Stem rust, caused by Puccinia graminis Pers. f. sp. tritici Eriks ＆ E. Henn., is an important disease of wheat （Triticum aestivum L.） in many countries. To estimate grain yield losses due race Ug99 （TTKSK）, repli...Stem rust, caused by Puccinia graminis Pers. f. sp. tritici Eriks ＆ E. Henn., is an important disease of wheat （Triticum aestivum L.） in many countries. To estimate grain yield losses due race Ug99 （TTKSK）, replicated experiments including fifteen wheat cultivars were screened for seedling and adult plant resistance. Greenhouse seedling test was conducted under controlled conditions. Field experiments were set up at two locations, Mau-Narok and KARI-Njoro, during 2008 and 2009 cropping seasons. The stem rust epidemics were created by inoculating spreader rows of a susceptible variety planted perpendicular to rows of non-protected plots. Rust severity and infection response were determined using modified Cobb scale. All the cultivars were susceptible at seedling stage, but some displayed adult plant resistance response despite of the high disease pressure. Mean grain yield losses ranged between 5.6% and 66.3% and were highly correlated to final disease severity （FDS） and the area under disease progress curve （AUDPC）. Genetic studies are needed to characterise the adult plant resistance in tolerant culti（,ars to race Ug99 for exploitation in breeding for resistance.展开更多
Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 20...Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 2009 growing seasons to evaluate the effectiveness of two new foliar fungicides： viz. Nativo 300 SC （trifloxystrobin 100 g L^-1 ＋ tebuconazole 200 g L^-1） and Prosaro 250 EC （prothioconazole 125 g L^-1 ＋ tebuconazole 125 g L^-1）, in controlling stem rust on susceptible wheat cultivar Duma. AmistarXtra 280 SC （azoxystrobin 200 g L^-1 ＋ cyproconazole 80 g L^-1） and Folicur 250 EC （tebuconazole） were used as checks. The treatment at each site and year included non-treated control and two spray applications of the fungicides at growth stages （GS） 55 （heading） and 65 （flowering）. Stem rust severities were scored using the modified Cobb scale at 14-day intervals after application. The data were used to calculate mean rust severity （MRS）. Stem rust epidemics were severe at KARI-Njoro in 2008 and the treatment effects on stem rust severities, grain yield and 1,000 kernel weights were significant at both KARI-Njoro and Mau-Narok sites. The fungicide treatments, significantly （P _〈 0.05） reduced stem rust severity, increased grain yield and 1,000 kernel weight of the susceptible wheat cultivar Duma compared to the non-treated control. Both fungicides： Nativo 300 SC and Prosaro 250 EC applied at the rate of 1.0 L hat were recommended for commercial use.展开更多
文摘Stem rust, caused by Puccinia graminis Pers. f. sp. tritici Eriks ＆ E. Henn., is an important disease of wheat （Triticum aestivum L.） in many countries. To estimate grain yield losses due race Ug99 （TTKSK）, replicated experiments including fifteen wheat cultivars were screened for seedling and adult plant resistance. Greenhouse seedling test was conducted under controlled conditions. Field experiments were set up at two locations, Mau-Narok and KARI-Njoro, during 2008 and 2009 cropping seasons. The stem rust epidemics were created by inoculating spreader rows of a susceptible variety planted perpendicular to rows of non-protected plots. Rust severity and infection response were determined using modified Cobb scale. All the cultivars were susceptible at seedling stage, but some displayed adult plant resistance response despite of the high disease pressure. Mean grain yield losses ranged between 5.6% and 66.3% and were highly correlated to final disease severity （FDS） and the area under disease progress curve （AUDPC）. Genetic studies are needed to characterise the adult plant resistance in tolerant culti（,ars to race Ug99 for exploitation in breeding for resistance.
文摘Stem rust race Ug99, also designated TTKSK （Puccinia graminis f. sp. tritici） cause stem or black rust, which is a serious disease of wheat worldwide. Field experiments were conducted at two sites during 2008 and 2009 growing seasons to evaluate the effectiveness of two new foliar fungicides： viz. Nativo 300 SC （trifloxystrobin 100 g L^-1 ＋ tebuconazole 200 g L^-1） and Prosaro 250 EC （prothioconazole 125 g L^-1 ＋ tebuconazole 125 g L^-1）, in controlling stem rust on susceptible wheat cultivar Duma. AmistarXtra 280 SC （azoxystrobin 200 g L^-1 ＋ cyproconazole 80 g L^-1） and Folicur 250 EC （tebuconazole） were used as checks. The treatment at each site and year included non-treated control and two spray applications of the fungicides at growth stages （GS） 55 （heading） and 65 （flowering）. Stem rust severities were scored using the modified Cobb scale at 14-day intervals after application. The data were used to calculate mean rust severity （MRS）. Stem rust epidemics were severe at KARI-Njoro in 2008 and the treatment effects on stem rust severities, grain yield and 1,000 kernel weights were significant at both KARI-Njoro and Mau-Narok sites. The fungicide treatments, significantly （P _〈 0.05） reduced stem rust severity, increased grain yield and 1,000 kernel weight of the susceptible wheat cultivar Duma compared to the non-treated control. Both fungicides： Nativo 300 SC and Prosaro 250 EC applied at the rate of 1.0 L hat were recommended for commercial use.
