Researching Maintenance

Pesticide certification What are the regulations governing pesticide availability and sale to non-certified applicators and homeowners?-New Jersey

This varies by state. State regulations must be at least as strict as the corresponding federal regulations which, in this case, stipulate that only certified operators or those under their supervision can use restricted-use pesticides. However, federal regulations do not limit general-use pesticides beyond what's printed on the label. Most states, including New Jersey, go further and stipulate that anyone who applies any pesticide for hire must be certified or under a certified applicator's supervision. A few states even require certification for fertilizer applications.

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This is a different situation than exists for homeowners, who can apply many of the same chemicals without certification. For example, most retail lawn-and-garden products use the same active ingredients and, in some cases, the same formulations as professional products. Homeowners can even use general-use pesticides packaged for and marketed to the professional market, as long as they adhere to label instructions. While this seems unfair to some people, it is a good idea to require pest-control professionals to demonstrate their competency through certification. Some people mistakenly believe that anyone can apply retail products meant primarily for homeowner use. But this is not the case if the product is used in "for hire" applications, which require certification.

You may notice that some general-use professional pesticides nevertheless have labeling noting that the product is "For Commercial Applicator Use Only" or some similar statement. It is unlawful for an unlicensed applicator, even a homeowner, to purchase or use such a product because it would be inconsistent with the label. Likewise, distributors should not sell such products without verifying certification of the applicator.

Though enforcement is not always what it should be, this system theoretically should work well. After all, no one can legally apply pesticides for hire without certification, and homeowners cannot legally obtain any product they are prohibited from using.

The perfect pH Do I have to wait for the perfect pH before re-seeding?-Connecticut There is no such thing as the perfect pH, but it should be within a certain range, depending on the turfgrass species you're trying to establish. If soil pH falls outside the preferred range, then you should take steps to correct it before seeding by incorporating the appropriate amendment-such as lime or sulfur, depending on pH-as recommended by soil-test results.

It is difficult to say exactly how quickly soil pH adjusts after you incorporate lime or sulfur-it depends on several factors. As a practical matter, though, it occurs quickly enough. Most turfgrass installers till in the amendment and proceed to sow seed as soon as all ground preparations are complete-often the same day-with no problems. Remember that it takes days or weeks for seed to germinate and send roots down into the soil, so it isn't necessary for the pH change to occur instantly. Thus, you can usually take it for granted that using the proper type and amount of material will achieve the desired result soon enough except in the most extreme cases.

This assumes that you're basing your application on the results and recommendations of a laboratory soil analysis. Some installers routinely neglect soil testing and automatically incorporate lime whenever they plant turfgrass. However, this makes little sense. After all, if you haven't had the soil analyzed, you don't know how much amendment to add. The soil might even be better off without it.

It's worth noting that lime, as well as sulfur, is graded according to the percentage of the material that will pass through certain screen-mesh sizes. Finely ground material will change pH more quickly than relatively coarse material, so the physical quality of lime and sulfur is important. Many states set minimum fineness standards that help ensure products are of adequate quality for this type of use.

Any time you have the chance to correct soil pH by tilling in the amendment before establishment, you should do so. It is much easier to correct pH this way. To not do so would be a wasted opportunity.

Webworms galore Oklahoma is being overrun with fall webworms. Is there a preventive treatment for them?-Oklahoma Fall webworms have been heavier than usual for the last few years, according to Oklahoma extension specialist Dr. Ken Pinkston, who notes that several factors influence population levels, causing them to vary from year to year. Pinkston explains that fall webworms have two generations per year in Oklahoma. The first will cause defoliation in June through early July, while the second generation is active in late summer and fall. Webworm feeding and webbing is highly visible, but the second generation is more numerous, producing heavier damage. Thus, complaints usually peak in the fall.

Autumn defoliation usually causes little harm to trees. By this time, the season has nearly come to an end, and trees will have already stored most of the resources they'll need for next year's growth. Thus, one approach to fall-webworm damage is educating clients and the public that the webworms pose little more than an aesthetic problem, and that treating actually provides little substantive benefit to the plants. Of course, pest control in ornamentals often is for aesthetic reasons, so valuable or high-visibility trees, or insistent clients or club members may justify fall treatments. Realistically, how hard you work to promote this concept may depend on whether you work from a fixed budget or sell the treatments.

The first generation may be more of a concern. Although the trees will leaf out again after being defoliated, the aesthetic effects will last a while at a time of the year when people expect trees to be in full leaf (whereas fall defoliation occurs shortly before the trees would naturally drop their leaves anyway). Many effective insecticides have registration for fall webworms. Using spray equipment that can reach high up into trees and that has enough force to penetrate the webbing is more important than using any particular product. Preventive treatment for webworms (and most other pests) is contrary to good IPM practices. However, a careful visual inspection should reveal webworms before they are large enough to produce conspicuous damage. Treating the first generation will not affect population levels in the second generation.

Pinkston states that the April cold snap that hit much of the Midwest this year may reduce webworm levels somewhat. However, parasitic wasps that prey on webworms may have been similarly affected, so it's difficult to tell how numerous webworms will be this year.

Those with decision-making responsibility for trees must balance the desire to preserve trees with the need to identify and remove hazardous specimens. In spite of the development of several tools for diagnosing tree decay, visual assessments remain the primary method of evaluating trees. Signs such as cracks, wounds, fungal fruiting bodies and cankers are evidence of problems. Researchers at the University of Florida asked the obvious question: How accurate are those in the field of arboriculture at predicting hazards based on outward signs?

To answer this question, the researchers selected 10 laurel oaks and marked cross sections at critical points such as branch bases or trunks. They then asked 10 tree experts to evaluate the trees and predict the degree of internal decay and loss of strength at each indicated cross section. Afterward, the researchers dissected the trees and compared the actual amount of decay with the tree experts' predictions.

The results indicated a high degree of accuracy in predictions made by the participants: an arborist, a head tree surgeon, two assistant tree surgeons, a consulting forester, a botany professor, a plant-ecology graduate student, two utility foresters and a horticulturist.

In addition, the researchers allowed some of the test subjects to perform preliminary tree dissections. In the actual evaluation, these individuals made more accurate predictions than those that did not participate in the preliminary dissection. The investigators point out that this is evidence of the value of in-service training for improving the skill with which tree managers assess tree decay.

Some turfgrass diseases thrive in high-nitrogen conditions and others prefer low-nitrogen levels. For example, dollar spot is known as a low-nitrogen disease, while high nitrogen favors brown patch. It follows, then, that the rate of nitrogen fertilization should affect disease incidence, and researchers have demonstrated this to be true. Because clippings affect the nutrient status of turf, you might also expect clipping-disposal practices to affect disease incidence. However, this has not been established through research on cool-season turfgrasses. Leaving clippings in place also could increase inoculum levels for some diseases. To determine the effects of these practices on perennial ryegrass, researchers at the University of Missouri conducted a 3-year study that looked at brown patch and dollar spot incidence under various rates of fertility, with and without clipping removal.

Using a blend consisting of four perennial-ryegrass varieties, the researchers established turfgrass plots, which they mowed 3 times weekly and monitored over a 3-year period. They applied various levels of nitrogen, potassium and iron to the plots. However, the potassium and iron treatments showed no effect on disease incidence, so they pooled plots with the same nitrogen treatments to determine the effects of nitrogen. Nitrogen treatments included 120 kilograms per hectare per year (about 2.5 pounds per 1,000 square feet per year) and 240 kilograms per hectare per year (about 5 pounds per 1,000 square feet), in the form of 50 percent urea and 50 percent IBDU (they used 100 percent urea for March and November applications). They mowed each fertilization plot and collected the clippings in one-half of each plot, while leaving the clippings in place in the other half.

The researchers evaluated the turf once a month for disease rates and overall quality. They found that the low-nitrogen and clipping-removal treatments increased the rate of dollar spot, while leaving clippings in place and higher nitrogen rates increased brown patch.

However, the researchers note that implementing a program using clipping disposition and fertility levels to manage disease could be impractical because of counteracting effects on disease. For example, if you increased nitrogen and left clippings in place to suppress dollar spot, you would probably increase your turf's susceptibly to brown patch. You would then have to monitor weather conditions closely to predict brown patch outbreaks. In the transition zone, this would be difficult due to rapidly changing weather.

These results are what you might expect given what we know about each disease. Still, this may be the first research on cool-season turf that confirms that clipping disposition can affect incidence of brown patch and dollar spot.

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