Unfortunately, there appears to be a shortage of captan products this year. There are quite a few alternative products for bloom. Likewise, chlorothalonil (e.g. Bravo) products work well for petal fall and shuck split, and other products are readily available for pre-harvest applications. Sooty peach can be controlled with ziram, but it does little otherwise as a cover spray material. Without adequate captan supplies, the biggest area of true weakness that occurs in spray programs is that of green fruit rot and possibly anthracnose management in the cover sprays.
Sulfur alone in cover sprays, though sufficient for scab control, is not efficacious for green fruit rot or other diseases, with the exception of powdery mildew. As I mention often, I prefer to hold other chemical classes, those for which Monilinia fructicola (brown rot) is most likely to develop resistance, for use in the pre-harvest sprays. However, if captan is unavailable and if conditions are wet during cover sprays, I would recommend application of two applications total of a QoI/SDHI product, such as Luna Sensation, Merivon, or Pristine for cover sprays as needed this year.
Also, though I do not like the idea due to resistance issues, I can also go along with using DMI materials if absolutely needed for cover sprays; again, I would advise you to avoid this if at all possible, and use the QoI/SDHI combos and any available captan before using DMI products in this timeframe. I fear that use of DMI fungicides could “prime the pump” for potential failure of the DMIs used in the pre-harvest sprays; hence that is why I would only use DMI-containing products during cover sprays as a last resort. If using DMIs, I would select for more active products like Indar, Tebuzol or Cevya and use these at the highest rates; another option could be the products that contain DMIs and other classes (e.g. Miravis Duo or Quadris Top). However, I think two applications of Qoi/SDHI products will give close to 20-28 days of activity, so I hope that will suffice for many varieties — along with any captan products you can wrangle.
I hope that we can limp along without captan till next year, while still providing excellent control of cover spray pathogens. Many of the products listed above will control scab and green fruit rot, so sulfur would not be necessary for these applications. Check the spray guide for efficacy ratings of various products relative scab in order to decide whether sulfur can be left out of the tank when using these materials. Other than this captan glitch, I hope the remainder of the season goes well. As always, please contact your local extension agent should you have questions.