Insect

VegNet Regional Pest Trends for the Week of August 17th, 2015

VegNet is an insect pest monitoring program funded by the Oregon Processed Vegetable Commission and managed by the Oregon State University Department of Horticulture. To add your name to this newsletter, please click the ‘subscribe’ button on the homepage. For a review on how to interpret VegNet tables, click here.

• Corn Earworm (Helicoverpa Zea  - CEW) is higher than historical norms but has, over the past 2 weeks, dropped below the level of the outbreak of 2008 (FIG. 1). The pattern appears to be shifted, with peak flight occurring about 2 weeks earlier than the 15-yr average. The trend may be a consequence of a mild winter, earlier corn plantings, and/or warmer temperatures (FIG. 2). The highest activity we’ve seen has been localized around a few geographical locations. Please note: trap counts are not a direct estimate of larval activity, so field scouting is recommended if there is concern. More information on CEW can be found on the VegNet pest profile page.
• Other pests that were detected at higher-than-normal levels this week are: Black Cutworm (BCW), Spotted Cucumber Beetle (12S), and Alfalfa Looper (AL)

 

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FIG. 1 – Corn earworm activity of adult male moths so far this year (2015) compared to historical data (2008 and the 15-year average). There are 1-3 overlapping generations of CEW per season.

 

FIG. 2 – Differences between growing degree-days and precipitation from year to year can be estimated by an online modeling program hosted at www.uspest.org/wea. According to a generalized model for pest insects (lower threshold 41, upper 130), degree-day accumulation this year for the Corvallis region is about 13 days ahead of 2014.

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