Cucumber help?

[John S.]

Hi there - I'm growing cukes in Earthboxes with Sunshine Mix this year (first time trying them in these boxes).

They're growing vigorously, but I'm seeing pitting and yellowing (see pics). The bottom older leaves are really looking ragged with holes. The mid-upper leaves are starting to fade.

Is it Spider Mites? Cucumber spot? Too much fertilizer?

Any help appreciated, thanks!

One image is of a much older bottom leaf. The other is of a leaf about half way up the vine.

 

[Chuck]

Without pictures of many of the leaves I would say it's too much nitrogen. What fertilizer are you using?

 

[John S.]

I'm using Vigoro All Purpose (12-7-5). I followed the Earthbox method of laying it down in a strip opposite of the plants (and a mound of sunshine mix). But maybe it's just too much? My tomatoes are exploding in these boxes - and the cukes appear to be growing nicely too. But... cukes have always been my nemesis.

A few more images:

(thank you!)

 

[Chuck]

Cucs are a warm weather plant. Why do you still have black plastic. Anyway, after seeing the total plant I would say it's too much nitrogen and the reason for this is the yellowing leaf margins and yellow new growth. The new growth will turn green. The plants look healthy though. It is very easy to over fertilize with synthetic fertilizers and the excess should leach away in time. I am not familiar with earthboxes so I don't know what the plastic is for but your cucs will be better off without it. If you leave it there and it gets really warm you might cook the roots of the plant.

 

[John S.]

Thanks for the reply! I'll just keep on keepin on for the time being.

The plastic in this case is because I live in the hills adjacent to the Bay Area fog line. May and early June are generally 65-70 degrees tops - with cool wind and morning fog. Trying to get them some extra heat in the day time. We don't get 75+ consistent weather until late July - and sometimes not until late August.

Appreciate the help.

 

[headfullofbees]

The wind also explains some of the leaf yellowing.
Cukes don't need 75+, 60f or more is fine.