Development of a Management Strategy for Geranium Rust Caused by Puccinia Pelargonii-zonalis
Dr. James Buck, University of Georgia, $19,656, 2 year project
Other Project Team Members -
Dr. Steve N. Jeffers, Associate Professor, Clemson University
Ms. Erika Stocco, Graduate Student, University of Georgia
Executive Summary
The presence of rust diseases on floriculture plants can result in total loss of a crop. Once lesions are present the plants are no longer marketable and the threat of moving disease (within an operation or to market) often necessitates destroying infected or potentially infected plants. Management of rusts requires an integrated approach combining the use of resistant varieties (if present or known), judicious use of fungicides, and early detection of the fungus. One difficulty in managing rusts on floriculture crops is the ethereal nature of the problem – the disease is often sporadic and thus ‘under the radar’ of the growers. Often it isn’t until the disease is present in a greenhouse that control measures are implemented. We propose to develop a management plan for rusts on floriculture crops using geranium rust as a model system. Specifically, what should a grower do if an infected plant is found or the possibility of contamination is present? Our first objective is to develop a PCR-based detection system for the rust and optimize microscopic detection of the pathogen. This will allow growers to determine if plants are infested when visual symptoms may not be present. Our second objective is to determine how to best kill spores on plant surfaces and in cull piles using fungicide dips and sprays. This will reduce inoculum and spread of the disease. The third objective is to determine how fungicides affect spore production and viability by spraying active lesions and assessing spore germination and infectivity. Very little is known about the affects of fungicides on the biology of rust pathogens yet once rust is detected in a crop all stages of the fungal lifecycle (spores to lesions) would be present and thus sprayed with product.
Drs. Buck and Jeffers have collaborated for the last seven years on different rust pathogens of ornamental crops, including geranium rust and daylily rust. Both researchers are part of the National Gladiolus Rust Technical Committee that was charged in spring of 2006 with determining what actions are necessary to eradicate Gladiolus Rust from a commercial operations and residential plantings in Florida and California. It was apparent from the questions being asked of the committee that much research needs to be done on rust diseases of ornamental plants to develop sound management practices.
For further information contact Dr. James Buck at jwbuck@uga.edu
