DISEASE DEVELOPMENT OF PYTHIUM ROOT-ROT IN BULBOUS IRIS AND CROCUS

Iris bulbs and Crocus corms were planted at two planting dates in sand y soil infested with Pythium spp. At monthly intervals during the grow ing season root rot infection was assessed over 3 consecutive years an d disease development curves were predicted for both crops. The diseas e development was remarkably different for Iris and Crocus and the cur ve shape was determined by the crop rather than by the Pythium species . Planting date had a significant effect on disease development in bot h crops. No correlation was found between disease development and soil temperature.