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10. Know How Tillage Affects Insects

In the 1970's and 80's, farmers nationwide made significant changes in tillage practices, adopting conservation tillage to protect the soil from erosion. And it paid off. The protective cover of crop residue brought erosion rates down. However, crop residue also provided a habitat for certain insects.

Even though some insects may be more of a problem in reduced-tillage and no-till fields during certain years, insect problems can still be controlled, and insecticide use doesn't necessarily need to increase. You can readily adapt other pest-management techniques to conservation tillage. With that qualifier in mind, it's important to know how tillage might affect different insects.

For corn growers, reducing tillage could have these effects:

For corn growers, reducing tillage could have these effects:

  • Black cutworm moths prefer to lay eggs in weedy fields and in fields with unincorporated crop residue.
  • Unincorporated crop residues and cooler, wetter conditions favor increases in slug populations and damage.
For corn growers, reducing tillage could have these effects:
  • Grasses are attractive to egg-laying armyworm moths and stalk borer moths.
  • Adult flies of the seedcorn maggot like to lay eggs where crop residue has been partially incorporated into the soil. No-till corn stubble may be less attractive to egg-laying flies.
For corn growers, reducing tillage could have these effects:
  • More grassy weeds and less soil disturbance favor survival of white grubs and wireworms.
  • Where reduced tillage leads to delayed planting or slower germination (due to cooler soil temperatures), corn may be less susceptible to attack by first-generation corn borers and more susceptible to second-generation damage.
For soybean growers, reducing tillage could have these effects:

For soybean growers, reducing tillage could have these effects:

  • Reducing tillage favors the survival of only those grasshopper species that lay eggs within fields.
  • Unincorporated residues and cooler, wetter conditions favor increases in slug populations and damage.
  • Where crop residues slow moisture loss, plants may be less drought-stressed than in conventional tillage. Reducing drought stress reduces mite outbreaks.
For wheat growers, reducing tillage could have these effects:

For wheat growers, reducing tillage could have these effects:

  • Hessian fly populations carry over where wheat stubble is not tilled and volunteer wheat is not controlled. No-till seeding of wheat into other crop residues poses no problem.
  • Crop residues may decrease the attractiveness of new wheat stands to airborne aphids. By spring, it is unlikely that crop residues will affect aphid invasions.
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