Introduction:

In her article ‘Cornboy vs. the Billion-Dollar Bug’ in Scientific American, Hannah Nordhaus explores the ongoing battle between agricultural technology and the corn rootworm, a pest causing significant financial strain on the U.S.’s $50-billion corn industry. Nordhaus discusses the evolution of the rootworm, its resistance to various pest control strategies, and the scientific community’s efforts to develop new solutions, such as Monsanto’s latest endeavor involving gene-targeting technology. However, these efforts face challenges due to the rootworm’s adaptability and concerns about the potential impact on non-target species. This scientific and agricultural dilemma sets the stage for Howard Vlieger’s personal insights and experiences. In his opinion piece, Vlieger, drawing from his own farming background, critiques the mainstream approaches to rootworm management and advocates for more natural, integrated methods that align with ecological principles. His perspective offers a contrast to the high-tech solutions discussed in Nordhaus’ article, emphasizing the importance of working with nature rather than against it.

Read the original article by Hannah Nordhaus in Scientific American

Howard Vlieger’s Perspective on Corn Rootworm Management:

I would like to share some information on the subject of corn rootworm. This is lengthy, but I do not know how to abbreviate it. This is from my perspective and experience and certainly NOT scientific.

In the early 90s, we (myself, other farmers, and crop advisors) began scouting for rootworm larvae feeding on corn plants during the growing season. If we observed a sufficient amount of root feeding and pruning of the roots on the corn plants (2.5 roots per plant was our threshold), we would apply the minimal amount of insecticide necessary to control this larvae and subsequent feeding. This proved to be an effective means of integrated pest management and plant protection.

By 1993, we realized that we needed to scout both corn-on-corn fields as well as corn following soybean fields. With further observation, we soon learned the reason why we had worm larva feeding following a soybean crop. The adult beetles were feeding on soybean plants and other vegetation in soybean fields during the growing season. It made sense that wherever the beetles fed, they would also lay their eggs. This realization explained to us the need to scout all cornfields, whether they were corn following corn or corn following soybeans. Regrettably, the universities and mainstream agronomists failed to recognize this simple and basic fact. Instead, they claimed there was extended diapause relative to the eggs and thus the reason for worm larva pressure in so-called first-year corn. They seemed to fall short in recognizing the basic life cycle of the rootworm and how it related to the timing of corn planting.

When corn was primarily planted in the first 2-3 weeks of May, it would emerge shortly after being planted, due to proper moisture and adequate soil temperature. As the soil temperatures continued to increase, the corn grew, and the timing of the egg hatch for the rootworm larvae was approximately concurrent with what was referred to as lay-by time (knee-high to waist-high) in the stage of growth of the corn. This enabled the application of insecticide into the whorl of the corn plant when the corn was cultivated the final or lay-by time. The larvae would feed on the corn roots as long as they were in the larval form. This is typically a two-week period from the start of egg hatch to the end of larval feeding. Then, the larvae would go into the cocoon state and re-emerge as the adult beetle.

The adult beetle would then be present at the time when the silks were emerging from the ear of the corn plant. This is the preferred food source for the adult beetle. As the timing of the planting of corn was moved further into April, this caused a natural off-timing issue for the presence of the beetle and the growth of the silks from the ear of corn. This caused the rootworm beetle to change its eating habits in order to survive. When the beetle population was at its highest point, the silks had matured and were no longer desirable for food. This caused the adult beetles to migrate to soybean fields and other forms of vegetation to use as a food source.

We witnessed the highest incidence of corn root damage from larvae feeding in fields that either had grass or volunteer corn (this was before RR soybeans and fields were not always weed-free) growing in soybean fields the previous year. Rather than recognize this basic fact of what was occurring, the theory of extended diapause was parroted by both industry and academia. This was an ineffective scare tactic to cause the use of planter-applied insecticide on more acres every year. Of course, the increased use of insecticide accelerated the resistance issue potential.

We witnessed failure of planter-applied insecticides because of poor timing of its placement in the soil relative to the actual time when the larvae egg hatch and subsequent feeding would occur. The whole issue of disruption of the adult beetle’s feeding habits increased as BT corn came into use because of the beetle’s reluctance to feed on BT corn silk.

After attending Dr. Elaine Ingham’s Soil Food Web classes in early fall of 2005, we applied the first compost tea to fields in the fall, after the growing season. By reestablishing the right fungal diversity in the field soil, we were able to eliminate the need for insecticides to control rootworm larvae. We continued to progress in our understanding and realized that the correct cover crop mixture(s) prior to a corn crop could establish the beneficial biology in the soil to have a natural predatory effect on the rootworm eggs and larvae. This enabled nature to take care of the problems.

The absolute answer to the corn rootworm problem, in my opinion, is to work with nature. The Almighty Creator knew what was needed and put in place the proper mechanisms for problem-solving. In order to be successful, you need to quit fighting nature because nature will win. Establish a broad and healthy diversity of microorganisms in cropping systems, and the problems will be resolved without the potential for resistance. Of course, by doing this, industry does not have financial gain, and thus the cycle continues.