New pest controls for the new millennium
As the clock passed midnight on January 1, 2000, you may have felt let down. "Gee, it doesn't feel any different. Business as usual." Your operation probably seems the same way. Take pest control. You mix a chemical in your tank, then you spray it. Or spread it. Same ol' thing, right?
Almost. The "how" may be similar, but the "what" is rapidly evolving. We are on the cusp of a new era in pest-control products. Manufacturers are introducing products that are effective at exceptionally low rates and narrowly target pests, sparing non-target organisms and reducing risks to applicators.
Their acceptance in the marketplace has been rapid. Many more products are in development and should be available soon.
You still have to spread or spray these products, but that's where most of the similarities end. In the following pages, university specialists describe what's new and hint at a few that are on the way.
Clearly, what the field of pest control is like now is different from what it was like 10 or 20 years ago, and the next 10 years promise to bring just as many changes.
Let's start with a look at new insecticides, beginning at right.
INSECTICIDES Most turf managers are familiar with the effectiveness of imidacloprid (Bayer's Merit) and halofenozide (RohMid's Mach 2). These products have set the standard for insecticides that are soft on the environment and tough on pests. Upcoming insecticide introductions also will maximize effectiveness with low use rates and few non-target effects.
Thiamethoxam Thiamethoxam, which Novartis will market as Meridian insecticide, is nearing release. Thiamethoxam controls a wide spectrum of sucking and chewing insects at low use rates. As a systemic, this chemical is rapidly absorbed and translocated within the plant. It also offers long residual (about 50 days in soil). Novartis also will market thiamethoxam as Flagship for use in ornamental (nursery and greenhouse) and Christmas tree production.
Meridian is effective on grubs such as Japanese beetles and masked chafers. It also controls a long list of other common insect pests including aphids, black vine weevils, leafhoppers, whiteflies, mealybugs, plant bugs and honeylocust pod-gall midges.
Insects that feed on plants treated with thiamethoxam begin showing abnormal behavior within an hour. Feeding ceases soon after ingestion, and death occurs in a day or two. Thiamethoxam is active on all life-cycle stages except the egg stage.
Pymetrozine Pymetrozine, Novartis's Endeavor, targets aphids and whiteflies. This new product is rapidly being accepted in greenhouses, landscape ornamentals, container-grown ornamentals, Christmas trees, groundcovers and interiorscapes. Endeavor is a short-residual, low-toxicity material well-suited for use in an integrated pest management (IPM) program because of its reduced toxicity to beneficial insects, including pollinators (bees), predators (lady beetles and predatory mites) and parasitoid wasps.
Endeavor is a contact insecticide that you apply as a foliar spray. After an aphid or whitefly comes into contact with the chemical, feeding ceases within hours. The insects may remain on the plant for a few days before dying from starvation.
Endeavor is also systemic in plants andthereby able to provide some residual systemic control. For example, residual pymetrozine can control aphids for up to 14 to 21 days after application, and whiteflies for up to 7 to 14 days after application. Endeavor is effective against all aphid life stages, but only the crawler and adult whitefly stages.
Deltamethrin Deltamethrin, Aventis's Deltagard, is a recent release. It is a broad-spectrum, low-dose insecticide for use on turf and ornamental plantings. It is effective against aphids, bagworms, crickets, leaf beetles, lacebugs, gypsy moths, adult chinch bugs, mole crickets, billbug adults, cutworms, leafhoppers, sod webworms and adult Japanese beetles.
Deltamethrin is a contact insecticide, available in two formulations: granular and a suspension concentrate (essentially a liquid formulation). Deltagard T&O is for landscape use, while Deltagard GC is available for golf course use.
As with any new product, the track record of these insecticides is limited. However, by traditional standards, they possess outstanding effectiveness and few non-target effects. Grounds managers should not treat these chemicals as panaceas, but they are excellent additions to your control options.
John C. Fech is an extension horticulture specialist, and Dr. Frederick P. Baxendale is a turf entomologist, both with the University of Nebraska (Lincoln, Neb.).
FUNGICIDES The new millennium presents new problems for disease management, but also promises new opportunities. On one hand, we are concerned about the loss of fungicides due to re-registration issues. On the other, we are fortunate because some new and effective fungicides are being brought to the market.
Unlike older fungicides discovered through the traditional process of mass screenings of random compounds for antifungal activity, many of the new fungicide classes are based on modifications of antifungal compounds produced by microorganisms. These new chemicals are active at low application rates and have low mammalian and avian toxicity, making them top-notch products by traditional standards.
One of the most promising new groups of fungicides is the strobilurins, also known as b-methoxyacrylates. These fungicides are based on an antifungal substance produced by the fungus Strobilurus tenacellus, which feeds on decaying plant materials in the soil. It is believed that the fungus produces this product to inhibit the growth of competing microorganisms. Chemical modifications of the original molecule have resulted in synthetic strobilurin fungicides with greater chemical stability and more desirable plant adsorbtive characteristics.
The strobilurin fungicides inhibit cell growth by preventing cells from efficiently generating energy in their mitochondria. Strobilurins are active against a broad range of fungi but are non-toxic to mammals and birds. The low toxicity characteristics of strobilurins have earned them the EPA's designation of "reduced risk."
Although the strobilurins inhibit fungal growth at low concentrations, one concern is that they act on a single target site, which may make them susceptible to the development of resistance. Also, a few groups of fungi, including the dollar-spot pathogen, are not sensitive to these compounds. Fortunately, manufacturers of strobilurin fungicides are monitoring fungal sensitivity to strobilurins and have made application recommendations to reduce the risk of developing fungicide resistance. The traditional advice for resistance management applies here-you should rotate among chemical classes, not just specific products. Therefore, for chemical rotation purposes, treat all strobilurins as the same thing.
Although manufacturers' primary intention in modifying the natural strobilurin molecule was to increase its chemical stability, these resulting strobilurins display different qualities that affect their fungicidal characteristics.
Below are two strobilurin fungicides available for turf and ornamental use. Additional forms of strobilurins are under evaluation, and some are slated to reach the marketplace in the next few years.
Azoxystrobin Azoxystrobin, Zeneca's Heritage, was the first strobilurin fungicide available for turfgrass use. This fungicide has both protective and systemic activity. Although azoxystrobin has good curative properties, the manufacturer recommends that turf managers use it preventively to reduce the risk that fungal pathogens will develop resistance.
Kresoxim-methyl Kresoxim-methyl is another strobilurin and is labeled for ornamental disease management as TopPro's Cygnus fungicide. Kresoxim-methyl primarily has activity on the leaf surface, is redistributed across the leaf surface and is able to translocate through the leaf to provide protection to the opposite leaf surface. In this fashion, kresoxim-methyl acts as a protectant. However, it also has some curative ability, such as on crab-apple scab.
Trifloxystrobin Trifloxystrobin, an oximinoacetate, is labeled for turf use as Novartis's Compass. It acts primarily as a contact but does have some systemic characteristics. The fungicide is initially adsorbed to the leaf's waxy cuticle and then is redistributed across the leaf surface, similar to kresoxim-methyl (this activity is termed mesostemic). This redistribution also may occur through the leaf from surface to surface. Only a small portion of the chemical resides within the plant tissue, and little translocation of the product occurs in the plant's vascular tissue. However, the amount that does move into the leaf is sufficient for some disease control.
One interesting characteristic of trifloxystrobin is its ability to redistribute itself to adjacent plants (within a range of about 2 inches) through a vapor state in concentrations high enough to provide some disease management to plants that were not directly treated.
Biological products A few microbial fungicides have been introduced recently. Unlike strobilurins, these products are not derived from microbes, they are microbes.
One such product, introduced in 1999, is Eco Soil Systems' Spot-Less, an irrigation-injected preparation of the bacterium Pseudomonas aureofaciens. Debuting a few years earlier was Wilbur-Ellis' BioTrek, consisting of the beneficial fungus Trichoderma harzianum. Sybron's Green-Releaf is developing a bacterial biofungicide that has performed nearly as well as conventional fungicides in some trials. This product is still undergoing testing and development, so registration may be a few years away.
Traditional definitions don't apply well to microbial fungicides. Their activity may be described as more antagonistic than fungicidal in the strict sense. In some cases, their value lies in their ability to suppress disease, rather than cure it in the traditional sense. Microbial products also may increase turf vigor, thereby improving disease tolerance.
Although the strobilurins have received considerable attention, they are not the only group of fungicides we can expect to see in the future. The newer fungicides will likely come from classes of fungicides with names like hydroxyanilides, phenpyrroles, anilinopyrimidines and cyanoimidazoles. Even though the names are daunting, the future is promising. The common characteristics of these fungicides, like the strobilurins, are that they provide disease management at low application rates and are safe for the applicator and the environment.
Dr. Jon Powell is a plant pathologist at the University of Minnesota (St. Paul, Minn.).
HERBICIDES Only a few new herbicides have been developed in the past few years. Most changes in the turf and ornamental herbicide market involve new formulations, new trade names or new combinations of existing chemicals.
Quinclorac Quinclorac, TopPro Specialties's Drive, is a post-emergence turf herbicide with some soil residual. An important use for Drive in turf is post-emergence control of crabgrass. Drive is both leaf- and root-absorbed and safe on Kentucky bluegrass, tall fescue, perennial ryegrass, common bermudagrass and zoysiagrass. Other turfgrasses are less tolerant of the compound. Check the label for treatment information for specific turfgrass species. You must not use Drive on golf greens or collars, nor should you apply it within 4 weeks after emergence of newly seeded Kentucky bluegrass or perennial ryegrass.
Drive controls large and smooth crabgrass and certain other annual grasses, but it will not control goosegrass. What separates Drive from many other post-emergence crabgrass herbicides is that it also controls some broadleaf weeds, such as white clover and dandelion. Include a crop-oil concentrate or methylated seed oil for optimum effectiveness.
Drive has an unusual weed-control spectrum. Because it will not control all broadleaf weed species, you may want to mix it with broadleaf herbicides. For example, you can mix Drive with phenoxy-type combination products for control of a wide range of broadleaf weeds as well as crabgrass in a single application.
Because Drive does not control goosegrass, another application strategy is to apply Drive plus a residual (pre-emergent) grass herbicide after the onset of crabgrass germination but prior to goosegrass germination. The residual herbicide will provide pre-emergence control of goosegrass, while Drive will control the emerged crabgrass. You can rotate Drive with other products to reduce potential for development of resistant weed species.
Drive can injure broadleaf ornamentals, so be careful to avoid drift. Also, use caution when spraying near the root system of trees and shrubs because this compound is root-absorbed as well as leaf-absorbed.
Clopyralid Lontrel, introduced in 1999 by Dow AgroSciences, can be used in both turf and ornamental sites. This chemical-clopyralid-is not new, but it has not previously been available to the turf and ornamental market except in mixes with other active ingredients. Lontrel is a post-emergent, although it has a degree of soil activity. You can apply it safely to a wide range of cool- and warm-season turfgrasses, but do not reseed turf areas for 3 weeks after application and do not apply it to tees or greens. Certain ornamental species tolerate Lontrel as well, but applications in ornamental landscape plantings should be in the form of spot treatments only.
Lontrel provides selective control of certain broadleaf weeds. It works best primarily on members of the legume and composite (aster) families. Weedy members of these families include vetch, white clover, thistles, horseweed, ragweed, groundsel, dandelion and mugwort, so this includes some prominent pests. This herbicide also controls some broadleaf weeds in other plant families, such as black nightshade.
In turfgrass situations, an advantage Lontrel has over other post-emergence broadleaf herbicides is white clover control. Some existing products do not always provide acceptable long-term control of this common weed. However, because Lontrel does not control all broadleaf weeds, it is best used in a tank mix with other products. Some prepackaged combination products already contain clopyralid: Dow's Confront (clopyralid + triclopyr), Riverdale's Millenium Ultra (clopyralid + 2,4-D + dicamba) and LESCO's Momentum (clopyralid + 2,4-D + triclopyr).
Lontrel can be applied to certain field-grown nursery crops and landscape ornamentals such as white pine, Norway spruce, shore juniper, red oak and red maple, among others. However, you must be careful when applying Lontrel in or near ornamental beds. As with weed species, ornamentals in the legume and composite families are sensitive to this herbicide. Therefore, do not spray near redbud, locust, mimosa, lindens, daisies, mums, nightshades or other members of the legume, composite or nightshade families. Further, do not plant these species into an area previously treated with Lontrel because some soil residual may still be present. Lontrel is also root-absorbed, so observe caution when spraying near the root system of sensitive ornamentals.
Envoy (clethodim) Clethodim, Valent's Envoy, is the newest post-emergence grass herbicide for ornamental beds. It controls emerged annual and perennial grasses such as Johnsongrass, quackgrass, bermudagrass, tall fescue and crabgrass. Despite Envoy's activity on annual grasses, its primary use is for control of perennial grasses, which cannot be controlled pre-emergently in most landscape beds. This herbicide, like other post-emergence grass chemicals, does not control sedges, rushes or any broadleaf weeds.
Most broadleaf ornamentals and non-grass monocots, such as daylily, iris, hosta and liriope, are tolerant of Envoy. Do not allow the spray to drift into turf areas or injury could occur. Include a nonionic surfactant in the spray tank to increase coverage and effectiveness.
One characteristic that separates Envoy from other post-emergence grass herbicides is control of annual bluegrass. The other available products either have no effect on annual bluegrass or cause only limited injury. Envoy will control this winter annual grass.
New combination products Within the past few years, manufacturers have introduced several pre-emergence herbicide combinations. For woody-ornamental beds, some of the newer combinations include UHS's Pre-Pair (napropamide + oxadiazon), and Regal's Regal O-O (oxyfluorfen + oxadiazon) and RegalStar (oxadiazon + prodiamine). A similar combination product for warm-season turf and tall fescue is Scotts' Kansel Plus 28-0-0 (oxadiazon + pendimethalin).
Oxadiazon is the active ingredient in Ronstar. Prodiamine (Barricade) and pendimethalin (Pre-M, Pendulum, Corral and others) are both dinitroaniline herbicides. Napropamide is the herbicide in Devrinol, and oxyfluorfen is the active ingredient in Goal. The concept behind these combination products is to mix a broadleaf herbicide with a grass compound for broader-spectrum weed control. This is one reason to learn the active ingredients in herbicides. You may hear about a new herbicide product and not realize that it is just a combination of existing products. If you know something about the individual components, you will have a better understanding of the product.
Take a look at the application rates for the components of a combination product. Rates for one or both components could be different from that which you would normally apply for that active ingredient. Combination products offer convenience, saving the trouble of mixing separate herbicides together.
Biological weed control Currently, no effective biological weed control has full registration. However, Eco Soil Systems is developing a product that uses the bacterium Xanthomonas campestris to control annual bluegrass on golf courses. This product-called XPo-is being used on some courses under an experimental use permit and should have full registration soon.
XPo is applied via boom sprayer. If environmental conditions are favorable, it infects Poa annua plants, causing vascular plugging and eventual death. XPo works gradually and requires repeated applications. Desirable turf is unaffected.
Glyphosate Most of you probably have used the newer formulation of glyphosate, Roundup Pro, which contains an improved surfactant system over traditional Roundup. The surfactant change appears to improve the uptake of the active ingredient into weeds, improving rainfastness and effectiveness. As with any non-selective herbicide, use caution to prevent contact of foliage or bark of desirable ornamentals.
For those wishing to use the old formulation, the earlier Roundup formulation is sold under the trade name Roundup Original for use in areas such as Christmas tree plantings. Another change with this chemistry has been the development of Roundup Pro Dry, a dry formulation of glyphosate.
All the products I've discussed here offer new options for pre-emergence or post-emergence weed control in turf or ornamental situations. When using a new product, you may want to treat a small area first to learn how that product fits your needs. You could even make a test application adjacent to areas treated with older products to determine the best product for your hardest-to-control weed species.
Dr. Jeffrey Derr is a professor of weed science with Virginia Polytechnic Institute and State University (Blacksburg, Va.).