I have been receiving a few questions about fungicide sprays over the past few days. i thought the answer may be helpful for others. “What fungi do I have to worry about this time of year?”Shot-hole, Anthracnose, Brown Rot, and Jacket Rot. For the varieties in petal fall/post petal fall, Anthracnose and Jacket Rot are the big ones to keep in mind. Most fungicides provide control for shot-hole, but not all provide control for Jacket Rot and Anthracnose. Make sure the spray you are spraying targets those pathogens. Remember, DMIs (FRAC 3) do not provide sufficient control of Botrytis, one of the pathogens that cause Jacket Rot. “How many days can I wait before I make another fungicide spray?”For the most part, fungicide sprays will last between 10 and 14 days, depending upon weather. If rainy conditions occur, the residual activity will be on the shorter side, while dry, warm, sunny weather may even extend the window beyond 14 days.. If continual wet, mild conditions that favor fungal growth persist, spraying every 12-14 days will provide control of most problematic leaf and flower infecting fungi.  “What if it rains, then clears up?”If post rain conditions are effective in reducing the duration of leaf wetness, a spray may not be needed after a single day rain event. Sunny, warm, and windy weather quickly dries the leaf surface, reducing the growth of shot hole, anthracnose, jacket rot, and brown rot. A single day of rain that falls on the later end of the spray window – lets say day 12 of the 14 day window – and has these post rain conditions probably will not warrant another spray. Several days of rain – 2-3days –  falling at the end of this period would. “When should I spray for Scab?”Scab sprays will should begin no earlier than

Rain is forecasted for the coming week. Many growers are wondering “Should I apply another fungicide?” Foliar diseases of concern at this time of year are scab, shothole, and anthracnose. Conditions of leaf wetness and mild conditions favor growth of these fungi, which can infect and kill leaves, nuts, spurs, and shoots. Currently, the forecast calls for 2-3 days of rain. If it rains all three days, there would be ample time for these fungi to infect your trees. Post-rain event weather conditions should also be considered when making this decision. If the weather looks to be warm and breezy, a spray might not be necessary as the conditions will dry out the trees. Some level of disease may occur, but the rate of secondary spread would be reduced to improper environmental conditions. A rain event following 4-5 days later, however, would increase the disease pressure within the orchard. Since spring rain events tend to be one to two days in length, broad spectrum fungicides are a viable alternative for orchard applications. Applications of Captan, Captevate, Maneb, and/or Ziram can provide a cheaper treatment option than some of the other fungicides. These products provide moderate to good control of scab, shothole, and anthracnose and reduce the chance of resistance formation. For more information of treatment options and fungicide efficacy, please see the Fungicide Efficacy and Timing Charts for Almond.