May 17, 2013: CAUTION – POTENTIALLY SERIOUS OUTBREAKS OF YELLOW (STRIPE) RUST IN CWANA REGION. VIGILANCE NEEDED IN EAST AFRICA

Source COLA/IGES (http://wxmaps.org/)

Source COLA/IGES (http://wxmaps.org/)

Conducive climatic conditions for rusts, especially yellow rust, are resulting in potentially serious outbreaks in the CWANA region. Cool and wet conditions have persisted in many countries from Turkey to Bhutan. Early yellow rust infections have been observed in several countries, with serious outbreaks developing on susceptible cultivars. The current yellow rust situation appears to be slightly less severe than in 2010, but is still a cause for concern. Warming temperatures may help to contain the disease, but further outbreaks on susceptible cultivars are likely. A brief regional summary compiled by national partners, ICARDA and CIMMYT is provided.

In India and Pakistan, where the wheat season is now complete, yellow rust was widespread on susceptible cultivars. Cultivars noted as susceptible were; Seher-06, Super 172, HD 2733, HD 2894, HD 2851, HD 2932, WH 711, PBW 343, Barbet. However, large scale epidemics were avoided in both countries due to a combination of newer resistant cultivars and chemical control. Recent reports in the Indian media (http://www.hindustantimes.com/Punjab/Amritsar/Despite-promising-start-wheat-yield-falls-in-Punjab/SP-Article1-1053795.aspx, http://www.hindustantimes.com/Punjab/Bathinda/Wheat-yield-considerably-lower-than-that-of-last-year/SP-Article1-1051819.aspx) do link lower than expected yields at least in part to yellow rust, although unfavourable weather may have played a bigger role.

In Afghanistan, yellow rust appeared in the East, North and Northeast zones at the end of March. Incidence and severity increased on susceptible cultivars until the last week of April. Warmer weather conditions then curtailed further disease development. In the cooler central areas, yellow rust appeared in the last week of April. Serious outbreaks / epidemics have been reported in farmer fields. Susceptible cultivars reported include; Misr1 (Muqawoom), Amu-99, Seson, Takhar-96, Furblan, Inqalab-91, Bakhtawar-96, Diama-96, PBW-343. As in India and Pakistan, Yr27 virulent races were implicated in the Afghanistan outbreaks.

In Iran, very early reports of yellow rust infections occurred in January 2013 in the south-west of Iran (South Khuzestan). Yellow rust developed rapidly and spread on Cultivars Chamran and Veery/Nacazori, causing epidemics in farmers fields. Over 100,000 ha are reported to have been sprayed with fungicide in the south-west and west of Iran.  Incidence of Yellow rust on susceptible wheat cultivars in other parts of Iran has also been reported from west (Ilam and Kermanshah), Caspian Region (Gorgan), south-east (Kerman and Jiroft), south of Fars province (Mamasani) and north west (Ardabil). Due to rising summer temperatures, yellow rust development is reported to have now stopped in most areas. Yr27 virulent races have been detected and again been implicated in the Iranian yellow rust outbreaks. Newly released cultivars such as; Parsi, Sivand, Sirvan, Gonbad, Morvareid, Zaerh, Uroum, Mihan, Dena, Arya, Kharkhah and Behrang are all reported to be resistant in Iran.

In Uzbekistan, severe epidemics of stripe rust occurred in the spring of 2013 on many of the widely grown commercial cultivars. However, overall losses are expected to be lower than 2010 due to a combination of good early surveillance and well planned fungicide spray schedules. Indications of pathogen change were observed, as some cultivars which were quite resistant in 2009/10 were highly susceptible in 2013. Out of six new winter wheat varieties released due to resistance in the 2009/10 epidemics, one showed high severity this year, and another was only moderately resistant. The remaining four new varieties were all resistant and are undergoing seed multiplication.

In other countries in the region, yellow rust is also appearing. Yellow rust is reported to be widespread in Northern Iraq. In Azerbaijan, the yellow rust appeared in Mid April and high severity has been reported from Sheki in the north. Additional surveys in Azerbaijan have found stripe rust to widespread and severe in farmers fields, especially in the south-east.  In Turkey, yellow rust developed in the south-east close to the Syrian border in March. Fungicides were applied, but yellow rust is reported to be re-appearing and a second spray has been applied. Yellow rust is just starting to appear in some parts of central Anatolia, although appears to have been halted by warm temperatures. In Georgia, yellow rust has appeared and it’s progress is being monitored. Active surveillance and monitoring efforts are underway in all these countries.

In Morocco, surveys revealed stripe rust to be severe and widespread in all areas except Abda and Doukkala in the west. Stripe rust severities >50S were observed in more than 40% all the bread wheat fields surveyed. Commercial cultivars Marchouch, Mahdia and to some extent Achtar and Amal were all susceptible to stripe rust in 2013.

Current regional weather forecasts derived from COLA/IGES indicate that despite rapidly warming conditions, some areas are still predicted to experience cooler and wetter conditions than the expected seasonal norm (see maps for short-term forecasts – up to 27th May 2013). Active surveillance and necessary control measures are advised in areas at risk from yellow rust.

Vigilance and caution is also advised in East Africa. Both Ethiopia and Kenya are experiencing heavy and persistent short rains. Similar conditions, coupled with yellow rust epidemics in the CWANA region, occurred in 2010 and resulted in a devastating yellow rust epidemic in Ethiopia. Monitoring of the current rust situation and detection of early rust outbreaks at the onset of the main wheat season is strongly advised.

Comments are closed.