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On-Farm Demonstration Trials Show that ‘Proof is in the Pudding’ (or Apple)

Content Author:
Melanie Ivey Lianna Wodzicki


fruit rot
Figure 1.  Fruit rot symptoms (left) and apple scab (right) on an apple at harvest.

The proverb “the proof of the pudding is in the eating” is thought to date back to the early 14th century and is used to say that the worth or effectiveness of something can only be determined by putting it to the test.  While I’m not sure I would want to test the worthiness of a pudding from the 14th century (haggis anyone?), I’m happy to taste an Ohio-grown apple, especially one produced using sustainable agricultural practices!

During the 2020 season, the scientists at The Ohio State University and USDA teamed up with a local apple producer to test the efficiency and effectiveness of intelligent sprayer technology in controlling fruit diseases and insect pests.  Without sounding like a broken record, the intelligent sprayer is a new, innovated technology that is revolutionizing the fruit tree industry.  Using a scanning laser, the tree shape and canopy density are determined, and combined with the tractor speed.  An embedded computer within the tractor cabin uses this information to automatically calculate the volume of pesticide needed to cover the tree and penetrate the canopy.  It then dispenses the pesticide based on the architecture of the tree by controlling which nozzles are opened.  The end result is targeted pesticide applications, reduced drift and ground drop-off, and the potential for extensive cost savings.

A demonstration trial was conducted on a farm in Rittman, OH and consisted of side-by-side plots that were either sprayed using conventional airblast technology or intelligent sprayer technology.  The plots contained a variety of cultivars including ‘Red Delicious’, ‘Granny Smith’, ‘Gala’, and ‘Fuji’, although data were only collected from the ‘Red Delicious’ apples.  Each plot contained 300 trees (on trellises).

Figure 2. A) Plum curculio adult with egg on an apple. Photo courtesy of Peter Jentsch, Cornell University; B) an apple with Plum curculio symptoms picked during harvest.
plum curculio


PC damage


Figure 3.  Some members of the Ohio State team getting ready to sort apples for disease and insect incidence after harvest.

The grower used their standard fungicide and insecticide spray program to treat the trees.  Their program was developed to target major apple diseases and insect pests in the region including apple scab, fruit rots (Figure 1), plum curculio (Figure 2A) and codling moth.  At harvest, apples were collected from 15 randomly selected trees from each plot and sorted by disease, the type of insect injury (Figure 3) and marketability.  So, is the proof of the pudding in the eating?

The answer is yes!  Percent marketable yield was greater than 95% in both plots (Table 1).  Less than 4% of the fruit were diseased and insect injury was negligible in both plots.  Plum curculio (Figure 2B) was the only insect for which injury was observed.  Apple scab and fruit rot were the only diseases observed.  The biggest and most noteworthy difference between the two sprayer technologies was in the amount of pesticide used.  The intelligent sprayer used approximately 30 gals/acre less pesticide than the airblast sprayer.  This is a 42% decrease in pesticide use to achieve the same level of disease and insect pest control.  That is some good pudding!


Table 1. Percent diseased, insect-injured and marketable fruit in a commercial Ohio apple orchard when using intelligent or airblast sprayer technology.

Pesticide Application

% Diseased % Insect injured % Marketable
Intelligent Sprayer Technology 3.78 0.53 95.69
Airblast Sprayer Technology 1.84 0.24 97.91
P-Value 0.2898 0.2466 0.2794


Click here to listen to the grower’s testimony on using the intelligent sprayer in the orchard.