Prancu
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Joined: Sun Apr 11, 2021 6:50 pm

Powdery Mildew??

I'm a new pepper grower and a few weeks ago I moved a couple of my peppers to bigger pots. After doing so, a white dusty coating started to appear on the leaves and leaves started dropping off. For context, these plants have never been outside. The white stuff only appears on the top of the leaves. And I've been letting the plant dry out completely between waterings (I have a meter I use) to no avail. They are under a grow light for about 15 hours a day and have a fan on them that whole time. When I first saw the white coating, I tried to treat with copper, but it seemed to make it worse and I'm not 100% sure it is powdery mildew, so I wanted to verify it first. Since most of the plant itself looks healthy, I'm just attaching some close ups of some of the leaves that fell off with the white on them. I know it's a bit difficult to see. Any help figuring this out would be appreciated!
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pepperhead212
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Location: Woodbury NJ Zone 7a/7b

Welcome to the forum!

As many peppers as I have grown through the years, I have never seen anything like this, or any diseases for that matter, indoors or out, but I know it can happen in some regions, especially in high humidity. Peppers aren't the ones I usually spray with potassium bicarbonate as a prophylactic, but it works on other plants for fungal diseases.

Maybe that is a very small pest, like mealybugs? Sometimes they are underneath, but the leaves show signs on top. Maybe someone else here has seen it.

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

It looks more like thrips or mites. It does not look like powdery mildew. Some thrips and mites are hard to see but the scars they leave behind are what you will find. Advanced cases would cause distortion of the leaves as well.

Try sulfur as long as you have not used an oil spray in the last two weeks. Sulfur works to prevent both fungal problems and as an insecticide for mites.

Pepper thrips are large, but western flower thrips are hard to see.

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

It seems like every time I’m puzzling over similar looking leaf condition because I don’t remember personally seeing anything like it, @imafan or other members from warmer climates come along and say, “oh that looks like thrips”

... I should just start posting, “I don’t remember seeing anything like it, so it must be thrips” Hope you get this resolved.

Prancu
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Joined: Sun Apr 11, 2021 6:50 pm

Thanks for all your input. Out of curiosity, how do thrips generally get inside? I sterilized all the potting soil thoroughly before I planted (from seed), and they've never been outside. So I'm just trying to figure out how it would happen so I can prevent it in the future. I use boiling water to sterilize the soil (I had a terrible fungus gnat infestation a while ago that taught me that lesson) but is there a better method for thrips?

imafan26
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Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

During some part of their lifetime thrips have fringed wings. They lay eggs and their larvae are wingless. Apparently since they are poor flyers it is not the main way they get on plants. Usually they are hitchhikers that live on other plants that more or less hop on to other plants. They are small and light and can be carried by the wind. They are ubiquitous in the environment and most of the time they come from new plants that are brought in or from flowers or plant parts brought in from other parts of the garden.

Thrips are pretty much year round pests in my yard. They do have preferred hosts which are thrip magnets like plumeria, gardenia, and orchids. in order to keep my honohono buds from being ruined by thrips and midges this year I planned ahead and treated them early before the buds started to develop. Normally, I don't bother to treat for thrips because whatever I use will kill the predators faster than the pests and I am unwilling to get rid of the thrip magnets that attract them.

Thrips do leave an etched look to the leaves called stippling and that is what the leaf looks like.



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