Apple Diseases

Kentucky apple growers are faced with numerous plant disease issues throughout growing seasons. These diseases limit grower profits by reducing yield and increasing input costs.

Diseases of Greatest Concern to Growers

While diseases of concern may vary from orchard to orchard, a survey of growers found that the bacterial disease, fire blight, was of greatest concern for growers in terms of amount of yield loss and management difficulty. Table 1 details the results of the grower survey.

Table 1: A survey of Kentucky growers resulted in the following rating of disease importance and management challenges. (Image: A Profile of Commercial Apple Production in Kentucky 2017)

Critical Times of Chemical Applications to Manage Diseases

In commercial orchards disease management includes applications of fungicides and/or bactericides. Chemical applications can be costly and add to production costs. Thus, chemical applications timed only during infection periods and critical times can result in fewer applications per season. Table 2 presents the infection periods and critical times for chemical application in commercial orchards.

Table 2: Infection periods and critical times for fungicide/bactericide application in commercial orchards in Kentucky.

Additional Information

  • A Profile of Commercial Apple Production in Kentucky 2017 (Link)
  • Backyard Apple Disease & Pest Management Using Cultural Practices (with Low Spray, No Spray, & Organic Options) (PPFS-FR-T-21)
  • Effectiveness of Fungicides for Management of Apple Diseases (PPFS-FR-T-15)
  • Fruit, Orchard, and Vineyard Sanitation (PPFS-GEN-05)
  • IPM Scouting Guide for Common Problems of Apple (ID-219)
  • Midwest Fruit Pest Management Guide (ID-232)
  • Scouting Guide for Problems of Apple Mobile Website (Apple Scout)
  • Simplified Backyard Apple Spray Guides (PPFS-FR-T-18)

By Kim Leonberger, Plant Pathology Extension Associate and Nicole  Gauthier, Plant Pathology Extension Specialist

Posted in Fruit