RELATIVE COLLECTION EFFICIENCY OF ROTOROD AND BURKARD SPORE SAMPLERS FOR AIRBORNE VENTURIA-INAEQUALIS ASCOSPORES

Rotorod spore samplers and a Burkard volumetric spore sampler were placed next to each other in an orchard and used to simultaneously collect Venturia inaequalis ascospores naturally discharged during rain. In addition, these spore samplers were operated next to each other inside a closed room in which V. inaequalis ascospores were released via the exhaust of a spore-release tower. These data were used to determine the relative collection efficiency of the two types of samplers for airborne V. inaequalis ascospores. In the relatively still air of the laboratory, E(Rotorod) was similar to 0.24 E(Burkard). In the field, E(Rotorod) was similar to 0.37 E(Burkard). A large part of this difference between the findings in the field and laboratory can be explained by the effects of wind on collection efficiency of the samplers.