Times change, products change. If you wander up and down the aisles at Barnes and Noble, you'll find that most modern day philosophers encourage managers not only to expect change, but also to embrace it. Grounds managers who use pesticides as tools in their maintenance of clients' landscapes have observed many changes in the past few years. The green industry itself has undergone many changes, including the ownership of pesticide companies and distribution techniques; but the change most likely to have the greatest impact on the day-to-day operation of businesses is the introduction of new pesticide products.
OUT WITH THE OLD: DIAZINON AND DURSBAN
Ask a group of grounds managers to quickly name two commonly used insecticides. The smart money says that, without much thought, 9 out of 10 of them would reply, “diazinon and Dursban”. Why? These materials — and several other popular products — have been used successfully for decades. They were inexpensive, easy to apply and controlled a wide range of insect pests. But now they're gone.
This is not really news; at least not in the sense of the up-to-the-minute information being disgorged from your television set on the 10 o'clock news. Green industry folks have been hearing rumblings of the demise of diazinon and Dursban for the past six to seven years or so. True to their word, the Environmental Protection Agency has determined these products pose an unacceptable environmental risk, and ordered a stoppage on their sale and distribution. Fortunately, you're not left to wring your hands in angst. Other options for effective insect control abound in the marketplace.
REPLACEMENTS: IN WITH THE NEW
The “newest” insecticides are primarily synthetic pyrethroids, which include products such as Astro (permethrin), DeltaGard (deltamethrin), Scimitar (lambda-cyhalothrin), Talsar (bifenthrin) and Tempo (cyfluthrin). These products are related in structure and similar in mode of action to naturally occurring botanical insecticides, the pyrethrins. Originally, pyrethrum was created by mashing up the flowers of Pyrethrum cinerareiafolium, a type of chrysanthemum. Later, pyrethrins were refined from this botanical product. When first developed, the synthetic pyrethroids were thought to have a much lower amount of mammalian toxicity than their organophosphate predecessors, diazinon and Dursban. However, as this class of insecticides was further refined and enhanced, the oral LD 50 rating declined (remember, the lower the LD 50, the more toxic the material). In fact, the LD 50 for many of these materials ranges from 56 to 500, which classifies them as moderately toxic. As a group, they are considered broad-spectrum insecticides, and are labeled for control of insects such as aphids, caterpillars, beetles, wasps, scale insects and mosquitoes.
WHAT'S STILL WORKING?
Another group of the newer products are still on the job. Actually, they're not so much new as what's left after the organophosphates are gone. Horticultural oils, insecticidal soaps, Merit, Mach 2, Conserve SC and Chipco Choice remain excellent options for control of many insect pests of turf and ornamentals. At this point, these materials look to remain available for the foreseeable future. Of course, as with any insecticide, be sure to read and follow all label directions to determine pests controlled, appropriate application techniques and important safety precautions. Specifics for this group:
- Horticultural oils and insecticidal soaps
These insecticides offer effective control of soft-bodied pests such as whiteflies, aphids, mealybugs, caterpillars and spider mites. An attractive feature of oils and soaps is their high LD 50 value; they are considered practically non-toxic. This feature can be a very powerful sales tool for the grounds manager — effective results with minimal environmental risk. However, these materials have several significant drawbacks. First, in order to be effective, the spray solution must physically contact the pest. Spray residues that dry on the foliage are no longer active against the insect pest. Thus, insects that hatch or arrive after the spray application has dried are usually not affected. Second, the target pest must be in a susceptible life stage. Mealybugs and scales produce coverings that can greatly reduce the effectiveness of oils and soaps. Only their “crawler” stages can be effectively controlled. Finally, thorough spray coverage is essential. If an aphid, for example, is hiding on the underside of the leaf and does not get sprayed, it stands a good chance of survival. (For more information on horticultural oils, see “How to” on page 52.)
Merit offers excellent control of white grubs in turf, and is a good choice for soft scales, black vine weevil larvae, most borers and adult Japanese beetles. The key to success with Merit is anticipating the need, because you need to make most applications 20 to 30 days prior to the anticipated insect problem. When using Merit, it is important to explain to your customers that they will not see hordes of dying bugs, gasping for their last breath in their lawn and landscape.
- MACH 2
Primarily a turf insecticide, MACH 2 offers good control of white grubs, billbugs, as well as caterpillars such as cutworms and sod webworms. Like Merit, MACH 2 provides long-term control of insect pests.
- Conserve SC
Derived from a naturally occurring bacterium, Conserve SC (spinosad) provides effective control of caterpillars (armyworms, cutworms, webworms), thrips, leafminers and other insects attacking turf and ornamentals. Conserve SC is active through ingestion or by contact exposure. Feeding generally ceases within a few minutes, and death of the target pest occurs after 1-3 days.
- Chipco Choice
This product continues to provide excellent control of mole crickets and fire ants in turf.
- IPM IS STILL CHIC
No matter which insecticide you choose, whether it's new or existing chemistry, the hallmarks of Integrated Pest Management (IPM) — right plant, right place; good cultural practices; use of resistant varieties; scouting; economic thresholds; and proper timing of control measures — are still the way to go in terms of your overall pest management program. None of these elements change — only the pesticide products, and these represent only one tool in your arsenal.
Dr. Frederick P. Baxendale is professor or entomology and extension specialist, and John Fech is an extension educator, both at the University of Nebraska (Lincoln, Neb.).
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