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Commercial Apple IPM Program

Principal Investigators:

Ric Bessin, Extension Entomologist Jerry Brown, Extension Horticulturist John Hartman, Extension Plant Pathologist
Doug Johnson, IPM Coordinator John Strang, Extension Horticulturist Terry Jones, Extension Horticulturist


The 1993 Apple IPM Program was funded mainly by USDA/ES/IPM funds allocated to Kentucky and in part by funds carried over from a previous USDA/ES/IPM grant; professional support was provided by the University of Kentucky Cooperative Extension Service. The purpose was to demonstrate to Kentucky apple growers the application of Integrated Pest Management practices in the management of their orchards. IPM relies on orchard management practices such as pest and tree monitoring and locally collected weather data to predict the activities of certain insects and diseases.

Apples on the tree

Using IPM, the grower applies pest management procedures as needed based on orchard monitoring and predictive models rather than according to a calendar schedule. In addition to saving money, reduced sprays result in decreased potential applicator exposure to pesticides, pest resistance development, pesticide residues on food, harm to bees, water contamination, soil compaction, and drift to other crops. Where IPM calls for more sprays, increased crop quality should occur.

Project Overview

The 1993 Apple IPM Program, funded in part by USDA/ES/IPM, involved Kentucky apple growers in the application of Integrated Pest Management practices in the management of their orchards.

There were three major changes in the program from 1992 to 1993.

1) Growers scouted their own orchards, rather than using University of Kentucky-employed scouts.
2) University of Kentucky specialists were available each Monday morning to growers who wished to call and ask for technical advice.
3) A part-time IPM technician accumulated and analyzed apple IPM data submitted by the growers. This served to better educate them about the presence and progress of various diseases and pests, so they could make more educated management decisions.

Daily weather and monitoring data from orchard weather stations were recorded on scouting forms by the growers and delivered weekly to the technician at the Lexington campus either by phone or by fax. The weather data were used to predict fire blight infection periods, and to calculate degree days for insect management. Pheromone traps for codling moth and San Jose scale placed in the orchards were examined weekly to monitor these insects. Several growers maintained and analyzed their own orchard data.

Four IPM orchard meetings for growers provided an opportunity for the specialists to address current apple IPM issues and for the growers to discuss concerns in an informal setting. Each of these meetings included a hands-on exercise in which the growers divided into small groups and scouted orchards. This approach was new for 1993, and was very productive. Growers practiced orchard monitoring while having University of Kentucky specialists available for questions. Kentucky Apple IPM Manuals were distributed to growers for use in scouting and implementing IPM in their orchards. Attendance at the apple IPM field days was good.

Evaluations of IPM versus standard (STD) blocks were made at the end of the season to determine disease and insect damage to the leaves and fruit. There were few significant differences in foliar and fruit pest and disease levels in IPM versus standard blocks. Foliar disease, insect, and mite levels were generally lower in IPM blocks. In addition, IPM did not significantly affect quality of the fruit based on disease, insect, and physiological defects evaluated. Overall, IPM use generated notable savings among the orchards. Growers with comparison blocks saved an average of $71 per acre using IPM. Individual case studies of each orchard are presented to show how each orchard fared using IPM.

Materials & Methods

Automated weather station

A weather station consisting of at least a minimum/maximum thermometer and a rain gauge, was set up in each orchard as was done in the 1992 program. Three growers used automated weather monitors, a Predictor (Reuter-Stokes, Inc., Cleveland Ohio), an Envirocaster (Neogen Inc., Lansing Mich.), and a METOS Disease Predictor (Pest Mgt. Supply Inc., Amherst, Mass.). The Envirocaster was purchased in 1991 with funds from a University of Kentucky program enhancement grant, and the METOS and Predictor were purchased by the growers. Weekly scouting data and daily weather data were recorded on scouting forms by the growers and collected weekly by the technician, in the manner described above. Growers also placed pheromone traps for codling moth and San Jose scale in the orchards and checked them weekly to help monitor these insects.

The data were used in several ways. Apple scab infection periods were determined when the weather data, including leaf wetness information were applied to Mill's Table. Growers quickly reacted to infection periods with eradicative fungicides to prevent symptom development. Fire blight prediction was accomplished when data were entered into the MARYBLYT predictive computer program. Last year two growers used the MARYBLYT program on their own personal computers; this year that number increased to seven. Data for the rest were entered on a MARYBLYT program installed in a University of Kentucky computer. Fire blight infection data were combined with weather forecasts to determine whether or not and when to spray. Insect management also relied on the weather data to calculate degree days and was used in conjunction with the scouting data to determine when certain insect pests would be active. Pheromone trap catches and degree day accumulations were used to predict the time of codling moth egg hatch and San Jose Scale crawler movement for optimum timing of insecticide applications. Insecticides were targeted at 3% egg hatch for codling moth.

Each orchard in the 1993 program was scouted weekly throughout the main growing season (March 29 - July 8). To scout, the grower would check a random sample of 5 trees for leaf and fruit damage and record any findings on the scouting log in both the IPM and standard blocks. Records of grower spray and other pest management activity were collected along with the weather and scouting data.

There were four IPM field day meetings for growers held at various orchards in the program periodically during the season. These informal meetings provided an opportunity for the specialists to address current apple IPM issues and for the growers to discuss problems of concern to them in an informal setting. Some of the meeting topics discussed were sprayer calibration, insect identification, San Jose scale and Japanese beetle management, thinning procedures, fire blight control, summer disease management, and pest problems anticipated before the next meeting. Growers were taught to look for the same insect and disease signs and symptoms that the scouts had looked for in the previous two years.


Overall, IPM use generated notable savings among the orchards. The number of pesticide applications and trips through the orchard were reduced in IPM vs. STD blocks. While the number of fungicide and insecticide sprays saved in the IPM versus the STD blocks was nearly the same this year and last, overall monetary savings were greater this year than last. On the average, growers used one less fungicide spray on the IPM block, saving an average of $17 per acre, compared with $1 per acre in 1992. Reducing insecticide use from 10 to 8 applications saved an average of $21 per acre for IPM blocks, compared with $38 in 1992. When insecticide, fungicide, and spray application costs ($25 per acre for each trip through an orchard) are calculated, growers with comparison blocks saved an average of $71 per acre using IPM, compared with $56 in 1992. Per acre spray costs for apple growers are typically divided between application costs ($425) and chemical costs ($425). One grower saved as much as $230 per acre overall by using IPM. However, another spent an extra $8 per acre. These figures reflect differences in levels of grower expertise and in perceived pest problems. In some locales, growers following good IPM practices in fact had to spray more than growers in other locales because of more disease favorable weather. As growers become more comfortable using IPM, savings could increase. Numbers of sprays applied to IPM blocks decreased from 1992 to 1993, possibly due to introduction of MARYBLYT in 1993. On the other hand, some growers, observing the success of IPM, began to adopt IPM practices and reduce pesticide use in their standard blocks, thus masking some of the real differences between IPM and standard programs.

Most growers followed through on their weather and orchard management records and took appropriate actions when needed. Growers were taught how to manage their orchard using IPM, one of the program objectives. The results of the IPM costs and benefits for each orchard were also helpful in showing IPM benefits and gaining grower acceptance and understanding. The MARYBLYT computer printouts of fire blight infection and progress impressed the growers since the information almost exactly matched what the growers were observing in their own orchards.

Kentucky IPM

Original document: 21 November 1996
Last updated: 21 November 1996

Scoutcat logo courtesy of C. Ware, copyright 2000

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