Analysing spatial patterns of spread of Lettuce necrotic yellows virus and lettuce big-vein disease in lettuce field plantings |
| |
Authors: | B A COUTTS M L THOMAS-CARROLL R A C JONES |
| |
Institution: | Plant Pathology Section, Department of Agriculture, Locked Bag No. 4, Bentley Delivery Centre, WA 6983, Australia |
| |
Abstract: | Spatial patterns of spread of lettuce big‐vein disease (LBVD) and Lettuce necrotic yellows virus (LNYV) were examined in two plantings each consisting of two blocks of lettuce. LBVD came from planting land infested with viruliferous Olpidium brassicae resting spores, while LNYV was introduced by aphid vectors from external sources consisting of LNYV‐infected sowthistle (Sonchus oleraceus) weeds. Clustering of LBVD was obvious in an area where the soil was heavily infested with only sporadic occurrence elsewhere. There was a steep decline in LNYV incidence over distance from a concentrated external weed source, with clustering of LNYV‐infected plants at the crop edge closest to it. There was no evidence of secondary spread with LBVD or LNYV. |
| |
Keywords: | LBVD LNYV lettuce gradients pattern clustering spatial analysis |
|
|