I need help indentifying my squash issues

Hello Permie Village,

I'm having a problem with squash in my garden. In spring my squash was killed off one at a time by this problem and now my fall planting is doing the same. These squash are delicata and Pensylvania Dutch crook neck. The latter is supposed to be resistant to squash bugs.

OK, the white starts slowly on one leaf and then spreads to the other leaves. It starts on the leaf, down where the stem is, and then goes all the way to the tip. Eventually, the plant is weak and droops horribly in even the least sunlight.

Eventually it goes to the next plant and then the next and then the next. My squash are about six feet apart in the garden.

I can't find anything on the net. It isn't fungus, I've seen that at a friend's house. This is purely a coloration issue in the leaf. Please see the pictures. One is a picture of a leaf starting to turn and the other is a plant that's totally taken over and going fast.

Any help would be earth-shattering for me at this point. Yeah, I need to calm down

Sounds like powdery mildew. I think the best thing for that is to increase air circulation and try to keep the foliage dry.

Paul Abbott wrote:Sounds like powdery mildew. I think the best thing for that is to increase air circulation and try to keep the foliage dry.

Now that I've uploaded the photos do you still think that? I've seen a friend's squash and that was very much a mildew and powdery. This is only color, no powder. let me know. Thanks for the help!

I'd have to say that it kind of looks like a micronutrient deficiency to me. What's your soil like? Do you know the pH, because at certain levels nutrients can become unavailable for absorbtion by the plant even if it's plentiful in the soil.

mnewby McCoy wrote:I'd have to say that it kind of looks like a micronutrient deficiency to me. What's your soil like? Do you know the pH, because at certain levels nutrients can become unavailable for absorbtion by the plant even if it's plentiful in the soil.

Interesting. My soil is nice and dark, but I may have a pH issue. I'll have to check it. Do you suggest a preferred method?

Those white leaf veins show signs that the plant could be deprived of a nutrient. And those look like pine needles under the squash plants. If the soil is too acidic, some nutrients will be unavailable to the plant. PH tests can be had at garden stores. If that ain't it....maybe leafhoppers...Now I feel like Bill Frist diagnosing Terri Schiavo from afar!

Weird and crazy. That white's all real, no flash whathaveyou?
I'm a fan of laboritory soil tests. If you're in the US, it's usually really cheap. Be aware that a basic soil test won't show micros, but I think it's worth stumping up for a big, expensive, one-off test of everything. Most mineral quantities are pretty stable so it doesn't need to be a regular thing.
Caveat: I haven't tested micros as I'm too broke, but many places are naturally low in various nutrients. Eg: in NZ, we're generally deficient in Boron, Selenium, Molybdenum... actually most micros are pretty low here.
NZ soils are mostly very low in Phosphorus, but soil tests showed mine as being off the charts for some unknown reason. Good to know so I can avoid high-Phosphorus things like manure.
If your interested, see if anyone in your area offers 'Reams' soil tests. Specifically designed for organic growers and show what's actually available, as opposed to what's in the soil, but might be 'tied up'.
Like I said, big fan
BTW, best to test spring or autumn.

Leila Rich wrote:Weird and crazy. That white's all real, no flash whathaveyou?
I'm a fan of laboritory soil tests. If you're in the US, it's usually really cheap. Be aware that a basic soil test won't show micros, but I think it's worth stumping up for a big, expensive, one-off test of everything. Most mineral quantities are pretty stable so it doesn't need to be a regular thing.
Caveat: I haven't tested micros as I'm too broke, but many places are naturally low in various nutrients. Eg: in NZ, we're generally deficient in Boron, Selenium, Molybdenum... actually most micros are pretty low here.
NZ soils are mostly very low in Phosphorus, but soil tests showed mine as being off the charts for some unknown reason. Good to know so I can avoid high-Phosphorus things like manure.
If your interested, see if anyone in your area offers 'Reams' soil tests. Specifically designed for organic growers and show what's actually available, as opposed to what's in the soil, but might be 'tied up'.
Like I said, big fan
BTW, best to test spring or autumn.

That's all real white. I didn't even use a flash. I'll have to check the soil with my local Extensions office. These are out in open air and the soil isn't too wet. I have used pine needles in this bed last summer. It's mulched with hay now, but the pine needles are still in the system. Thanks for the advice everyone.

I'm surprised about NZ being so low in nutrients. It looks like a lush, amazing place from what I've seen.

Put some leaves in a baggie, and take the baggie to the extension office. Someone will help you diagnose the problem, but it might take a few days.

Also, what do the roots on the affected plants look like?

jacque greenleaf wrote:Put some leaves in a baggie, and take the baggie to the extension office. Someone will help you diagnose the problem, but it might take a few days.

Also, what do the roots on the affected plants look like?

I'll have to dig it up and check out these roots. That's an idea.

sunshine ax wrote:

Paul Abbott wrote:Sounds like powdery mildew. I think the best thing for that is to increase air circulation and try to keep the foliage dry.

Now that I've uploaded the photos do you still think that? I've seen a friend's squash and that was very much a mildew and powdery. This is only color, no powder. let me know. Thanks for the help!

You're right this looks like it is moving from the inside out. Not sure what it is.

sunshine ax wrote: I'm surprised about NZ being so low in nutrients. It looks like a lush, amazing place from what I've seen.

OT for a quick New Zealand tour and rant...
A lot of it's pretty green, but that's also what the touristy photos/ Lord of the Rings type stuff focuses on.
NZ's got an extremely diverse climate for such a small place and many areas are very parched in summer.
I'll take a punt that some of the mineral deficiency stuff is because the extremely young soil, but it's most likely a geological thing I don't understand.
I know the high winter rainfall exacerbates nutrient loss. Down South, they can get over 700 inches/1800cm of rain a year.
While the native plants evolved to grow in our specific conditions, we're very keen on dairy cows and chuck astronomical quantities of phoshate-rich chemical fertilisers on pasture, then irrigate it with the local river.
End rant/tour

This is just a thought because the white on the leaves really does look fungal to me, but if you rule that out, AND if your soil micronutrients look okay, you might want to look at the stems of your squash closely. Look down near the bottom -- at the biggest part of the stem, usually 3 or 4 inches from the soil -- and see if there is a hole or a slash/crack in the stem. Vine borers will lay an egg in stems and you may never notice they are around or see the hole, but once the larva starts to grow (because its eating your squash from the inside out) the stem will swell a bit and the leaves will start turning yellow and drooping. It seems to go from one end of the patch to the other with plants dying in succession. (I don't know why, unless the vine borer just lays one egg each day or something and likes to start where she left off the day before.) I've had whole squash fields wiped out by this pest. The first time I saw it, I didn't know what was going on. I kept thinking the plants just needed more water (because of the way they wilted and drooped), but that didn't help. Then I thought moles might be tunneling under the soil, exposing the roots so they couldn't take in water or nutrients. Finally I began to notice that the stems were geeting swollen and looked kind of icky. I took a knife and cut one open and found the culprit.

By the way, if you do have vine borers in the stems, you can cure the plant if you catch it early. Just carefully cut out the larva without cutting through the whole stem. Then put the stem back together and hold it in place with strips of cloth (like a bandage). You may need to splint the stem too if it wants to keep drooping and opening back up. Put a couple of popsicle sticks (or similar) on either side of the stem before wrapping it.

The best thing I have found so far to keep vine borers away in the first place though, is to wrap the bottom 12 to 15 inches with elastic vet wrap (that stretchy bandadge stuff people use on horses legs, etc.). Rolls are usually really cheap from a ranch and farm supply store, and it comes in a lot of pretty colors and patterns if you want to dress up your garden at the same time. Don't get yellow though -- it attracts a lot of pest insects. Anyway, it stretches as the plant grows and does not interfere with rain. It makes the stem too tough for the vine borer's proboscis however, so they move on and look elsewhere to lay eggs. The vet wrap also works great for tying up vines. (Just cut it into 1/2 inch wide strips. Wrap one end around the plant branch or vine and the other around a fence or trellis. It is self stick so you don't even have to tie a knot -- just press the end to itself after winding around the plant.)

Looks like a condition called Silverleaf. Check out the info here.... http://edis.ifas.ufl.edu/pp160


Silverleaf
Silverleaf was first observed in squash in Israel in 1963. It was then described as a distinct disorder differing from the genetically controlled leaf silvering that is common in zucchini-type summer squash. Although observed in Florida, and the cause of squash silverleaf is not known, but does not appear likely that drought stress causes the condition, as reported in Israel. However, stress induced by other factors may be related to the disorder. Extremely high populations of the sweetpotato whitefly are frequently noted in association with severe silverleaf. Therefore, it is thought that this insect may cause a physiological imbalance that leads to silverleaf symptoms by (a) direct feeding, (b) introduction of a toxin of some sort, or (c) by vectoring a heretofore unknown disease. No other biotic or environmental factor has been consistently related to the occurrence of silverleaf.




Silverleaf symptoms appear first at the leaf veins, as opposed to interveinal silvering that is genetically controlled, and is common in many zucchini cultivars. Symptoms develop in the interveinal area so that the entire upper leaf surface is distinctively silver. Symptoms do not occur on the leaf underside.

Fruit symptoms are not noticeable in cases of mild leaf silvering, but when leaf silvering is severe, fruit color is lighter than normal. Yellow summer squash is very pale-colored, zucchini squash is light-green to yellowish-green, acorn squash is mottled green to yellow, and golden acorn squash is white. Yield reductions and poor fruit quality are usually associated with leaf silvering.

Silverleaf symptoms have been noted on all types of squash but have not been observed in muskmelons, cucumbers, or watermelons.


Figure 21. Silverleaf on squash (foreground) and normal squash (back)

Credits: Photo by P. Gilreath

White veins are normal in Delicata leaves. I thought I had a problem the first time I grew them, too.

Powdery mildew looks different. It's inevitable up here in western Washington but healthy plants will outpace it. You can slow it down with neem oil but as the plants age the mildew takes over. Doesn't seem to effect production. I've learned to live with it.

sometimes it can be caused by rain splashing soil onto leaves
sending soil bacteria where it isn't supposed to be.

i would try some experimentation like buying a small roll of
mulch cloth and putting down a layer around each plant or
you can drive a couple of tall stakes and attach some fencing
so you can "train" the plants to grow vertically.

I grew some squash this way last year and then i added a second
layer of fencing to the top going horizontally with even more stakes
and this created a micro climate of shade underneath them and they thrived.

Wet leaves help the mildew grow. Watering the soil directly is better than letting a sprinkler wet the leaves.

My squash are turning bleach white on some of the leaves. Maybe I got to close with the roundup  ?

Bob Balmer wrote: My squash are turning bleach white on some of the leaves. Maybe I got to close with the roundup  ?

I hope you're not serious.

Bob Balmer wrote: Maybe I got to close with the roundup?

Roundup is the sort of thing that permies.com considers so bad that we won't even discuss it here.  We're looking for better ways, and I suspect you're beginning to understand why.  

I just read about issues with mulching with hay that had been stayed with a chemical to help it dry. Perhaps it's the mulch.