In general, insect pressure has been relatively low this year. However, over the past week we have noticed an increase in insect activity.
Start scouting for European corn borer at the mid-whorl stage, before the tassel begins to emerge from the plant. Look for flattened, white egg masses on the under surface of the leaves. Newly hatched larvae often hide in the developing tassel during the heat of the day. Window panes, pin-hole feeding and small amounts of saw dust-like frass are all signs of feeding. Optimal control occurs during the early stages of insect development, before the larvae enter the stalk. Young larvae range in colour from almost translucent to yellow to brownish, with a black head.
Based on information from the website insectforecast.com, it appears the risk of corn earworm flights into Southwestern Ontario has increased significantly over the past week. The University of Illinois Fruit and Vegetable News also reports increased trap counts this week.
Female earworm moths lay their eggs on sweet corn at the green silk stage. One female can lay up to 100 eggs per night over a 10 night period. The eggs incubate for 2- 10 days, depending on the temperature. After the egg hatches there is a narrow window of opportunity to control this pest before it enters the protection of the husk.
During periods of potential corn earworm activity, apply a corn earworm insecticide at 50-60% silk, with a second insecticide application 4 days later. Note: corn earworm populations may have a high degree of resistance to pyrethroid insecticides. The level of resistance varies greatly from year-to-year.
Pheromone trapping is an excellent tool to help monitor localized populations in specific sweet corn fields. For more information on trapping, visit Ontario CropIPM.
Darren Robinson, Weed Researcher, Ridgetown Campus – University of Guelph
Sandea and Permit are Group 2 herbicides that are taken up by roots and shoots and are systemic in the plant. The herbicides will translocate to the new growing tissues, and if applied to a sensitive crop or weed, it will cause stunting, chlorosis (yellowing) and may even delay maturity of sensitive species. These herbicides are particularly useful for control of preemergence control of common lamb’s-quarters and postemergence control of yellow nutsedge. They have also provided good control of common ragweed and redroot pigweed. The labels should be consulted before use in all cases, and are available at:
The Sweet Corn, Bean and Pea Integrated Pest Management Workshop will now also be available by webinar. If distance or time was preventing you from registering for the workshop, you can now get all the same great information, without the travel!
The workshop and webinar are planned for:
Tuesday, May 20th, 2014
1:00 pm to 3:30 pm
Room 102, Rudy Brown Rural Development Centre Ridgetown Campus, Ridgetown Ontario