PATH 372 Diseases of Horticultural Crops

Disease cycle
P.I: Collateral hosts or through Cleistothecia
S.I: Wind borne conidia
Management
Spray Calixin 0.1% or Karathane @0.2%
3) Cucumber Mosaic: Cucumber mosaic virus
Host range: Cucumber, Pumpkin, gourds, Cowpea, tomato, chilli, etc.
Symptoms
Leaves curl downwards and become mottled, distorted, wrinkled and reduced in
size
Stunting and rosetting of young leaves
Fruits are often misshapen, mottled, warty and reduced in size
Fruits may be bumpy or deformed in late infections
Survival and spread
Survive on weeds, ornamentals or other crops
Transmitted by aphids (Aphis craccivora, Myzus persicae) and spotted and striped
cucumber beetles
Collateral hosts: Banana, clover, corn, passion fruit, safflower, spinach, sugarbeet,
wild cucumber, Commelina communis, C. diffusa, C. nudiflora, Solanum
elaegnifolium, Phytolacca sp., periwinkle, Gladiolus sp., Impatiens sp. and Phlox.
Management
Rogue out infected plants
Eliminate perennial weed hosts
Vector control by spraying monochrotophos or phosphamidon, 1.5 ml per liter of
water
4) Cercospora leaf spot: C. citrullina, C. melonis, C. lagenarium
Common on watermelon, muskmelon and cucumber
Symptoms
Minute water soaked spots mostly on leaves
Spots enlarge rapidly and becomes circular to irregular with pale brown, tan or
white centers and purple to almost black margins
Spots coalesce to form large blotches
The leaf may dry and die presenting the leaf a scorched appearance
Stems and fruits are also attacked
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