The selection of pesticides to be used on the turf area should be based on many criteria including the pest to be controlled, the turfgrass species the pest is infesting, the season and growth stage of the pest, the level of control desired, the application method required for the pesticide, the duration of control from the pesticide, the possibility of environmental contamination, and the need for frequent rotation of pesticides of different modes of action for the targeted pest to discourage pesticide-resistant plants, insects, and diseases. After all factors are considered, there may be two or three possible choices of pesticides for the control of the pest.
Pesticide leaching potential (PLP) ratings are now available for many chemicals (see Tables 1, 2, and 3 ). The pesticide leaching potential (PLP) value was computed based on formulas defined by R.L. Warren and J.B. Weber in Evaluating Pesticide Movement in North Carolina Soils.
Trade names listed are examples and pesticides may be sold under other trade names. A pesticide with a low rating would be very unlikely to move into groundwater or surface waters. A pesticide with a high ranking may be easily transported offsite, leach into groundwater, or may persist long enough to allow it to enter surface or groundwaters even though it moves very slowly.
The PLP values given in the following tables are based on the soil retention, persistence of the pesticide, rate of application, and percent pesticide reaching the groundwater. The PLP rating may change from site to site depending on microbial decomposition, soil pH, soil type, photodecomposition (degradation from sunlight), or transformation of chemical properties due to exposure to light, volatilization (changing of solids and liquids into gasses), and water volumes applied after pesticide application.
Leaching potential is only one of many considerations in selecting a pesticide. There will be some instances where a pesticide exhibits low leaching potential, but because of its high potential toxicity to wildlife such as fish, extra precautions may be necessary around water. These precautions should be mentioned on the label.
Labels Are Contracts
Pesticides currently available for use on agricultural, turfgrass, horticultural and residential pests in North Carolina have been thoroughly tested by the pesticide manufacturer and approved by the United States Environmental Protection Agency (EPA) before registration and release to the public. Pesticide applicators should be aware that the pesticide label is an official and binding contract between the chemical manufacturer, the EPA, and the purchaser of the product. If the label directions are not followed, the applicator may be subject to prosecution resulting in penalties which may include fines and imprisonment.
Use Best Management Practices for Herbicides on Turfgrasses
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