface which at later stages leads to rotting.

Control measures:

• Soak seeds in tap water for 30 minutes followed by hot water dip at 52^oC for 30 minutes and finally in streptocycline solution (0.01%) for the same duration.
• The seed treatment may be got done by the growers from the University /nearest Research Station laboratories.
• Give fortnightly spray of streptocycline (0.01%) after curd formation.

Bacterial soft rot (Erwinia carotovora):

• A weak parasite which penetrates the plants through damaged tissue e.g. lesions caused by other pathogen.
• In the field, it occurs only following black rot or after mechanical injury of nearly mature cabbage head.
• Infection favours by high humidity.
• The affected plants show a soft, slimy, bad smelling rot that under favourable conditions rapidly spreads throughout the plant.

Control measures:

• Controlling other diseases and preventing damage can keep down the disease.
• Spraying 100-200 ppm streptocycline or plantomycin combined with copper oxychloride (0.3%) at 15 days interval.

Integrated spray schedule for disease control in cole crops
a. Before sowing

• Treat the nursery beds with formalin (1 part formalin: 7 part water) 20days before sowing and rake it well.
• Soak seeds in tap water for 30 minutes followed by hot water dip at 52^oC for 30 minutes.
• Give a subsequent dip in Streptocycline solution (0.01%) for 30 minutes.
• Get the seed treatment done in University/ Research Station laboratories.

b. Post-emergence stage

• Drench the nursery beds with a mixture of mancozeb (0.25%) and carbendazim 50 WP (0.05%) after disease appearance against post –emergence damping-off and root rots

c. After transplanting

• A week after earthing up, spray the crop with carbendazim 50WP (0.05%) and repeat at 15 days interval.

d. After curd formation stage

• Protective spray with a mixture of mancozeb (0.25%) and streptocycline (0.01%) be given twice at 8-10day interval.
• Spray boric acid @ 0.1% as protective spray and repeat after 8-10 days.
• Pick out diseased leaves and destroy them.
• Small rotten areas on the curd may be cut with a knife and painted with Bordeaux mixture (Copper sulphate 800g+Llime 800g +100L water) or copper oxychloride (0.3%).

e. Curd formation to pod setting stage

• Spray the crop at 10-15days interval with a mixture of carbendazim 50WP (0.05%) and Mancozeb (0.25%) from the curd initiation stage to pod setting stage.
• Repeat after 10-15days interval.