Integrated Pest Management is a practical concept of pest control in agricultural crops. It uses all the tools to make informed decisions regarding pest management. When a crop pest is deemed to pose such a risk that the cost of the treatment would be less than lost crop revenue if nothing is done, that’s an economic threshold.

Integrated Pest Management incorporates all the factors involved with pest control – biological, crop harvesting, judicial use of pesticides, crop rotation, variety selection, field tillage and many more subtle considerations. It’s defined as a broad-based approach that integrates practices for economic control of pests by suppressing pest populations to less than the economic-injury level.

The United Nations defines Integrated Pest Management as “the careful consideration of all available pest-control techniques and subsequent integration of appropriate measures that discourage the development of pest populations, and keep pesticides and other interventions to levels that are economically justified to reduce or minimize risks to human health and the environment. (It) emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest-control mechanisms.”

This past week I recommended both spraying and cutting for two new-seeding alfalfa fields due to potato leafhopper populations that were beyond the economic-treatment thresholds. One alfalfa field was flowering. Cutting it would eliminate the insects laying eggs in young-alfalfa-plant stems, which were seriously threatening stand yield and survival.

The other alfalfa field was only 6 inches tall and had leafhopper populations at well more than the economic threshold. The cost of the spray treatment was much less than the lost hay crop and possibly the lost stand.

Another example of Integrated Pest Management I performed this past week regarded armyworms. A neighbor spotted armyworm damage in our cornfield along the field edge that bordered his field; being a good neighbor he informed me about it.

The University of Wisconsin has established an economic threshold for true armyworms in corn at 25 percent of plants with two or more larvae, or 75 percent of plants with one larvae. That level of infestation was close to being represented along the cornfield edge’s outer-most rows, but it was nowhere near that within the field. We held off spraying an insecticide.

Curious about the armyworm population in the cornfield, I walked the field edge the morning of July 4. I discovered there were four corn rows showing signs of feeding. But when I closely inspected the armyworms I noticed there were eggs on the backs of about half the larvae.

Some of the other armyworms I found were much smaller than those with eggs on their backs, so I eviscerated them and found maggots squirming in the armyworm guts. Both armyworm scenarios were forms of biologic pest control and an important part of Integrated Pest Management.

The Wednesday following my July 4 observations I revisited the same spot in the corn field and found only one armyworm alive. But on closer examination I found that individual had an internal parasite. It was doomed and was no longer feeding on the corn plant.

Crop scouting pays and is an important Integrated Pest Management tool.

Tim Boerner is a career agronomist who has worked in many regions of Wisconsin. Currently serving farmers in northwest Wisconsin, he's advising growers on Integrated Pest Management techniques, writes Nutrient Management Plans, works on composting projects, and employs GPS soil and data collection for precision-ag implementation. He has a passion for clean-water advocacy.