Insecticides and Miticides: What’s new? What’s old? By Jim Bethke

Wouldn’t it be nice if you had about 135 different optionsfor mealybug control like I had options for governor a few months ago? Yes,that’s right, I live in California. If you had that many options, you would bejust as confused picking the best pesticide as I was picking the best governor.

Unfortunately, you don’t have that many options. Controloptions are few indeed and diminishing with respect to some of the moreimportant pests. I keep harping about the fact that leafminers are back, andthey will be more difficult to deal with because there are few registered,truly effective pesticides. This means that those of you with real leafminerproblems are limited to as few as two effective compounds, and I have seenpopulations that are resistant to virtually all registered pesticides. Toughbug!

Leafminers are an extreme case, but some of the most commongreenhouse pests, such as western flower thrips, silverleaf whitefly,greenpeach aphid and of course, two-spotted spider mite, can be just as toughto control. Last year there were some new numbered compounds on the horizon,and the same amount are basically still there. The latest generation ofpesticides, the chloronicotinyls — like the pyrethroids of the past — arestill in development, but there are very few potentially new modes of action oractive ingredients beyond that. We have just gone through a plethora of newmiticides that were sorely needed, and several Japanese companies are stillworking on a few more.

With the merging of so many companies and the continuedgrowth of government regulations, there appear to be fewer competing laboratoriesin the search for new insecticides. Generics, forged from patent expiration,will become the next wave of registered pesticides. This means nothing reallynew. Instead, it means compounds that pests have already been exposed to willbe available from companies other than the developer. There is potential fornew formulations of generics that may be more effective, and your price willchange with more competition. However, an unanswered question remains. Willpests that are difficult to control already, become more difficult to controldue to enhanced pesticide tolerance? I can’t answer that question yet, but pastexperience dictates that they will.

Miticides

I mentioned TetraSan 5WDG (etoxazole) from Valent USA in lastyear’s article as a new miticide that would be registered by the end of 2002.Currently, the federal registration is for greenhouses only, and it is not yetregistered in California, though it should be approved next year. Sometime in2004, the EPA should approve a label for nursery, outdoor and landscapeapplications. Of course, the label for California will come later. TetraSan iseffective against spider mites and has translaminar abilities, which means itdoes not necessarily have to be directed at the undersides of the leaves.

Ultiflora 1EC (milbemectin) from Gowan Company was submittedconcurrently to California and EPA for both indoor and outdoor uses. Gowanexpected registration in the fall of last year. But have no fear, the EPA istelling Gowan “any day now.” Ultiflora is a naturally derivedbroad-spectrum miticide with activity on spider mites, eriophyids andtarsonemids. It is translaminar and acts on contact or by ingestion. Like Avid(abamectin) from Syngenta, Ultiflora also has activity against leafminers.

Akari 5SC (fenproximate), a miticide from SePRO, ispresently registered for greenhouse use, but is expected to receive a newoutdoor/nursery label that could be in distribution by February, or June 2004if you live in the republic of California. This label expansion will alsoinclude tarsonemids, both the broad and cyclamen mite, as well as eriophyidsandmealybugs, which we’ve notedin some of our trials on roses here at University of California, Riverside(UCR).

A new name you may begin to hear is Piton15SC (acequinocyl)from Arvesta Corporation (formerly Tomen Agro). Piton has a unique mode ofaction and should provide control in all life stages of most important mites. Iwill try to clarify about Piton’s mode of action without getting too technical.Let me just say that it is a mitochondrial electron transport inhibitor (METI)like Akari but has a different site of action. At present, there are noindications of cross-resistance, but time will tell. Federal registration ofPiton is expected any time for greenhouse and outdoor ornamentals.

One of the numbered compounds I’ve previously written aboutnow has a name. Forbid 4F (spiromesifen), is being developed as amiticide/insecticide by Bayer Crop Science. It is a new chemical class from thecyclic tectronic acids that interfere with lipid biosynthesis. That helpsclarify that, doesn’t it? I know you don’t really care because all you want tosee is dead pests, but new modes of action are the kinds of things that excitethose working in resistance management. It has activity on mites and whitefliesand has been tested extensively on vegetables. Bayer also says it is safe forbeneficials. Look for more about this one in the future.

Insecticides

The big news with insecticides is the development andregistration of several new chloronicotinyls. The latest registration was forTristar 70WSP (acetamiprid) from Cleary Chemical. Bayer had to divest interestin acetamiprid, and Cleary Chemical has picked it up. Trials here at UCR showit to be a very good pesticide with a slightly broader scope of activity thanimidacloprid. The label will not include any drench applications, but it hastranslaminar activity. The product was registered in the United States lastyear, but it had not yet been divested. During the divesting process, there wasa bureaucratic error in the labeling, and the re-entry interval (REI) iscurrently 24 hours. All proper agencies are aware of the snafu and are workingto correct the problem. It should have been and will be back to a 12-hour REIby the end of the year.

Flagship 25 WG (thiamethoxam) is another chloronicotinylfrom Syngenta that was recently registered for greenhouse and nursery use.Flagship is a broad-spectrum insecticide that can be soil or foliar applied forcontrol of sucking and chewing pests on ornamental plants. It has excellentactivity against aphids, whiteflies and mealybugs on ornamentals as well asgrubs, billbugs and chinch bugs in turf.

A new chloronicotinyl is in development by Valent (V-1011220SG, dinotefuran). In our trials, we are seeing very good activity against anumber of insects, especially Homopterans. We are testing the product as aspray and as a drench. Registration isn’t expected for a while, but I’m asexcited about this compound as I was for Tristar when I first began work withit.

I mentioned thiacloprid last year as a new chloronicotinylbeing developed by Bayer; however, Bayer has decided not to pursue this productin the ornamental market. However, I have known companies to change theirminds.

IGRs

Michelle Bell covers IGRs on page 54, so I will keep thisbrief. If you are not aware, Pedestal 10SC (novaluron) by Crompton/Uniroyal isnow registered in California with no changes to the federal label. It is mainlyfor thrips, worms, whitefly and leafminer. Recent research indicates thatPedestal has mealybug activity when used in combination with horticultural oil.It’s a new product and worth a try, but as with all newer compounds, use themwisely. Follow the IPM recommendations on the label.

Another IGR making its way into the market is Talus(buprofezin) from SePRO Corp. It is a new insecticide for control of immaturestages of whitefly, scale, mealybug and leafhoppers. It is a chitin synthesisinhibitor, so it affects the insect as it molts and should be a good fit forearly use in ornamentals, especially those using beneficials. An ornamentallabel should be approved in most states by late spring. It has been availableto greenhouse tomato and tomato transplant growers since September 2002.

New Chemistry

Bayer is developing a miticide in a new chemical class, aketoenol (AMS-13839). I have seen some of the results from trials againstmites, and it looks good. I look forward to trying this new compound. However,it’s a long way off.

Dow Agrosciences is developing new spinosyn derivatives thathopefully will produce new formulations of products like Conserve, which hasbeen very effective against thrips.

Flonicamid 50WG is still in development by FMC. It is anicotinoid, a close relative of the chloronicotinyls, but its true mode ofaction is unknown. It appears that the site of action is different than mostcommon chloronicotinyls. Flonicamid 50 WG is considered an OP replacement andreceived reduced risk status, which usually streamlines the registrationprocess. It will be registered for greenhouse use on ornamentals. Flonicamid issystemic and suppresses the feeding of sucking insects like the Homopterans andplant bugs. We’ve seen good activity with this product, but it also has a waysto go yet before it’s registered.

Finally

Obviously, the ornamental industry would like to have asmany pest control options as we had options for governor of California, butthat is not to be. We are hoping our problems here in California will now be”terminated,” so, I’ll keep mentioning some of these products here inthe trends update on a yearly basis until they are either terminated orregistered. As always, check with your state and local agencies to make surethat the use of these new products is okay in your area.

Jim Bethke

Jim Bethke is a research associate in the Department of Entomology at the University of California-Riverside. He can be reached by phone at (909) 787-4733 or E-mail at bethke@citrus.ucr.edu.



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