ISOLATION AND IDENTIFICATION OF RESIDUES OF 4''-(EPI-METHYLAMINO)-4''-DEOXYAVERMECTIN B-1A BENZOATE FROM THE SURFACE OF CABBAGE

Cabbage was treated with a single application of [C-14]-MK-0244, a sem isynthetic avermectin analogue, at 0.3 lb/acre and harvested 1 day aft er application. The wrapper leaf and exterior head surface of the cabb age were rinsed with methanol, and 12 degradates were isolated from th is rinse and identified by structural. analysis. Ten of these residues can be accounted for by six previously reported transformations and t wo are apparently formed by novel transformations. This represents the first time that avermectin residues isolated from a plant have been u nequivocally identified by direct methods. The cabbage residue profile bears a strong resemblance to that seen in the photodegradation of MK -0244 thin films on glass.