Crop management and breeding for control of Pyrenophora tritici-repentis causing yellow spot of wheat in Australia
1998
Loughman, R. (Agriculture Western Australia, South Perth, WA (Australia)) | Wilson, R.E. | Roake, J.E. | Platz, G.J. | Rees, R.G. | Ellison, F.W.
Pyrenophora tritici-repentis is a major leaf disease in the northern wheat growing areas of Australia and also occurs sporadically in southern wheat growing areas. In Western Australia, the disease occurs in combination with Phaeosphaeria nodorum, and losses of 5-20 percent are frequent in medium to high rainfall areas. Pink grain occurs sporadically in seasons that are very favorable for disease development. The disease has increased in the last 20 years due to intensified cropping and adoption of stubble retention/reduced tillage. Stubble burning and crop rotation are the main means of control. Single applications of triazole fungicides, such as propiconazole and tebuconazole at 62 g ai ha-1 applied around the time of flag leaf emergence, can provide economic control but are rarely practiced because of uncertainty of seasonal growing conditions. Breeding programs for white grained, high quality wheats are pursuing resistance as a high priority in Western Australia (WA), Queensland (QLD), and northern New South Wales (NSW). Approaches to breeding in Australia include complex crossing and backcrossing strategies combined with glasshouse and field based screening. In WA, resistance to P. tritici-repentis is sought in combination with P. nodorum. Moderate resistance has been developed from a broad range of genetic material. This has resulted in the release of cvs. Cascades (Tadorna.lnia/3*Aroona), Carnamah (Bolsena- 1CH/77W:660), and Cunderdin (Flicker sister/Sunfield sister) with moderate resistance to P. tritici-repentis. In QLD and NSW, a backcrossing program using known sources of recessive resistance has resulted in the release of Leichhardt (CNT2/4*Hartog). In some cases, susceptible parents appear to contribute to the resistance. Among pathogen isolates nec+ chl+ types predominate.
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