Applying Precision Agriculture To Tree Fruit

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The Faces Of Extension: Jim McFerson

How are pruning and fruit thinning like precision agriculture? In tree fruit, pruning has long been considered an art, requiring the skill of a surgeon and the insights of a poet. Fruit thinning is viewed as an excruciatingly tedious and expensive hand process, and/or a spray program relying on hunches and wishful thinking.

Precision ag is the opposite, relying on accurate measurement, statistics, and modern technological tools. More like a robot with a two-year degree in agronomy who doesn’t care about the weather or time of day.

Precision ag conjures up images of a very large GPS-equipped tractor dispensing a variable rate application of seed, fertilizer, lime in a very large corn field, or perhaps a GIS-based brightly colored aerial map diagramming soil types and drainage patterns, or a photographic image of relative vegetative vigor generated in an aerial flyover or even via satellite.

It would seem that precision ag, in which we seek to measure and manage variation at the field level, has such tremendous potential for tree fruit, since the cost (and potential return) on our input and management investment per unit area are so much higher than extensive crops like corn, wheat, and cotton.

Additionally, the cost of management inaccuracies or inefficiencies in the early years of orchard establishment are compounded annually, so it would seem even more attractive to understand, characterize, and account for site variability from the get go.

Yet, precision ag remains largely conceptual for tree fruit.

Perhaps part of the problem is that precision ag has tended to highlight the use of tools like satellite imagery, information technology, and geospatial analysis, with a particular emphasis on satellite positioning systems like GPS. These tools are of more obvious and immediate application in field crops. In many orchards, for example, the canopy cover prevents reliable connection with satellites necessary for GPS.

If we shift focus, however, to the approach, rather than the tools, it would seem most tree fruit horticulturists are in fact applying the principles of precision ag every day. They have visceral knowledge of their need to measure and manage intra-field variation. In fact, it would be even better if we could manage at the plant to plant, or even the intra-plant level.

Here is where pruning starts to resemble precision ag. And as we finish up pruning in the Pacific Northwest, blessed with a relatively mild winter, we have already completed the first step in precision management. As pomologists have preached for years, crop load management should start early, with pruning.

This step defines the framework for subsequent management of vegetative and reproductive growth in the tree. As the industry moves unilaterally from low- to high-density plantings, pruning actually becomes more predictable and less poetic, but it is still done by hand. It’s not an easy job even when conditions are mild, and every year there are fewer workers willing to perform it. It is a practice that cries out for optimization.

Jim McFerson is manager of the Washington Tree Fruit Research Commission in Wenatchee, WA.

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