Question
i am growing a potato plant in my cellar. last week a white baby powderish fungus started growig on its stems and leaves overnight.what i did to treat this was i mixed dish detergent and vegitable oil and put it on the leaves.i started seeing result right away but when i checked the plant the next day, the leaves were died but the plant was alive.the fungus was died, but so were the leaves.is it possible i didnt treat the fungus right?what sould i have done?

Answer
Amber, dish soap and vegetable oil will kill insects, but not cure fungus diseases. Your plants contracted a fungus disease called powdery mildew. Although the disease seldom proves fatal, it can cause the plant to prematurely lose its foliage which could result in a smaller harvest.

The best treatment for powdery mildew is lime sulfur. This is an all-purpose fungicide which will help control the disease. Other options include copper and fungicidal soap. Gardens Alive markets an excellent copper-based organic fungicide called Soap Shield. You can research this product online at:

http://www.gardensalive.com/

If this ever reoccurs, make sure you spray at the first sign of mildew. This will prevent it from spreading. Like all diseases, if you wait until the fungus spreads, it is usually too late.

I hope this helps. Good luck, and please write again if I can ever be of assistance.

Regards,

Mike