Tips for orchard floor management

With a decade of orchard floor management research under their belts, Washington State University scientists offer an extensive list of findings to share with growers.

“The herbicide strip-grass alley system still represents a good compromise for achieving desirable tree performance at low cost and risk,” says David Granatstein, a WSU sustainable agriculture specialist.

Key Points

• WSU research offers orchard floor management tips for growers.

• Mulching, tillage and cover crops are studied.

• A wide spectrum of floor management impacts are observed.

Mulching, which costs more, also offers floor improvements, he adds. Much of his work seeking alternative floor management is triggered by a lack of effective, cheap organic herbicides for organic producers.

Here’s information from Granatstein on what he’s discovered to date:


• Generally improves tree performance

• Reduces irrigation needs

• Rodent problems can elevate

• Soil quality improvements can occur


• Can provide low-cost weed control

• Generally degrades tree performance

• Discourages rodent attacks

• Degrades soil over time


• Generally too competitive with trees down the row

• Can help soil quality and deliver natural nitrogen to trees

• Can stir up rodents

Mulching is particularly notable, he says, with research findings that spur tree growth, yields (plus 50% for apples) and fruit size. Some data reveal that a 50% increase in trunk size is achievable using mulching, and root numbers may triple.

Among organic growers, where tillage is the weapon of choice to manage orchard floors, producers could see a drop in tree growth of 15% below that of herbicide-treated rows, research shows. Cover crops can also be a menace to growth, adds Granatstein, who notes that “living” mulch can reduce new tree growth by up to 30%. However, he adds cover crops in Wenatchee, Wash., trials, where a living mulch of clover was used, exhibited increased yields in apples and boosted nitrogen found in leaves.

In related WSU studies using the least amount of material to mulch, Granatstein is probing weed “fabrics” in the orchard. “In recent research in berries, white fabric led to greater berry yields than black,” he reports on the mulching material placed on orchard floors. “Fruit quality was also improved,” he adds. “This fabric could provide multiple benefits that would improve its economic feasibility.”


FLOOR SHOW: WSU research is checking into several options for managing orchard floors, offering growers tips after 10 years of research.

This article published in the October, 2010 edition of WESTERN FARMERSTOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2010.