Q. In my attempt to plant seedlings this year in my 4x8
raised bed, I noticed the day after I planted some pepper plants they were
decimated by some kind of insect. When I was amending the soil a few weeks
before, I noticed some small worm-like critters in the soil. I sprayed a bit of
Bt on the soil but it evidently didn't do anything to help the situation. I was
told to use a powder called "milky spore disease” to kill any grubs or
grub-like insects. Have you ever heard of this product? They said it works and
I only have to apply it one time. Sounds too good to be true. This store said
they used to carry the product but not any more for reasons unknown. I went to
the Home Depot and Lowe's, but neither store had the product.
Can you advise me on this product and
where I might find it or some other solution?
I removed the damaged plant and I'm trying to revive it.
A. The milky spore product only works on some types of
insects such as Japanese beetle which we do not have in southern Nevada, and a
few closely related insects. “Milky spore” is a bacterium and works rather
slowly, if it will work at all, on pests in southern Nevada.
Bt works
on those insect larvae that mature or pupate into either moths or butterflies.
So if the larva turns into a beetle, for instance, it will not work. So without
knowing which insect larva you have it is hard to know what will work unless
you use a conventional pesticide approved for use on vegetables and has insect
grubs or larvae on the label.
 |
| Cutworm larva |
This time of year Bt is a good product to use in home gardens because of the presence of cutworms. I am sending you a picture of what the cutworm larva looks like and its adult form (posted also on my blog), a moth. Bt can be sprayed on the soil and left undisturbed (no hoeing or irrigating) for a few days.
 |
| Dipel in this form is a dry flowable product. Dry flowable pesticides are the same as what we call "water dispersable granules". These can be mixed with water and they disperse in water easily and quickly BUT the spray mix MUST be constantly mixed or shook while applying or the pesticide with settle out and you will not be applying it anymore but will collect at the bottom of the sprayer |
This is the time of year that this moth is flying and laying eggs. Their larvae “hatch” from the eggs and are out looking for food right now. Usual cutworm damage is at the soil surface, not on the leaves. Other products to try to protect your plants are those that leave a poisonous residue for insects on the leaves. You can also use insect netting covering the rows in a low tunnel.
This is great to know, I though we did get Japanese Beetles here and thought they were synonymous with the non-specific June Beetle. Whoops! I need to figure out what these brown beetles are that look identical (color difference only) to the Japanese Beetle. Trying to formulate a better IPM that I'm not just shooting chemicals every time I have an issue.
ReplyDeleteJim and Kristin. I am not an entomologist. I am a horticulturist but if I see something I dont know I try and track it down. If you are in the LV area we have several types of "June beetles". But to my knowledge we dont have Japanese Beetle (Popilla japonica) in Nevada, north or south. So in the south that leaves us with other kinds of "June" beetles which I have personally caught here like the Green Metallica June Beetle (Probably Continus nitida), Ten-Lined June Beetle (Probably Polyphylla decemlimineata), white grubs which also make a "June" Beetle as an adult (many kinds including Japanese Beetle) and the common June Beetle (Probably Phyllophaga hirtiventris). So when a person asks for a control of grubs feeding on plant roots it can be any of them! The problem with controls like Milky Spore bacterium and others is they are very specific in what they may control. Without an real entomologist identifying the immature forms (grubs, and it can be done) it is impossible to know. So a general killer like an insecticide is usually the answer unless they want to try and see if something works.
DeleteI used your question for the newspaper. Great question. I am also concerned with using pesticides more often than we need to. Like you found out, there are lots of different kinds of "grubs" out there and to my knowledge Japanese beetle is not yet in the state of Nevada. I suspect when and if it calms it will come to the north and hopefully not the south. Milky spore bacterium is really only for Japanese beetles and very close relatives of Japanese beetles. You might try some of the nematodes which are safe to use around plants but hunt down other types of grubs. It can be obtained from places on the Internet like Arbico which I usually send people to for these kinds of products. These nematodes like cool air temperatures and wet soils so Springtime is the best time to apply them. They have a shelf life which I think is about two weeks long because they are living. So if you buy them from a company like Arbico ask lots of questions like how long can they be stored, when to apply them, what is the best mixture of nematodes to use, etc.
Delete