Sept. 30, 2011: Zimbabwe rust survey summary – Stem rust persists in the Lowveld, leaf rust widespread

Photo Credit: B. Mutari

Wheat rust surveys were undertaken by the Crop Breeding Institute and Plant Protection Research Institute throughout the key wheat growing areas of Zimbabwe during the period 19th – 24th September 2011. The primary focus of the surveys was to assess the status of wheat stem rust in Zimbabwe compared to the situations in 2009 and 2010 and to monitor the potential spread of new virulent races of wheat stem rust (Ug99 race lineage) in Zimbabwe and Southern Africa as a whole. In the survey area, wheat was grown at elevations ranging from 413m to 1535m. A total of 20 wheat fields, distributed throughout the main agro-ecological zones, were surveyed using standard BGRI survey methodology. Wheat stem rust was recorded at 6 of the 20 survey sites – Gwebi Variety Testing Center (GVTC), Chiredzi Research Station, Chisumbanje Research Station, Birchenough*2, and Sisal Farm Mutare. For the third year running, stem rust was widespread in the Lowveld, with 4 out of 6 Lowveld sites below 800m recording the disease. High or moderate stem rust severity (>20%) was recorded at 3 of these Lowveld sites. At Chiredzi, high levels of stem rust infections were observed in Preliminary Variety Trials with SC Sekuru (improved variety) showing highly susceptible reactions together with three other experimental lines. At GVTC, low incidence of stem rust was observed in Intermediate Variety Trials with Dande (improved variety) and four other experimental lines showing highly susceptible reactions. Low incidence and very high severity of stem rust was recorded at Sisal farm in a CIMMYT rust resistance screening nursery. Trace amounts of stem rust were recorded at Chisumbanje Research Station in contrast to last year where very high incidence and severity was recorded at the same station. Stem rust samples were collected and sent for molecular diagnostic analysis and  race analysis.. In addition to stem rust, leaf rust was recorded at 13 of the 20 sites surveyed. Severe leaf rust infections were observed at 4 of the survey sites. Powdery mildew was also regularly recorded at survey sites. No stripe rust was observed at any survey location.

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