Something wrong with my cucumber plants...

[Cael]

Hi there,

I have been having trouble with my cucumber plants lately. Little spots on the leaves are turning various shades of whitish, yellowish, greyish brown and then dying, leaving holes in the leaves. This is also happening around the edges of the leaves. I'm in central Canada and we've been having a wet season with cool temperatures. Does anybody know what it is and what I can do about it without using chemicals?

Thanks!

[Meatburner]

Cael, without pictures of the leaves and an overall of the cucumber plant, soil composition, more accurate weather conditions, when did the condition start, etc., it is impossible for anyone to help you. Have you tried the "search" function to see if you can get some insight there?

[rainbowgardener]

without picture etc, I'm just guessing. But does it look something like these:



https://gardeningintunewithnature.bangor ... r-Leaf.jpg


https://www.stclareseeds.com/gardendisea ... mildew.jpg

Powdery mildew, the commonest disease of cucurbits (squash family plants)

Starts out looking talcum powder-ish, but: In advanced stages, however, powdery mildew can cause foliage to yellow, curl or turn brown, and eventually defoliate the plant prematurely. https://www.stclareseeds.com/gardendisea ... ildew.html

[imafan26]

Cucumber and squash always end up that way for me. Weekly preventive fungicides, good spacing, and drip watering helps prolong the life of the plants.

Fungicides are especially important in humid weather and overhead watering will make it worse.

[rainbowgardener]

since you said without chemicals, organic fungicides include diluted milk (let it sit a little while at room temp to culture the bacteria and spray on), baking soda solution, 3% hydrogen peroxide sprayed straight from the bottle, Neem oil (which you can get from garden stores). Whatever you spray, be sure to do it thoroughly including the undersides of leaves. They all work best preventatively. Remove the worst affected leaves and then spray weekly. Don't mix them, but you can alternate treatments.

But come back and let us know if this is the problem you are having!

[Cael]

It doesn't look quite like that. More brownish/greyish and more full of small holes. I would post a picture, but I don't have any online. Wish there was a way to just upload them here. The weather has been cool; between 15 C and 22 C and we've had about 70 mm of rain in the past week. The spots started after the second day of heavy rains. As for the soil composition... I don't know. It's just topsoil with a bit of bloodmeal to keep the squirrels out. A friend of mine just suggested a compost tea solution, which I will make and try out tomorrow. Hopefully it will work. Might do the milk thing at the same time. Still open to more suggestions though, in case it doesn't work.

[rainbowgardener]

there is a way to just upload from your computer, very easy. In the new post box, scroll down below where it says Preview, Submit etc. There's a box that says Upload Photos. In it is

File Name ________________ Browse.


If you click on the Browse button, it will show you the files on your computer. Just find the picture file you want, click on it to Select and then click Add the File, Submit.

[Cael]

Awesome, thanks! That is so much easier than what I read in the "how to post photos" thread. Hope this works...

[applestar]

I may change my tune later, but right now, my cucumbers and squash as well as beans are taking off -- rapid growth every day. In the mean time, the lowest leaves are starting to yellow or get spotty.

So I'm just cutting off everything that doesn't look whole or healthy and putting them in the trash. So far it's only the beans, sunflowers, and tomatoes that are getting spotty leaves on the bottom.

The cucumbers and squash are getting faded yellow leaves, occasionally slug and snail holes. They all get cut off and tossed. I'm not even bothering to identify the cause.

Just one way of dealing with it.

Oh, btw, when I cut off cucurbit leaves, I cut where the leaf stem joins the leaf where it's solid.

[rainbowgardener]

Your yellowing spots look like the damage from some kind of sucking insect. Have you checked closely?

Squash bug damage can look like this:


https://kathrynanddavid.com/wp-content/u ... 10-adj.jpg

this has more info about them:

https://kathrynanddavid.com/2010/08/squa ... le-garden/

but there's lots of other sucking insects

[Cael]

I did pick off a green caterpillar a little while ago. It was rolled up in one of the leaves, but more damage has occurred since then and I have examined every inch of the plants every day. No more caterpillars. I did also find two tiny green bugs. They were a touch bigger than aphids, but the same lime green colour, with wings folded against their backs. I tried to look them up, but couldn't find a picture. I squished them and haven't found any more of them. Maybe they're to blame?

[imafan26]

The light green bugs with folded wings could be leaf hoppers or plant hoppers.
The brown spots on the leaves may be from downy mildew.

Powdery mildew shows up as white or gray cloudy spots on the top of the leaves. Downy mildew attacks leaves from the undersides and the top shows round tan spots

https://www.cals.ncsu.edu/plantpath/exte ... Mildew.htm

Fungal diseases are easier to prevent than treat.

[Lindsaylew82]

Yeah either downy mildew or bacterial wilt. I'm thinking bacterial wilt.

You said you saw little green bugs, but have you seen any little beetles that look like striped or spotted lime green lady bugs hanging out anywhere? They look like this...

Spotted and striped cucumber beetle

image.jpg (29.55 KiB) Viewed 3758 times

https://www2.ca.uky.edu/entomology/entfa ... otcuke.jpg

They carry bacterial wilt, and they're sneaky AND they're wicked fast.

Your injured spots look a lot like bacterial wilt, and I'm thinkin your green bugs are cucumber beetles. (But your description of them made me think leaf hopper, too )

[Cola82]

Is the leaf in the photo you posted the worst on the plant? Is the plant doing well overall? Still putting on new growth? Or does it seem stunted? Is it aborting its fruit?

It could be a mix of things--caterpillars, spider mites, aphids, a little fungal thing. Bugs will do a certain amount of damage no matter what, so depending on the overall condition, this could just be normal wear and tear. Could you share a photo of the whole thing?

Sorry for the barrage of questions. I think there's probably something going on, I just think it would be helpful to know.

[Cael]

I have not seen anything like those beetles on them. I did pick a couple more of those super fast bugs that look a bit like aphids off of them though. That leaf is not the worst. I'd say it's average. There is still new growth and the first bloom just opened this morning, so it doesn't seem like it's stunted. The spots that were brown last week are now holes, but there are not many new spots, so it seems that something is working. I haven't seen any more of the green caterpillars on them, but I've picked them off my dill, kale, tomatoes, rhubarb, parsley, and basil. Clearly they're not picky.