Advancements in organic coatings and treatments

While many consider genetics and seed selection the best first step in preventing crop loss, seed processors offer another way to address seed health. With advancements in diagnostic technology to evaluate seed health, new diseases and threats to seed health are exposed. Genetics, environmental contaminants and other challenges specific to individual seed lots or species can result in crop loss. Seed processors strive to improve each seed lot’s germination and vigor, and to eliminate the possibility of problems that may emerge later in the growing cycle. Organic philosophy and techniques are influencing the seed processing industry.

After seed is harvested, it must be milled to remove weed seed and other impurities. Proper milling improves the germination of the final sellable lot. Other services such as sizing and density grading further improve seed lots by removing the seed that may have a lower performing germination. More processors recognize that greater attention to evaluating individual seed lots and species prior to treatment is best practice. Jan Van der Heide of Bejo Seeds says, "What the seed tells you suggests its proper treatment."

Susan Bassi of AgriCoat, says, "We have committed a great deal of resources to the proper diagnoses of what needs to be done to a particular seed lot."According to Bassi, the entire processing industry has started focusing on diagnosing and treating infections that occur in a particular seed lot.

The first step for both growers and processors in minimizing disease is testing. However, commercial testing is expensive and commercially available lab tests may not provide the comprehensive information necessary to address an individual seed lot properly. Thus huge variations in results occur. Bassi says producers and testing labs are working together to develop methods that will offer more affordable and consistent results. "When we are looking to improve the performance of a seed lot, we evaluate the lot under specific stress protocols. If we find a problem, or if a customer requests seed be tested, we send it to a third party certified lab and order the test for the disease that may be of concern."Diagnostic methods can, Inc.lude simple evaluation and assay of the external seed coat or can involve the more complicated process of growing plants out to evaluate possible infection. Bassi says the type of testing varies by species, region and information desired.

Next, to eliminate disease, fungi or other pathogens that may interfere with a seed’s ability to germinate or cause soil infection, the processor may clean seed with hot water or disinfect it with hot air or more elaborate materials or methods. The Verticillium affecting California spinach growers right now is just one example of many threats to seed health. Processors like AgriCoat utilize their own proprietary methods to remove pathogens and bacteria like Verticillium.

"By starting with clean seed we are seeing very positive results in greenhouses and field production,"says Bassi. "When seed is not burdened with diseases, it performs much better and produces overall healthier plants."

The third step, seed treatment, is not always necessary. However, it offers additional benefits for seed health and provides an efficient delivery system. For those who prefer treated seeds, many companies offer both organic and conventional treatments. Organic materials used on seed typically differ from conventional counterparts in that they focus on health and "beneficials."Bassi says AgriCoat’s Natural II product line provides a film coating that delivers micronutrients and biological inputs directly to seed. The coating competes against pathogenic soil and seed borne bacteria and fungi and helps seedlings perform better under adverse environmental conditions. She says conventional treatments utilize synthetic materials to accomplish the same thing. AgriCoat and other companies like Harris Moran and Bejo Seeds offer organic pelleting or film coating to improve flow through mechanical feeders.

In search of an organic coating to protect seeds from pathogens, Bejo researchers are currently experimenting with microorganisms. However, they are designing the coating to do more than protect organic seeds like conventional fungicide and insecticide treatments work.

"Organic growers don’t have the luxury that conventional growers do to ‘improve’ performance of a seed via chemical inputs,"says van der Heide. While he acknowledges that most organic growers put extra effort into building the health of their soil, he points out that growers cannot avoid all climactic inputs. If land becomes water-logged due to excessive rainfall, the seeds are subject to attack from pathogens. "But, if you have strong, healthy seed, it may be able to withstand that attack,"he says.

If Bejo’s researchers succeed in creating an effective organic coating, it will promote a healthy seedling that could withstand such attack. Van der Heide stresses that this treatment is still in developmental stages. "We’ve seen some exciting results already, but we still have a few things to do before we can make these treatments available to growers,"he says.

In the past, the industry focused effort, investment and attention mainly on seed germination and genetics. Bassi believes it is far more efficient to improve seed health, thereby improving plant health, which will, Inc.rease yields and reduce losses associated with diseased seed. Just as seed producers bring genetics to the marketplace, seed processors will have to look beyond genetics to determine how to improve other aspects of seed performance. This will mean greater attention to diagnosis. In effect, seed producers may become more like doctors, determining the course of treatment for a patient presenting symptoms.

The author is a freelance writer based in Massachusetts.