[Silva]

Hello all.

I'm hoping somebody will be able to help me with my cucurbits. Last year my cucurbits suffered from a disease(?) that started as quite regular yellow spots on the leaves, these join to form brown patches and eventually the whole leaf dies and sometimes the stem of the plant splits. Growth is stunted and usually the plant dies. It appeared first on the cucumbers, very early in their growth, and then spread to the squash who were a little more resilient to it.

This year I made sure to use clean pots, new seed and kept the plants as spaced out as possible, thinking perhaps last year it was an air circulation issue. Unfortunately the same thing happened again straight away to the cucumbers and is now spreading to the squash plants. Last year I was able to plant the squash out early before many were affected but with these frosts I'm not able to (my plot is not close to the house). I've tried to isolate affected plants as much as possible, but I don't have much space and with moving plants in and out constantly it's difficult to stop cross-contamination. I remove the worst affected leaves, but of course this continues to stunt the growth.

Does anybody know what is causing this and how best to control it? It's difficult to source new plants, and last year some of the squash outgrew it so I'm reluctant to throw them away. However I have thrown away all but two of the cucumbers because these were the worst affected. I have shown pictures to those more informed than me that didn't think it looked like mosaic virus, but perhaps it can manifest in different ways. I don't think it's watering because I'm usually pretty consistent with this. I've attached some photos to see if anybody could help identify the problem. They are my favourite veg plant to grow so its really quite dispiriting. Thanks!

[Silva]

And just to show it isn't just the cucumbers in their dinky little pots here is an otherwise very healthy courgette showing early signs of the disease.

[JayG]

Seems to me as if it's mainly the seed leaves affected - judging from the size of the plants now, they were probably scorched by the hot sun we had a few weeks ago.

Others may take a different view, but I wouldn't be unduly worried at this stage.

[Silva]

Thank you for your reply JayG. It certainly starts with the seed leaves, but then spreads to the other leaves. Those pictures are from a week or so ago and the effects have continued to spread but I can't currently show new pictures as I have begun removing the badly affected leaves. If it is the same thing as last year (which I believe it is) it certainly can kill the plants. However I do badly want to believe what you say is true!

[Growster...]

I reckon JayG is spot on here, Silva, never fear, cucurbits are such fussy veg, and moan at every little draught and sun-ray!

You'll be fine, the seed leaves die back anyway, and the main ones will be the ones to watch and feed as they get bigger and better!

In fact, I'd be proud of all those you have here, so keep 'em going! They're much better than ours!

[JayG]

Have you fed them?

Cucurbits are all hungry plants and they are in quite small pots.

Not everyone agrees that wetting leaves during watering causes sun scorch, but it's best to avoid doing so if possible.

[AnneB]

It looks like a fungal disease of some kind to me.  There are a few that afflict cucurbits.  You don't mention what compost or soil you have grown your plants in.  Fungal diseases can persist in soil.  Also how humid are you keeping the greenhouse as that can encourage fungal problems.

[Silva]

Thank you for your replies. Most are potted on now but I can certainly give a seaweed feed as it can't hurt.

They were planted in Humax multi-purpose compost which is also what I used last year (although a different bag of course). Aside from the cucurbits I have never had any problems with it. However I had considered this might be the common denominator so I bought some Westland MPC and have started potting them on in that- at least that way if its in the soil they aren't getting a repeated dose!

Last year I kept most in a cold frame as it was warm but they were quite close together and I thought this might have been the cause. So this year I spread them out on a table along my balcony window which gets quite a lot of light, with a couple kept in the cold frame as a sort of control. During the day they harden off on the balcony. If it is a fungal disease do you have any suggestions for control?