UPDATE 23-AUG

Some current hypotheses (from processors, OSU plant clinic, researchers, growers, field reps):

1. The damage may have been 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

2. 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:

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. 🙂

3. 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.


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.

 

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.

Plants, like insects, are ectotherms, which means that their rate of development depends on external conditions. Sure, most companies put ‘days-to-harvest’ on the seed packet, but we all know that is just an estimate, and can vary widely by region. It’s greatly influenced by temperature; especially if we encounter variations from the ‘normal’ levels of heat and/or rainfall.

Faculty at OSU Extension’s Small Farms Program and the Integrated Plant Protection Center have developed an online, predictive tool to help guide grower decisions and crop planning. The resource is called CROPTIME, and it provides models for a few of the crops grown in Oregon, with aims to develop 50 models (vegetables and weeds) eventually. Here is a 9-minute video that describes how to use the program.

This tool can greatly aid vegetable growers in estimating regional, temperature dependent phenology for a specific variety. For instance:

[table id=6 /]

For more information, visit http://smallfarms.oregonstate.edu/croptime