Disease spread patterns of Banana streak virus in farmers' fields in Uganda

Three surveys were conducted to establish the disease spread patterns of Ba nana streak virus (BSV) in farmers' fields in Uganda. Transects were traced both across the fields and from infection foci within a field. BSV inciden ce in adjacent quadrats was also determined to quantify statistically the s patial relationships of infected plants in the fields. Severity assessment along transects across fields revealed clusters of plants with moderate to high severity and clusters of plants with no BSV or low severity. Symptom s everity decreased away from foci of infection (b =-0.014; P= 0.0081). Obser ved frequency of infected quadrat counts differed from corresponding expect ed frequency of infected quadrat counts (Poisson's distribution, chi (2); p less than or equal to0.01). BSV-infected plants, therefore, were aggregate d in well-established fields. Aggregation of infected plants in farmers' fi elds and the decrease of severity away from infection foci suggest the like ly involvement of a slow moving vector in BSV transmission.