man4mac
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Identify whats killing my cucumbers [pics]?

We have 2 cucumber plants next to each other. One is a normal cucumber, and the other is a pickling cucumber. Recently though the leaves started "drying" up. Generally from the outside in. I'm pretty sure they've been getting enough water though

We did have some cucumber beetles earlier on but were able to get them away, and it doesn't look like bacterial wilt from what I can tell. The only bug that seems to be on it I cant quite identify (looks like a black stink bug). The normal cucumber looks the worst, but they both are affected. Any ideas what this could be?

Image

Image

DoubleDogFarm
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Re: Identify whats killing my cucumbers [pics]?

It looks like you may have both Downy mildew and Powdery mildew.

First picture: Slightly low left of center looks like Powdery mildew. With the grass stuck to the leaves, I would say the leaves have been wet.

Eric

man4mac
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Re: Identify whats killing my cucumbers [pics]?

Are you referring to how the edge of the leaf is kind of "dried out"?

man4mac
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Re: Identify whats killing my cucumbers [pics]?

Also, we did have a spell of rain every day for practically a month...that would probably lead to mildew. I always assumed it manifested itself as kind of a white "powdery" look, but I'm not really seeing that.

DoubleDogFarm
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Re: Identify whats killing my cucumbers [pics]?

Image

In the red box. Powdery mildew? All the blotchy yellow looks like Downy to me.

Eric

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Re: Identify whats killing my cucumbers [pics]?

Pretty sure that's a Brown Marmorated Stink bug -- are you somewhere along the mid Atlantic coast?
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rainbowgardener
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Re: Identify whats killing my cucumbers [pics]?

The stinkbug is not a good guy in the garden and can cause damage, especially to the fruits.

But, unfortunately, I think eric is right about the downy mildew:


Image
https://www.apsnet.org/publications/imag ... 000044.jpg

note the "dried" edges.

earlier in the process, it looks like this:


Image
https://www.maine.gov/agriculture/pestic ... ke-big.jpg

Here's the article the second picture came from:

https://www.maine.gov/agriculture/pestic ... mildew.htm

But downy mildew is much more virulent than powdery. Plants often survive with powdery mildew for a long time, often long enough to be killed by fall frost instead. Downy mildew kills plants.

At this point, given how badly affected your plants are, I think they are toast and I would pull them and trash them (in a bag in the trash, NOT in your compost pile) to keep from spreading it to more of your garden.

For future reference, here's things you can do to try and prevent it:

1. Despite some strains of downy mildew overcoming currently available genetic resistance, the use
of disease-resistant or tolerant cultivars is still highly recommended as some degree of resistance remains. A list of these can be found at the North Carolina State University Cucurbit Breeding web site at https://cuke.hort.ncsu.edu/cucurbit/cuke/cukemain.html.
2. Select growing sites with good air drainage, full sunlight, and low humidity.
3. Avoid overhead irrigation to prevent leaf wetness.
4. Insure adequate, but not excessive fertility.
5. Monitor the crop frequently, and make use of the North American Plant Disease Forecast Center at https://www.ces.ncsu.edu/depts/pp/cucurbit to monitor reports of downy mildew throughout the country. Local updates are also available on VegNet (https://www.ag.ohio-state.edu/~vegnet/).
6. If early in a downy mildew epidemic, removal of infected plants may help to slow the spread of the
disease. When doing this, make sure not to spread the disease by hand or infested equipment.

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Re: Identify whats killing my cucumbers [pics]?

Cucumber, squash, tomatoes and other plants with hairy leaves and stems hold on to water. When there is a lot of rainy days and the days following rain are humid then fungal diseases show up. It is best to start an anti fungal spray program when the weather conditions are ripe for fungal disease. Prevention is much easier than cure. I start spraying withing three days of the rain stopping and every three to seven days after that until the weather gets drier.
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