Here's what killed my cukes
 

Last season my small garden was crowded almost exclusively with tomato plants. Since everybody in the family also likes cucumbers, I decided to plant four plants which by the way were assigned a pretty bad spot with not much light and under a plum tree.
With my surprise they didn't seem to bother the spot. Plants were vigorous, tall and full of flowers. We soon started to get the first fruits and everything seemed to be going in the right way. All of a sudden then, I noticed the stems were changing color and becoming brown. Eventually, fluffy, brushed-like mold started growing on top of each plants and the cucumbers started to distort (I stopped eating them, they looked gross). This thing was so fast that in less than a couple of weeks all of my cukes were dead:?:.
This year I'm growing fewer tomato plants and I gave a better spot to my cucumbers. Nevertheless, some of the same symptoms appered a week a ago. After asking people who know more than I do and after doing some researches, it seems like my plants are being attacked by powdery mildew. By looking at the pictures that I'm attaching here I guess last year I was also dealing with Sclerotinia. The picture were my beautiful son and assistant:lol: is picking a cuke, shows leaves that are stained with the typical white spots of the Powdery mildew. Something I didn't notice at the time. The other pics show you the strange mold which was probably caused by sclerotinia.
This year no mold has appeared yet. But the leaves did have the same white spots again. I'm treating my plants with sulfur and it seems to work. At least the plants are not dead yet.:twisted:

Where I live in Michigan, we have lots of hot, humid weather coupled with clay loam soil. I am a HUGE proponent of using a thick layer of spoiled hay/straw for mulch throughout my entire garden (buying hay/straw bales in the fall, letting them sit out in the open, uncovered during the winter, then using it for mulch when I plant in the spring). This has virtually eliminated Septoria and all other fungal disease.



With that said, it does not stop powdery or downy mildew on my squash, melons, and cukes. From a distance, it seems like you might have powdery mildew but I can't tell for sure. If it is powdery mildew, frequent applications of a foliar copper spray like Bonide or Daconil after watering/rain should help stop the spread.



Good luck!


Steve

That’s what is happening with my cukes this year - the ones that I’m growing in the same area as my cherry tomatoes. I recently sprayed with Serenade - but it looks worse since I sprayed. There are cucumber’s growing but for how long I don’t know and it’s looking like it’s spreading to the other cucumber plants. I might have to get the copper spray, or cut them down! And even my cucumber plants were slow this year - which almost never happens. Bummer.

I just want to add that I grow in Pro Mix HP so soil borne diseases shouldn’t be a factor, hopefully. But we have had a very humid, hot summer, after some very cool days and nights in June. Obviously the cucumber plants were most affected.

Believe it or not, I have had a lot of success keeping powdery mildew under control by spraying a diluted milk solution on the leaves when I first see signs of mildew. I just take a 24-30 oz spray bottle, pour in some milk (a tablespoon or so), and spray tops/bottoms of leaves. It actually really helped! I use it on cucumbers, zucchini, yellow squash, and melon plants.