WEEK 24 – Cabbage maggots are one of the most challenging pests for brassica growers. They tunnel through root tissue and increase the risk of exposure to plant pathogens Read this cabbage maggot page, which includes more info on biology and how to sample for them. Another late season pest is diamondback moth. Many sites are listed as "n/a" this week, because fields have been harvested and traps are being removed.
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WEEK 20 – Diamondbacks continue to hatch; corn earworm flight; beneficial insect tracking. Perhaps most importantly: we found 5 Large Yellow Underwing Moths (the adult phase of winter cutworm)in traps this week. More information is available here.
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WEEK 18 – Diamondback moths are exploding, and I try my hand at interactive maps!
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We monitor for cabbage loopers because they are pests of brassica crops. Feeding can occur on a wide variety of vegetable hosts including: beet, celery, cucumber, lettuce, pea, pepper, snap bean, spinach. Not all hosts are suitable for complete development of the insect, but feeding is feeding, from a grower or gardener’s perspective.
The 2nd generation of 12-spot beetles has emerged, and activity will likely remain high through September. Sweep ﬁelds with a sweep net to accurately assess population levels. Take a minimum of four samples (ten arcs of the net per sample) from different parts of the ﬁeld. Beetles tend to concentrate on ﬁeld edges. At this time of year, adult beetles are pests within snap bean and squash fields. They feed on folliage and developing pods.
There has been a boom of adult diamondback moths detected in pheromone traps. Development will be rapid under warm temperatures. Intensify field scouting so that treatments can be applied to avoid contamination.
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WEEK 13: Early earworms; diamondback overlap – FULL REPORT HERE
Diamondback Moths are one of the smallest crop pest moths one is likely to encounter, but damage can be extensive. Part of the problem is their capacity to reproduce quickly, which leads to population buildup in a very short time. This is temperature-dependent and if not monitored, can catch growers off guard.
Corn Earworm is normally considered a late-season pest, but trends so far this year suggest a pattern similar to 2014, which resulted in a boom of moths in August, just as corn is silking. Larvae feed on corn silks and burrow into the ears. The resulting damage and frass (insect poop!) can cause delays in processing, or reduction of fresh-market value. This page shows how to identify corn earworm adult moths.
VegNet was featured in the July-Aug issue of OSU Linn & Benton Cty Extension’s Newsletter! Click photo to read the article.
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* Continued pressure of cabbage loopers. An outbreak occurred in the Valley in 2008, when trap counts reached 100+ per day. Review last week’s post for details, interpretation of looper flights, and recommendations for scouting.
* A diamondback moth ‘point-concern’ for the Corvallis location. More data will be available in the coming weeks.
* True armyworms (M. unipuncta) are not traditionally monitored by VegNet, because damage is most notable in grasses and forage crops. However, feeding on peas, beans, and brassicas can occur in outbreak years. Visit the armyworm page for more info.
Diamondback moth (Plutella xylostella) is the most serious insect pest of Brassica crops (including cabbage, broccoli, etc), both in the US and worldwide. Economic impact estimates exceed $4 billion annually.
One of the reasons DBM is so hard to manage is because it quickly develops resistance to insecticides. In fact, (IR) has been noted in over 600 cases, for nearly 100 unique active ingredients such as carbamates, pyrethroids, and spinosyns. The most recent concern of IR is within the diamide insecticides. Diamide products that Willamette-Valley brassica producers rely on include chlorantraniliprole, cyantraniliprole, and flubendiamide. Trade names are Coragen, Exirel, and Synapse. We are currently conducting research to test for IR in regional populations of DBM and related pests.
Scientists at Cornell University have developed an “insecticide-free management approach” that involves releasing genetically-modified DBM moths into the landscape to cause eventual mortality of females. This research, while novel, is also controversial. Cornell has applied for a permit to make field releases of their transgenic moths in NY state. An environmental assessment has been conducted by USDA-APHIS, and public comment is welcome until MAY 19th, 2017.