The following are Japanese beetle insecticide questions from the spring garden seminar March 3.
Q: I saw in a catalog there was a new organic insecticide for Japanese beetles, called BT Plus or something like that. What can you tell me about that?
A: Thanks for bringing this to my attention, and you are right! I’m going to try it for sure, as an effective organic product for Japanese beetles hasn’t been available previously.
The name is beetleJUS!, manufactured by Gardens Alive, Inc., a well known company bringing natural and organic products to home gardeners for several decades. The active ingredient is Bacillus thurengiensis (aka ‘BT’), but a new “strain” of it has been isolated as effective on Japanese beetles and a few others, some weevils and borers. These other insect pests aren’t significant in the Jefferson City area that I am aware of. The BT strain of beetleJUS! is “subspecies galleriae strain SDS-502.”
To label a product for a specific pest, it must be proven to be effective to the EPA. This BT strain has been available to commercial companies for some time as “grubHalt!,” but labeled only for lawns. A home garden label of “grubGone!” is available, but (ironically) currently sold out due to high demand (at www.growitnaturally.com).
On beetleJUS!, the price at Gardens Alive is $25 for 4 ounces. This makes 1 gallon of spray. Unfortunately, this is quite pricey. Furthermore, the label says to mix at 4-12 ounces per gallon. Typically, we advise the higher rate when pest pressure is high. The label doesn’t specify how much area 1 gallon covers, but for low growing plants, up to 1,000 square feet is possible and less on small shrubs/lager vegetables (400-700 square feet) or large shrubs/small trees (200-400 square feet). It also says multiple applications may be needed.
I hope the product works well and the price comes down in future years. The BT product that controls common caterpillar pests are very affordably priced, comparable to synthetic insecticides.
Q: I heard that the insecticide Sevin has changed for this year. Is this true and is that a good thing?
A: It appears to be true. The old Sevin used the active ingredient carbaryl, and the concentrate was kind of a thick, white liquid and low odor. The new Sevin uses the active ingredient that is quite popular with commercial vegetable and fruit growers called Mustang Max (active ingredient of zeta-cypermethrin). It is somewhat clear, not very thick and has a discernible odor.
Carbaryl is known as very effective on Japanese beetles, but zeta-cypermethrin provides decent control as well. The primary advantage with the latter is the label allows fewer days between its application and harvest of produce. For example, ‘new’ Sevin is one day from application on blackberries to their harvest, where old Sevin required a seven-day wait.
The new Sevin sells for about $15 for 16 ounces of concentrate and mixes at 4 ounces per gallon, so a little less than $4 per gallon of mix.
Q: What about Sevin dust?
A: Now this gets confusing. Sevin dust (according to a product posting at the same major retailer for the question above) continues with the older active ingredient carbaryl. That could change. It is up to the manufacturer; they could be selling down old inventory, having formulation difficulties with the other active ingredient or still undergoing label review with the EPA.