Crop rotation reduces the density of volunteer plants in processing tomato fields and the inoculum of bacterial spot

Volunteer plants are a problem for agriculture because they compete for nutrients and can be the inoculum sources of many diseases. We investigated the contribution of crop rotation in the control of volunteer plants in commercial fields of processing tomato in the Central-West Region of Brazil and the occurrence of tomato diseases in these plants. The number of volunteer plants per hectare was estimated and compared between commercial fields with 1 and 2 years of crop rotation or without crop rotation. The rotation of processing tomato crops with soybean, maize, sweet corn and bean crops was able to significantly reduce numbers of volunteer plants. Consecutive tomato cultivation promoted a higher number of volunteer plants for the next crop. Samples of volunteer plants symptomatic for bacterial spot were collected for identification of the causal agent. Thirty-nine isolates were obtained from two areas. These isolates were pathogenic when inoculated in tomato plants. All isolates were identified as Xanthomonas perforans by specifics primers. We concluded that crop rotation is an efficient practice to reduce volunteer plants in processing tomato crops. This method can reduce the inoculum sources of disease transmitted by seeds, like bacterial spot.