A comparison of sticker adjuvants for their effects on retention and rainfastening of fungicide sprays

Abstract

Sticker adjuvants enhance adhesion of pesticide sprays to plant surfaces and increase their resistance to rain. This study evaluated the effect of two different sticker adjuvant types, organosilicone/latex and terpene based polymers, on the retention and rainfastness of a protectant fungicide, tolyfluanid, on Vicia faba (broad bean) and/or Brassica oleracea (cabbage) foliage. On hard-to-wet cabbage, the organosilicone/latex stickers provided better spray retention than the terpene polymers. Increasing rates of the former resulted in increased retention of spray, while use rate had no effect on terpene polymer performance. After 4 mm rain (applied as a heavy rain event), up to 86% of fungicide deposits applied with organosilicone/ latex stickers were retained on cabbage. In comparison, <45% of deposits containing terpene polymers were retained post-rain. On easy-to-wet broad bean foliage, pre-rain deposits containing terpene stickers were approx four-fold higher, and post-rain deposits were much greater, than on cabbage. There were differences in retention and rainfastening properties between commercial stickers of the same chemical type.