What is damaging my cucumber?

Cucumber    Jupiter, FL, United States

Suyo long variety, sowed in May. It was producing beautifully but suddenly the plant is damaged. It looks like an insect is eating it but I have not seen any frass nor insects on the plant. The leaves are kinda disintegrating. What is causing this and how can I get this cucumber plant to thrive again?

Posted by: Alyssa Wood (1 point) Alyssa Wood
Posted: July 17, 2014

Lindsay McMenemy commented,
Could you get some close-up images of some of those yellowing areas? The leaf edges and in the first picture I can see some kind of yellow and brown lesion too
over 5 years ago.


This is hard to diagnose. Because it is a common disease and because it causes irregular holes in the leaves I am inclined to suggest it is angular leaf spot casused by the bacteria Pseudomonas syringae pv. lachrymans.

Another bacterial leaf spot is Bacterial Leaf spot caused by Xanthomonas campestris.

This from the APS Compendia on Curcurbits https://www.apsnet.org/apsstore/shopa...
"Symptoms may appear similar to those of angular leaf spot. On cucumber, small, water­soaked lesions first appear on the lower sides of leaves and are later visible as indefinite yellow areas on the upper sides. In about 5 days, the lesions become round or angular with a thin translucent center and a wide yellow halo. The lesions enlarge, reaching diameters of up to 7 mm.
Symptoms on winter squash, pumpkin, and gourd leaves can easily be overlooked because of their small size. As lesions co­alesce, they may appear similar to those caused by Pseudo­monas syringae pv. lachrymans."

I dont think it is fungal.

Another possibility is that it just mechanical and you recently experienced a hail storm? But I guess that is not the case

What to do? Remove affected leaves and dont spray water over the leaves

If you want to use chemicals then one recommendation is copper sprays. But APS Compendia above says that is ineffective once the epidemic has begun (page 33).

can you get any closer up images and inspect around on the healthier leaves to see if anything is beginning

Posted by: David Hughes (52 points) David Hughes
Posted: July 18, 2014

I'd give it a good hit of compost tea! The combination of probiotics will probably knock out the issue unless the plants are nearing the end of their lives anyhow.

Posted by: David Goodman (67 points) David Goodman
Posted: July 30, 2014

Jocelyn commented,
Have you already had a good crop of cucumbers? The plants have a life cycle and once they have produced their crop the plant begins to die. So pull it, compost if it doesn't have any diseases and mulch the bed for more stuff!
over 5 years ago.

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