downy mildew: trouble in paradise

Right or wrong, it’s not always easy for gardeners to talk about the things that aren’t growing well. But sometimes those very things teach the most indelible lessons.

From the beginning my cucumber plants have had a rough go this year. The rains came and stayed for a month. Now the plants are positively sickly.


Since there are so many similar diseases that can kill cucumber plants, I decided to submit a question and some images to Ask an Expert, a service run by the Extension Agency.

A prompt and thorough answer came the next day; Downy Mildew. Arg.

“There are few management practices that can be used to control downy mildew in the home garden.”

“The early appearance of downy mildew in Michigan, along with the wet and humid weather, may make cucumber growing especially challenging this year.”

Uh, yeah.

Well, suck it up and learn, mister.

The first change I’ll make in next year’s cucumber plantings are the varieties. I planted open pollinated heirloom varieties this year in hopes of saving seed. I’d rather have a harvest than no seeds and dead plants. So it’s Downy Mildew resistant hybrids all the way next time.

I may have aggravated the problem by spacing the plants too closely along the trellis. I planted 9 plants on a trellis that might have done better with 3 or 4.


2015 wall of fungus

Gardens aren’t always easy to figure though. Last year my cukes were amazing, planted using the same spacing. They eventually succumbed to disease, but not until I had cucumbers coming out my ears.

wall of pickling cakes

2014 wall of cucumbers

That leads me to believe that timing may have more to do with the problem than spacing. Last year’s cukes went in early; for various reasons this year’s crop was planted almost a full month later than last year’s. An early start means a greater likelihood of getting the cukes harvested before disease hits.

So much to learn, so little time.



Last year my cucumbers, cantaloupe and watermelons were humming along, with big lush vines and lots of fruits. Then suddenly the leaves turned spotty and within a week they were all brown and shriveled and useless.

The cukes managed a bumper crop before that happened, but after tending the melons for a couple of months I had nothing to show for it. I’ve generally had putrid success with my vining crops for the past few years. Most likely some soil-borne fungus that hangs on from year to year.

This year the cucumbers were iffy from the get-go, but they’re still hanging on with spotty lower leaves.


I read about an organic product called Serenade, ‘a broad spectrum, preventative biofungicide recommended for the suppression of many plant diseases.’ It’s OMRI listed so I feel comfortable using it. It’s supposed to control some of the potential culprits of my cucurbits, anthracnose, downy mildew and leaf spot.

I treated the vines about a week ago, and so far so good. The leaves are still spotty, but they haven’t yet started to turn brown. I sprayed some on my pepper plants too, because they’ve had some nasty problem since the big rains in June.


Cantaloupe vines…still there

I’ll let you know how it all turns out.

The watermelons got a late start like the cukes and cantaloupe, but so far they don’t show any signs of disease.


It was also time to pull the first planting of corn stalks and turn the chicken tiller lose. What fun for all of us.


And one funny, but no so funny side story; for the second day in a row, user error led to another chicken break. As I was lifting the chicken tractor to move it, I inadvertently lifted too high, and two quick-thinking prisoners made their getaway.

I caught one easily, but the last holdout ended up in a chicken rodeo that lasted a good twenty minutes. They really want to be in that woods. But we finally got her close enough to her caged sisters to leave freedom voluntarily. No harm, no foul.

garden app

The other day I noticed some leaf nastiness on one of my wax bean plants.  I spent some time in Google images, but couldn’t definitively identify the culprit.  There were lots of possibilities.


I decided to try out an app that purported to identify plant diseases with personal attention, based on an uploaded photo.  The app is called ‘Garden Compass‘.

I snapped a picture, added a brief explanation and sent.  The next day I had an answer:

IMG_4917 (1)

Pretty nifty.  The catch is that you get 3 free credits.  I’m assuming you’d have to pay for more.  I got 3 additional credits by making my wife download the app 🙂

Another sort of catch…they didn’t suggest a remedy.  But since they identified the disease, I was able to search for organic remedies online.  It looks like the only way around bacterial leaf spot is getting decent weather or using copper spray.  I’m not convinced that copper spray is something I want to do.  It’s not heartily recommended as an organic method.

Since I only noticed the problem on one or two leaves, I guess I’ll live by the creed “First, do no harm”.

Anyway, the Garden Compass app is free and gives specific personal service for a few instances, so it might be worth your while