I have been collecting some yield data on an orchard planted in 2006* at the UMass Cold Spring Orchard in Belchertown, MA this past week. I can't help but observe how much more apple 'scab-resistant' Honeycrisp is compared to McIntosh. Now, this orchard received a 'normal' fungicide schedule to control scab, but, it was a very wet summer, so scab became more apparent on McIntosh fruit (pictured) as the summer wore on. I estimate 5-10% fruit scab on McIntosh. I observed no scab on any of the Honeycrisp fruit or foliage. It's clear Honeycrisp orchards can get by on a reduced -- not necessarily none -- fungicide spray program compared to McIntosh.
*Honeycrisp, and 'Rogers Red' and 'Snappy Mac' McIntosh on M106, M26, and B9 rootstocks planted to three systems (NZ central leader-3m between trees, vertical axis-2m between, and tall spindle-1 m between) with three replications.