A new method to monitor airborne inoculum of the fungal plant pathogens Mycosphaerella brassicicola and Botrylis cinerea

We describe a new microtiter immunospore trapping device (MTIST device) tha t uses a suction system to directly trap air particulates by impaction in m icrotiter wells. This device can be used for rapid detection and immunoquan tification of ascospores of Mycosphaerella brassicicola and conidia of Botr ytis cinerea by an enzyme-linked immunosorbent assay (ELISA) under controll ed environmental conditions. For ascospores of M. brassicicola correlation coefficients (r(2)) Of 0.943 and 0.9514 were observed for the number of MTI ST device-impacted ascospores per microtiter well and the absorbance values determined by ELISA, respectively. These values were not affected when a m ixed fungal spore population was used. There was a relationship between the number of MTIST device-trapped ascospores of M. brassicicola per liter of air sampled and the amount of disease expressed on exposed plants of Brassi ca oleracea (Brussels sprouts). Similarly, when the MTIST device was used t o trap conidia of B, cinerea, a correlation coefficient of 0.8797 was obtai ned for the absorbance values generated by the ELISA and the observed numbe r of conidia per microtiter well, The relative collection efficiency of the MTIST device in controlled plant growth chambers with limited airflow was 1.7 times greater than the relative collection efficiency of a Burkard 7-da y volumetric spore trap for collection of M. brassicicola ascospores. The M TIST device can be used to rapidly differentiate, determine, and accurately quantify target organisms in a microflora. The MTIST device is a portable, robust, inexpensive system that can be used to perform multiple tests in a single sampling period, and it should be useful for monitoring airborne pa rticulates and microorganisms in a range of environments.