Relax for a moment! The above photo was taken exactly one year ago at my Glomerella Gala research block at the MHCREC in Mills River, NC. When I looked back on my notes we had similar Memorial Day weather, rain and more rain.... However, it was a bit cooler last year at this time compared to this weekend's temperatures. Before we go further on disease management though, I've seen photos of the flooding throughout the Edneyville area and thoughts are with the affected apple growers through this challenging time. Of course, if myself or my colleagues can assist with perhaps tough management decisions ahead do not hesitate to reach out.

Since Friday, every major apple production county in NC has had 90+ hrs of leaf wetting, 3.8-7+ inches of rain, and ideal temperatures given the extending wetting events for most pathogens of apple, including Colletotrichum fungi that cause Glomerella leaf spot and bitter rot. While Gene Klimstra did not see any GLS symptoms in Polk County orchards where we usually first observe the disease, I've got a slight pit in my stomach that symptoms will be reported by the end of the week. Complicating disease risk even more is of course the hilly terrain sprayers may not be able to navigate. Originally Wednesday and Thursday looked rain-free, but this evening looking at the Edneyville forecast, Thursday looks to be the best opportunity to get a fungicide application out this week. As of tonight (5/26/26) rain is predicted to return Friday and Saturday. For orchards you can get into here are my fungicide thoughts for the week:

• If you are pressed for time due to rain, focus on applying fungicides to cultivars susceptible to GLS, cultivars that are highly susceptible to bitter rot (such as 'Honeycrisp'), and blocks with a history of GLS and bitter rot.
• Captan, ziram, and mancozeb will to an extent be redistributed by light rains. However, heavy rains will wash off the initial deposits of these fungicides. That said, I would apply Captan 80WDG/Captan Gold this week at 5 lb/A, and would shy away from using the 4L as it has tended to wash off quicker than the WDG formulation in our trials.
• If applying a singles-site/locally systemic fungicide such as Merivon, Cabrio, Aprovia, Luna Sensation, etc. keep in mind that these fungicides must dry completely prior to a rainfall.
• There really isn't a way to "burn out" GLS and bitter rot lesions. If you've already applied two applications of Merivon, Cabrio, Pristine, Luna Sensation, or Flint Extra, or you have resistance to the strobilurins (FRAC 11), I'd consider an application of Aprovia (7 floz/A) + Captan 80WDG (5 lb/A), OR Captan 80WDG (5 lb/A) + Topsin 4L (20 fl oz/A; use for GLS cultivars only - not traditional bitter rot), OR Captan 80WDG + Omega 500F (13.8 fl oz/A).

If you have GLS develop and would like us to screen for fungicide resistance to the strobilurins please reach out to myself, your orchard consultants, or your Cooperative Extension agents.