Diseases of Potato and Tomato

2.Progressive defoliation and collapse of plants under favourable conditions.

3.Water soaked stripes on stem which becomes necrotic

4.Purplish brown spots appear on skin of tubers. On cutting, the affected tubers show rusty brown  

5.Dark brown spots appear on skin of tomato fruits.

6.Decay of plant parts under favorable weather which emits foul smell

2. Fully developed spots are irregular, brown to dark brown in color, and with concentric rings inside the spot.

3.Spots coalesce to form large patches resulting in the leaf blight.

4.In severe attacks the entire plant may be defoliated.

5. Lesions/ spots may also develop on stems and petioles, which break at the point of infection.

2.Foliage becomes chlorotic and the leaflets tend to roll upward at the margins.

3.Stems of infected plants exhibit an inky black decay.

4.The base of the stem is often completely rotted.

5.Plants may wilt

6.Soft rot include rotted tissues that are wet and cream in color.

7.Rot begins on the tuber surface and progresses inward.

8.Infected tissues are sharply delineated from healthy tissue by dark brown or black margins.

9.In the early stages of decay, rotting tissue is usually smell-less, but develops a foul

10.smell as secondary organisms invade infected tissue.

 or seeds or oospores

Secondary infection by zoospores dispersed

by wind or water

Secondary infection: Conidia dispersed by wind, water or rain splashes.

Spread through contaminated soil and tubers

2.RH: >90% and with suitable temperature (12-24⁰C)

3.Night temperature below the dew point for 4 hours or more

4.Night temperature not below 10°C

5. Cloudiness on the next day.

6.Rainfall at least 0.1mm on the following day

2.In the presence of free moisture and at an optimum of 28- 30°C (82-86°F), conidia will germinate in approximately 40 min.

 Cultural practices:

ü  Sanitation (elimination or exclusion of infected plant parts from a farm) is important in the overall management strategy.

ü  Regulatory measures

ü  Select healthy tubers/seeds for planting

ü  Delayed harvesting

Resistant cultivars: using resistant cultivars if available.

Prophylactic measures/Chemical control:

•          Metalaxyl (0.1%) or Mancozeb (0.25%) can be applied at 10 to 15 days intervals in potato field.

•          Dip sprouted tubers/seeds in 0.2% metalaxyl for 30 min.

Cultural practices:

v   Sanitation (elimination or exclusion of infected plant parts from a

    farm) is important in the overall management strategy.

v   Select healthy tubers/seeds for planting

v   Delayed harvesting i.e., after maturing tubers/fruits.

Resistant cultivars: using resistant cultivars if available.

Prophylactic measures/Chemical control:

q   Mancozeb or Zineb@ 0.25% spray at weekly intervals.

q   Dip sprouted tubers/seeds in 0.2% metalaxyl for 30 min

Ø   Remove and destroy infected plant debris.

Ø   Sow the crop early

Ø  Treat the seeds with Thiram or Carbendazim at 2 g/kg.

Resistant cultivars: using resistant cultivars if available.

Prophylactic measures/Chemical control:

Dip cut seed pieces of potato in a solution of Streptocycline 100ppm and CuSo4 40ppm for 30 min.