Trouble in Paradise

This week I noticed my cucumber plants started developing strange little yellow spots on the leaves.  Of course, I immediately started researching this online and discovered my plants were being affected by downy mildew.  You can see the yellow spots starting to show up in the photo below.

I was advised by someone working at American Beauty Garden Center (a great local garden store) to try Serenade Disease Control spray, which is a bacterial fungicide safe for organic gardening.  So, I did.  The bottle of Serenade specifically says not to expose plants to water for at least four hours after application.  This also just happened to be one of the rainiest weeks we've had all summer.  Of course, every time I applied it, it would start raining within a couple of hours, sometimes continuing into the night.

This just exacerbated the mildew problem and I ended up having to cut off a lot of the leaves from my cucumber vines because it was starting to spread to the peppers, okra, chard, and lima beans.  Mildew spores hang onto the underside of leaves and are carried by wind, so it only took a couple of days for it to start affecting everything.  I also noticed that my tomatoes had started developing septoria leaf spot (photo below).

So, tonight I spent two hours in the garden clipping leaves off of nearly everything where I noticed the mildew had spread.  Information online is conflicting as to whether removal of leaves containing mildew spores is necessary, but it seems to make sense that it would be if the mildew infection spreads from one leaf to another via the spores.  Some information suggests removal of diseased plants in their entirety while other sources say that the mildew only affects the leaves.

I decided to take a risk and remove the leaves for a couple reasons.  First, my cucumber vines are way too intertwined to decide which are diseased or not, and even if I could tell, removal of just those affected would be nearly impossible.  Also, I have read in a couple different places that this specific mildew only affects the leaves, so I figured there would still be a chance the plants would survive if the problem areas were removed.  Throwing out the entire vine seemed a bit premature if there would be any chance it would sprout new leaves and survive.  For now, I just plan to apply fungicide every seven days as suggested and hope for the best.

Here is the bag of affected leaves I ended up with at the end of the night.  It's important to remember that if you are faced with this issue, the leaves need to be completely removed from your garden.  This means no compost bin, because the spores can continue to thrive there.