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Home HortTechnology Innovative Technology Creates Fast, Convenient Mulching for Minimum Input Orchards
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SUMMERLAND, BC—The use of organic mulches is on the rise in both integrated fruit production and organic fruit production. Keeping with the trend, tree fruit producers are interested in finding new methods of providing effective nonchemical weed control. Unfortunately for orchardists, the alternative weed control methods tested in high-density apple plantings have most often been deemed unsatisfactory. A new research study from British Columbia contains promising news for organic apple producers.

According to the study the cost of mulching—along with a concern for rodent damage to trees—has been a major impediment to widespread adoption of organic management strategies. Gerry Neilsen, the study's corresponding author, noted that another critical factor in the higher cost of mulching is ease and method of application. "Using mulch that can be sprayed on a tree row using machinery would increase the speed and convenience of application, thereby reducing overall costs," Neilsen explained.

Neilsen and colleagues introduced a new mechanical mulching technology in the study, which appeared in HortTechnology. Using a spray-on-mulch slurry made from by-products of recycled newsprint, the scientists designed four experiments using 'Gala', 'Granny Smith', 'Ambrosia', and 'Honeycrisp' apple trees on 'Malling 9' rootstock. The trees were exposed to a series of treatments including a glyphosate check, spray-on mulch slurry (SOM) waste paper, SOM over an organic underlay, SOM incorporated with dichlobenil or tackifier, SOM over black landscape fabric, rowcover cloth, or polyethylene plastic.

The spray-on-mulch was applied using a customized applicator equipped with a recirculating trash pump and gate valve to regulate output and direct the slurry onto the tree row using a splash plate. "The SOM formed a hard crust on the surface that acted as barrier to weed germination and growth," said Neilsen.

Results showed that the spray-on-mulch provided superior weed control in comparison with the glyphosate check treatment. SOM application over compost, paper, and especially over cloth barriers were found to be more effective weed barriers than SOM alone. In comparison with glyphosate checks, SOM improved tree growth during tree establishment. "Benefits of the SOM included moderation of soil temperature, conservation of soil moisture, control of weed growth, and increased growth of newly planted apple trees on dwarfing rootstocks in most plantings, consistent with reports on other organic mulches," the researchers said.

The scientists added that commercial adoption of the new technology will depend on the availability of cost-effective sources of mulch product free of contaminants and effective delivery systems able to provide long-term weed control before the requirement for reapplication.


The complete study and abstract are available on the ASHS HortTechnology electronic journal web site:

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at


Original Article:

Spray-on-mulch Technology for Intensively Grown Irrigated Apple Orchards: Influence on Tree Establishment, Early Yields, and Soil Physical Properties
John Cline, Gerry Neilsen, Eugene Hogue, Shawn Kuchta, and Denise Neilsen
HortTechnology August 21:398–411. [Abstract][Full Text][PDF]

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