Spring is a critical time to assess wireworm populations because when soil temperatures warm to 50°F, larvae begin to migrate up within the soil column and seek underground plant tissues to feed on. Root crops are most commonly damaged, but chewing on seeds, seedlings, and fruit also have been reported.
I am coordinating a pitfall trapping effort to determine if non-native adult click beetle species are present in western Oregon (contact me if you’d like to participate). To monitor your own fields, bait stations are recommended, because they are a better indicator of actual, larval (wireworm) pressure.
I will post a more detailed pest profile page in the coming weeks, but for now:
For more information, click the link to read a publication by Nick Andrews et. al re: Biology and Nonchemical Mgmt. in PNW potatoes.
Seed corn maggot – Poor emergence may be a sign of underground feeding by seed corn maggots, which are the immature stage of Delia platura, the bean seed fly. Plants are most susceptible at seedling stage. Host plants include: green and broad beans, onion, brassicas, peas, pepper, potato, spinach, and beet.
SCM is especially attracted to newly-tilled soil with high organic matter / manure inputs.
They have multiple, overlapping generations per year. This image by U. of Illinois highlights how adults, eggs, and maggots may all be present at the same time.
If emergence is low, scout 2-ft row sections for seed damage and white, tapered maggots that look very similar to cabbage maggot. Both species favor cool conditions for egg-laying, but D. platura are more active as adults in warm weather.
There is a fascinating biological (fungal) control for SCM that alters the fly’s behavior: It causes the flies to settle on tips of grain stems or high-up flowers and die, which increases dispersal of the fungus to spread farther.
Seed bugs– There have been recent complaints of high numbers of ‘small, flying insects’ in both urban and rural areas since mid-April. The bugs are 3-4mm with elongate bodies and wing covers with 4-5 veins. Experts agree that the taxonomy of this group is in need of a major revision, so they are usually referenced to genus level only.
More than half of all known Nysius species are from Hawaii, including the endemic wēkiu bug, that migrates to the summit of Mauna Kea each year.
Nysius spp. are seed predators and tend to be less selective then other, related Lygaeidae. Extensive damage can occur in wheat, quinoa, canola, and sorghum. Occasional feeding can occur on ornamentals, other cereals, and tomatoes.
Similar to boxelder bugs, they are attracted to large, sunny, white buildings, which has led to nuisance reports by homeowners. Various Ask-an-Expert questions have been submitted, one of which I was able to identify last week as Nysius, probably N. raphanus. The high numbers we are seeing now is likely the result of overwintered nymphs maturing into active, winged adults. There are 4-7 generations per year.
…the slimy worm-looking things covering the sidewalks around campus this week. They are the immature form of craneflies, commonly known as leatherjackets.
I’m hoping it’s not too late to save our campus lawns, but by the time this kind of damage is apparent, insecticides may not be effective. By mid-May, the leatherjackets will pupate then hatch into adults. Adults are harmless (other than a nuisance).
Maintaining grass health is the best defense against craneflies. Monitoring should be done from January to March, when larvae are feeding underground. More information is available at: http://whatcom.wsu.edu/cranefly/Index.htm
Participating in the OSU Extension Open House last night was fun and rewarding (thanks, staff!!). I enjoy outreach events and inevitably learn something from interacting with the public.
Yesterday’s conversations led to today’s topic: “Problems with my PEAS”
In the span of two hours, three different citizens came to me wondering why their early-planted peas are being “attacked by an unidentified marauder” (direct quote).
All 3 inquiries were similar and there were some important clues present: leaves are being damaged from the edge inward (chewing mouthparts); not cut off at soil level (cutworm); nothing obvious when scouting at night.
WEEK 0: Spring has sprung and we need field sites. Broccoli plantings will be starting soon, cooperating growers are encouraged to contact me to reserve their spot. Cutworms and armyworms are likely going to be a problem this year.
Many have been spotted already, even on campus sidewalks (see below)! This species is especially fond of ryegrass and orchardgrass, and outbreaks have occurred in western Oregon.
So..why did the caterpillar cross the road? Because it overwinters as a partially mature larvae and peristaltic searching mobility increases when ambient temperatures exceed 10°C, of course!
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Tis’ the Season! According to a pest model for this region, the summer generation of brown marmorated stink bug (BMSB) adults start appearing this week. This pest is very mobile, and will move into fall crops readily. I caught a glimpse of an egg mass in sweet corn today (photo below), and nymphs are expected to peak within the next few days.
Bell pepper, sweet corn, and tomato are all considered desirable hosts. Symptoms include sunken kernels, whitening on fruits, and spongy tissue. Rather than re-invent the wheel, I decided to direct you to some GREAT resources (see list below) for BMSB ID and management in vegetables.
FOR MORE INFO:
Wiman lab page – Oregon State University – Identification, monitoring efforts, and resource list
WEEK 16 – Two types of rootworm are now widely present in the Valley. See this page to learn how to ID and differentiate between them. Another, third species, may be on its way. Western corn rootworm has been moving westward since 2004.
Read the full report here: http://bit.ly/VNweek16 and subscribe on our homepage to receive weekly newsletters during field season. Thanks!
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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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.