YELLOW SPOT RESISTANCE SCREENING IN PARENT CANES AT BSES MERINGA 2000–2008

YELLOW SPOT is an important leaf disease affecting the yield of commercial crops in the wet tropics region of Queensland. The disease has been recognised in Australian sugarcane crops since 1950 and has reduced yields in selected crops since then. Previous research suggests yield losses and disease incidence are more prevalent in higher rainfall districts and periods. Resistance screening in parent varieties is needed to ensure commercial varieties with adequate resistance are released to industry. Since 2000 the most important parents have been assessed for their resistance to the disease at BSES Meringa. Potential standard varieties with known field reaction to yellow spot were selected and assessed for disease severity in most years through to 2008. Average disease levels over this period were used to apply ratings to standard varieties, which in turn were used to calculate resistance ratings for other parent clones/varieties. This paper describes the consistency of the reaction of standards in each year of disease assessment. Yellow spot resistance data were generally variable and it was found that in some years, the application of reliable resistance ratings was not possible. There is a range of reaction amongst parents, and parent populations do not possess a high level of resistance to the disease.