Dr. Phil Brannen, University of Georgia Extension pathologist, reports on blueberry rust below:
We are now receiving additional field reports of blueberry rust, likely as a result of the recent heavy rainfall observed in many blueberry production areas. Leaf Rust-BB-Brannen Final was revised for publication in the Compendium of Blueberry Diseases, and it provides good information relative rust identification. The blueberry IPM guide at www.smallfruits.org provides information on specific fungicides for rust management. If a variety is susceptible to rust, early defoliation can result, and this will reduce yields next year as a result. Scouting is required to determine whether rust is developing in specific varieties. Many fungicides applied for other leaf spots will also have rust activity; this is particularly true of the strobilurin (Abound, Pristine, etc.) and DMI fungicides (Quash, Tilt, Orbit, Indar, Bumper, etc.). Please advise your commercial blueberry producers that they should be concerned about post-season leaf spot management, and they should consider fungicide application as needed to prevent premature defoliation due to rust, Septoria, and anthracnose leaf spots.
The rust spores are not always this clearly observed in the pustules, so this is the “ideal.” More often than not, the spots are observed, and one has to use a hand lens or dissecting scope to find the rust spores for confirmation.