Abstract
Stem rot, caused by Sclerotinia minor Jagger, is the major factor limiting the production of sunflower seed under irrigation in northern Victoria. Three field trials evaluated whether sowing date influenced incidence of stem rot in two sunflower cultivars. Hysun 22 (short season) and Hysun 32 (long season) were sown on five different dates at approximately 14 day intervals between mid-October and early January. Crops sown during October and early November had a lower incidence of stem rot at an early growth stage, and greater yields than plants sown after late November and therefore had some degree of “disease escape”. Hysun 22, which flowers 7 days earlier than Hysun 32, generally had fewer plants infected and greater yields than Hysun 32. Both cultivars had greater yield losses when plants were infected before late flowering (GS 4.5), and the number of plants affected by stem rot prior to this stage gave the best correlation with yield loss. Results from this study suggest that if sunflowers are to be sown in infested soils in the irrigated areas of northern Victoria, then short-season cultivars should be sown by mid-November.
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Clark, R.G., Porter, I.J. & Woodroofe, M. Effect of sowing date on the incidence of sclerotinia stem rot caused by Sclerotinia minor and yield of a long- and a short-season sunflower cultivar. Australasian Plant Pathology 22, 8–13 (1993). https://doi.org/10.1071/APP9930008
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DOI: https://doi.org/10.1071/APP9930008