Crop loss of pepper plants artificially infected with Xanthomonas campestris pv. vesicatoria in relation to symptom expression

Crop losses in peppers artificially infected with Xanthomonas campestris pv. vesicatoria (XCV) were determined during 3 years of field experiments in three areas of Israel. Direct losses of 23–44% in fruit yield were recorded when severe leaf infection occurred or was induced at an early stage of plant growth. Yield losses and disease index were markedly lower in plants inoculated at later stages and near maturation. Indirect losses in severely infected fields were mainly due to shedding of leaves and exposure of fruits to sun. In this case, up to 95% of the fruits lost their commercial value. In artificially infected symptomless plants with massive endogenous populations of XCV in the leaves, a loss of 24% in yield was measured, compared with plants free from an endogenous pathogen population.