Hi
After bringing my Thai Basil outdoors I noticed some of the leaves developed some yellow dried junk on it. Anyone here know what this is, and how to get rid of it? I hope it's treatable.
Here is a healthy set of leaves for reference:
https://s44.photobucket.com/albums/f24/weapons_hot/?action=view¤t=HEALTHY2.jpg
Here is a picture of the yellow junk I was talking about:
https://s44.photobucket.com/albums/f24/weapons_hot/?action=view¤t=GUNK1.jpg
Here is another picture of the junk:
https://s44.photobucket.com/albums/f24/weapons_hot/?action=view¤t=GUNK2.jpg
Oh, and I just noticed this today when I took pictures. Just one of my leaves has this. Looks like little dots.
https://s44.photobucket.com/albums/f24/weapons_hot/?action=view¤t=DOTS.jpg
So basically, only a few (< 5%) of the leaves have the yellow dried stuff on it, and one leaf has the dots, the rest all appear to be healthy. I keep it outside on the shaded porch, facing south. I water every other day, although sometimes it gets hot and I water it to keep it from wilting.
Oh, not sure if relevant, but sometimes when I cut off the buds, I don't cut off the 2 leaves next to the buds, and when those leaves grow bigger, they kind of look funny... like curled and with sort of dents. come to think of it, most of my leaves have little dents, like they're not flat. I'm not sure if that's relevant, or part of thai basil's anatomy, or a sign of disease/insects, etc.
I'm hoping that someone here is experienced, and can take one look at these pictures and immediately see the problem. Thanks.
--Alex
Well, just my guess, but what you refer to as "yellow gunk" looks like leaf miners to me. You can see examples of their damage [url=https://images.google.com/imgres?imgurl=https://www.gi.alaska.edu/ScienceForum/ASF17/1753pic2.jpg&imgrefurl=https://www.gi.alaska.edu/ScienceForum/ASF17/1753.html&usg=__6hJZK0PnqvKSl7dwe6yeNMtW9zw=&h=375&w=500&sz=13&hl=en&start=1&tbnid=sRvukX0NW4p4DM:&tbnh=98&tbnw=130&prev=/images%3Fq%3Dleaf%2Bminer%2Bdamage%26gbv%3D2%26hl%3Den]here[/url] and [url=https://www.hort.purdue.edu/rhodcv/hort410/peas/lfminer.jpg]here[/url].
I can't see the little dots very well, but they might be associated with the leaf miners, or they might be from something like red spider mites. You can see an example of red spider mite damage [url=https://ipm.ncsu.edu/cotton/insectcorner/photos/images/Spider_mite_damage2.jpg]here[/url].
I use Safer's Insecticidal soap for red spider mites. I believe you can also use neem oil. I don't know if either is effective against leaf miners. Whatever treatment you decide to use, you should apply it 3 or 4 time, with each application 7 to 10 days after the previous one, to be sure you kill any newly hatched critters.
ETA: A quick Google tells me that leaf miners can be controlled by removing the infected leaves, or else through the use of parasitic wasps. You can find some earlier threads on the various Helpful Gardener forums regarding leaf miner control if you do a search.
I can't see the little dots very well, but they might be associated with the leaf miners, or they might be from something like red spider mites. You can see an example of red spider mite damage [url=https://ipm.ncsu.edu/cotton/insectcorner/photos/images/Spider_mite_damage2.jpg]here[/url].
I use Safer's Insecticidal soap for red spider mites. I believe you can also use neem oil. I don't know if either is effective against leaf miners. Whatever treatment you decide to use, you should apply it 3 or 4 time, with each application 7 to 10 days after the previous one, to be sure you kill any newly hatched critters.
ETA: A quick Google tells me that leaf miners can be controlled by removing the infected leaves, or else through the use of parasitic wasps. You can find some earlier threads on the various Helpful Gardener forums regarding leaf miner control if you do a search.
Hi Kisal,
Thanks! Based on other pictures I googled, I'm pretty convinced it's leaf miners. Sounds like a tough critter to kill. I'm going to just use insecticide and cut off the infected leaves. I guess I might as well cut off the spotty leaf as well.
Appreciate your help. Hopefully the insecticide will work.
--Alex
Thanks! Based on other pictures I googled, I'm pretty convinced it's leaf miners. Sounds like a tough critter to kill. I'm going to just use insecticide and cut off the infected leaves. I guess I might as well cut off the spotty leaf as well.
Appreciate your help. Hopefully the insecticide will work.
--Alex
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The Helpful Gardener
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Umm, Inane?
That would be questionable to do to a food crop... see, the miner is inside the leaf, shielded from pesticides or even nematodes (a common organic method), so you would have to use a systemic insecticide, in other words, one that distributes itself throughout the plants systems; roots, shoots and fruits. I do not know of a systemic you can safely use on food crops, the only one that comes close is imidocloprid, for which there is good evidence of a hydrogen cyanide breakdown component, not what I like to add to my veggies and herbs...
Not sure it's worth it...
HG
That would be questionable to do to a food crop... see, the miner is inside the leaf, shielded from pesticides or even nematodes (a common organic method), so you would have to use a systemic insecticide, in other words, one that distributes itself throughout the plants systems; roots, shoots and fruits. I do not know of a systemic you can safely use on food crops, the only one that comes close is imidocloprid, for which there is good evidence of a hydrogen cyanide breakdown component, not what I like to add to my veggies and herbs...
Not sure it's worth it...
HG
Insecticide will kill the beneficial insects whose mission is to eat aphids and other harmful insects. Insecticides will also have residual effects on soil and, potentially, your plants. Some toxins have half-lives longer than the growing season of most popular vegetables.
There is also the question of the "inert" ingredients. In some cases (e.g., "Checkmate," which was scheduled for aerial spraying over cities, towns, and suburbs in northern California last year), the "inert" ingredients are even more toxic than the declared active ingredients.
Cynthia H.
Sunset Zone 17, USDA Zone 9
There is also the question of the "inert" ingredients. In some cases (e.g., "Checkmate," which was scheduled for aerial spraying over cities, towns, and suburbs in northern California last year), the "inert" ingredients are even more toxic than the declared active ingredients.
Cynthia H.
Sunset Zone 17, USDA Zone 9
HelpfulGardener Scott and I posted at the same time.
I've just found an excellent thread with discussion of soil/plant biology. Although its title refers to compost, the thread has lots of good food for thought (image selected on purpose).
Please see
https://www.helpfulgardener.com/forum/viewtopic.php?t=13426
Cynthia
I've just found an excellent thread with discussion of soil/plant biology. Although its title refers to compost, the thread has lots of good food for thought (image selected on purpose).
Please see
https://www.helpfulgardener.com/forum/viewtopic.php?t=13426
Cynthia
heh... I didn't expect any more replies to this thread. Thanks for the warnings you guys. But too late!
I already bought and used "ortho max flower, fruit, & vegetable insect killer" which said on the back label that it can kill leaf miners. So I misted it lightly over everything, and the plan was to see what happens these next few days, then apply again a week from now.
I was under the impression that the stuff would work, since it says fruit and vegetable and leaf miner right on the label. I don't plan on eating the basil until it's huge and growing like a weed. Like if anyone has ever tried Pho noodles, the resturants will give you gigantic stems of thai basil, and the leaves will have pronounced bumpy veins, and the stems will be fat and purple - fatter than my main stem right now. I want something of that caliber someday to eat! =)
I already bought and used "ortho max flower, fruit, & vegetable insect killer" which said on the back label that it can kill leaf miners. So I misted it lightly over everything, and the plan was to see what happens these next few days, then apply again a week from now.
I was under the impression that the stuff would work, since it says fruit and vegetable and leaf miner right on the label. I don't plan on eating the basil until it's huge and growing like a weed. Like if anyone has ever tried Pho noodles, the resturants will give you gigantic stems of thai basil, and the leaves will have pronounced bumpy veins, and the stems will be fat and purple - fatter than my main stem right now. I want something of that caliber someday to eat! =)
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The Helpful Gardener
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[url=https://www.pesticideinfo.org/Summary_Chemical.jsp?Rec_Id=PC37273]Acetamiprid[/url] is safe for mammals, although the group of pesticides it belongs to, [url=https://www.pesticideinfo.org/List_Chemicals.jsp?ChemClassList=Neonicotinoid&dUseList=y&dDPR_Chem_Code=y&dEPA_PCCode=y&dCAS_No=y&dClassList=y&ChemRegList=&ChemUseList=&dS_BA=y&dEPA_Reg=y]neonicotinoids[/url] are still suspect in causing [url=https://wildlife-conservation.suite101.com/article.cfm/update_on_bee_colony_collapse_disorder]colony collapse disorder.[/url] They disorient hive creatures like ants or termites or... y'know 
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HG
.HG