Gladiolus Corm Rot Caused by Sclerotium rolfsii in Argentina.

In 2000, rot was observed on Gladiolus sp. corms produced and stored in a production locale of the Province of Corrientes, Argentina. Symptoms were associated with the development of whitish mycelial strands and light brown 0.8- to 1.5-mm-diameter globose sclerotia typical of Sclerotium rolfsii Sacc. The fungus was isolated on potato dextrose agar. Pathogenicity tests were done by placing plugs of agar media containing mycelium and sclerotia on corms previously wounded with a scalpel. The corms were planted in sterilized soil, incubated at 20 ± 3°C, and watered frequently. Wilt symptoms were observed 40 days after planting. Basal leaves turned yellow and crown and corm rot developed. Thirty-eight percent of the plants failed to emerge due to corm rot. The pathogen was reisolated from inoculated corms that had become diseased. Control corms, which had been inoculated with sterile agar plugs, did not become diseased. The causal agent of the disease was confirmed as S. rolfsii. To our knowledge, this is the first documentation of gladiolus rot caused by S. rolfsii in Argentina.