Potyviruses in New Zealand buttercup squash (Cucurbits maxima Duch.): Yield and quality effects of ZYMV and WMV 2 virus infections

Abstract The Obisu type ‘Delica’ buttercup squash (Cucurbita maxima Duch.) was inoculated at early, mid, and late stages of growth with zucchini yellow mosaic virus (ZYMV) and watermelon mosaic virus 2 (WMV2). The results of these field trials demonstrated that early‐ and mid‐season ZYMV infections and early‐season WMV 2 infections caused serious yield losses and adverse quality effects in comparison with yields from uninoculated plots. Total yield losses from ZYMV were 48% for early‐season and 26% for mid‐season infections. Yield losses from WMV 2 were statistically significant only after early infection (38%). Numbers of marketable fruit were similarly affected as was marketable fruit weight and incidence of fruit blistering. For example, early season single or combined infections of ZYMV or WMV 2 reduced the mean marketable yield of ‘Delica’ from 84 to 23% of the total yield of uninoculated plots. In a second trial, the effect of a mid‐season infection on three squash types showed that the Miyako type ...