Monday, July 30, 2007

Japanese beetle and Honeycrisp

Chalk up another Honeycrisp disorder. At the UMass Cold Spring Orchard in Belchertown, MA, I planted an orchard in 2006 with Honeycrisp and McIntosh (cvs. Rogers and Snappy Mac) on three different rootstocks (MM.106, M.26, and B.9) and three tree training systems (NZ central leader, vertical axis, and tall spindle). The point is to demonstrate training systems and collect some yield and economic data. But, although there has been lots of anecdotal evidence that Japanese beetles are particularly attracted to Honeycrisp, I am now able to put some numbers on it. This morning I did a quick look at all trees (150 total, 75 of each cultivar divided across the three rootstocks) and determined that 36% of the Honeycrisp had reached a treatment threshold -- which to me was active beetle feeding -- vs. 0% (that's right, zero) on the McIntosh. Now, if McIntosh were the only choice, would they be on those? I don't know. But clearly Honeycrisp are significantly more attractive to Japanese beetles than McIntosh, requiring some kind of treatment for control. And although the beetles are largely foliar feeders, which is bad enough in itself, they can also damage fruit. And Honeycrisp are just too darn valuable to lose any!