Causal Agent:
Fungus (Alternaria alternata f. sp. cucurbitae)
| Characteristic Symptoms: | |
 |
Lesions begin as tiny, tan or brown spots that may appear water-soaked on the underside of leaves. |
|
Spots darken with age and appear as round, brown and with concentric rings. Sometimes, these spots may be surrounded by a halo of yellow tissue. |
|
Alternaria infections occur only on leaves. |
| Conditions for Disease Development | |
|
The disease is spread by infested soil, by wind, by irrigation water and by seed. |
|
The optimum temperature for disease development is 26˙C.
|
| Management and Control: | |
|
Maintain good field sanitation (e.g. remove & burn affected plant/plant parts).
|
|
Rotate with non-host crops for 2-4 years to reduce the amount of inoculum. |
|
Apply fungicides such as copper-containing compounds (e.g. Champion®, Kocide®, Nordox®) or pyraclostrobin+dimetomorph (e.g. Cabrio to Cabrio TeamⓇ)
|
References:
https://www.extension.purdue.edu/extmedia/bp/bp-44.html
Compendium of Cucurbit Diseases (2010) by The American Phytopathological Society
To view other diseases, click here.
Need more help? Ask the Doctor.
