Question
We grow our squash in our greenhouse due to the cold conditions here (zone2c).  It is a challenge to minimize the humidity yet still have ideal growing temperatures.  Our spaghetti squash and to a lesser extent our zuchinnis haved developed a lot of grey mould on the leaves.  What can we do next year to mitigate this problem?  Thanks

Answer
Wren, squash are highly susceptible to a fungus disease called powdery mildew. This disease is especially prevalent in rainy seasons and areas with consistently high humidity.

Powdery mildew can be prevented if the plants are sprayed starting in mid-June with a fungicide every 10 days. I use a product called Soap Shield, produced and sold through Gardens Alive. Attached is a link to their website:

http://www.gardensalive.com/product.asp?pn=8066&ss=Soap%20Shield

There are also varieties that are less susceptible to this disease. Your best option is to search through various seed catalogs, where they list the plants' resistance to different diseases. My three favorites are Park Seed, Burpee, and Johnny Seed. All three offer free catalogs, or you can search through their products on-line at the following web sites:

http://www.burpee.com/home.do   

http://www.parkseed.com/   

http://www.johnnyseeds.com/default.aspx   

I hope this information helps. Good luck, and please write again if you ever need assistance.

Regards,

Mike