Submitted to: New York State Fruit Quarterly
Publication Type: Trade Journal
Publication Acceptance Date: February 11, 2005
Publication Date: March 1, 2005
Citation: Koller, W., Parker, D., Turechek, W., Rosenberger, D., Carrol, J., Agnello, A., Reissig, H. 2005. Fungicide resistance of apple scab: status quo and management options. New York State Fruit Quarterly. 13(1):9-17.
Fungicides that allow post-infection management of apple scab, caused by Venturia inaequalis, have become valuable tools in the commercial production of apples. Starting with dodine in the early 1960s, five classes of fungicides have allowed post-infection management of apple scab. Unfortunately, resistance has now been documented for all five classes. The current status quo might appear discouraging. The options for managing scab without risking control failures caused by resistance are either complete reliance on protectant fungicides or the site-specific management of resistance (SMOR) based upon measuring the sensitivities of individual orchards to all post-infection fungicides available. Research that began in 2002 has recently led to the development of a simplified procedure for measuring the levels of resistance in Venturia populations to all classes of post-infection fungicides. This test will provide the opportunity to implement SMOR, allowing the utilization of all available fungicide options in full awareness of their limitations and benefits which will be the key to reliable control of apple scab in the future.