In previous commentary, fungicides recommended for control of bitter rot in the Northeast included captan, ziram, and QoI fungicides, but continued dependence on the latter is probably neither sustainable nor advisable. Read my recent article published in Scaffolds Fruit Journal for the rationale in suggesting that either Aprovia or Fontelis might be advisable in summer sprays during July in blocks where bitter rot has been a problem. Click here to access the complete article. New York readers should note that Aprovia is not registered for use in New York State.
For links to other articles that discuss recent research on the bitter rot pathogen, see earlier information posted here. Several photos have been posted under “Bitter rot” on my “Apple Diseases” page.