Impact of various yield-reducing agents on open-field sweet peppers

Abstract

Major damaging agents of open-field pepper crops in Spain are potato virus Y (PVY), the green peach aphid, Myzus persicae (Sulzer), and black nightshade, Solanum nigrum L. Yield loss of pepper affected by associations of these interacting agents was quantified in 1993 and 1994 under field conditions. Yield loss was greatest (82% both years) when all 3 yield-reducing factors were present. Aphid damage caused greater impact on total marketable vield than weed damage (56 versus 40% yield loss in 1993 and 65 versus 45% in 1994). Both agents combined (aphids and weeds) had a nonadditive effect on marketable yield loss. The number of marketable fruit per plant was the yield component most affected by aphid, weed, or virus damage in both years. Spread of PVY in pepper plots caused no additional yield losses over those produced by the other 2 damaging agents. In 1993, spread of PVY on pepper plots was higher in the presence of virus-infected nightshades than when infected peppers acted as the inoculum source. Therefore, S. nigrum may enhance aphid movement and increase the rate of virus spread.