Yellow, pale courgette foliage

[Marb67]

I don't know what is happening but my container grown courgettes are still producing fruit but the leaves and foliage are very pale and yellow. No green at all. I feed as normal with comfry every week and I did some time ago give a feed of nitrogen with chicken manure pellets when they showed early signs of yellowing.

Why have they not returned to green ?

[Penellype]

They could be suffering from the first stages of powdery mildew. Its been a more than averagely windy summer and courgettes dry out very easily with their big leaves - particularly if they are in pots. They then become very vulnerable to mildew which slowly kills them. The leaves tend to wither go whitish grey and then die, or they can go yellow and then crispy brown, either way there doesn't seem to be much you can do to revive them. They will continue to produce some smallish fruit for a while before they expire. I cut off the leaves when they go brown.

This is one of my potted green bush courgettes:



As it happens I cut off the worst affected leaves about 20 mins ago, but you can see that the bigger leaves are going yellow and some brown patches are developing. This started to happen almost immediately after it was thrashed about by the wind last week. There are still some flower buds though, so I am leaving it where it is for now.

[Marb67]

Thanks. I will do that.

Yes, I hate these constant windy days we have had of late. Horrible muggy, humid and windy. can't wait for the fresh, crisp air of Autumn. Why has the weather been constantly like this for weeks and weeks now ?

[vixylix]

I've had the same problem with mine - as Penellype says keep cutting off the brown leaves - I also cut off the yellow ones if the plant has sufficient green ones to keep it going. Mine had an excellent growth spurt a few weeks ago, loads of new leaves, flowers and fruit, all of which now appear to be frozen in time!!

[Penellype]

I think the short answer to that is that the jet stream has been consistently near to or south of the country, leading to cooler than average temperatures (the jet stream divides the warm tropical air from the cold arctic air). Occasionally, as now, it has moved slightly west, allowing us to have warmer spells, but these have not lasted, and the fact that it is near to us means that the weather in the north west at least, has tended to be rather wet and windy. Currently the jet is strengthening (normal as you get nearer to autumn), and this means more vigorous areas of low pressure. The forecast for the next week is very wet and windy I'm afraid.

This rather gorgeous map shows the wind speeds high in the atmosphere which is where the jet stream is.

earth :: a global map of wind, weather, and ocean conditions

The brighter the colours the stronger the wind, and at the moment you can see that the jet stream is forming a U shape over the atlantic, bringing it slap over the top of Ireland and Scotland. To the north of it is a low pressure spinning round and to the east of us, over Scandinavia, is a high pressure. They currently have summer type weather as the jet stream runs to the north of them. High pressure in this position, and also over Greenland where it also is, is bad news for us. The Scandinavian high shows all the charactaristics of a blocking high, which stops the atlantic lows in their tracks and pushes them over the top of us. This is why we had that slow moving band of heavy rain running north to south recently.

Why is the jet stream where it is instead of being well to the north of us, where it "should" be? My theory is that it has something to do with an unusually cold atlantic ocean in an otherwise record hot year (over the whole world). Why is the atlantic so unusually cold? I have absolutely no idea.

[Snadger]

I think the short answer to that is that the jet stream has been consistently near to or south of the country, leading to cooler than average temperatures (the jet stream divides the warm tropical air from the cold arctic air). Occasionally, as now, it has moved slightly west, allowing us to have warmer spells, but these have not lasted, and the fact that it is near to us means that the weather in the north west at least, has tended to be rather wet and windy. Currently the jet is strengthening (normal as you get nearer to autumn), and this means more vigorous areas of low pressure. The forecast for the next week is very wet and windy I'm afraid.

This rather gorgeous map shows the wind speeds high in the atmosphere which is where the jet stream is.

earth :: a global map of wind, weather, and ocean conditions

The brighter the colours the stronger the wind, and at the moment you can see that the jet stream is forming a U shape over the atlantic, bringing it slap over the top of Ireland and Scotland. To the north of it is a low pressure spinning round and to the east of us, over Scandinavia, is a high pressure. They currently have summer type weather as the jet stream runs to the north of them. High pressure in this position, and also over Greenland where it also is, is bad news for us. The Scandinavian high shows all the charactaristics of a blocking high, which stops the atlantic lows in their tracks and pushes them over the top of us. This is why we had that slow moving band of heavy rain running north to south recently.

Why is the jet stream where it is instead of being well to the north of us, where it "should" be? My theory is that it has something to do with an unusually cold atlantic ocean in an otherwise record hot year (over the whole world). Why is the atlantic so unusually cold? I have absolutely no idea.

And this is the short answer!!!!!!!!!

[Jay-ell]

The leaves on my courgettes have turned yellow - but only on the Shooting Star F1, the other courgettes and squash haven't.

[Penellype]

And this is the short answer!!!!!!!!!

I could give the long answer, but I'd probably lose myself half way through and send the entire forum to sleep!

[rosiepumpkin]

Another possibility is lack of light. I have this problem a lot, but especially this year as it's been cloud cover for so many days.

[Penellype]

Hmm, I would agree, but the records I keep of my solar panel performance give the lie to that one, at least in York. There is a table of expected generation for a given system, orientation and geographical area which I compare each month's total generation to. Every single month this year so far has been above average, with June generating 25% more than expected and April nearly 33% more. August needs to generate just 6kwh per day for the last 11 days (including today which is quite sunny) - the average daily output in August is expected to be around 10.7kwh, so we are currently running above average for sunshine again this month. I realize this may well not be the case for other parts of the country, particularly the west which has had a lousy summer.

Leaves are similar to solar panels and therefore this sort of data is very relevant to how much sun the plants are getting (unless of course your garden is very shady).

[Slugsnsnails]

Thank goodness I just found this site...the ones I've tended to find are American, and they go on about different zones and stuff I've never heard of LOL.
Anyhow, I've been having the same problem with my courgettes, plus the fruit has started to go mouldy at a couple of inches (have looked that up elsewhere on this site). I've been very busy and away, so this is the first time I've had a chance to find out what's up with the plants.
So, per some of your answers, I've just been out to remove the affected leaves, but am not sure if it's ok to put them in the compost? If any mildew will affect the compost and thus plants when I use it?

[Bigmallly]

Welcome to the vine SnS, I'm sure your Courgette leaves will be fine on the compost heap. All mine go on the heap mildew or not. Although Colorado says we shouldn't:

http://www.ext.colostate.edu/pubs/garden/02902.html

[Slugsnsnails]

Thanks Bigmalley.
Interesting link you posted. Sounds like I've been getting the leaves too wet...then again, I did go on hol for 3 weeks and left the watering and things to my son to take care of. I thought I'd better not give him too many detailed instructions as to what to do LOL. But he did prevent my plants from dying. The link said not to put in plants too low if mildew is a problem...but not sure how I could plant'em any higher, not unless I constructed a platform, and climbed a step-ladder . And they're actually in a large planter because I've not got too much room in my garden, so probably they are somewhat overcrowded, so don't get much air circulation. Never mind, live and learn