Fruit Pathology - Botany and Plant Pathology, Purdue University

Fruit Pathology Specialist

Janna Beckerman

Dr. Janna Beckerman

Professor of Plant Pathology
765.494.0363 (fax)

Program Description

The goal of our research is to develop environmentally sound disease management strategies that are economically feasible for Indiana growers producing apples. To do so, we are developing two web-based programs: 1) a program to assist growers in developing effective fungicide rotations and 2) a forecasting tool for the major diseases that infect apples. Our research effort is directly tied to our extension work, and focuses on the identification and management of fungicide resistance. To that end, we are currently surveying Indiana orchards to evaluate the incidence of fungicide resistance in Venturia inaequalis, the fungus that causes apple scab, and Glomerella cingulata, the causal agent of bitter rot. An effective fungicide rotation, coupled with good forecasting tools reduces chemical inputs, and minimizes the likelihood of fungicide resistance developing.

Apple scab is one of the most serious diseases of apple and ornamental flowering crabapple, and affects both leaves and fruit. In commercial apple production, foliar infection by the apple scab pathogen results in defoliation that leads to a loss of apple quality, and impacts winter-hardiness. Fruit infections result in blemished and deformed fruit that cannot be sold. In commercial apple production, this disease is primarily managed through the use of fungicides. However, fungicide resistance is an emerging problem. We are currently surveying the Venturia inaequalis population for the presence of fungicide resistance.

apple scabApple Scab

Bitter rot of appleBitter Rot

Recent restrictions in fungicide registrations have resulted in the development of management issues for diseases that were previously minor problems.  Bitter rot is a common orchard disease, but has been increasing in incidence and severity across the Midwest due to changes in pesticide labeling. We are currently collecting isolates from Indiana orchards to determine if fungicide resistance, or changes in fungicide use has resulted in the increase of this problem.


Current research involves the examination of surfactants combined with captan and mancozeb to reduce the rate and extend the interval between fungicide applications to control apple scab and other apple diseases, how to improve the management of overwintering inoculum, and fungicide trials to inform the recommendations in the Midwest Fruit Pest Management Guide​

Selected Publications

newsletter logo Facts for Fancy Fruit Newsletter
bp198 Publication cover Fruit Diseases: Using Adjuvants in Apple Disease Management (BP-198-W)
bp-179 publication cover Fruit Diseases: Disease Management for Fruit Trees After Crop Loss (BP-179-W)
bp45 publication cover Fruit Diseases: Brown Rot on Tree Fruit in the Home Orchard (BP-45-W)
bp138 publication cover Fruit Diseases: Cedar Apple and Related Rusts on Apples in the Home Landscape (BP-138-W)
bp30 publication cover Fruit Diseases: Fire Blight on Fruit Trees in the Home Orchard (BP-30-W)
BP1 publication cover Fruit Diseases: Apple Scab on Tree Fruit in the Home Orchard (BP-1-W)
bp132  publication cover Fruit Diseases: Disease Susceptibility of Common Apple Cultivars (BP-132-W)
bp72 publication cover Disease Management Strategies for Horticultural Crops: Fungicide Resistance Management for Pome Fruit (BP-72-W)
ID146 publication cover Managing Pests in Home Fruit Plantings (ID-146-W)