Longevity of Uromyces transversalis, Causal Agent of Gladiolus Rust, under Various Environmental Conditions

摘要

To help determine if gladiolus rust may spread to new areas of the United States, we studied effects of different temperature and moisture conditions on longevity of Uromyces transversatis urediniospores. Treatments consisted of gladiolus leaf pieces,with actively sporulating uredinia. placed in mesh bags in a plastic beaker without soil (dry) or plastic bags covered in damp soil (damp). These treatments were either held in a greenhouse at 22-26°C (warm) or refrigerator at 4°C (cool). After 14 days, 59% of urediniospores maintained under warm, dry conditions were viable compared to only 1 % under warm damp conditions. After 56 days, viability dropped to 3% and near 0%. respectively. Under cool conditions, by 91 days germination dropped to 0.7% and 0%, respectively. To determine the potential for conns orsoilless mix from infected plants to harbor inoculum, infected gladiolus plants were maintained in a growth chamber progressively simulating fall and winter. Following foliage senescence, conns from infected plants were removed from the soilless mix, stored 11 months at 4°C, and planted in noninfested soilless mix in the greenhouse. The pots containing soilless mix in growth chambers, upon removal of conns present on infected plants, were maintained in the chambers until fall and then replanted with healthy corms. No pustules developed on either set of plants, indicating that conns from infected plants had not been infected, urediniospores had not survived in the soilless mix, and urediniospores on or in soil did not perpetuate the disease.