Population dynamics of Xanthomonas campestris pv. vitians on different plant species and management of bacterial leaf spot of lettuce under greenhouse conditions

Abstract

The population dynamics of Xanthomonas campestris pv. vitians ( Xcv) was studied both externally and internally in lettuce, tomato and pepper plants. In addition, the application of bactericides during transplant production period was carried out for the management of bacterial leaf spot of lettuce under greenhouse conditions. Epiphytic populations of Xcv were recovered on leaves of lettuce plants (10 5 CFU/g) 5 weeks after sprayed than the other plant species when inoculated with 10 8 CFU/ml of Xcv. When plants of each crop species infiltrated with the bacterium at 10 5 CFU/ml, the highest populations were developed in lettuce (10 8 CFU/cm 2) followed by pepper with 10 6 CFU/cm 2 and tomato with 10 5 CFU/cm 2 10-days after infiltration. Application of a mixture of Maneb and Kocide or Kocide alone as a foliar spray on lettuce significantly reduced the incidence and disease severity of bacterial leaf spot by 29 and 27% respectively. Spread of the bacterium and development of the disease may partly be managed by avoiding intercropping of these plants commonly grown in close proximity to lettuce. For the management of leaf-associated populations of Xcv in lettuce, use of a mixture of Maneb and Kocide is advocated to minimize the effect of attacks.