Cabbage damage

[Cranraspberry]

There I was thinking I outsmarted the cabbage butterflies with my row cover, but looks like something else still got in. Flea beetles? And if flea beetles, any recommendations? Last year I used spinosad on our eggplant a few times and that seemed to take care of the issue, wish I had brought it to the garden today.

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[GoDawgs]

Kind of looks like the very beginnings of that. I use pyrethrin on the plants and the ground around them for flea beetles.

Yesterday during a break in the rain I checked the garden and found the first ragged holes starting in the broccoli and cauliflower leaves. Time to get out the bT once this rain ever stops.

[pepperhead212]

No help for cabbage, or any greens, but to prevent flea beetles on eggplants I spray them with Surround, making sure I get the undersides of the leaves, and I spray frequently, to get the new growth. Good thing about it is that light rain doesn't wash much off, especially from the undersides, where it is most needed. With all those brassica greens I grow napa cabbage is a magnet for flea beetles, and will get covered with it, while hardly a hole in any others! And some of those early holes are from slugs, so I try to remember to treat the area with Sluggo, well in advance of planting...which means about now, around here!

[Cranraspberry]

@GoDawgs thank you! I’ve never used pyrethrin, can it burn/damage leaves? If spinosad doesn’t do the trick I’ll have to give it a try.

@pepperhead212 that’s the kaolin powder, right? For some reason I didn’t realize it could be sprayed on. I’ve been curious about it. And thanks for the reminder about Sluggo, I have some left from last year and should probably sprinkle it around.

[pepperhead212]

@Cranraspberry Yes, that's the kaolin powder, and spraying is the only way I apply it, as it sticks much better, than being dusted on. And I use that ThermX70, as a spreader/sticker. I have a 2 gal sprayer I use just for this - I keep a very fine SS strainer, which I put 1/2 c of the powder into, then wash it into the sprayer (I do this with everything I put into sprayers, and any large particles is filtered out), and do this a half cup at a time, using 1½-2 c/gal. I just leave it in the sprayer, as it is inert, and lasts until I mix more. Can't use it on greens, especially headed ones, as it doesn't wash off easily, but it wipes off eggplants and tomatoes easily...just not cherries!

[bower]

That does look like flea beetles alright. They are nuts for brassicas especially napa, at the farm.
I don't know what to suggest. In my garden I've only seen them really infest radishes, of all things. Same thing has happened at the farm, that the cover protecting from cabbage butterflies made a cosy safe place for them.
Edited to add: well the pros say row cover is good for them. The only problem, if they are already present or get on the crop before it's covered.

What do they do when they're not eating leaves? Hide under them? In the soil perhaps? IDK.

This one says that cabbage and other 'waxy leaved' brassicas are less damaged and less attractive to the flea beetle:
https://ag.umass.edu/sites/ag.umass.edu ... tsheet.pdf

[pepperhead212]

The reason I specified green napa as being a magnet for flea beetles is because I have grown two types of red napa, and never found a single flea beetle on them! Maybe regular red cabbage varieties won't attract them, as well?

[Cranraspberry]

@Bower an unexpected (for me) side effect of the netting is just how much stuff gets trapped under there. I don’t know if what I’m seeing are fungus gnats or actual mosquitoes - they sure are mosquito sized - but there’s basically a cloud of them under there with nothing to do but keep reproducing in close quarters!

[Cranraspberry]

@pepperhead212 I have some green napa in that bed, but it looks like they started at the opposite corner and haven’t found it yet. Will give everything a spray of spinosad today and see what happens.

[GoDawgs]

@GoDawgs thank you! I’ve never used pyrethrin, can it burn/damage leaves? If spinosad doesn’t do the trick I’ll have to give it a try.

Here's a good article on it. Pyrethrin is also used in the shampoo used to get rid of head lice.

https://www.thespruce.com/pyrethrin-ins ... on-1902891

[bower]

@Cranraspberry we get something here called Winter Crane flies. They're as big or a little bigger than mosquitoes, and they turn up late fall, during winter thaws, or other times of year - you notice them in winter since there's nothing else around. They have a characteristic pattern of flying up and down vertically in whatever spot they're over, often a cloud of them.. They are harmless and don't bite. So assuming you are really early season there, it might be these guys!
Row cover is a miracle for organic growers when it works as intended. I had never seen pristine broccoli plants before. I think a loose cover is fine for cabbage butterflies, but for other things you really have to dig the edges right into the soil to prevent any from getting in.
According to what I read last night, the flea beetles overwinter in weeds or forest at the edges of fields. Then early spring they fly over and find your baby brassicas, and lay their eggs on the soil surface underneath em. The eggs need moist soil contact, they will perish if they dry out. So the extra moisture from the row cover probably helps them to hatch if they managed to get in.

[Cranraspberry]

@Bower oh interesting, I’ve never heard of these! I’ll take a closer look. They do seem much larger than gnats, and since I’m not getting bitten yet they don’t appear to be mosquitoes either (I’m one of those people that attracts all the mosquitoes, if any are out they will find me first), so looks like this might be it.

As for the flea beetles, I suspect the tulle I got isn’t fine enough to keep them out. The bed is new with new soil and I built/filled those in January, so guessing there wasn’t much to overwinter. Next year I’ll definitely get some finer mesh! I didn’t have any flea beetle issues last fall (at least not that I noticed) so I was focused on keeping butterflies and harlequin beetles out. We also had some aphids, but those were fairly easy to deal with and I thought paying extra for the super fine cover wasn’t worth it. Oh well, you live you learn!