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Some of the leaves on my courgettes have gone very yellow- a bright yellow, not just pale, Any idea what may cause this? They are only just starting to fruit.

Has the soil been a bit dry, they are such thirsty birds, plus up their feeding? Are you using a different feed than usual perhaps?

Caroline, this has happened to me occasionally. Squash sometimes seems to get colour on their leaves as they grow! It doesn't seem to affect the growth.

I've had a PM to say there's a yellow gene in some squash/courgettes  that can cause it and since the plant most affected is a yellow-fruiting one, maybe that's it..

I grow a lot of courgettes, both green and yellow, and this symptom is not uncommon in both types.
A simple liquid feed with something like Miracle-grow has always sorted it out, and you can then revert to a tomato feed.
I don't think it's genetically linked.

Quote from: Pescador on July 11, 2014, 21:33:08
I grow a lot of courgettes, both green and yellow, and this symptom is not uncommon in both types.
A simple liquid feed with something like Miracle-grow has always sorted it out, and you can then revert to a tomato feed.
I don't think it's genetically linked.

Ditto, doesn't seem to affect the plants productivity

Would comfrey liquid help? That's what I mostly use.

Personally, I'd use something with more woomfp! But each to their own

Quote from: caroline7758 on July 11, 2014, 22:09:34
Would comfrey liquid help? That's what I mostly use.

Yes and (don't do this with tomatoes or potatoes) it will also feed the leaves directly if you water with a fine rose onto the leaves.  They can take up nutrients more directly.  It is called foliar feed and it gets the nutrients to the plant faster than through the roots.  Don't do this in full sunshine, but first thing in the morning or when the sun is near setting at night.  After feeding, a mulch also helps to keep moisture in the ground.  Cut grass is good for this purpose and there is quite a bit of nitrogen in grass which becomes available to the plants rather quickly because it rots so fast. 

Thanks, Galina.

I think that some yellow varieties tend to have yellow leaves however much whoomph you use.  It does not seem to adversely affect the cropping.

I guess the genes that affect fruit colour also affect the foliage (that's certainly the case with peas).

One of the three varieties I have this year is Verde di Italia (from Real Seeds) which has light green fruits. The leaves are showing very light-coloured markings which I thought at first was maybe disease or deficiency but now I'm sure is just how it's meant to be.

Some courgettes have silver spots on the leaves this is also quite normal.  But mould spots is quite another matter and tends to doom the plant in the end,

My Paradore and Yellow striped courgettes both have quite yellowish leaves naturally, I wouldn't worry. I do use liquid seaweed as a growth stimulant, pelleted chicken poo for a boost, works for me! They usually fruit their hearts out whatever you do, you will be needing the carrier bags to give them away usually.....

Verde di Italia this morning.

On closer inspection, the white patches seem to be air pockets inside the leaves exactly like the silver markings you get on pea leaves. Far to regular to be disease! And apparently the fruits have pale markings too. It can't be unhappy, it's growing like the clappers!