IInnsseecctt MMaannaaggeemmeenntt oonn OOrrggaanniicc FFaarrmmss by H. M. Linker, D. B. Orr, and M. E. Barbercheck nsect management presents a challenge to satisfactory control of chronic pest species. IIorganic farmers. Insects are highly mobile Certified organic farmers can use a wide and well adapted to farm production range of practices to create an integrated pest systems and pest control tactics. On organic management approach that complies with the farms, where the focus is on managing insects standards of the USDA’s National Organic rather than eliminating them, success depends Program (NOP): www.ams.usda. gov/nop/, on learning about three kinds of information: (202) 720-3252. The standard states that a farmer must use management practices to • Biological information.What the insect prevent crop pests, weeds, and diseases, needs to survive can be used to determine if pest insects can be deprived of some vital resource. • Ecological information. How the insect interacts with the environment and other species can be used to shape a pest- resistant environment. • Behavioral information about both pest and beneficial insects. How the insect goes about collecting the necessities of life can be manipulated to protect crops. This knowledge can be used to craft a management plan that incorporates many different elements to suppress pest insects. No Figure 1. Striped cucumber beetle (Acalymma vit- single tactic, employed alone, is likely to give tatum) (Photo courtesy of USDA.) Contents Cultural Practices—Page 2 Biological Control Using Insect Natural Enemies—Page 17 Pheromones and Other Attractants—Page 8 Insecticides—Page 26 Biological Control Using Insect Pathogens—Page 10 Recommended Reading—Page 33 species and encourage their natural including but not limited to these: crop enemies, also referred to in this chapter as rotation and soil and crop nutrient beneficials. management practices; sanitation measures to • Pheromones and other attractants. remove disease vectors, weed seeds, and Organic farmers can use chemical habitat for pest organisms; and cultural attractants to trap pest insects, disrupt practices that enhance crop health, including their reproduction cycle, and monitor selection of plant species and varieties that are their population levels. suitable to site-specific conditions and Biological control using insect resistant to prevalent pests, weeds, and pathogens. Organisms that cause disease diseases. in insects can be exploited to help control pest populations by managing the According to the organic standard, insect pest environment to favor insect disease or by problems may be controlled through cultural, applying allowable purchased products. mechanical or physical methods; augment- The use of insect pathogens to manage ation or introduction of predators or parasites pests is called microbial control. of the pest species; development of habitat for • Biological control using insect natural natural enemies of pests; and nonsynthetic enemies. Farmers can manage their fields controls, such as lures, traps, and repellents. to provide habitats for species that eat and When these practices are insufficient to live on pest insects. This can be prevent or control crop pests, a biological, accomplished through conserving and botanical, or chemical material or substance augmenting beneficial populations. included on the National List of nonsynthetic • Insecticides. Allowable organic and and synthetic substances allowed for use in inorganic chemicals, insecticidal oils and organic crop production may be applied to soaps, microbial insecticides, particle prevent, suppress, or control pests. However, films, and botanicals, when used in the conditions for using the material must be combination with the above pest documented in the organic system plan. management strategies, can help to suppress pest insect populations. Pest management plans are site-specific. Farmers should develop their own strategies based on their knowledge, available time, and All of these practices used together comprise capital—the resources they can devote to pest an integrated pest management (IPM) management. This chapter provides basic approach. information on pest insects and the management tactics that organic farmers can CULTURAL PRACTICES: THE PLACE TO use to keep pest insect populations at levels START that do not pose an economic threat to crops. It is not a how-to guide that can be followed Pest insect problems are influenced by three step by step. We will focus on the following components of a farming system. Farmers can topics: manipulate all of these components to suppress pest species. • Cultural practices. The first key step toward managing pest insects is using • The crop species and cultivar present a set of cultural practices that suppress pest resources, growth habits, and structure. Organic Production Series— Insect Management 2 • Production practices, such as rotation, insects. This can involve one or all of the timeliness of planting and harvesting, following strategies: spacing of plants, fertility and water management, tillage, mulching, sanitation, • Reducing initial pest levels by making the and companion planting. crop environment unattractive, • Agroecosystem structure includes field unfavorable for pest reproduction and borders, natural vegetation, and other growth, or both. crop production areas that resupply fields • Producing favorable conditions for with pest insects and beneficial species natural enemies. when crops are replanted. • Increasing the plants’ ability to withstand pest damage. Insects require a basic set of resources to live When used together, the cultural practices and reproduce. Production practices that described on the following pages provide deprive a pest species of at least one needed useful tools for reducing or preventing pest element of life may maintain pest populations problems. below economically damaging levels for extended periods. It is unlikely, however, that cultural practices will provide permanent Monitoring control because the most troublesome insect Monitoring insects is fundamental to good species are those that are well-adapted to the management. Determining when a pest insect production systems used on a farm. first colonizes a crop and measuring its abun- Populations of these pest insects will tend to dance on a regular schedule provides the in- increase under a particular production formation needed to make control decisions. system, while populations of less well- adapted species will decrease. Monitoring does not have to be a rigorous procedure, but it needs to be done on a regular Pest insects must be very adaptive to succeed basis using the right procedure. because their physical environment changes as production systems change. Insects must In some cases (as for mites and aphids) simply deal with many environmental changes, checking crops by direct observation is all that is including different tillage practices, fertility needed. For other pests, it is easier and quicker to regimes, and planting dates. Each individual use a device, such as a sweep net, to sample practice can change pest insect population crops. Many devices—from plastic lunch trays to dynamics. In organic systems, farmers use ground cloths—are used to sample pests. Some many different cultural practices and cultivate pests, like thrips, require a different procedure. a wide array of crops. The interactive effect of this array of interacting elements on pests is Local Extension offices have information on how difficult to predict and usually can be and when to monitor many crops for pests. This determined only through research and procedure is essentially the same for organic or experience. conventional crops. Farmers can use cultural control measures to modify the crop environment enough to increase environmental resistance to pest Organic Production Series— Insect Management 3 Crop Cultivar mobile foliar pests—such as the Colorado potato beetle (CPB), subterranean pests, or Plant breeders traditionally have placed more pests with one generation a year—may be focus on creating disease-resistant varieties substantially suppressed with proper rotation. than on creating insect-resistant varieties. The distances required, however, may exceed Where they are available, however, insect- the space available on small-scale operations. resistant varieties can be an effective defense. For example, to reduce insecticide It is important to find out about the applications for CPB by 50 percent, potatoes mechanism of insect resistance in a crop have to be moved 1/4- to 1/2-mile away from variety because genetically modified crops previous potato crops (Weisz et al. 1994). To (GMOs, transgenic crops) are not allowed in be most effective, rotations between organic production systems. Even when susceptible crops should be three to seven insect-resistant cultivars are not available, years. some varieties may be less attractive to pest species or tolerate more damage than others. Planting Date and Method Plant size, shape, coloration, leaf hairs, and natural chemicals—both attractants and The stage of crop development can have a repellents—all affect the outcome of insect profound effect on a crop’s attractiveness to crop colonization. Note that changing pest insects. For some pests and crops, stage cultivars to reduce pests can also reduce of development dictates whether or not a pest beneficial insects either directly is a problem. If very few crops are available (characteristics that affect pest abundance when