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Blueberry Exobasidium

Many producers have heard about using lime sulfur for exobasidim. Some questions have been asked about using it early. According to Dr. Phil Brannen, we can’t say for sure that lime sulfur would not have activity against Exobasidium during this timeframe, but we do not have research data to support that an early-dormant application will be as effective as a late-dormant application. In addition, you can damage leaves with the lime sulfur; chemical defoliation is not the same as natural defoliation.  A rule of thumb (by variety) for planning the lime sulfur application would be to ask the question, when was the earliest budbreak that occurred in previous years at this location (buds that actually would produce leaves or fruit), and back up the lime sulfur to 1-2 weeks prior to that for planning purposes; at the same time, keep an eye on the weather and the plants for movement or predicted movement based on chill hours and temperatures.  Application of lime sulfur is truly an individual judgment call, and predicting budbreak is difficult at best.  Applying lime sulfur three weeks prior to budbreak, should be just fine; getting it out exactly within the 1-2 week pre-budbreak timeframe is not critical, but December will generally be too early for lime sulfur applications in Georgia. Mid- to late January is more likely the correct target for southern highbush varieties.  Relative lime sulfur, this will be a first for all of us, but the good news is that Captan and Indar also work very well.  Lime sulfur is not the only solution for Exobasidium; if greentip or bloom happens earlier than expected, apply Captan + Indar for management.