Squash leaves turning yellow ... what can I do

jen1996July 29, 2012

Hi all. This is the first year I have done raised beds. I am a beginner re gardening.

I did the lasange method (cardboard, composted leaves, grassclippings, pine needles, composted food scraps and loam and composted cow manure.

Over all everything seems to be thriving but every squash plant (a few pumpkin, a few spagetti squash and a few yellow squash) all have some yellowing of leaves. Including few that I have in containers. Green beans are getting eaten I will do a separate post for that.

The first pic attached is of yellow or spag squash reaching through the pumpkin. That plant has the most yellow.

I searched through the forums and on google for causes of yellow leaves. Saw things like nitrate, too much water, too little water, squash borers, cucumber beetles and wilt bacterial infection.

I read to test for infection to break off a stem and see if it oozes. It did not. Juice was thin and clear. I looked at all of the stems for borers. So far there is no wilt.

I do not have any mulch down as you can see in the pictures. I do not think I have been watering too much though we have more rain this week. It is possible they were getting too little (I was afraid of over watering) but we have had some light rain off and on several times to day and over the past couple of days and I fel like leaves are getting yellower.

Over all the plants seem healthy. Just want to catch any problem early on.

Is it too late to mulch? Can I use composted leaves or grass?

How can I tell if it is nitrate problem and what do I do if it is the problem? Where do I get good nitrate? I read some use urine????



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Pic of squash plants

    Bookmark   July 29, 2012 at 11:23PM
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Pumpkin leaf
(sorry for the multiple posts, I do not know how to post multiple photos in one post)

    Bookmark   July 29, 2012 at 11:25PM
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After sifting through the forums looking for answers as to why my plants are yellowing, i am now paranoid about squash vine borers. I went out this morning to closely examine my plants. I did not see any holes or signs of the frass looking stuff. I did however see that many stems have fractures or cuts. Most very slight. I cut off one of the stems (is this ok?) And slit it lengthwise. There was no larve that looked like the svb .... or at least not any that looked like the pics. But there was another worm. It was very tiny ... too small i think to get a decent pic. It was about a mmm or so and moved around like an inchworm ... very active, standing up etc. It was translucent with a black spot.
Does this sound like a harmful bug?

    Bookmark   July 30, 2012 at 12:38PM
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This is my first year gardening, so I don't think I'll be much help to you. I couldn't see anything that looked like yellowing from your pictures, so I don't just don't know. They looked a lighter shade of green, but that's all I could tell.

I keep checking back to this post to see if you've gotten any helpful replies because I also have a yellowing problem with my pumpkins. They are yellowing at the base of each plant and then turning a crispy brown. I've struggled this year with squash bugs, powdery mildew (on the squash right next to the pumpkins, so I treated the pumpkins also), and I've seen SVB but haven't felt their wrath yet. I've seen no eggs or squash bugs on the pumpkins yet, and I've fertilized with a 10-10-10 fertilizer about every 2-3 weeks. I've got flowers in the garden that goes from dull yellow to a deep rich red whenever I add fertilizer, so I always add fertilizer whenever the newest blooms are yellow. But I'm noticing now that blooms are falling off many of my winter squashes, and I'm noticing what I think is blossom end rot on the winter squashes as well. This makes me think there is a deficiency in some nutrient for all of them, but I'm not sure what! Because this was the first garden, the expenses have been high. I'd like to keep the solution cost as low as possible, if possible. Got any ideas?

Here's a picture of the pumpkin leaves.

Here is a link that might be useful:

    Bookmark   July 30, 2012 at 1:58PM
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The first picture the leaf is pretty yellow and pale. Does it not look yellow on your computer?
I looked at the link you posted. I have a couple that look like that too. But after veiwing many squash gardens on google i have seen many healthy gardens have some leaves simular to the pics we have posted.
So far i have not found any svb and have been checking obsessively.

Do you have a lot of the yellow burnt leaves?

I am going to try and post on some gardening blogs too and see if I can get more replies.


    Bookmark   July 30, 2012 at 2:53PM
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Jen-- I think the yellowing is natural if it's the bottom leaves-- the upper plant blocks the lower part of the plant from the sun, so the leaves turn yellow. I usually remove those from my plant so they don't decay and attract disease. I am far from an expert, but if the plant is otherwise producing and the leaves look strong, I wouldn't worry.

IBSmilin-- I wonder if a 10-10-10 fertilizer is the source of your flowers falling off. My understanding is that additional nitrogen can cause blooms to fall off as the plant uses the N to create more leaves. If the plant has blooms you might want to use a low-N fertilizer.

Hopefuly a more experienced gardener can chime in here. I would be interested in knowing the best proportion fertilizer for blooming plants that will maximize fruit production.


    Bookmark   July 30, 2012 at 4:10PM
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Thanks for your reply.
I keep going out to check. A couple of plants near eachother are looking weaker and weaker. Stems are pale and some fruit and blossoms are dying off too. Getting worried these plants will die.

Can I mulch with composted leaves?
Should I look dor some other mulch instead? Should I assume nitrogen issue and put down fish emulsion or something?

    Bookmark   July 30, 2012 at 4:16PM
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There are about a dozen leaves between the four pumpkin vines that look like yellow and crispy along the edges. I will see if I can get a lower nitrogen fertilizer as I'm about out now anyway and due to get some more. That would definitely explain the blossom droppage. The winter squash is just flinging them all over the place. Thanks. I also just found some more powdery mildew on some squash not previously affected, so it looks like it's time for another fungicide application. Darn.
At this point in the summer, it's definitely feeling like a fight against nature! Just killed a few hordes of squash bugs this morning too. These plants just want to rot or be eaten. Definitely will be putting more energy into getting the soil just right next year and learning more about fertilizing and timing for application.

    Bookmark   July 30, 2012 at 5:16PM
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Here are pics of the weaker looking plants. They are pretty close to eachother. Should one be pulled out?
They are both still growing very long vines (the second two pictures)

I am going to the local farmers union today to see if they have anything to help these plants. Will also look for some straw.

    Bookmark   July 31, 2012 at 12:08PM
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Wonder what this blossom is going to look like???

    Bookmark   July 31, 2012 at 12:11PM
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jen1996 - mulching with leaves or dried grass clippings is a great idea as it keeps the soil moist which squash love!

Squash are heavy feeders, so you need a complete fertilizer. In my area Dr. Earth or Whitney Farms are the brands. A 4# box is around $8 and a larger bag under $20 with 4x the amount at least. If you can keep it dry over winter it will last for next year, too. When I started using the granular organic fertilizer it made a huge difference in our vegetables as compared to just manures & mulch. Follow directions on the container, don't over do it.

Even used coffee grounds feeds them a bit, but won't be enough to increase fertility very much quickly.

Besides the fertilizer you can mix up a liquid compost tea that is easy -- a handful of your composted leaves in a bucket or watering can. I usually let it sit for a few days, but in your situation it would help to feed them today. Make 2 batches & let the 2nd one sit for a few days in the sun. It's fine to water with it daily as it's not too much fert, but just a little bit of instant feed.

Hope that helps.

    Bookmark   July 31, 2012 at 12:16PM
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That was my first thought too when I saw the thinned out leaves. Have they been fed much lately? I feel like 2-3 weeks between feedings (ferts or composts) should offer enough nutrients for strong growth. But I am a knownothing on this.

    Bookmark   July 31, 2012 at 12:35PM
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Some people say mulch is a bad idea for squash because it harbors squash bugs.

    Bookmark   July 31, 2012 at 12:48PM
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Thank you for your replies.
I bought this product today
I applied it yo everything. It got pretty good reviews so I hope it helps. How long should it be before I see improvements?

I have been researching the teas. We took a composting class recently and learned of method. But then today while researching it i kept reading you need to aerate it and so forth. Do you find that the simple tea you make to be helpful?

Have you ever had a problem with squash bugs due to using mulch?
I was all set to put leaves down until i read what the above poster said.

    Bookmark   July 31, 2012 at 8:51PM
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