Latest Situation Updates
Rust surveys undertaken in Azerbaijan by Konul Aslanova and colleagues from the Azerbaijan Agricultural Research Institute of Crop Husbandry in May/June 2015. Of the 11 widely dispersed sites surveyed, stem rust was observed at 6 sites (55%). High or moderate severity of stem rust was observed at all these sites, with both bread and durum wheat infected. Stem rust incidence and severity was highest in the Jalilabad area in the south-east Caspian Sea region of Azerbaijan, close to the Iranian border. Samples are currently undergoing race analysis and the current race(s) are unknown. In previous years the Digalu race (TKTTF) has been reported from Azerbaijan.
Rust surveys undertaken by Dr Emad Al-Maaroof and colleagues from Suleimaniyah University, Iraq in April/May 2016 covered 89 fields in Central and North-east Iraq. In the North-East – the Suleimanyah, Kirkuk, Erbil region – stem rust was detected in 40 fields, with high or moderate severity at most sites. The durum variety Adana-99 was most severely affected. Samples are currently undergoing race analysis and the current race(s) are unknown. In previous years the Digalu race (TKTTF) has been reported from Iraq.
These surveys combined indicate the potential increasing presence of stem rust in the region.
The latest version of the Mehtaensis newsletter (a 6 monthly newsletter named after Prof. K.C. Mehta) has just been published by ICAR-Indian Institute of Wheat and Barley Research, Regional Station, Flowerdale, Shimla. Compiled and edited by Pramod Prasad, Hanif Khan, O.P. Gangwar, and S.C. Bhardwaj with technical assistance from S.B. Singh and Subodh Kumar. Mehtaensis contains a detailed summary of all the rust activities and race analysis results from India and neighbouring South Asian countries during the period Jan – July 2016. The executive summary is reproduced here:
“A new Lr gene was identified in local wheat LWH2. This gene confers resistance to all the pathotypes of Puccinia triticina (except pathotype 5R9-7) in India. Wheat rusts did not appear in epidemic form during 2015-16 in India. The sporadic occurrence of yellow rust was reported from few areas of North western plains and northern hills zones, but its further spread was halted through joint efforts of ICAR-IIWBR, SAUs, State Department of Agriculture and farmers. Black rust was restricted to Central and Peninsular India whereas brown rust was observed across all the zones but their severity and incidence was quite low. During 2015-16, 1028 samples of different rusts of wheat and barley were received/collected for pathotype analyses from Ravi and off season crops. About 580 samples of three rusts of wheat and yellow rust of barley were analyzed. Many of the yellow rust samples could not be revived. Yellow rust population was avirulent to resistance genes Yr5, Yr10, Yr11, Yr12, Yr13, Yr14, Yr15 & YrSp and black rust to Sr 26, Sr 27, Sr31, Sr32, Sr 35, Sr39, Sr 40, Sr 43, SrTt3 & SrTmp; and brown rust to Lr24, Lr25, Lr29, Lr32, Lr39, Lr42 and Lr45. The frequency of pathotype 46S119 (virulent on Yr2, Yr3, Yr4, Yr6, Yr7, Yr8, Yr9, Yr17, Yr18, Yr19, Yr21, Yr22, Yr23, Yr25, YrA) of yellow rust, 79G31 (virulent on Sr2, Sr5, Sr6, Sr7b Sr9a, Sr9b,Sr9c, Sr9d, Sr9f, Sr9g, Sr10, Sr13, Sr14, Sr15, Sr16, Sr17, Sr18, Sr19, Sr20, Sr21, Sr28, Sr29, Sr30, Sr34, Sr36, Sr38, SrMcN) of black rust and 121R60-1 (virulent on Lr1, Lr3, Lr10, Lr11, Lr12, Lr13, Lr14a, Lr14b,Lr14ab, Lr15, Lr16, Lr17a, Lr17b, Lr18, Lr20, Lr21, Lr22a, Lr22b, Lr23, Lr26,Lr27+31, Lr30, Lr33, Lr34, Lr35, Lr36, Lr37, Lr38, Lr44, Lr46, Lr48, Lr49) of brown rust was the maximum in their respective categories. More than 3300 lines of wheat and barley which includes AVTs, NBDSN, EBDSN and breeder’s material were evaluated for rust resistance and/or characterization of rust resistance genes. None of the entries in AVTs was resistant to all the rusts. AVT IInd entries WB2 and HD2864(C) were resistant to all the pathotypes of yellow and brown rust, respectively. AVT Ist entries AKAW4842, HS623 and TL3006 were resistant to all the pathotypes of black and brown rust and two entries viz. DBW220, WH1310 were resistant to all the pathotypes of brown rust. WB2 conferred resistance to all the pathotypes of yellow rust. Wheat rust resistance genes (Sr, Lr, Yr) were characterized using gene matching technique. Five Yr, seven Lr and ten Sr genes were characterized in AVT IInd material. Similarly in AVT Ist entries, four Yr, seven Lr and ten Sr genes were inferred. AVT entries UAS456(D), HI8759(D), HI8728(D)(I)(C), MPO1215(D)(C), MACS3949(D) and NIDW295(D)(C) showed APR against 117-6 pathotype of black rust. Twenty entries of AVT Ist and seventeen entries of AVT IInd were resistant to 110S119 and 110S247, new pathotypes of yellow rust at adult plant stage. Likewise eleven entries of AVT IInd and three entries of AVT I conferred APR to pathotypes 77-5 and 104-2 of brown rust. Rust resistance in EBDSN and NBDSN entries was identified against selected pathotypes of yellow and black rusts and mixture of brown rust pathotypes. Entries BCU7911 and VLB140 in EBDSN and VLB147 and PL891 in NBDSN were resistant to all the pathotypes of brown, black and yellow rust. Studies on host pathogen interaction of brown rust pathotype 77-5 with wheat NILs: HW2020 (HS240+Lr24) (Resistant) & HS240 (Susceptible) were carried out. More than 126 pathotypes of wheat, barley, oat and linseed were maintained as live cultures as well as cryo-preserved. Nucleus and bulk inocula were supplied to more than 30 scientists/centers. To develop rust resistant genetic stocks and study genetics of rust resistance, different crosses were attempted and generations of previous crosses were advanced. Wheat disease monitoring nursery (WDMN) and SAARC WDMN nurseries were organized”.
Mehtaensis Vol. 36 (2). ICAR. Indian Inst of Wheat and Barley Research, Regional Station, Flowerdale, Shimla 171 002 H.P. India
Race analysis undertaken by EIAR, Ambo, GRRC, Denmark and USDA-ARS CDL on samples collected in 2015 from Ethiopia and Kenya indicates that stem rust populations in East Africa are changing. The detection of race TKTTF (“Digalu” race) in Ethiopia in 2012 and the subsequent epidemics in 2013, 2014 and 2015 (see Olivera et al 2015) appears to have profoundly influenced the stem rust populations in East Africa. For over a decade the Ug99 race group has dominated in both Ethiopia and Kenya, however the latest results indicate that this situation is now changing.
A total of 214 stem rust samples from Ethiopia in 2015 were analysed by the 3 different laboratories. The results indicated that the original Digalu race (TKTTF) dominated throughout the country, with 86% (n=185) of samples being this race. Other presumed variants of the Digalu race were also detected – TTTTF (n=9), TTTTC (n=3), TRTTF (n=3), PKPTF (n=4), PKPTC (n=2), PTTTF (n=1), PTPTF (n=1). Other races included: SJPQC (n=1), JRCSF (n=1), JRCQC (n=1). Ug99 (race TTKSK) was still present at very low frequency, only 2 samples out of 214.
In Kenya, only 17 isolates were analysed by USDA-ARS CDL however the results indicated that the Digalu group of races were also emerging. A total of 7 races were identified in Kenya. Races presumed to be variants of the Digalu race pre-dominated. The most frequent race was PTTTF (n=7), with PKPTC (n=3) and PKPTF (n=1) also detected. Interestingly, the original Digalu race (TKTTF) was not detected in the Kenya samples. Three Ug99 races were also detected in the Kenya 2015 samples: Races TTKSK (n=4), TTKTT (n=1) and TTKTT (n=1).