Integrated Pest Management (IPM), a bland term for a hot agricultural topic, is a multi-faceted approach, applicable to home gardening and commercial production. IPM attempts to apply a holistic, environmentally friendly approach to pest management. IPM has existed as an area of study since the 1970’s, but is largely unfamiliar outside the industry: many gardeners are already practicing some IPM without awareness that their practices fall into an IPM framework.
Understanding IPM provides home gardeners desirous of applying earth-friendly approaches to pest management a system for doing so. IPM is flexible, and uses an ecosystem approach, so practices can vary substantially from one plant or garden type to the next. Advanced application of IPM requires deeper understanding of pest and plant biology than the “see and spray” pest management approach common in previous decades: however, even the novice can use IPM principles in the garden and landscape to manage pests with minimal application of chemicals.
Key to success of an IPM approach is the use of multiple tactics simultaneously- thus the moniker Integrated. IPM applies layers of management: plant selection, plant cultivation, physical barriers, chemicals, and more, in a tiered approach. The home gardener who has experienced soil borne disease of tomato might next year select a resistant tomato variety, move tomatoes to a different spot in the garden, and apply a fungicide- appropriately timed for both the plant’s development, and when conditions are favorable for disease development. Multiple tactics, requiring some knowledge of the issue at hand.
Since only about 5% of identified insect species are pests, chances are that an insect randomly seen visiting a plant is providing some beneficial service like pollination, or predation upon plant- feeding insects. Even plant professionals have mistakenly applied insecticide to a disease issue, or treated a nutrient problem as biological.
Internet based resources for insect and disease identification have vastly improved in the last decade, making identification easy for the most common problems. The website “Bugwood” has a substantial collection of pest and disease images confirmed by professionals. Users can search by crop or plant type, using filters to only display pictures of the same symptoms as the plant being investigated.
Also called scouting, and crucial to IPM success. In a large commercial field, it may mean hiring scouts to estimate the number and maturity of stinkbug eggs every ten feet. In the home garden, it means making regular observations about changes in plant material.
Some insects and diseases progress so rapidly that the difference between a non-chemical solution and insecticide application is just a few days. For example, caterpillars are easy to control with Bt, a naturally occurring bacteria that disrupts digestion, while the caterpillars are small and young. Once caterpillars have completed the bulk of larval development and are about to pupate there is little digestion happening, so Bt is not effective. Aphids are notorious for quietly building up a population on a single plant until the population maxes out the plant’s resources. Caught early, management involves one plant. A few days later, numerous plants are involved.
Usually, the mere presence of a single pest is not indicative of treatment. IPM practice includes determining thresholds for action that consider the cost of doing nothing vs. anticipated return on investment if treatment is applied. In commercial production, treatment might be warranted when aphid numbers are twenty aphids per net sample, but have no economic value when only five aphids per net were captured.
In the home garden, give natural enemies a chance to balance pest populations before applying pesticides that affect both pest and natural enemy. When natural enemies are present in numbers sufficient to suppress the pest, the threshold for chemical treatment is not met.
In IPM, pest management is an ongoing process, not a response to pests that happen to arise in the system. IPM uses a variety of actions from plant selection (choosing resistant varieties) to the way plants are watered (not overhead!) to using traps to monitor for and catch insect pests, and much more. Control types range from natural controls (a killing frost also kills mealybugs outdoors) to chemical controls, the “big guns” used last in an IPM program. Next week’s column will explore the various controls in an IPM system in detail.
While more fully developed for commercial operations, IPM can be applied in the home garden in a variety of ways. Willingness on the gardeners’ part to learn more about the life cycle of the most common pests, and the conditions that allow pests to thrive, is a great place to start.