In reviewing the weather forecasts for the next 15 days or so, I am concerned about bacterial spot development. The current warm temperatures are certainly increasing bacterial numbers, and any temperature above 65 F is sufficient for multiplication. Temperatures in the upper 70s or lower 80s provide perfect conditions for bacterial multiplication and disease development. Moisture is also needed, and we have plenty of that on the way as well if the forecasts are accurate. Petal fall and shuck split are critical time periods for infection of leaves and fruit, but the highly susceptible timeframe extends for a 2-3 week period immediately after bloom, and it tapers off gradually. I think most producers are aware of the danger, and I likewise think that they are spraying according to the IPM guide for peaches and nectarines, but now would be a good time to panic if coppers are not applied in sufficient amounts to address the disease. I think it will be possible that moderately resistant varieties will have issues this year as well. Again, application of bacterial spot materials will be critical over the next few weeks, and I hope the weather will not work against us.
