Peppermint Variety Trial, Central Oregon, 1999-2003

Summary In 2003, Peppermint line B90-9 suffered wilt-related stand decline in both non-infested (moderate) and infested (severe) parts of the variety trial. Lines M90-11 and M0109-1 manifested nearly no wilt symptoms and continued to yield very well in the presence of Verticillium wilt infestations. M90-11 again showed no mite damage. For all varieties and lines, menthol levels were somewhat low, and total menthone levels were high. Over 4 years, B90-9 yielded better than all other varieties when wilt was low (although wilt became moderate even in noninfested B90-9 plots by year 4), but yields of B90-9 dropped off rapidly in infested plots and was nearly all dead by year 4. Advanced lines M90-11, 87M0109-1 and 84M0107-7 (“gray” or “hairy” mint line) withstood wilt pressure extremely well – far better than ‘Todds’. Oil compositional analysis is discussed for these wilt-resistant lines, and seemed acceptable for B90-9. Composition of varieties that otherwise performed well might improve if harvested on a different schedule than selected in these 4 years. Line 92(B37 x M0110)-1 was nearly totally dead by year 4 in both infested and noninfested plots – wilt was severe, but this line may also suffer from other undetermined problems. Line M83-14 performed very similar to ‘Black Mitcham’ in many respects, but this line offered only slight advantage with respect to yield or wilt tolerance. In noninfested plots, the private variety ‘McKellip’ (a selection from ‘Black Mitcham’) yielded better than ‘Black Mitcham’ over 4 years, but wilt tolerance was nearly identical to ‘Black Mitcham’ and no yield advantage was measured in infested plots.