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.
Read the full pest report HERE and subscribe to receive alert updates.
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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….Cutworms and armyworms, that is. Many studies report increased activity of these pests in years following record rainfall, and moisture dependency is common. This simply means that more eggs hatch if there is sufficient moisture in the soil.
Some species I have noticed on the rise over the past few years:
Spodoptera praefica is native to the Western U.S. It is considered a generalist feeder. Larval feeding causes extensive defoliation of leaves and also fruit damage. As the name implies, these worms are gregarious (feed in groups), and therefore can cause extreme damage.
Host plants include: alfalfa, asparagus, bean, beet, cabbage, carrot, corn, clover, lettuce, onion, ornamentals, pea, potato, wheat, and many others.
Apamea cogitata is considered a pest of grasses and grains (Poaceae). It is a cutworm, and has one generation per year, usually peaking in mid-July. This species is widespread in the Northwest. One of the identifying characteristics is a pink-hued fringe on the margins of the hindwing.
Flea beetles invade fields rapidly, and can cause substantial damage to newly emerged leaves. Scouting is simple, thanks to the characteristic leaf damage. See photos and learn more here.
Rootworm is the common name for larval Diabrotica beetles. They feed underground, but can be distinguished from maggots by the presence of thoracic legs and a brown sclerotized plate just behind the head.
Cabbage Looper moths continue to be very abundant in the landscape. There is no diapause in this species, so 6-7 generations per year are possible if environmental conditions are suitable. Although trap counts are way above normal, the effect on crops has yet to be determined, and depends on a variety of factors. We will be discussing some of these in the weeks to come.
Read the full pest report HERE and subscribe to receive alert updates.
* 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.
WEEK 5: First of two looper flights. Read the full report HERE.
The most notable trend this week is the sharp rise in looper activity. As seen in the graph below, 2016 levels (blue bars) were well above the historical norm (gray shaded line), and they remained that way throughout the season. This early 2017 peak (orange dot), while alarming, just means we’ll need to keep an eye on activity. It is the 2nd flight (Jul-Aug) that causes the most damage, because larvae and pupae contaminate crops headed for the processor. A contaminated crop can mean load rejection.
Home gardeners should be wary of looper levels, because larvae feed on a variety of crops including lettuce, tomatoes, peas, and other garden favorites. If you are concerned about defoliation, begin scouting between May 18th and 23rd. Look for ‘windowpanes’ or ragged holes, depending on how big the larvae are.
Processed vegetable growers are mostly concerned with looper flights near button-stage, as the main concern of this pest is contamination.
Looper larvae are light green with a white lateral stripe down each side, and display characteristic movement – ‘looping’ along the leaf surface by gathering the rear legs to meet the front legs and then extending forward. More info on loopers is available here.
WEEK 4: Moth movement is low, rootworms in the landscape.
Don’t worry if you’re getting a late start to the planting season. So are the bugs. Many of the pest moth species we track are LOWER than normal for this time of year.
You may start to notice those familiar 12-spot beetles around, particularly on the dandelions in your yard or garden. These are the overwintered females, looking for suitable egg-laying sites (seedling corn, cucumbers, beans).
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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.
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Traps are being set this week. Stay tuned for a full report next Friday.
Adult rootflies are abundant; they love this cool rainy weather! If possible, protect seedlings with row covers. (Cabbage maggot info)
Did you know that winter cutworm is also a problem in Spring?! Visit this blog post for more info: http://bit.ly/2p9mC2Q
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.