tailieunhanh - Controlling foliar blight of wheat in south Asia: A holistic approach

Foliar blight is a major biotic constraint to wheat in the Gangetic plains of south Asia, particularly in the rice-wheat system. The disease occurs as a complex of spot blotch and tan spot caused by C. sativus and P. tritici-repentis, respectively. Yield losses reach on average 15% but are variable depending on sowing time, years, locations and stress conditions. | Turk J Agric For 29 (2005) 129-135 © TÜB‹TAK Controlling Foliar Blight of Wheat in South Asia: A Holistic Approach E. DUVEILLER1,*, R. C. SHARMA2, D. MERCADO3, H. MARAITE3, M. R. BHATTA4, G. ORTIZ-FERRARA1, D. SHARMA2 1 CIMMYT South Asia, Singha Durbar Marg, . Box 5186, Kathmandu, Nepal 2 Institute of Agriculture and Animal Science, Rampur, Chitwan, Nepal 3 Université Catholique de Louvain, Place Croix du Sud, 2 Bte 3,1348 Louvain-la Neuve, Belgium 4 Nepal Agricultural Research Council, . Box 5459, Kathmandu, Nepal Received: Abstract: Foliar blight is a major biotic constraint to wheat in the Gangetic plains of south Asia, particularly in the rice-wheat system. The disease occurs as a complex of spot blotch and tan spot caused by C. sativus and P. tritici-repentis, respectively. Yield losses reach on average 15% but are variable depending on sowing time, years, locations and stress conditions. Resistance breeding has been the cornerstone of the control strategy. Through international agricultural research efforts in collaboration with National Agricultural Research Systems (NARS), resistance sources from China, Zambia and Brazil were identified and novel germplasm such as synthetic hexaploid wheats derived from crosses with Aegilops tauschii and tetraploid wheat were generated. Materials resulting from these pre-breeding activities are now combined to adapted spring wheat to produce new high yielding genotypes showing a lower disease progress. On-going regional efforts include several wheat nurseries jointly organized by CIMMYT and NARS and specially targeted for warmer wheat growing areas. The stability of resistant genetic stocks remains essential considering that C. sativus is non-specific and forms a continuum of strains that may change rapidly. Although high moisture and temperature are known to favor the disease, little information is available on the exact role of climatic factors on symptom development. Stress factors appear to .