COMPARISON OF DIFFERENT METHODS TO DETECT PHYTOPHTHORA SPP IN RECYCLING WATER FROM NURSERIES
K. Themann, S. Werres, H.-A. Diener, R. Lüttmann
Five methods for the detection of Phytophthora spp. in water recirculation systems of four commercial nurseries were compared: direct plating, three bait tests (apple, lupin seedling, Rhododendron leaf test) and DASELISA with two Phytophthora specific polyclonal antisera. Water and sediment samples were taken from different places in the recirculation systems over one year. With all methods except direct plating Phytophthora spp. could be detected in the four nurseries. In most cases the detection rates were influenced more by the method itself than by different conditions on particular nurseries. The Rhododendron leaf test trapped the widest range of Phytophthora species and was the most successful method followed by ELISA with antiserum against P. cinnamomi. Although the chemical analysis of the water samples showed a good water quality for nursery cultivation, there was a close relationship between the detection rates obtained with ELISA and the total salt content of the water. The results are compared with those of in vitro experiments and their relevance for commercial nurseries is discussed.