Rainfall and irrigation in the presence of cool conditions have an excellent chance to wash inoculum through the soil to the tubers, so again it is critical to achieve the best possible control of late blight on the foliage. We generally do not recommend application of Curzate late in the growing season as the vines begin to senesce. The rest of the protectant materials including maneb, mancozeb, metiram, chlorothalonil, fixed coppers and TPTH and the late blight materials such as Tattoo-C or Acrobat MZ are still available and useful. In past years, some tuber infection in storages can be directly related to the presence of infected green stems in the field at the time of harvest. Having the field completely dead for two weeks before harvest should pay dividends in terms of disease-free tubers.
Early blight continues to progress as vines begin to reach the end of the growing season.
Quadris continues to provide excellent control of early blight. Most fields have received three sprays of Quadris earlier in the growing season. In the past we observed that three sprays of Quadris appeared to provide adequate control of early blight. These sprays would have been applied during late June and July. Given the wet season we've experienced this year and the increased pressure from early blight, growers might want to take a close look at their scouting reports and to apply an additional Quadris spray if early blight appears to be increasing.