Highlights of the 8th North American Strawberry Symposium

Like the Olympics, this Strawberry Symposium occurs once every 4 years, bringing researchers, ag business and growers together from across North America and the world. Organized by the North American Strawberry Growers Association and a team of volunteers, this year's strawberry olympics were held in Ventura, California. The meeting included over 50 speakers, 30 posters and a field tour. Much has changed since I attended the 6th symposium, also in Ventura, 8 years ago. Here are some highlights.

ASD = Anaerobic soil disinfestation. This is the new hot topic in California as growers search for alternatives to methyl bromide and other soil fumigants. Eight years ago, alternatives to methyl bromide were "other fumigants". Now there is a very focussed effort on ASD and other alternatives as restrictions on all fumigants get tougher. Anaerobic soil disinfestation involves a series of steps: 1. Incorporate a carbon source, such as rice bran, or whatever is economical. 2. Cover with an impermeable tarp. 3. Irrigate under the tarp to soil saturation, then maintain at field capacity for 3 weeks. 4. Hope for sunshine. Soil temperatures under the tarp should reach an average of 20C at 6 inch depth, for at least a week. Done properly, ASD is helping to reduce plant disease from soil pathogens such as verticillium (Figure 1).

Joji Muramoto and Oleg Daugovish explain ASD in an organic strawberry field. It is too early to know if ASD will control the Macrophomina which causes plants to collapse in hot dry conditions.

Figure 1: Joji Muramoto and Oleg Daugovish explain ASD in an organic strawberry field. It is too early to know if ASD will control the Macrophomina which causes plants to collapse in hot dry conditions.

Walmart sustainability initiative. The Walmart foundation provided $3M in 2013-2015 for a national strawberry sustainability initiative, through a series of competitive grants administered by the University of Arkansas. Many research reports at the NASS symposium were a result of this research funding.

For example:

  • Sustainable off-season production of high quality hydroponic strawberry in desert southwest - Chieri Kubota, University of Arizona
  • Sustainable soil management practices for strawberries: evaluation of individual and integrated approaches - Michelle Schroeder-Moreno and Amanda McWhirt, North Carolina State University
  • Placement of additional drip lines to enhance soil fumigation and irrigation efficiency and minimize environmental impacts - Oleg Daugovish, University of California Cooperative Extension

You can read more about these projects and download the report at http://strawberry.uark.edu/. There are videos and links to presentations on lots of great projects.

California Cooperative Extension employs a well-connected group of knowledgeable pest management and horticulture specialists. Web pages for Ventura County, San Luis Obispo, Santa Barbara and Santa Cruz counties provide a wealth of information for growers, in English and Spanish (in your browser type "cecountyname.edu"). Cooperative extension agents post their presentations and meeting handouts on line. Ontario berry growers might be interested in Mark Bolda's blog http://ucanr.edu/blogs/strawberries_caneberries/ , or the presentations from recent local berry meetings www.ucanr.edu/meetingpresentations, or Oleg Daugovish's video on anaerobic soil disinfestation http://ceventura.ucanr.edu/Com_Ag/Strawberry/

National Clean Plant Network for Berries receives stable funding from the USDA to ensure that clean, disease-free Generation 1 material is provided to plant propagators in the USA. Plant material and new selections can be tested for viruses and "cleaned up" using various methods at one of 3 centers before it is released to plant propagators. This funding is also used for research and improved diagnostics of berry plant virus and virus like diseases. Additionally, a national standard for strawberry certification is being developed for strawberries in the USA. The question is, will Canadian programs develop in synchrony with the American process?

Water shortages: The drought conditions in southern California range from extreme to exceptional. After 6 years of drought, the Ventura River and many other lakes and rivers have gone dry, and the snow pack is a small fraction of normal in the Sierra and other mountain ranges. Growers are dealing with this shortage by drilling deeper wells, and salt water intrusion is becoming a problem. Desalinization, which is expensive and energy-intensive, seems to be the back-up plan if it doesn't rain soon.

Insects: It's no surprise that mites are a huge problem in hot, dry California, both two spotted spider mite and a newer species, the Lewis mite. Resistance to miticides is a concern as some of the older products are showing les efficacy than in the past. Growers use both insecticides and bug vacuums for lygus bugs, a relative of the eastern tarnished plant bug. Bug vacs are known to be inefficient, capturing a small portion of the population with each pass, so growers use them twice a week! Researchers are working to improve the efficiency of these expensive machines.

Farm Tour: The highlight of the tour was a visit with Will Terry, of Terry Berries. Will is a 5th generation farmer in Oxnard, with a very large acreage of strawberries and leafy greens. There were 3-4 harvest aids in the field. These machines move along the field ahead of the workers, who simply deposit their flats onto a conveyer belt, reducing time walking back and forth in the field. These harvest aids are widely used especially in the Oxnard area. Although labour costs are substantially reduced, it takes approximately 5 years to pay off the initial investment of over $100,000 per machine (Figure 2). What keeps Will Terry awake at night? His three biggest concerns for the future of strawberry production are: alternatives to soil fumigants, water issues, and availability of labour.

Strawberry harvest in Oxnard, California. Harvest aids save labour costs by reducing the time workers spend walking to drop off their flats. They are best suited to the large flat fields around Oxnard.

Figure 2: Strawberry harvest in Oxnard, California. Harvest aids save labour costs by reducing the time workers spend walking to drop off their flats. They are best suited to the large flat fields around Oxnard.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca