Current Research Studies on Potato Wart Disease in Newfoundland1

Research includes studies on physiology of germination of the causal agent, infectivity parameters, and systemic chemotherapeutants. Germination is studied with plant and fungal extracts, plant exudates and soil leachates. Sporangia are not found to respond readily to exogenously applied chemicals. Maturity appears to be hastened under incubation with plant products. Inoculum density, sporangial age, temperature and irrigation are studied for their influence on infection. Infection appears to be less dependent on external influences, and more dependent on internal timing mechanisms. Tomato varieties tested are found to be susceptible. European races 1, 2 and 8 are used in comparative studies. Germination and infectivity are studied to throw light on possible eradication mechanisms. Chemical control is studied with systemic fungicides. To date, no control is promised. Techniques have been developed to assay germination by secondary fluorescence, and to examine large numbers of soil samples by flotation.