With Raspberry Fumigation, Less May Be More
Less fumigant may actually improve raspberry crops, as an ongoing study by Washington State University small fruits horticulturalist Thomas Walters indicates. Raspberry growers typically use broadcast fumigation to deal with root lesion nematodes and root rot, but increasing Environmental Protection Agency restrictions inspired Walters to research alternative methods.
Raspberry plants are finicky about soil and climate and optimal land for commercial cultivation is in short supply. While many farmers rotate crops to stay ahead of pests, raspberry growers don’t have enough suitable land to move their crop. When pests and pathogens find a permanent home for their favorite snack, they can reproduce until they become unmanageable. A soil-borne pest, root lesion nematodes, and a fungal pathogen, raspberry root rot, are particularly troublesome to raspberry growers. Every five to eight years, the culprits get so troublesome that the plants are removed, the field is broadcast fumigated, and new raspberries are planted.
Increasing restrictions have growers seeking alternatives to broadcast fumigation. New EPA Environmental Protection Agency regulations require a buffer zone for two days after fumigation. The size of the buffer zone depends on the field size, the fumigant, and associated rate used and other factors, but it can easily be 600 feet or more. With many raspberry fields in close proximity to houses, this approach is no longer practical.
To more selectively apply fumigant, Walters borrowed a concept from California strawberry growers, and adapted a bed fumigation apparatus. This multi-stage tractor-drawn tool uses a shank to cut the soil. Fumigant is injected into the soil through a hose behind the shank. The apparatus then shapes the three-foot wide bed and pulls a fumigant-resistant plastic tarp over it. Raspberry rows are spaced 10 feet apart, with no fumigation in the alleyways.
Because the new process uses only one third as much fumigant as broadcast fumigation, the statutory buffer zone drops to 25 feet, making the process much more neighbor-friendly. However, the expense of the tarp makes the cost about the same as broadcast fumigation. The biggest drawback of bed fumigation is that it requires more planning to be sure the beds are properly placed for irrigation.
Since the study began in fall 2010, results have been promising. Twice a year, Walters and his colleagues from the United States Department of Agriculture measure plant growth and take soil and root samples to evaluate pests. When compared to broadcast fumigation, the raspberries grown with bed fumigation are doing at least as well, if not much better. Soil tests from some sites show 10 times more nematodes in broadcast-fumigated plots than bed-fumigated plots. Also, all raspberry plants in bed-fumigated plots are the same size or larger than plants in the broadcast-fumigated plots. Walters will soon compare raspberry yield from the test plots, as well.
Walters notes that this project was possible thanks to cooperation from the USDA and Trident Agricultural Products, Inc., and support from the grower community.
–Bob Hoffmann
Eastern Washington Oilseed Farmers Tell How it’s Done in WSU Publication
Eastern Washington farmers considering oilseed production can now learn from those who have already succeeded, thanks to Oilseed Production Case Studies in the Eastern Washington Low-to-Intermediate Rainfall Zone, an electronic publication by Karen Sowers, Dennis Roe, and Bill Pan of the Washington State University Department of Crop and Soil Sciences.
Whether interested in growing canola, sunflower, or mustard, farmers can take advantage of the experiences recounted by five of their peers with the agronomics and marketing of oilseeds, as well as the challenges and advantages of these crops. Bob Hutchens of Dayton recommends yellow mustard for higher elevations, as it is not palatable to deer and elk. And Jason Echelbarger of Reardan notes that dense stands of canola don’t produce as high a yield as areas with fewer, larger plants, so low seeding rates are advisable.
Oilseed Production Case Studies, a 29-page PDF, is available as a free download from http://bit.ly/MprvxO. WSU Extension’s complete catalog of numbered publications can be searched at http://pubs.wsu.edu/.
The Field Days of Summer
Field days focused on oilseed crops will be taking place all over the state now through July. “Enthusiasm and interest in oilseed crops is definitely on the rise, and there is multi-stakeholder involvement fueling that interest,” said Bill Pan, professor and scientist with WSU’s Department of Crop and Soil Sciences. “We are seeing growers as well as ag industry, university, and agency folks coming together as the value of the entire supply chain of oilseed crop production is realized. Growers are telling us about higher wheat yields, improved weed and pest control, and more efficient use of water and nutrients with an oilseed in rotation. High demand by local processors coupled with a strong canola market is resulting in a positive bottom line for oilseed growers.” Learn more »
June 14 – Lind Field Day. Research presentations will include an on-site demonstration and discussion of advances in development of new deep-furrow drill prototypes, winter wheat, club wheat and spring wheat breeding, camelina oil processing, timing of primary spring tillage, and soil microbial changes with irrigation. WSU administrators, state legislators, and wheat industry leaders will provide updates during the noon program. Learn more »
For a complete calendar of upcoming field days, check out http://arc.wsu.edu/fielddays/index.html.