Rational Approaches to Managing Insect Pests of Trees and Shrubs

By Robert D. Childs Entomology Dept., UMass Amherst

In the mid-1940's, an amazing thing happened in the field of insect pest management: the idea of being able to totally control insect pests with chemicals seemed to have finally become a reality. The initial results, from such compounds as DDT, were so overwhelming that making coverts to this new paradigm in pest management was easy; pest populations dropped dramatically, crop quality increased noticeably, and crop yields soared. These new compounds for pest control quite simply acted as a form of insurance for pest managers. They could apply these relatively inexpensive compounds on a regular calendar basis and not have to worry about pests while their "clean" crops would most likely earn them a good profit.

As we all know, this new trend did not persist for more than four or five years. Somewhat abruptly, growers started to discover that the insect world was quite adept at developing resistance to chemicals, even those very harsh ones made by humans. Rachel Carson's book "Silent Spring", which appeared in 1962, was the most scientifically researched book on the subject of pesticides, human health and the environment, to have ever been written up to that point in time. Despite the fact that this book was the beginning of the environmental movement in the United States, it was not well accepted by some factions. The public became alarmed while industry, farmers, and Extension were slow to recognize and acknowledge the ramifications set forth by Rachel Carson. After all, it was the function of Extension to help the farmer and those pesticides played a major role. The American public "demanded" a bountiful and clean harvest, while the chemical producers claimed to be meeting those demands (while making a profit). All of these are very legitimate issues but were not addressed, to their full extent, in the first 20 or more years of using these chemicals.

Without delving into a deep history of this era, it is important to note that Integrated Pest Management (IPM) for insect pest management originated during this time period. The essence of this new thing called IPM was not new. Plant pathologists never had the arsenal of chemical pesticides like that of the entomologists. Therefore, pathologists had to always encourage the smart use of cultural practices in order to prevent or minimize the occurrence of disease. Such practices included: culling out of infected plant material, planting disease resistant varieties, paying careful attention to irrigation practices that might encourage pathogens, removal of plant parts (stubble, etc) from the field that may harbor infectious organisms, and so on. Although these smart management practices were not called IPM at the time, they do represent the very foundation of what we practice today.

The reliance on chemical pesticides did not disappear; as we all know, their use is still an important factor today in pest management. However, the way we view and implement their usage has changed greatly. Today, pesticide users need to be aware of the connection between placing chemicals in the environment in relation to human health effects, environmental ramifications (such as ground water contamination), preserving our beneficial organisms that help to keep pest organisms in check, public perception of chemical pesticides (issues that are both well-founded and sometimes not), pesticide resistance, secondary pest outbreaks, and political trends.

The first IPM programs to be developed through the 1970's and 1980's primarily focused on food crops. Therefore, this area of IPM is now very well researched and documented. Implementing IPM for the Green Industry (non-food agriculture) came along after the initial work on food crops was fairly well established. It was slower to be accepted and implemented by this industry than it was by traditional farming. Extension services across the country began stressing IPM practices for all areas of agriculture, yet as late as 1990, the Green Industry had not yet begun to truly implement the foundations of IPM.

Robert D. Childs is an Extension Entomologist at the University of Massachusetts, Amherst. His specialty area is in the identification and management of insects that attack trees and woody ornamentals in the Northeast. He teaches 3 entomology courses a year at UMass and most of his students there are enrolled in the Stockbridge School of Agriculture. He is a frequent speaker at Green Industry conferences and writes for Extension. He can be reached at: rchilds@ent.umass.ed

Additional Information:
Foundamentals of An Insect and Mite IPM Program
Bio-Rational Pesticides
Monitoring: Growing Degree Days and Plant Phenology
Monitoring and Management Checklists
Current Growing Degree Day Accumulations

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