Date of Award:

12-14-2011

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Brent L. Black, Ph.D.

Abstract

Orchard floor management is vital to tree health, yield, and fruit quality. Current standard management practices include maintaining a vegetation-free tree row and a grass-covered alleyway. This system is effective at limiting competition from undesirable vegetation and creating a favorable environment for the fruit trees. However, limitations to standard orchard floor practices are that the grass alleyway provides no nutrient benefit, and current practices do not readily lend themselves to organic management constraints. Alternative in-row and alleyway systems are requisite to creating improved orchard floor management systems. Three different approaches were used to investigate alternative orchard floor management strategies, including: alternative in-row weed control with combinations of mulch and organic herbicides, alternative alleyway management with legume cover crops, and combinations of in-row and alleyway alternative strategies. Although organic in-row weed control was best accomplished with combinations of straw and acetic acid, this management approach was not economically viable at current costs of labor and supplies, and current fruit prices. Alfalfa and alfalfa clover treatments contributed the most aboveground biomass and nitrogen among alternative alleyway covers, but consumed 45% more water than the conventional grass alleyway. In combinations of in-row and alleyway alternatives, birds-foot trefoil alleyway had a beneficial effect on tree growth compared to grass, while consuming the greatest amount of water. Peach yields were the highest for the integrated compost and NPK fertility treatments that used herbicides to minimize competition. Treatments that experienced the most competition from weeds, no herbicide and reduced herbicide treatments, resulted in lower yields. Weed fabric and tillage in-row weed control methods resulted in the highest tree growth as compared to the straw and alyssum treatments. Finally, results from the combined studies were integrated into a series of recommendations for commercial fruit growers. While alternatives to orchard floor management show a number of potential benefits for growers in the Intermountain West, additional work is needed to determine the long-term viability of these approaches.

Comments

Publication made available electronically December 21, 2011.

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