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I have recently planted a few cucumbers from seed in pots on my porch
The soil is a mix of promix bx and soil from outside some of the plants are doing better than others but I just can't figure out what's wrong with them any help would be greatly appreciated Andrew

It is not downy mildew. Since the spots start from the edge and the ones in the middle of the leaf stop when they reach a vein, it could be one of the bacterial diseases like anthrachnose. It is a common problem of cucurbits. It helps to mulch heavily and try to keep the water off the leaves as much as possible.

I don't think it is powdery mildew either. I think it might be damage from some kind of piercing/ sucking insect or what imafan said.

Powdery mildew would look very different.
https://agronomyday.cropsci.illinois.edu ... ry_mildew/

Were those plants just recently transplanted without being gradually exposed to their new location?

ButterflyLady29 wrote:Were those plants just recently transplanted without being gradually exposed to their new location?

Nope they have been in the same pots and same locations

imafan26 wrote:It is not downy mildew. Since the spots start from the edge and the ones in the middle of the leaf stop when they reach a vein, it could be one of the bacterial diseases like anthrachnose. It is a common problem of cucurbits. It helps to mulch heavily and try to keep the water off the leaves as much as possible.

Thanks for the info, if it is a bacterial infection is there anything I can do?

This is a link to diagnostic keys from cornell. Cucurbits have fuzzy large leaves and those leaves probably evolved in a relatively dry climate to capture as much water as possible.
In wetter climates that adaptation can lead to more bacterial, and fungal diseases.
https://vegetablemdonline.ppath.cornell. ... afKey.html

Plant high on mounds and cover the ground where the leaves sprawl with weedblock and mulch with straw to keep the leaves and vines off the ground as much as possible. You can trellis some squash and use panty hose or mesh bags to support the fruit. You need a strong trellis to carry the weight. Water only where the vines are planted and try to keep the leaves dry. Drip systems are good for that. When the weather is wet or humid, begin a preventive anti fungal spray program. It is easier to prevent than try to cure fungal problems. chlorothalanil and mancozeb are a good preventive combination. For powdery mildew copper sulfate can be enough if it is used early and it is easier to find.
https://www.ct.gov/caes/lib/caes/pdio/di ... icides.pdf
Remove, bag and trash diseased leaves, don't let the spores multiply or leave the leaves on the ground.