Insect Invasion – What’s eating my crops?

  • Aug 07
    Laura Johnston
    Insect Invasion – What’s eating my crops? By Laura Johnston on August 7, 2013
    Categories: Grain Corn, Silage Corn, Soybean

    Standard thresholds for soybean defoliation from bloom to pod fill is 15%. It increases to 25% during pod-fill to maturity (unless pod feeding is occurring). When scouting, be sure to look at leaves from the center of the canopy to get a representative sample. Most often, the feeding looks worse than it is and a spray is rarely warranted.

    Japanese Beetles seem to be more frequent in corn and soybean fields this year. They are pheromone feeders, which is why there are often multiple beetles feeding in the same area. Japanese Beetles cause a skeletonized feeding pattern on soybean leaves and can clip silks in corn. When scouting, be sure to scout the whole field and move away from field edges where beetles may be more populous.

    Aphids could still cause problems in soybean fields, so keep scouting! I have noticed a few fields in Elgin County where populations have increased over the last week (so far, still well below threshold). Ideal temperatures for aphids are 22-25°C. Check out Cain’s article, Aphid Update in Reproductive Soybeans for details on thresholds and scouting. The free Aphid Advisor app is another tool that can help with decision making and scouting.

    Western Bean Cutworm peak flight may have just taken place according to reports from Tracey Baute, OMAFRA Entomologist. Any fields that do not have protection (SmartStax®, Agrisure Viptera® or Herculex®) and have not reached full tassel should be scouted.

    Laura Johnston, CCA-ON, Maizex Seeds Yield Specialist, West Elgin County
    Twitter: @lmjohnston8