PRODUCTION SYSTEM IMPACTS OF STACKED WEED MANAGEMENT TACTICS DURING THE ESTABLISHMENT PERIOD OF A HIGH-DENSITY, CERTIFIED ORGANIC APPLE ORCHARD

Other Titles
Abstract

In the United States, certified organic apples comprise over 11,000 ha and represent $9 billion in annual sales. Organic apple production in New York State and the Northeastern U.S. lags behind production in Washington State where more arid conditions limit pressure from pests, disease, and weeds. Weeds, which compete for resources and provide habitat for tree-girdling rodents, are regularly identified as a major barrier to more widespread adoption of certified organic apple production in the Northeastern U.S. In the present study, we sought to build on the existing body of work focused on efficacious, in-row weed management strategies for organic apple production by combining tactics. The first component of this project was evaluating the impacts on weed biomass, soil chemical, biological, and physical characteristics, apple trees nutrient status, and growth and productivity of the trees during the first four years after planting. The second component was an in-depth analysis of the weed species and changes to weed community assembly in response to the various weed management approaches during this time period. Eight rows of ‘Honeycrisp (Firestorm)’/‘Budagovsky.9’ apple trees were planted (0.9 m × 3.7 m) in a certified organic block at the Cornell University Agricultural Experiment Station Orchards in Ithaca, New York in 2015. Twelve combinations of weed management tactics were implemented in 2016 comprising a split plot experimental design with three main (Mulch, Cultivation, Control) and four split (Mowing, Ammoniated soap, Capric acid, Control) treatments. Between 2016 and 2019, the Mulch treatment improved soil health regardless of the split treatment with improvements to soil organic matter and soil respiration being notable compared to the other main treatments. Although the Mulch treatment also maintained less weed biomass than the other main treatments through 2018, regardless of split treatment, these factors did not optimize tree growth; instead, only the Cultivation treatment resulted in trees with a trunk cross-sectional area (TCSA) significantly greater than the weedy check. Over time, the split treatments became the significant factor influencing weed biomass and the weed community. Within the split treatment Control, an abundance of creeping perennials Solidago spp. and Symphytotrichum lanceolatum was observed regardless of main treatment. As a result, this treatment had significantly greater biomass than the other split treatments by sample period 2 in 2018 and 2019. The organic herbicide split treatments of Ammoniated soap and Capric acid increased biomass from monocot weeds compared to the split Control and Mowing treatments, but always maintained weed biomass significantly lower than the weedy check. Nutrient management was a challenge, as leaf tissue analysis revealed macronutrients were commonly deficient throughout the experiment. Although the Cultivation treatment increased apple leaf nitrogen content compared to the other main treatments, there was no statistically significant correlation between leaf nitrogen and tree growth. Site selection, site preparation, and choice of apple rootstock and scion combination for this study are the main factors that may have influenced apple tree response to these management practices. However, the results of this experiment affirm the relationship between weed management and several horticultural aspects of the orchard production system and underscores the challenge of balancing weed control and nutrient management during the establishment period of the orchard. This work highlights the need for continued research in this subject area to facilitate greater adoption of certified organic apple production.

Journal / Series
Volume & Issue
Description
118 pages
Sponsorship
Date Issued
2022-08
Publisher
Keywords
organic apple production; soil health; weed management
Location
Effective Date
Expiration Date
Sector
Employer
Union
Union Local
NAICS
Number of Workers
Committee Chair
Peck, Gregory Michael
Committee Co-Chair
Committee Member
DiTommaso, Antonio
Kao-Kniffin, Jenny T.
Degree Discipline
Horticulture
Degree Name
M.S., Horticulture
Degree Level
Master of Science
Related Version
Related DOI
Related To
Related Part
Based on Related Item
Has Other Format(s)
Part of Related Item
Related To
Related Publication(s)
Link(s) to Related Publication(s)
References
Link(s) to Reference(s)
Previously Published As
Government Document
ISBN
ISMN
ISSN
Other Identifiers
Rights
Rights URI
Types
dissertation or thesis
Accessibility Feature
Accessibility Hazard
Accessibility Summary
Link(s) to Catalog Record