UPDATE 23-AUG

The current consensus (from processors, plant clinic, researchers, growers, field reps) is that the damage was caused by heat stress during a critical time of development. In May and again in July, there were extreme variations of temperature:

Max daily temperature fluctuation in critical periods of seedling/transplant development likely contributed to poor growth observed this season

Auxins are phytohormones known to regulate growth processes in plants, and can spike rapidly in response to heat-shock. Increased auxin levels can ‘present’ as abnormal root growth or phototropism, which was noted at some of the sites:

Another possibility is that young plants were sensitive to residual carryover from synthetic auxin herbicides (2,4-D, Dicamba, Fluroxypyr) remaining in the soil, which is possible with a grass-brassica rotation.

As auxins move throughout the plant, the gradient shifts and, at least in other types of plants, declining levels causes leaves or petioles to break off. I don’t know much about abscission zones in broccoli, so if you are still reading, please know that these are just my rambling thoughts, and not an official diagnosis. 🙂


Recently, there has been some concern about odd symptoms of wilting and reduced stands in broccoli and cauliflower here in the Willamette Valley. See photos below.

Symptoms include: Weakened stems – necrosis of lower leaves – poor stand – girdling/calloused tissue at soil level – stem breakage – possible association with weed hosts – abnormal root growth

NOTE: AT THIS TIME, I HAVE ONLY EDUCATED GUESSES OF WHAT MIGHT BE CONTRIBUTING FACTORS TO THE FOLLOWING SYMPTOMS IN BRASSICA FIELDS. THIS ISSUE IS CURRENTLY UNDER INVESTIGATION IN CONJUNCTION WITH FIELD FACULTY AND DIAGNOSTIC LABS.

Thanks for your interest/input.

 

 

Cabbage rootfly (CRF-Delia radicum) is a well-known foe for brassica growers in this region. Normally, we do not expect them to be an issue mid-summer because

    • There are presumably two distinct peaks of CRF activity 1:
      • Spring – newly emergent adults; ~330 GDD = Mar 11th, 2018
      • Fall – breeding flight; ~ 2400 GDD = Jul 14th, 2018
    • CRF prefers cool weather and activity tends to diminish during the summer heat.

HOWEVER: Summer activity is measured by pan traps, and

Eggs were detected 4WAP and continued to be evident throughout the summer. There was a clear and steady increase in root damage starting at 3WAP in summer. Eggs were present in the fall as well, but the level of root injury was more gradual. (EGG count = top graph each season; ROOT damage rating = bottom) FROM: S.V. Joseph, J. Martinez / Crop Protection 62 (2014).

the authors of the model above agree that summer activity might have been underestimated because of ‘visible competition’ and attractiveness of blooming crops and weeds vs. yellow traps. The spring generation can be extended up to 3 weeks or more, depending on how long rainy, cool weather conditions persist. Also, we know that there are overlapping generations of CRF, and a study from California suggests that egg-laying behavior and subsequent damage during summer months is markedly different than fall:

 

ANOTHER FACTOR is that Delia radicum is actually part of a much larger ‘rootfly complex’, and different species have different ecological niches, behavior, and activity periods. This table explains some of those differences. Identifying rootflies is hard enough when they are adults, and nearly impossible as maggots and pupae. Thus, they are referred to as a pest complex that can affect growers year-round.

This puparium was found 27-Jul-18, suggesting that rootfly activity continues yearround in the PNW. It may be seedcorn maggot, radish maggot, or turnip maggot, as all are known to infest brassica roots.

 

1According to a regional model (Dreves 2006), and current 2018 data (Agrimet station CVRO)

Squash bugs have an elongated body shape and striped abdomen. Eggs are red and laid in clusters. Nymphs are gregarious, and progress in color from light gray to dark.

Anasa tristis is one of the squash bugs common in the PNW.

This pest is notoriously hard to detect, because they can hide on the underside of foliage, on plant stems, near irrigation lines, or even under fabric mulch.

Squash bugs use their piercing-sucking mouthparts to feed on leaf tissue and inject their saliva, which causes wilting of leaf tissue and, depending on the species, vectors cucurbit diseases.

Damage tends to be localized but can occur quickly because nymphs are gregarious, and feed alongside adults. If left undetected, vines eventually wilt and die.

Squash bugs have been a problem this year in the southeastern U.S., as noted by this news article.

According to a laboratory-based estimate, nymphal instars may be present in July, with a possible 2nd generation of adults in early August (model source: GDD58 single-sine, Fargo and Bonjour, 1988).

Consult this PNW Insect Management Handbook section for more info.

This page shows how to differentiate squash bug, BMSB, and other similar-looking bugs.

…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

Heavy infestation of leatherjackets (marker = approx. 2″)
turf damage
Grass can be pulled up like a carpet if severe cranefly damage has been done (CLICK FOR VIDEO).

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.

The probable pest producing pack perturbation

IS ….

Pea Leaf Weevil !

(More info available in the pest profile section)

Captain Turbot; endless enthusiast of echoic expressions ©Nickelodeon

 

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.

©2018 Ben Phalen, used with permission

 

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!

 

 

 

**NOTE: this blog site will be used for extended story content, photos, etc. To access weekly pest reports and data (APR-SEPT), please subscribe to the email newsletter using the box at left**

In anticipation of this month’s release of Oregon’s Agricultural Progress research magazine, I wanted to put a brief post up to help orient OAP readers.

As you saw in the article, VegNet uses an email marketing platform to inform program subscribers about insect pest trends throughout the Willamette Valley. Our readership includes vegetable growers, crop consultants, and home gardeners from across the country.

This program has been operational for 20+ years (!) and is truly a community resource.

The blog now has a ‘search by category‘ function located at left, if you are interested in a particular insect, or just want an easy way to browse through content. There is also an FAQ page. Or, you could go here to view all the reports from last year.

If this program interests you at all, please do join the mailing list to be included this season. Pest reports are delivered straight to your inbox, once a week, and only between April and October. The program is free, and you can unsubscribe at any time.

Thanks for your interest !

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.

Read the full report here: http://bit.ly/VNweek24 and subscribe on our homepage to receive weekly newsletters during field season.

WEEK 23 –
WEEK 23 – Corn earworm flights have been consistently high, and scouting this week revealed late stage larvae, pupal exit holes, and newly-emerged adults that will lay eggs within 3-5 days. This diversity makes control difficult, and scouting is recommended. Spotted cucumber beetles do become active in the fall, but levels this year are about 500% higher than historical norms.

Read the full report here: http://bit.ly/VNweek23 and subscribe on our homepage to receive weekly newsletters during field season.