This article by William M. Stall appeared in the
"Journal of Vegetable Crop Production," 1999, Vol. 4(2)95-96.
arold Coble [North Carolina State] and the USDA IPM Committee have drafted a ‘definition’ for IPM. This document, which follows, may have great impact on areas of IPM programming, especially in the measurement issue and the 75-percent goal.
A key in determining whether the Administration goal of 75 percent of U.S. cropland acres under IPM by the year 2000 has been reached is having a rational definition of what growers must do in order to qualify as IPM practitioners. Adoption of IPM systems normally occurs along a continuum from a ‘largely reliant on prophylactic control-measures and pesticides’ system to a ‘multiple-strategy biologically intensive approach’. IPM is site-specific in nature, but certain general criteria must be met at each site for control methods to qualify as IPM practices. At a minimum, each site should have in place a management strategy which includes Prevention, Avoidance, Detection, and Suppression of pest populations (the PADS approach). Adoption of the PADS approach will help reduce reliance on broad-spectrum, highly toxic materials. While pesticides should be applied as a last resort in suppression systems, some use will remain necessary. The more biologically intensive the approach in each of these strategies, the further along the continuum the grower is likely to be.
Prevention is the first line of defense, and includes such tactics as using pest-free seeds and transplants, preventing weeds from reproducing, cleaning tillage and harvesting equipment between fields or operations, using irrigation water free of pest organisms, using field sanitation procedures, and eliminating alternate hosts or sites for insect pests and disease organisms.
Avoidance may be practiced when pest populations exist in a field or site but the impact of the pest on the crop can be avoided through some cultural practice. Examples of avoidance include crop rotation such that the crop of choice is not a host for the pest, choosing cultivars with genetic resistance to insects or diseases, using trap crops, choosing cultivars with maturity dates that may allow harvest before pest populations develop, and simply not planting certain areas of fields where pest populations are likely to cause crop failure.
Detection and proper identification of pests through surveys, scouting programs, or monitoring, including trapping, weather monitoring, and soil testing, should be performed as the basis for any suppression activities. Records should be kept of pest incidence on a temporal and spatial basis for each field. Such records form the basis for crop rotation selection, economic thresholds, and suppressive actions.
Suppression of pest populations may become necessary to avoid economic loss if prevention and avoidance tactics are not successful. Suppressive tactics may include cultural practices such as narrow row-spacings or optimized in-row plant populations, cover crops or mulches, or using crops with allelopathic potential in the rotation. Physical suppression tactics such as cultivation or mowing for weed control may be beneficial where soils are not prone to erosion, and temperature management or exclusion devices may play a role in post-harvest pest management. Biological controls, where available, should be considered as alternatives to conventional pesticides, especially where long-term control of an especially troublesome pest species can be obtained. Chemical pesticides are the most widely-used suppression tactic, particularly on large-acreage or high-value crops.
Chemical pesticides are important in IPM programs, but sound management of pesticide use involves the following:
- The cost-to-benefit ratio should be confirmed prior to use (economic thresholds);
- Sprayers or other application devices should be calibrated prior to use and occasionally during the use season;
- When available and where economically feasible, precision agricultural technology should be utilized to limit pesticide use to areas in fields where pests actually exist;
- Pesticides should be selected based on least negative effects on environment and human health in addition to efficacy and economics; and
- Chemicals with the same mode of action should not be used continuously on the same field, in order to avoid resistance development.
