I have a love-hate relationship with tree fruit plant pathologists. LOVE, because diseases -- apple scab, fire blight, brown rot, etc., you get the idea -- are arguaby the most problematic pest management issue pome and stone fruit growers face year in and year out. (And climate change, with more frequent rainfall is not going to make life any easier.) But tree fruit plant pathologists are the experts working on it! HATE though because of all the jargon they espouse when describing fungicide MoA's. There we go, I mean Mode of Actions. And you know what I mean, SDHI's, DMI's, QoI's (Strobies), AP's (what did I miss?) and now they say multi-site and single-site? Give me a break!
Here is my suggestion -- let's just ALWAYS ONLY use FRAC numbers. As in: https://www.frac.info/fungicide-resistance-management/by-frac-mode-of-action-group. If I am correct, most tree fruit fungicides fall into one of six FRAC Groups:
- M1 - coppers; M2 - sulfur; M3 - mancozebs, Ziram; and M4 - Captan, M7 - dodine/Syllit. These are Multi-site as designated by the "M." Good rotation partner for resistance management. M is good, good, good. M=good.
- 1 - Topsin, t-methyl. Thus starts the single site fungicides. (Last time we will ever use single- or multi-site. OK guys and gals?) Not so good for resistance management when used time after time after time. Right?
- 3 - Indar, Rubigan, Vintage, Procure, Cevya. Formerly DMI's. And before that, SI's! Ackkk!!! No more! Banned. 3's from now on!
- 7 - Aprovia, Fontelis, Sercadis, Excalia. Formerly SDHI's.
- 9 - Vangard, Scala. Formerly AP's. Formerly.
- 11 - Flint. Formerly known as a QoI. Banned.
Of course there are the pre-mixes too, common ones include: 7+11 (Pristine, Merivon, Luna Sensation); 3+9 (Inspire Super), (Merivon), and 7+9 (Luna Sensation/Tranquility). Oh, and then there's Syllit (Dodine), label says it's a U12. But according to FRAC it's an M7, multi-site, but the verdict seems to be out on that. Who wants to use that DANGER signal word causes irreversible eye damage $%&# anyways???!!!
So, go ahead and use M's. All the time if you want, but remember, they are largely preventive, i.e. have to be applied before the infection occurs. And then go ahead and use the 1's, 3's, 7's, 9's and 11's. But only in up to two back-to back-applications. Then use another number (or combination of numbers). These fungicides have some kickback (post-infection) activity, ranging from 1 to 4 days (maximum, at best), as well as preventive activity. I like them.
Ok, there you go. I made a fungicide recommendation while ditching the alphabet soup! I invite the tree fruit pathologists to follow suit! :-)