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United States Department of Agriculture

Agricultural Research Service

Research Project: Automation of Dormant Pruning of Specialty Crops

Location: Horticultural Crops Research

2013 Annual Report

1a.Objectives (from AD-416):
Research will focus on automating dormant pruning of four major specialty crops—grape, apple, peach and sweet cherry—by carrying out four integative project goals to:.
1)formulate and evaluate rules that describe optimal pruning in terms of measurable physical attributes of canopy structure;.
2)develop 3D imaging, decision system, and robot control technologies for automating dormant pruning operations;.
3)determine social and economic impacts of the proposed autonomous pruning system; and.
4)communicate results and involve growers, industry groups, academia and students so they can adopt these technologies and incorporate the knowledge gained into their orchards, vineyards, businesses, classrooms and laboratories.

1b.Approach (from AD-416):
1. Formulate standardized crop-dependent pruning rules to ensure that pruning cuts result in favorable outcomes (since improper pruning rules will result in negative outcomes) 2. Since fruit canopies are three-dimensional, develop 3D sensing and image analysis to determine which specific branches to remove to obtain optimal canopy dimensions 3. Create a decision system for the application of the pruning rules to the sensed data to form action steps that result in appropriate pruning cuts 4. Field test and analyze research results to assure that the outcomes of mechanized pruning are equivalent to or better than the outcomes produced by manual pruning and result in economic benefits 5. Train the growers in the application of automated pruning. Analyze social and economic implications to reduce or eliminate barriers to implementation

3.Progress Report:

This research was conducted in support of NP305 objective 1 "Determine effects of water management on wine grape productivity and fruit maturity" of the parent project. Grapevines must be pruned, or removed of old shoots, every winter. This is a labor-intensive process that is expensive. In addition, the availability of farm labor is becoming increasingly restrictive. Pruning by a machine that replicates the shoot removal made by humans can alleviate the labor availability bottleneck and can potentially reduce pruning costs. A robotic, or self-controlled automated pruner is under development but the machine must be programmed to replicate the human decisions. We refer to these decisions as pruning "rules." To move forward the development of the automated pruner, we used questionnaires that were completed by growers to establish common practices, or the "rules" that manual pruners follow. Of questionnaires used in Washington State, 40% of wine grape acreage was represented. One questionnaire was returned by a large winery in California. Common "rules" include the space between cuts--the old shoots that are retained; the length of the old shoot that is retained; and the desired total number of fruit buds per grapevine. Fruit buds are the part of the grapevine that produces this year's fruit. Variabilities include adjusting the pruning for the age of the vineyard, the variety of grape, and how much yield is desired for the specific vineyard, which often depends upon the quality level of the wine that is produced after harvest. All of these decisions are made based on historical data kept by the vineyard owner. Growers also shared their pruning costs, which varied two-fold per acre based on labor rates and how much mechanical work was conducted (called "pre-pruning") before the human pruners completed the operation. Larger operations tend to pay pruners by the vine, called "piece rate," because speed is paramount, whereas smaller vineyards often pay pruners by the hour to increase the quality of the shoot removal decisions. The automated pruner can be programmed for these factors but must be given the set of grower's "rules" for each vineyard. Currently, the automated pruner, using a single set of rules, cuts accurately 90% of the time but is severely limited by its slow speed and thus is not ready for the marketplace. Adoption of the automated pruner will depend upon farm size and capitalization for purchasing an expensive piece of equipment that performs only one function (pruning).

Last Modified: 4/20/2014
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