Diesel21
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Cucumber leaves have brown spots

Hi all. This is my first post. I seem to be having a big problem with my cucumber plants. They are flowering and growing but most of the leaves look like this. I have been spraying with liquid copper and Neem oil once a week since I transplanted.
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Gary350
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Re: Cucumber leaves have brown spots

Did you get fertilizer on the plant leaves and not wash it off that can cause dead spots. I know copper sulfate spray will make dead spots on leaves.

I read something about leaf spots 2 days all I can remember is it has something to do with certain minerals that are not available in the soil. I don't remember where I read it. Soil needs, calcium, potassium, phosphorus, magnesium, iron, sodium, zinc, nitrogen. You can not get all of these in any factory made fertilizer that I know of.

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applestar
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Re: Cucumber leaves have brown spots

Are you making sure to spray when the spray droplets on the leaves are not exposed to sunlight and heat of the day?
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Ksk
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Re: Cucumber leaves have brown spots

Hi.
Try spraying Neem at twilight vs in the morning. Keep it off the new growth and see if it comes in clean without these spots. If the new leaves are looking normal then that is possibly the problem. They almost look like burns. Also, if the new leaves look like this try a trace mineral fertilizer like Maxsea or something similar. It has copper; calcium, iron, sulphur and other trace minerals not found in common NPK fertilizers.

imafan26
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Re: Cucumber leaves have brown spots

The spots are being limited in part by the veins and the cell wall margins, and the holes look like necrotic areas have dropped out.
It suggests that the problem may be angular leaf spot which is a bacterial disease and neem may not be able to help that much.
If you have planted cucurbits in the same spot before and had this problem. It may be infecting this crop as well. It can be transmitted by seed as well as by plant residues. It is a problem in wet and humid weather and copper sprays work better in controlling it, but like most fungicides it works better preventively and not as a cure. Keeping the leaves dry would help. Maybe grow it in a different location and trellising the plant. Copper or bordeax sprays may work better as a preventive in humid wet conditions.
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7481.html
https://ipm.illinois.edu/diseases/series900/rpd919/
https://ipm.ucanr.edu/PMG/r116101511.html
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