Powdery mildew
Powdery mildew
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C.O :Erysiphae cichoracearum DC.
Sphaerotheca fuliginea (Schlecht) Poll.

Symptoms:

• Small white or grayish superficial spots on upper surface of leaves.
• Spots enlarge and form large patches.
• Entire leaves are covered with fungal growth.
• Infected leaves dry off and fall down.
• The fruits of affected plants remain small and deformed.

Favorable condition :

• Moderate temperature
• Sultry weather (hot and humid)
• Reduced light intensity and succulent plant growth
• Conidial germination 21o to 31o C, optimum 28o C with low R.H. (20 %).

Management :

• Do not use sulphur dust as cucurbits are very sensitive to it.
• Spray dinocap @ 0.05 o r 0.2 %, wettable sulphur or 0.05%, carbendazim or 0.1% or thiophanate methyl or Tridemorph or benomyl @ 0.1 %,
• Alternate weed host may be destroyed
• Resistant variety:
• Muskmelon – Res.var- Diguria, Hargola.
• Cucumber – Burpless 30 and 33, Burpless Green king, Burpless F1 Tasty Green, Table Green 65, Victory.


Downy mildew
Downy mildew:
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C.O:Pseudoperonospora cubensis

Symptoms:

• On upper leaf surface pale green coloured patches observed and exactly corresponding on lower surface faint purplish fungal growth is observed. Occasionally the colour ranges from white to almost black.
• The entire leaf dries quickly.
• Usually leaves near the center of plant are affected first. Then the symptoms appear progressively on younger leaves.
• Infected fruits have poor flavor and they (muskmelon) are covered with a fungal growth.

Favourable condition:

• For fungus infection 100 – 270C with optimum 160 to 220C
• They survive for several days when temperature is over 370C. Maximum disease development occurs at 250C day time and 150C night time

Management:

• Good drainage system
• Wider spacing for good sunlight
• Difolatan 0.2% or mancozeb 0.2% or chlorothalonil 0.2% or maneb spray
• Spray ridomil MZ – 72 0.1% at 30 days interval (muskmelon) or daconil 2 kg/ha
• Seed treatment with apron 35 SD 2g / kg


Mosaic
Mosaic
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C.O : Cucumis virus - 1 – Common mosaic
Cucumis virus - 2 – Green mottle mosaic
Cucumis virus- 3 – More dangerous and cause severe
mosaic

Symptoms :

• Soon after emergence, the cotyledons become yellow and seedlings show wilting
• On young leaves alternate green and yellow patches observed
• Spots are of irregular shape and rapidly enlarge, covering entire leaf
• Leaf mottling and stunting of plant
• Fruits are mottled, tough and deformed.

Transmission :

• Mechanically and vector transmitted, aphid - Myzus persicae and Aphis gosypii helps in virus transmission.

Management :

• Remove weed hosts
• Spray monocrotophos @ 0.05% or methyl-o-demeton @ 0.03 % at 15 days interval for vector control