June 12, 2025
By Bryan Wilkins, APGA Science Advisor
Hard to believe that we are already in the middle of June. So far, it is shaping up to be a good year. This spring was dry, and the temperatures were perfect for an excellent pollination window. The dry spring was not only great for pollination, but it also kept the scab pressure at a minimum. But, like they say, if you do not like the weather just wait a few minutes. The dry April and May have turned into a hot, wet, and Humid first part of June and scab is really starting to explode. Now is the critical time to really get on top of and stay on top of your spray schedule. We are at that critical time of rapid nut growth and expansion when the nuts are most susceptible to scab. Scab control for the next 6-8 weeks will be critical to the success of this year’s crop. The best options for scab control during the nut sizing period from June to August will be Miravis Top, Miravis Prime or Dodine (Elast). Miravis Top or Miravis Prime should be rotated with Dodine whether you use it as a stand alone or mixed with Tin. Miravis Top and Miravis Prime are both excellent products on nut scab. Make sure that you rotate these products with Dodine, DO NOT use the Miravis products back to back to back. It is tempting to do so because everyone wants to use the best “medicine” they can get, however if we over use them resistant strains of scab can develop, and we will ultimately lose their effectiveness. Dodine is still an excellent product and is one of the best for rotation with Miravis and other products.
Another thing is the use of surfactants/spreader/stickers when spraying fungicides. Growing up spraying on our family farm we always used surfactants. However, over the years I have learned through my studies and talking with other researchers like Lenny Wells and Monte Nesbitt that under dry or normal conditions they are not needed. If we get into a rainy/wet period they are beneficial because they help the fungicide stick to and stay on the nut better and they help move the fungicide into the nut tissue better. Always read the label to make sure the product is safe to use with a surfactant. The Miravis products are safe to use with a surfactant. Dodine has surfactant properties built in, and surfactants are not necessary. The label for Tin products states specifically not to use surfactants with them due to phytotoxicity.
Another thing you can do to stay on top of scab is to tighten your spray intervals. Most growers spray about every 3 weeks. If we are in an extremely wet period, it does not matter what you spray, if you wait too long between sprays it is not going to do you any good. The nuts are rapidly growing even when it is raining. During times of rapid nut growth what you sprayed today will have tissue in 5 days that is not protected. Therefore, in rainy periods susceptible varieties need to be sprayed every 7-10 days. Also, it is better to get the fungicide on ahead of the rain if you can. Miravis Top and Miravis Prime need 5-6 hours of drying time to be effective. Dodine and Tin need at least 24 hours of drying time since they are pure protectants. Finally, it does not matter what fungicide you spray with, if you get rain within one hour of spraying , you need to spray everything that you sprayed within the last hour as soon as you can.
Alabama Pecan Growers Association 