catfromouterspace
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Joined: Tue Jul 18, 2017 7:34 am

Pumpkins and other vining plants turning yellow

Hello all,

Sorry if this is not the correct forum for this, let me know if I need to post this somewhere else.

My pumpkin, squash, melon, zucchini and cucumber plants all seem to be turning yellow. Some are doing better than others, but none of them are the healthy green that I might have expected them to be. They are getting worse as time goes on, but I want to find out if this is fixable or if they are doomed. I live in Southern California and the temperature has been consistently in the 80s and 90s for a while now. The garden gets sun all day until about 4 or 5 in the evening when the trees give it some shade. Each of the plants are in beds which have some compost, manure, native soil and garden soil. The soil pH was about 6.5 when I put the beds together. I have been fertilizing them as directed on the fertilizer package, using Vigoro vegetable fertilizer.

At first I thought that the problem might be that I was over-watering, but after cutting back on watering and measuring the moisture levels daily to keep them from getting soggy, they still seem to be getting worse just as before. They are getting yellower, the vines are getting skinnier and the leaves are getting smaller. Their growth seems to be very slow. The yellowing begins at the stem and works its way out to the leaves until they are completely yellow and shriveled up. I recently added some Ironite fertilizer as well after reading online that this can help plants get back to a healthy green after over-watering, but it does not seem to be making a difference at all.

One of the plants does have a ton of tiny black bugs on the undersides of the leaves, but the rest of the plants do not seem to have any bugs so I don’t think that’s the problem, at least not for all of them.

If anyone knows how to stop this, please let me know. I had the same problem trying to grow pumpkins and squash last year - the plants would either die before producing fruit or would produce one puny fruit and then promptly die afterword. They never grew big vines the way that squash plants are supposed to, they would be very short and sparse and would never get much larger than what you might buy at a nursery to transplant. I wouldn't be surprised if this is a case of gardener-error as I am a complete novice at this and have yet to grow a very successful squash plant. Photos are attached. Thank you all in advance for any ideas.
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jal_ut
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Location: Northern Utah Zone 5

Re: Pumpkins and other vining plants turning yellow

Those poor things look like they have been hit with a dose of weed killer.

You say, " a ton of tiny black bugs on the undersides of the leaves"
Well that will certainly set the plant back.

You say, "Each of the plants are in beds"
By this do you mean you are growing in containers? If so this is your problem . Squash has a very large root system and it will go to 8 feet deep in the ground and spread as wide as the plant is on top of the ground.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-

bri80
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Posts: 282
Joined: Sat Nov 19, 2016 10:12 pm
Location: Portland, OR

Re: Pumpkins and other vining plants turning yellow

I'll take a stab here...
catfromouterspace wrote:Each of the plants are in beds which have some compost, manure, native soil and garden soil. The soil pH was about 6.5 when I put the beds together.
Can you be more specific? Where'd you get the compost? Is the manure fresh or aged? Where'd you get the native soil? Was it potentially sprayed with an herbicide before being put in your garden beds? Define "garden soil." What kind of beds are you talking about here? Do you have a wider shot of the garden?

I suspect your growing medium here, first and foremost.
At first I thought that the problem might be that I was over-watering, but after cutting back on watering and measuring the moisture levels daily to keep them from getting soggy, they still seem to be getting worse just as before.
Over-watering can definitely be a problem, and probably was a factor. Once weakened, it may be too late to fix by stopping the over-watering.
One of the plants does have a ton of tiny black bugs on the undersides of the leaves, but the rest of the plants do not seem to have any bugs so I don’t think that’s the problem, at least not for all of them.
This is most likely more a symptom of the problem than the cause. The bugs are attacking weak plants, not the root cause of the plants dying.

Even the plants in your pictures that aren't dead yet show severe stress, and I would consider them goners, personally. Where did you get your seedlings? Nursery seedlings are usually weak, stressed, underfed, root-bound, etc. Especially at big-box stores. Much easier to grow from seeds.

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rainbowgardener
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Location: TN/GA 7b

Re: Pumpkins and other vining plants turning yellow

I agree, these are tiny seedlings and even if you could save them somehow, they are likely to always be stunted after this. It sounds like you are doing everything right, but clearly something isn't working. It looks like despite everything you are doing they are under-nourished.

You need to start over and try to figure out what is going on so that the next ones do better. I agree that squash are so quick and easy from seed it would be better to do that. I suspect the soil mix isn't right. In the picture, it looks pretty woody. I would suggest that you get a soil test to see if there is something missing from the soil.
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