PREDICTION OF YIELD LOSS CAUSED BY OROBANCHE SPP IN CARROT AND PEA CROPS BASED ON THE SOIL SEEDBANK

Root parasites of the genus Orobanche cause serious losses in many sub tropical crops. Direct control options are very limited and crop yield loss can reach 100%. Prediction of potential damage in a crop before sowing or planting would support farmers in their choice of crop. This paper discusses the relationship between the number of Orobanche spp. seeds in the field and yield loss in peas (Pisum sativum L.) and carr ots (Daucus carota L.) in Israel. Yield loss due to Orobanche crenata Forsk. in peas was 100% at high infestations, whereas in carrots when O. crenata and O. aegyptiaca were present it stabilized at about 50% f or moderate infestations of 200 seeds per kg of soil. Statistical anal yses related the yield loss from parasitism in peas and carrots to the numbers of Orobanche seeds remaining in the soil. A rectangular hyper bolic model, previously applied to competition data, fitted the data w ell. Confidence intervals for per cent yield loss were calculated usin g the bootstrap method. The practical applications of these models in predicting yield loss are discussed.