Monday, September 14, 2009

Apple scab-resistance: Honeycrisp vs. McIntosh judged no contest


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.

2 comments:

Dan Cooley said...

I definitely wouldn't go with no fungicides! It's interesting to note that in the early 1900's, Baldwin was considered resistant to scab, and during the 50's in Europe Golden Delicious had relatively few scab problems. Yet, as these varieties became widely planted, scab got worse. The fungus adapts. It wouldn't surprise me to see the situation with Honeycrisp change with time.

Dan Cooley said...

I definitely wouldn't go with no fungicides! It's interesting to note that in the early 1900's, Baldwin was considered resistant to scab, and during the 50's in Europe Golden Delicious had relatively few scab problems. Yet, as these varieties became widely planted, scab got worse. The fungus adapts. It wouldn't surprise me to see the situation with Honeycrisp change with time.