This morning we looked a Spaghetti Squash in the southern part of the county that is showing symptoms of downy mildew. We were able to get back to the office and confirm both downy and powdery mildew. We usually see powdery on the upper side of the leaf and downy on the lower side. With downy, the yellowing will stay within the veins, and powdery will cross over the veins.
Upper leaf
Underside of leaf
Microscope – PM (left) DM (right)
Here is some information from UGA Extension Pathologist Dr. Bhabesh Dutta:
These observations indicate that inoculum of downy mildew is currently in GA and under favorable conditions (cool and wet conditions) potential disease outbreak in cucurbit can occur. I would suggest our cucurbit growers to look for the downy mildew symptoms in their fields and start applying protective spray of below stated fungicides.
Watermelon: Rotation (foliar application) with Orondis+Bravo/Manzate;
Ranman+Bravo/Manzate;
Previcur flex+Bravo/manzate
Please do not use bravo after fruit set.
Other cucurbits: Ranman+Bravo; Previcur flex+Bravo
If Orondis was used as a soil application, please do not use it as foliar (use restriction according to label).
If Orondis was not used as a soil application, foliar application can be done for controlling downy mildew.
Thomas County Ag 