Washington State University Extension

Integrated Pest Management Program


IPM in Riparian Buffers

Over a three-year period, a team of researchers led by Doug WalshTim Waters, and Ron Wight from the Irrigated Agriculture Research and Extension Center (IAREC) in Prosser investigated the arthropod populations in a variety of riparian areas in the Yakima Valley. Specifically, the team studied the relationship between different vegetation regimes and the presence of both pest and beneficial arthropods. Plant diversity was categorized as pristine (primarily native plant), rehabilitated (replanted with primarily native plant species), or weedy (invaded by exotic weed species).

In the lower Yakima valley, riparian buffers are often near agricultural areas. The research team hypothesized that arthropods in these buffers could migrate into the adjacent agricultural areas and contribute—for better or worse—to the arthropod fauna within the crop system. The results indicated that riparian areas consisting of invasive flowering broadleaf weeds hosted significantly more pest arthropods than the riparian areas that were maintained in a more pristine condition with a greater number of native plants. In addition, beneficial arthropods were seen to thrive in the more stable native environments.

These data have implications for buffer rehabilitation planning and implementation. Choosing native plant species creates a habitat less likely to harbor pest arthropods that could potentially migrate into adjacent agroecosystems and inflict damage to crops. Fewer pests migrating into the adjacent agroecosystem translates into fewer pesticide applications by farmers and a safer, healthier environment. This integration of weed management and insect management is a classic example of using IPM to protect both crops and the environment.

For further information

Walsh, D. B., and R. P. Wight. 2000. Riparian Buffer Zones: Summer 2000 Field Study Results. Agrichemial and Environmental News. Issue No. 175, November 2000.

Walsh, D. B. 1999. Implications of Buffer Zones on Agricultural Lands: Impacts on Beneficial and Pest Organisms. Agrichemial and Environmental News. Issue No. 163, November 1999.

Office of the State IPM Coordinator, WSU- IAREC, 24106 N. Bunn Rd., Prosser, WA 99350, 509-786-2226, IPM Site Webmaster