Insecticides and Miticides: What’s new? What’s old?

Wouldn't it be nice if you had about 135 different options for 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 be just as confused picking the best pesticide as I was picking the best governor.

Unfortunately, you don't have that many options. Control options are few indeed and diminishing with respect to some of the more important pests. I keep harping about the fact that leafminers are back, and they will be more difficult to deal with because there are few registered, truly effective pesticides. This means that those of you with real leafminer problems are limited to as few as two effective compounds, and I have seen populations that are resistant to virtually all registered pesticides. Tough bug!

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

With the merging of so many companies and the continued growth of government regulations, there appear to be fewer competing laboratories in the search for new insecticides. Generics, forged from patent expiration, will become the next wave of registered pesticides. This means nothing really new. Instead, it means compounds that pests have already been exposed to will be available from companies other than the developer. There is potential for new formulations of generics that may be more effective, and your price will change with more competition. However, an unanswered question remains. Will pests that are difficult to control already, become more difficult to control due to enhanced pesticide tolerance? I can't answer that question yet, but past experience dictates that they will.

Miticides

I mentioned TetraSan 5WDG (etoxazole) from Valent USA in last year'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 yet registered in California, though it should be approved next year. Sometime in 2004, the EPA should approve a label for nursery, outdoor and landscape applications. Of course, the label for California will come later. TetraSan is effective against spider mites and has translaminar abilities, which means it does not necessarily have to be directed at the undersides of the leaves.

Ultiflora 1EC (milbemectin) from Gowan Company was submitted concurrently to California and EPA for both indoor and outdoor uses. Gowan expected registration in the fall of last year. But have no fear, the EPA is telling Gowan "any day now." Ultiflora is a naturally derived broad-spectrum miticide with activity on spider mites, eriophyids and tarsonemids. 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, is presently registered for greenhouse use, but is expected to receive a new outdoor/nursery label that could be in distribution by February, or June 2004 if you live in the republic of California. This label expansion will also include tarsonemids, both the broad and cyclamen mite, as well as eriophyids and mealybugs, which we've noted in 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 of action and should provide control in all life stages of most important mites. I will 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 no indications of cross-resistance, but time will tell. Federal registration of Piton is expected any time for greenhouse and outdoor ornamentals.

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

Insecticides

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

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

A new chloronicotinyl is in development by Valent (V-10112 20SG, dinotefuran). In our trials, we are seeing very good activity against a number of insects, especially Homopterans. We are testing the product as a spray and as a drench. Registration isn't expected for a while, but I'm as excited about this compound as I was for Tristar when I first began work with it.

I mentioned thiacloprid last year as a new chloronicotinyl being developed by Bayer; however, Bayer has decided not to pursue this product in the ornamental market. However, I have known companies to change their minds.

IGRs

Michelle Bell covers IGRs on page 54, so I will keep this brief. If you are not aware, Pedestal 10SC (novaluron) by Crompton/Uniroyal is now registered in California with no changes to the federal label. It is mainly for thrips, worms, whitefly and leafminer. Recent research indicates that Pedestal 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 them wisely. 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 immature stages of whitefly, scale, mealybug and leafhoppers. It is a chitin synthesis inhibitor, so it affects the insect as it molts and should be a good fit for early use in ornamentals, especially those using beneficials. An ornamental label should be approved in most states by late spring. It has been available to greenhouse tomato and tomato transplant growers since September 2002.

New Chemistry

Bayer is developing a miticide in a new chemical class, a ketoenol (AMS-13839). I have seen some of the results from trials against mites, 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 that hopefully will produce new formulations of products like Conserve, which has been very effective against thrips.

Flonicamid 50WG is still in development by FMC. It is a nicotinoid, a close relative of the chloronicotinyls, but its true mode of action is unknown. It appears that the site of action is different than most common chloronicotinyls. Flonicamid 50 WG is considered an OP replacement and received reduced risk status, which usually streamlines the registration process. It will be registered for greenhouse use on ornamentals. Flonicamid is systemic and suppresses the feeding of sucking insects like the Homopterans and plant bugs. We've seen good activity with this product, but it also has a ways to go yet before it's registered.

Finally

Obviously, the ornamental industry would like to have as many pest control options as we had options for governor of California, but that 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 in the trends update on a yearly basis until they are either terminated or registered. As always, check with your state and local agencies to make sure that the use of these new products is okay in your area.