Causal Agent: 

Abiotic(Genetic mutation)

Characteristic Symptoms:
 
Spontaneous genetic mutation in plants causes changes in color or shape of melon leaves.
   
Typical symptoms of chimera are variegation or distortion of leaves resembling with those caused by viruses or herbicide injury.
   
Conditions for Disease Development:
 
Chimeras are caused by spontaneous genetic changes in the plant.
   
Control and Management:
Use the best quality of seeds available.
   
References:
Pepper and Eggplant Disease Guide by Seminis
   
Aphids
   
Common Species:
Aphis gossypii - cotton aphids
   
Myzus persicae - green peach aphids
   
Aphis fabae - bean aphid
   
Common Name:
plant lice
   
greenflies
   
blackflies
   
Damaging Stage:
Adults and nymphs
   
Crops Affected:
Cucurbits, solanaceous, legumes, papaya, cotton
   
Characteristic Damage:
Initial damage includes yellowing of leaves.
   
High aphid population causes downward curling of leaves, stunted plant growth and wilting.
   
Aphids produce honeydew, a sticky exudate that serves as substrate for the growth of sooty mold.
It also interferes with the leaves’ photosynthesis and transpiration.
   
They are known vectors of different groups of viruses including Potyvirus (PRSV, ZYMV,
ChiVMV), Luteovirus (CAYV/NMK) and Cucumovirus (CMV).
   
Management and Control:
Monitor the area regularly.
   
Remove weeds and volunteer plants that may serve as alternate hosts for the aphids.
   
Regulate use of nitrogen fertilizer, excessive nitrogen fertilization favors aphid reproduction.
   
Use yellow sticky traps to minimize aphid population.
   
Use plastic mulch to repel the aphids.
   
Use botanical extracts like neem, kakawate and hot pepper and canola oil.
   
Apply imidacloprid, acephate, thiamethoxam, acetamiprid, azadirachtin, dinotefuran,
acetamiprid, spinosad, pymetrozine when necessary.
   

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