LANCASTER, PA — Entomologist John Tooker, a Penn State extension specialist, told his audience at Lancaster’s Farm and Home Center, pesticides are made to limit life. He added, Integrated Pest Management (IPM) should be your guideline on what pesticides to use. Tooker started by reminding them prairies, which used to dominate the midwest, were the predecessor of agriculture. Herbivore outbreaks are rare in prairies.“It’s very rare to have an abundance of insects eating plants because there are a lot of things that eat the things that are trying to eat the plants,” he said. “Anything that is eating something else will likely be eaten themselves.”
He offers what he calls Take Home messages: Healthy soil improves crop productivity/quality; healthy soil: no-till, diverse rotations, cover crops, IPM; Soil is alive; Pesticides will limit soil life — insecticides, fungicides; IPM should guide pesticide use.
There is a diversity of things out there and they are relying on each other to survive. “If this was the African savannah I could show you pictures of lions and cheetahs eating wildebeests and things like that.” He notes the same type of food web which exists here in the U.S. would be beetles eating organic matter put into a system through the growing plant instead of decomposing plant. Farmers often seek solutions in a jug (fertilizers, pesticides). Herbivore outbreaks in these systems are a lot more common. “If we go from a diverse eco-system to a simpler one,” Tooker says, “we’re decreasing a number of plant species there. That, in turn, will support fewer insect species, including the good insect species you want to foster.” In this simplification, there will be fewer species, little genetic diversity, ‘natural’ replaced with ‘synthetic’, less organic input and a weaker soil-based food web.
“If you are interested in building soil health, one of the first things people ask is ‘what kind of organic matter do you have in the soil? What is that percentage?’ Your goal would be to increase that,” Tooker says. “You increase that through no-till or cover crops or diverse rotations.” To put it another way — soil matter matters. No-till affords soil structure and stability. Rotations and cover crops, depending upon which you use, contributes to pest management, and organic matter. All three provide structures in the soil. Where is the healthiest soil on your farm? Some would say the hedgerow or the fence line. It’s the soil with roots in it all the time and isn’t disturbed. “You have to think about what’s happening there and imitate that in the rest of your field,” Tooker advises. One way to carry out the suggestion is with IPM. In other words, if you’re simply feeding pesticides into the soil without really thinking about what you’re doing, you could be limiting the soil life you’re trying to build.
IPM was introduced in 1959 by a group of entomologists at the University of California at Riverside. It was introduced against something called the spotted alfalfa aphid. It was engineered to eliminate four problems California entomologists encountered with some regularity: calendar sprays, resistance, pollution, and non-target effects. “Many farmers just applied insecticide based on what day of the month it was,” says Tooker, explaining calendar sprays. “Overuse of insecticides were occurring. June 1 and June 15 were dates alfalfa could expect sprays. In turn, that generated resistance. If you use less insecticide but use it more when necessary, there won’t be as much challenge with resistance or with pollution.” Non-target effects could be called side effects because the insecticides could kill natural enemies like ground beetles.
No-till provides habitat stability. “I encourage people to use no-till,” Tooker says, “because it provides a higher population of predators, decomposers, and lower populations of pests.” If you are brazen enough to put cover crops on top of that, you will foster good insect populations even more. Research shows, you will have insect pest species, but you will also have more good enemies outnumbering the bad enemies. Stability and diversity give predators a chance to be effective. On Penn State’s Ag website, found at http://tinyurl.com/hzfjc6x , it is described this way:
‘In both of our diverse cropping rotations, we use cover crops for multiple benefits, including providing habitat for beneficial organisms. Beneficial organisms include weed seed predators and pollinators, to name a couple of them. They can help keep certain herbivore pests in check. In general, we strive to use integrated pest management (IPM) at our site, while also avoiding the use of restricted herbicides, such as atrazine.’ There is one two-year corn-soy rotation, and two six-year rotations (cover crops, alfalfa, corn, small grains). “Pathologists that I’ve talked to,” says Tooker, “more often than not believe that the fungicides on your seeds are providing a benefit. They provide more value than insecticides on seeds. There are two exceptions. Those fungicides can limit growth of mycorrhizal fungi in the soil. And there is new evidence on the decomposition of weed seed. When you use a fungicide, it seems you can get a different weed seed population sprouting weeds.”