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Integrated Pest Management (IPM) is the practice of integrating various pest management methods (chemical, cultural, biological, genetic, etc.) and pest control disciplines (entomology, plant pathology, weed science, etc.) into a systematic approach to pest management decision making that targets optimization of net return in crop production while minimizing environmental impact. As a management practice, IPM decision making is based on information collected from the field in a systematic manner. As a result, the practice of IPM depends on a field monitoring of pest populations and crop developments which is often referred to as field scouting.
Application of IPM procedures to corn production may be executed by (1) growers scouting fields themselves, (2) contracting the services of a field scout or consultant, or (3) commercial ag service personnel including field scouting as part of their service to clients purchasing their products. The pest management decision making process may be exercised by anyone if procedures are clearly understood and field information has been collected and recorded in an accurate and timely manner.
An IPM program applied to field corn may include one or more of the following features:
Depending on the pests targeted in an IPM program, a field scouting program may include observations ranging from April through October. However, most field scouting for pest activity focuses on the months May, June, July and August. Average field corn planting, silking and maturity plus peak activity of key pests are illustrated in Figure 1. Comparison of corn development with the occurrence of peak activity of key pests illustrates the need for scouting from corn emergence through corn maturity. However, if evaluations of soil pest activity is needed prior to planting and yield data is required, then the period of field scouting for evaluation of pest populations and impact may be significantly expanded.
The occurrence of peak activity of key pests of corn is illustrated in Figure 1. These key pests include (1) the early season pests, namely black cutworm, common stalk borer, armyworm and slugs, (2) 1st brood European corn borer, and (3) adult corn rootworm beetles. Periodic field inspections are needed throughout the growing season if economic infestations are to be managed in an effective manner. However, it should also be recognized that serious problems with these pests warranting corrective rescue treatments occur infrequently. The probability of having problems with cutworm, stalk borer, armyworm or slugs is generally associated with the use of reduced tillage practices, especially the practice of no-till. Economic infestations of European corn borer seldom occur in Ohio, but timely treatment is needed when significant problems develop. The problem of rootworms is only associated with planting of continuous corn. As a result, fields may be prioritized in regard to their need for field scouting based on cultural and tillage practices.
Figure 1. Ohio field corn development and peak activity of early season pests, 1st brood corn borer and adult corn rootworm beetles.
In addition to the key pests cited, attention may focus on other pest problems such as those attacking the seed stage, early season pest problems such as flea beetles or webworms, chinch bugs and corn leaf aphids attacking corn prior to the silking stage, or any other unusual pest problems that may develop. These pest problems occur much less frequently than the key pests, but periodic inspection for the key pests will detect the less common pests if they should occur at noticeable levels of activity.
Field scouting for weeds in an IPM program is a routine practice during the early stages of corn development, especially when such observations may influence the application of post-emergence herbicides. A comprehensive survey and assessment of weeds in a field is generally conducted during the mid-whorl stage to identify the weed complex in a field and assess their relative abundance. Such a weed survey provides the basis for determining the forthcoming weed management herbicide program, which represents the primary pesticide expenditure in corn production.
The accurate recording of field observations is fundamental to providing information on which pest management decisions are based. The Ohio IPM Program has developed a series of field data forms, which have been used by many field scouts and modified over time to enable practical recording of field observations.
The field corn survey form displayed in Figure 2 can be used throughout the growing season. The form is printed in a pressure sensitive 3-copy format allowing 1 copy for the grower, 1 copy for the field scout, and 1 copy for a third party that may be making pest management decisions. A multi-field version of this survey form is also available. Computer software has also been developed to enable organization and analysis of data collected from multiple sites and numerous farms.
Figure 2. Ohio IPM Program Field Corn Survey Form.
Effective field scouting in an IPM program requires skills in pest identification (insects, diseases & weeds), familiarity with pest life cycles, recognition of injury associated with various pests, understanding the development of the crops, and knowing the sampling methods for measuring various types of pest activity. The party making the pest management decisions must understand the criteria and logic included in decision making application to the different pests. In addition, the decision making party must be familiar with the alternative control measures available including procedures for selecting appropriate pesticides and making recommendations.
The total pest management process is not a simple job and years of experience are often required to develop a full comprehension of the process and the variables that influence a final pest management decision. As a result, the pest management field scout, grower or decision making party must invest a significant amount of time and effort studying materials available plus achieve a significant amount of field experience to be effective.
Study materials on field corn pest management recommended by the Ohio IPM program include the following sources of information:
Copyright 1993, The Ohio State University
OPMS Circular # FC-11 CORN IPM
Prepared by: Harold R. Willson, Dept. of Entomology
January 1990
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868