Here is another photo of the shriveled cucumbers. What should I do?

Thanks-
Ron

Since you have self-pollinating plants, are you sure they aren't just the male blossoms shriveling up and dying, or maybe the female flowers aren't being pollinated? If it is a nutrient problem, magnesium deficiency might be an explanation. If you haven't increased the calcium yet, I'd try cal-mag for that and hope it did the trick, now that they are fruiting. Doesn't really look like disease for me ...

This post was edited by PupillaCharites on Fri, Mar 21, 14 at 0:57

Thanks for your input. Currently I'm running a fertilizer solution designed for tomatoes as a convenience . A 4-18-38 with calcium nitrate and magnesium sulfate.

My book on hydroponics says to use a 8-16-36 for the cucs also with cal-nitrite and mag-sulfate. I can't justify adding another reservoir and pump. We'll see how it goes.

Another pump??? Is that because tomatoes are sharing the reservoir and you can't change anything at all?

If you are already adding calcium and magnesium separately, you can just bump up your calcium nitrate (15.5-0-0) and magnesium sulfate (epsom salt) about 15% each in tandem and leave the 4-18-38 precisely where it is. That will get you the Cal-Mag I suggested, and not surprisingly, it is also be closer to the the cucumber recipe vs. using the regular mixed 4-18-38 tomato recipe.

If that's not possible for some reason, and you want to K.I.S., I would just use a one time light foliar spray of 10% epsom salt by weight for the most immediate remedy, and watch a week to see improvement. Also, in lieu of that but slower, simply drop in 15% extra (based on the original recipe) of dry epsom salt crystals directly in the reservoir.

Also, hand pollinate.

I think I see powdery mildew. Look for it on green leaves. If that is the problem you should spray with some sort of fungicide. Daconil is widely used. I think copper would work, too. Some people use a milk and water mixture and report good results. Hydrogen peroxide might be worth trying as well, about a 1% solution.

I looked hard at the pictures for mold/fungi but only see leaf damage and no colonies. Maybe some is there, you could be right about that. But then you would expect the mildew to be obvious on the underside of the leaves, for which the OP didn't mention anything, and not specifically attack the old leaves and leave the middle and new growth untouched. Not enough was really posted, but I can see your point if the higher leaves were getting better ventilation or something like that.

On the other hand the mud green color of the big leaf is uniformly blah colored which suggested a nutrient deficiency, as well as the dog-eared papery condition. Once the leaf is unhealthy, mold and mildew have an easy time, so my thought was to correct what seemed as the underlying nutrient deficiency ASAP. Fear of mildew was actually the reason foliar spray was second choice, and at that with 10% epsom salt finely sprayed vs. a typical 2% drenching. But a closer look to see if any colony is visible would be helpful, and I'm sure the OP would have told us if he cleaned mildew residue off (washed the leaves).

This post was edited by PupillaCharites on Mon, Mar 24, 14 at 17:48