Downy mildew

Downy mildew
Downy mildew:
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C.O.: Plasmopara viticola

Symptoms:

• The pathogen infects all the tender plant parts, showing small light green patches on upper surface of the new leaves and a whitish downy growth on a corresponding lower surface.
• The disease may also spread to the floral parts and the fruits.
• The infected flower dies and drops away prematurely.
• The infected fruit become greyish, the skin hardens and shrivels
• The infected berries and bunches become mummified.
• The juice quality of fruit is reduced

Favourable condition:

• Sporangia germinates at 100-230C and disease development is favoured during rainy season when there is heavy dew, RH 80% and temp. 23-270C

Management:

• Pruning of infected branches.
• Use recommended spacing for planting vines
• After pruning spray BM 1% or difolatan 0.2% or chlorothalonil 0.2% or metalaxyal 0.25% is effective. This may be repeated weekly intervals.

Anthracnose/Bird’s eye spot:
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C.O.: Gloeosporium ampelophagum

Symptoms:

• The fungus affects the stem , young shoots, leaves and berries.
• With small circular spots with grayish black centres and yellow margin are produced on the leaves.
• Characteristic round, brownish , sunken spots resembling bird’s eyes appear on the berries and hence the name bird’s eyes
• The infected berries rots.

Favourable condition:

• Heavy rains after pruning leads to more incidences.
• Warm weather favors the disease development.

Management:

• Diseased leaves and twigs should be pruned and burnt.
• Spray B.M. 1% or copper oxycholoride 0.25%, or carbendazim 0.1%, or mancozeb 0.2% baycor 0.1% found effective
• Grow resistant varieties i.e. Bangalore blue, Gulabi, Golden queen, Golden Muscat, Hussaini and Bharat early are resistant.


Powdery mildew

Powdery mildew
Powdery mildew :
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C.O.: Uncinula necator

Symptoms:

• Small whitish patches appear on both the surfaces of young leaves, stems, flowers and fruits.
• The affected berries become malformed with grayish to dark brown patches on the skin.
• The skin of affected berries cracks and the pulp is exposed
•
Favourable condition:

• Warm weather 200 to 33.50C, dry atmosphere favours the disease development.
• North India- observe in Oct-Nov
• South India- observe in Feb-June

Management:

• Over crowding and dense growth of vines should be avoided by proper pruning
• Spray Wt.sulphur 0.2% or dinocap 0.04 % or Carbendazim 0.05%
• Sulphur dusting at berry development stage as prophylitic treatment (20 – 25 kg/ha)
• Use resistant variety i.e. Red Sultana, Saint George and No-1613 are highly resistant.