A Case Study: Connecticut’s Sweet Corn IPM Program 1990–1993

One of the challenges of developing and implementing an IPM program is to successfully balance the goals of reducing pesticide use while maintaining the crop quality demanded by the farmer and the market. In the case of sweet corn IPM in Connecticut, crop quality has not only been maintained, but also substantially improved, resulting in a rise in whole-farm profitability. Connecticut’s growers attained these results by learning to precisely time pesticide applications using field scouting, pheromone traps to monitor insect populations, and action thresholds to determine if and when sprays were necessary based on pest numbers and plant phenology.

In the four-year period between 1990 and 1993, 35 sweet corn growers participated in the IPM program in Connecticut. The numbers reported here are averages from answers that growers provided to the following pre- and post-season survey questions:

1. How many acres of early, mid-season and late-season sweet corn did you grow?
2. To what percent of your sweet corn crop did you apply IPM methods?
3. How many bags of sweet corn did you harvest per acre (before culling)?
4. What percent “wormy ears’ did you get on your early, mid-season and late-season sweet corn prior to your IPM training and after your IPM training?
5. What percent of your early, mid-season and late-season sweet corn ears were culled or not picked due to worms prior to and after your IPM training?
6. What was the average price for which you sold a dozen ears (or a bag) of sweet corn wholesale and retail?
7. How do you market your crop? _____% wholesale ______% retail

Answers were based on growers’ records or estimates. Where no answer was given, the average response was used to compute savings. For example, if a grower had no idea how many bags of corn were harvested per acre, then the average yield of growers on the program the same year was used to help calculate his approximate savings. It was assumed that an increase in yield (due to reduced culls) could be marketed at the grower’s usual price. By “culls,” I am referring to any ear discarded by the grower, his workers or his customers or left unharvested due to worm damage. By “wormy ears,” I am referring to sweet corn fruit infested or damaged by any one of the common caterpillar pests of this crop: European corn borer, fall armyworm or corn earworm.

The cost of culls was computed for each individual grower by multiplying his percent culls by his yield per acre, by the price charged (per dozen or bag) and by the number of sweet corn acres raised. The cost of culls after program participation was subtracted from pre-program results to determine the total profits each grower received due to improved pest control.

Over the four years, 1990-1993, 35 growers increased their profits by $191 per acre on 1,867 acres of sweet corn by reducing their culls from 14% pre-program to 3% after their IPM training. That’s a total savings of $357,000 or $10,200 per grower, and means that the average grower (53+ acres) could save an additional $10,200 per year if he continued to utilize IPM after his initial training.

These 35 growers wholesaled approximately 68% and retailed 32% of their crop at an average price of $6.50 per bag and $3.16 per dozen, respectively, and estimated their yields at 186+ bags per acre. Dollar savings varied considerably between individual growers and years due to differences in pest pressure, yields, prices, ratio of the crop wholesaled or retailed, and insect control methods at the farms.

Additional IPM program savings occurred due to reduced pesticide use ($16/acre), reduced labor and machinery costs for spraying (not calculated) and, sometimes, reduced labor costs from not having to cull wormy sweet corn. For instance, a grower who formerly lost 20-25 hours of labor per week (at $6.50/hour for 12 weeks) culling wormy corn ears reported that he no longer needed to cull corn when using IPM (saving $1,700+ per season). It is difficult to calculate additional profits that result from having satisfied customers and their return business.

Savings from reduced pesticide use, reduced machine hours, and reduced labor from spraying and culling more than offset the costs of scouting and trapping equipment. In fact, 58% of the growers participating in the program over the last four years reported that they spent “the same amount of time,” or “less time” on pest control using IPM when they considered the time saved by spraying less frequently. If we assume that all IPM costs are offset by pesticide, machine, and labor savings, then all of the income due to increased quality and sales (11% fewer culls) represents profit.

According to our survey results, it costs a retail grower $29.39 and a wholesale grower $12.09 for every one percent increase in culled corn. Based on the average retail and wholesale prices of the growers in our survey, and assuming it costs approximately $700 per acre to plant, maintain and harvest sweet corn, it is four times more profitable to retail than to wholesale this commodity.

Retail: $3.16/doz. X 930 doz./acre = $2,939 -700 = $2,239 profit

Wholesale: $6.50/bag X 186 bags/acre = $1,209 -700 = $509 profit

You may mistakenly assume it is more profitable for a retailer to utilize IPM than a wholesaler, based on these results. However, if we divide the dollar value of one percent of their crops by their respective profit margins, a one percent crop loss translates to a 1.3% loss in profits for the retailer but a 2.4% loss for the wholesaler. To rephrase it, the wholesale grower on the IPM program who reduced his culls by 11% saved 26% of his profits, while the retailer saved 14% with the same reduction in culls. Thus, it is almost twice as important for a wholesaler to practice IPM and maintain his yields as it is for a retailer.

Sometimes growers say that they suffered crop damage because they did not have time to scout or properly maintain traps. It takes about one hour per week to scout 30 acres of sweet corn for a sixteen-week season. It takes only slightly more time to scout and monitor 300 acres because it takes the same number of plantings to maintain a steady supply of corn, regardless of size. Considering the potential profits to be saved, scouting may just be the best wage you have ever been paid:

$191/acre X 30 acres = $5,730 / 16 hours = $358/hour

$191/acre X 300 acres = $57,300 / 32 hours = $1,791/hour

Isn’t it worth assigning someone on the farm the responsibility of scouting and monitoring your corn?

By: Jude Boucher, Vegetable Crops IPM Program Leader
University of Connecticut, Cooperative Extension System Agricultural Center, P.O. Box 607, Litchfield, CT 06759, Reviewed 2012.

Originally published in Proceedings, New England Vegetable & Berry Conference. 1993. p. 121-123

This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.

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