A Call for an Ecological Approach to Pest Management

By Joe Lewis

Editor’s note: This article is an excerpt from A New Farm Language: How a Sharecropper’s Son Discovered a World of Talking Plants, Smart Insects, and Natural Solutions.

“You can’t have any good guys without a few bad guys. That’s fact.”

So says Alton Walker. Alton and I have been friends since our days at Mississippi State where we went through our master’s degree program at the same time. Also a native of Mississippi, Alton continued his education at Clemson University, obtaining a Ph.D. in entomology prior to his career in agricultural consulting and farming in Georgia. He and I came to have a shared interest in ecologically sound farming, and in the mid ’90s we collaborated with a team of scientists on sustainable cotton production following the boll weevil eradication. Alton is a scientist with some skin in the game. He’s pursued the application of his conservation/ecologically based ideas with cotton production on a 600-acre portion of his own farm.

As Alton will tell you, the common practice of cleaning a field down to bare soil after harvest and leaving it barren over the winter is a harmful practice for multiple reasons.

“Farming’s been the victim of the advances of highly mechanized ‘big farming’ approaches,” he says. “Through the use of large equipment like harrows, plows, and mowers, enormous portions of biomass are removed from countless stretches of land. The land is then tilled and planted into monocultures from ditch bank to ditch bank. Then, mechanical cultivation and chemical pesticides are used to restrict diversity, while fertilizers and irrigation foster a lush growth of crops. Every year, the process starts over, meaning there’s never an opportunity for a true, natural ecosystem to develop and remain in place for the length of time it takes for it to become balanced and efficient. It’s no wonder pest outbreaks occur. On the other hand, perennializing the field—growing something year-round—helps promote a much more stable and balanced environment. We have to find our way back to approaching farming, including pest management, with an understanding of how to manage the ecosystem in which we live.”

The team Alton and I collaborated with in the ’90s was an interdisciplinary group of researchers that included Sharad Phatak, Rick Reed, John Ruberson, and Jim Hook, and Glenn Harris with the University of Georgia, and Philip Haney with my laboratory in Tifton. Eradication of the boll weevil, which had been completed in Georgia in 1990, and, later, essentially all of the United States, presented the cotton industry with a unique opportunity to advance sustainable agriculture. The eradication had been one of the greatest technical successes in agricultural history, with immense potentials in economic and environmental benefits. In Georgia, insecticide use was already dropping sharply, with average crop revenues increasing markedly. By 1995, the use of fifteen to twenty treatments per year had been reduced to three to five treatments. Grower interest in biological control and sustainable agriculture had never been higher, but a shift in thinking on when and how to give nature more time was going to be needed. The boll weevil had been an invasive pest without any effective natural enemies. Quick to reach damaging levels in early season, it was an especially devastating primary pest because the necessary insecticidal treatment for its control regularly spurred a sequence of secondary pest outbreaks. But now, for the first time, we could put in place an ecologically based management system without the disruptive influence of the early season boll weevil treatments.

In this new era, we could promote the adoption of cotton production as part of a healthy year-round landscape system, with approaches to pest management that deal with the natural enemy/pest complex being a vital part of that overall system. But to take advantage of this new era, we knew there needed to be a lot of educational outreach to the grower community, including on-farm demonstrations with associated data. Otherwise, we could miss the opportunity and drift back to pesticides as the dominant pest-management practice. 

The conventional, high-intervention approach has predominated cotton production and pest management for years, particularly since the advent in the 1950s of big farming. After harvest, the field is mowed and harrowed, rendered barren until spring when the process starts over. Because of this winter and early spring “wipeout” of everything prior to planting, the ecosystem—as represented by the typical “ecological growth curve”—is never able to achieve equilibrium status. So, there are no relays of natural enemy/pest balances into the following season. As one consequence, the pests show up first with a lag time before the natural enemies can be expected.

During the growing season, the crop is kept clean of pests such as weeds, insects, and other undesired variables by thorough cleaning, pre-planting tillage, and other soil preparation and operations, and by diligent mechanical and chemical interventions during the growth and fruiting phase. Use of fertilizers, irrigation, and other inputs are used to ensure a lush, mono-cultural growth of cotton plants from one end of the field to the other. Other plants are considered undesirable and out of place. So, this lush abundance of cotton plants, without alternate vegetation as food sources and shelter for the natural enemies of pests, along with high frequency of mechanical and chemical intervention, creates an environment prone to disruption and resistance, ultimately leading to the pesticide treadmill. This is why, prior to the boll weevil eradication, the number of pesticide treatments for cotton production would sometimes approach twenty per season.

Moreover, the lack of winter cover and the high-intervention approach with substantial removal of the biomass, along with frequent harrowing and tilling, contribute to heavy depletion of organic matter and soil microbial quality, plus extensive water and wind erosion. All of this leads to a host of other issues including lower air and water quality; higher use of fuel, labor, and machinery wear; soil compaction; and the loss of associated wildlife.

Yes, after the boll weevil eradication, we had the opportunity to shift to a less disruptive, environmentally sound, sustainable approach, but it was going to take some time and outreach to bring about such a change in practice. We were up against methods of farming that had dominated pest management in every cropping system for over sixty years. Rachel Carson’s call for concern had brought about change, but the change was to move to softer, less toxic pesticides. Still treating the symptoms, in other words. But we had come to understand that the real issue stemmed largely from a lack of understanding of how and why external interventions are disruptive and unsustainable, in contrast with sustainable “built-in” mechanisms, which we had concluded should always be the first line of defense.

 I began having discussions about this lack of understanding with Sharad Phatak, a respected pioneer on the subject, and from whom I had gained much insight. We decided to present our case as a profession-wide argument in a highly respected publication. In 1997, he and I, along with Joop van Lenteren and Jim Tumlinson, published a paper in the esteemed journal Proceedings of the National Academy of Sciences of the United States of America (Proc. Natl. Acad. Sci. USA). Our paper, “A Total Systems Approach to Sustainable Pest Management,” stressed the urgent necessity for a fundamental shift in how we think about and approach agricultural pest management to resolve escalating economic and environmental problems. We drew on our discoveries to show that an ecosystem is just that—a system, with interactive parts that behaves not like a collection of unrelated pieces, but more like a living organism. We emphasized what we’d learned about the remarkable built-in mechanisms that agricultural ecosystems have, mechanisms that act through a set of feedback loops to maintain balance and to protect against herbivore feeding, diseases, climatic stress, chemical imbalances, and other similar attacks or interventions. To our great satisfaction, the paper turned out to be a major factor in reshaping foundations around sustainable agriculture at grower, research/education, and policy levels. The USDA Sustainable Agriculture and Education Agency adopted the paper for nationwide use as a standard in guiding constituents toward grant proposals, and used it as a standard in developing a sustainable pest management brochure.

The gist of our argument then (as now) centers on the obvious contrast between our sustainable approach making use of the built-in defenses, and the interventionist “treadmill” approach. The built-in defenses respond only when, where, and at the level needed. They are need-induced and target specific. The chemical SOS signals sent by plants under attack are a perfect example of this. Parasitic wasps searching for these plant feeders, thereby rescuing the plants in distress, create pest control only in fields and around plants with actively feeding populations of caterpillar pests, thus avoiding non-target collateral damage and disruptions.

Furthermore, these parasite-host/predator-prey interactions are free of resistance and maintain balance, within fluctuating bounds, through a density-dependent phenomenon, meaning that levels of attack are determined by the availability of hosts or prey. On the other hand is external therapeutic interventions, such as applications of pesticides, act continuously at full level throughout the field without regard to need or target. The consequence is high collateral damage and disruption, and maximum selection for resistance. Next stop: the pesticide treadmill.   

The interventionist approach is engrained deeply into not just the agricultural mentality, but in the way we, as a society, think about corrective actions in any system. You can observe the same treadmill effect in how we approach the health of the human body. On the surface, it seems that the proper corrective action for an undesired entity is to apply a direct external counter force, hence a “healthy” dose of antibiotics for infections or painkillers for pain. But there’s now a long history in medicine where it can be demonstrated that such interventionist actions never produce sustainable desired effects. They always become less effective, requiring more and more to get results. The attempted solution eventually becomes the problem. You can find vivid examples with the growing resistance to antibiotics, and problems of addiction stemming from drugs for treatment of pain or mental distress. Black-market crime is on the rise as people seek illegal sources of drugs, just as it rose during the days of prohibition as an intended solution for alcoholism.

As a matter of fundamental principle, the application of external corrective actions into a system can be effective only for short-term relief. Long-term, sustainable solutions can only be achieved through a shoring up or restructuring of the natural system—in the case of the body, through nutrition, sleep, exercise, etc.—so that natural built-in forces, such as the immune system and other regulators that function on an as-needed basis, act effectively.

The same thing is clear with pest control strategies centered on toxic chemicals and other therapeutic interventions, such as prophylactic treatments. New and “better” pesticides are continually required, just as new and “better” antibiotics are continually required in the field of medicine. It’s a constant footrace with nature. The use of pesticides and other treat-the-symptoms approaches are unsustainable and should be the last, rather than the first, line of defense. A pest management strategy should always start with the question, “Why is the pest a pest?” and seek to address underlying weaknesses in ecosystems or agronomic practices that have allowed organisms to reach pest status.

Back in 1990s, with all this in mind, we set out to demonstrate and promote the adoption of pest management in cotton as a part of a year-round landscape management system. This included the use of cover crops. Cover crops had often been used for soil conservation benefits, but their value for enhancing natural enemy/pest balances and relaying them into the cropping system as part of whole-systems pest management and, further, into a year-round agroecology program, had received scant attention. By choosing the appropriate combinations of cover crops with the correct mix of attributes, interplanted with cotton through the use of minimum-till, strip-till, or no-till methods, such an ecosystem pest management approach with cotton production could be piloted.

With the guidance of the University of Georgia Extension Service, and local extension agents, a combination of progressive growers in four Georgia counties were enlisted. By mutually agreed upon guidelines, these growers produced cotton in both conventional and year-round ecosystems on ten- to thirty-acre fields for comparative study and demonstration. The Georgia Cotton Commission and USDA Natural Resources Conservation Service participated in the collaboration as well. Each grower chose the cover crops—wheat, cahava vetch, crimson clover, or crimson clover and rye—depending on their preference.

Philip Haney of my laboratory coordinated the monitoring of the fields and assimilated the data. We knew that by the nature of a single-season arrangement, only some of the potential benefits of the year-round ecosystem could be expected to be realized. The benefits would be much stronger if the perennialized system was established over multiple seasons. Yet, the biological and economic benefits in our single-year demonstration were dramatic and encouraging. The densities of nearly every predator group were significantly higher in cotton crops interplanted in the fields with cover crops as compared to the cotton planted in barren clean-tilled fields. In other words, the cover crops were, indeed, relaying natural enemy populations through to the subsequently planted cotton.

Further, the average yield obtained from these year-round management fields was 100 pounds of lint per acre higher than the conventionally managed fields, and the net return after costs was $60 per acre higher. Another benefit for these year-round fields, not calculated in these figures, was that 1.6 fewer per-acre tractor trips, and the accompanying time and fuel costs, were required because of less cultivation and harrowing.

These findings helped expand the acreage of cotton under sustainable practice in Georgia and other areas of the region. Data from the demonstrations were widely distributed by cooperating agencies and stakeholders, including four presentations at the 1997 Beltwide Cotton Conferences. We continued for several years to cooperate directly with local agents in grower group exchanges to advance such practices. And advance we did. Sustainable practices in Coffee County, Georgia, for example, under the seasoned leadership of agent Rick Reed, shot up from 200 acres in 1990 to over 30,000 acres by 2000. One beneficial step utilized was that rotating farmers, including Max Carter, Donnie Smith, and Wayne Fussell would host on-farm “Shade Tree” meetings to discuss their practices and results.

Alton Walker put his money where his mouth was. During all these years, he’s pursued the application of these ideas on his own farm. Over the last six years, he’s made major progress toward his objectives. His central goals have been to develop a perennial, vegetation/landscape system that:

• Is largely self-sustaining with minimal input and upkeep requirements;

• Provides for all-around soil and water quality including in the areas of nutrients, moisture, residue, structure, microbial make-up, leaching, wind, and water erosion;

• Provides for good year-round natural enemy/pest balances in all the pest areas of arthropods, diseases, and weeds; 

• Provides plants with the right structure, height, and thickness level to accommodate inter-planting of cotton with very limited requirements of mechanical and herbicide interventions.

Alton has advanced all of these objectives. He’s established a mix of plants that are largely self-renewing including several clovers, rye grass, rape seed, wild mustard, and others. His soil and water health are rapidly improving.  He’s able to interplant cotton each spring with a need for minimal strips of herbicide intervention, and with minimal need for mechanical intervention with his own customized equipment. He’s had no need to intervene with insecticides in the last three years. He’s able to produce his cotton crop with one half the number of tractor trips and less than half the fuel costs as compared to the conventional system. And his yield is averaging one-hundred pounds per acre, beyond the average of the surrounding area.

Alton is now in the process of adding rotations of corn and soybean crops into this system. He has just completed his first year with corn and with excellent results. Historically, reasonable corn production in his location would require irrigation. However, due to the improved water holding capacity and other high quality attributes of the soil, Alton’s corn yield averaged ninety-three bushels per acre with only six and one-half inches of rain, and minimal need for other inputs, a very solid yield for the area and conditions. His net profit was approximately $300 per acre.

These real-world practices by Alton show the advantages of the year-round ecosystem management approach. So why, after years of data and demonstration, starting with those early successes in the ’90s and continuing to this day on farms like Alton’s—why isn’t every grower on board with these practices?

Lewis spent his career in entomology with the USDA-Agricultural Research Service at the Tifton Campus of the University of Georgia. It was there that he worked to unlock the secrets of how plants and insects communicate with one another, particularly how plants use SOS signals to recruit beneficial insects to their defense. Based on those groundbreaking insights, Lewis and his colleagues developed holistic and sustainable approaches to pest management within agricultural systems. In 2008, along with his colleagues John A, Pickett and James H. Tumlinson, Lewis received the prestigious Wolf Prize in Agriculture.