shinyfirefly
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Joined: Wed Jul 06, 2016 11:52 pm

Zucchini leaves browning overnight

I came home from work today to an issue I've not seen before. This is only my second year gardening and last year's squash plants did well. This year a new bed was created with new soil. Overnight the leaves on one of my zucchini plants have turned brownish, a little mottled and have curled edges. The other zucchini plant behind it is fine and the Heirlook straightneck squash plant to the left is fine. Cucumbers climbing behind are fine although they are ballooning out at the bottom due to the heavy rains.

I've seen some aphids, but not many. A few squash bugs - not out of the norm. We have had significant rain lately - but today's thunderstorm was about 20 minutes. Does anyone have any ideas? pH is 6.8
Attachments
Squash plant to left of damaged plant
Squash plant to left of damaged plant
Normal zucchini plant behind damaged plant
Normal zucchini plant behind damaged plant
Close up of damaged leaf
Close up of damaged leaf
Damaged zucchini plant
Damaged zucchini plant

Peter1142
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Posts: 313
Joined: Sun Apr 13, 2014 1:23 pm
Location: SE NY ZONE 6B

Re: Zucchini leaves browning overnight

Did you spray the leaves with anything?
Zone 6b SE NY
My blog Peter's Vegetable Garden

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Lindsaylew82
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Posts: 2116
Joined: Thu May 22, 2014 1:26 am
Location: Upstate, SC

Re: Zucchini leaves browning overnight

Yeah, same question!

It looks a lot like herbicade damage, to me. I think it's odd though, that this is the only one showing cupping like that, especially since they are so close.

I'm just wondering if maybe they were grown or started in different potting medium, or if maybe this one got sprayed with remnant herbicide from the leftovers in the wand of a sprayer?
Lindsay
Upstate, SC
USDA Zone 7b/ Sunset Zone 31

imafan26
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Posts: 11387
Joined: Tue Jan 01, 2013 1:32 pm
Location: hawaii, zone 12a 587 ft elev.

Re: Zucchini leaves browning overnight

Do you have sandy soil and do you have enlarging fruit? or low pH?

It could be a magnesium deficiency.
5. Magnesium deficiency is more likely tooccur on sandy soils with a low pH, especially in dry years. Symptoms
first appear as a yellowing between the leaf veins (interveinal chlorosis), beginning on the oldest leaves and slowly spreading to newer growth. Yellowed tissues may turn brown, die, and drop out, giving the leaf a shot-hole pattern.

Magnesium deficiency usually appears during periods of rapid growth, when the fruit is enlarging.
Management—Maintain the soil pH near 6.5.
Soil test results should show at least 200 lb of
magnesium/acre. Potential sources of preplant
magnesium include magnesium oxide and dolomitic
lime. If necessary, fertigate Epsom salts
(magnesium sulfate) and magnesium oxide
through a drip irrigation system. Avoid heavy
applications of fertilizers containing competing
cations (K+, Ca++, NH4++). Foliar sprays
are generally ineffective in correcting significant
deficiencies.
Happy gardening in Hawaii. Gardens are where people grow.

shinyfirefly
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Joined: Wed Jul 06, 2016 11:52 pm

Re: Zucchini leaves browning overnight

I don't spray my plants with anything except a little insecticidal soap for squash bugs and that's typically just on the bug. These plants were grown from seed. pH is 6.8. I created the bed with 2/3 topsoil and 1/3 organic matter, just like last year. Not particularly sandy, no.

The fruit is enlarging a bit now Large on blossom end, narrower on the other. Everything is rather pear shaped. The first fruits were of normal shape and size and I was watering consistently twice a week. We've had decent rain for about ten days. Isolated showers each day. Enough to cause some end rot. From what I read, that is largely due to a calcium imbalance. So perhaps this is a part of that. I just find it strange that it is just on one plant. The plant behind it is about 10 days behind the damaged one. The first seeds didn't germinate so I reseeded.

The only other odd thing is that I have radishes planted all around them to help with pests and they bolted last night too.

Peter1142
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Posts: 313
Joined: Sun Apr 13, 2014 1:23 pm
Location: SE NY ZONE 6B

Re: Zucchini leaves browning overnight

I would take a guess that long periods of cloudiness followed by insecticidal soap spraying and extremely intense sun has burned the leaves of this particular variety.
Zone 6b SE NY
My blog Peter's Vegetable Garden

senseimitch
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Joined: Wed Jul 01, 2020 8:01 pm

Re: Zucchini leaves browning overnight

Did you ever find out what happened? We just had the same thing happen to our plants?!?

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