Photo Credit: R.F. Park
Wheat leaf rust (Puccinia triticina) is the most widespread of all the rusts that affect wheat. Losses are usually less than for either yellow rust or stem rust. Under suitable conditions, yield losses of 10-20% or more are possible. However, serious epidemics can result when conditions are favourable. Recent epidemics have occured in Pakistan and Mexico.
Regularly updated situation reports on cereal rusts are given based on information provided by a global network of rust workers.
Currently, most of the global surveillance and monitoring efforts reported in RustTracker.org have focused on stem rust, but it is hoped to expand the information on leaf rust in the near future
The latest version of the Mehtaensis newsletter (a 6 monthly newsletter named after Prof. K.C. Mehta) has just been published by the IIWBR, Regional Station, Flowerdale, Shimla. Compiled and edited by Dr. S.C. Bhardwaj, O.P. Gangwar, Pramod Prasad and Hanif Khan 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 July – Dec 2015. The executive summary is reproduced here:
“During offseason 135 samples of three rusts of wheat were received from Himachal Pradesh, Punjab, Tamil Nadu and Uttarakhand. 49 samples of all three rusts of wheat were analyzed, some of which were spill over of main season. Ug99 type of virulence was not identified anywhere in India. In brown rust pathotype77-5 (121R63-1) of brown rust, 46S119 and 110S119 of yellow rust and 40A (62G29) of black rust were found most frequently among the analyzed samples. Nucleus inocula of three rusts were also supplied to 38 Scientists/Research centres to facilitate research work elsewhere in India. More than 2850 lines of wheat and barley were evaluated against the pathotypes of different rusts. The tested material included the breeding lines provided by breeders from various parts of India, exotic wheat lines from CIMMYT and ICARDA. In addition 150 lines of AVT I and II are being evaluated against different pathotypes to identify rust resistant wheat lines. For monitoring the occurrence/spread of different diseases of wheat, Wheat Disease Monitoring Nursery (WDMN) and SAARC-WDMN were planted at 50 and 28 locations, respectively. Early occurrence of yellow rust was reported from Ropar, Anandpur Sahib and Hoshiarpur district of Punjab. Three Ug99 resistant genetic stocks namely FLW31, FLW32 and FLW33 have been developed. FLW31 and FLW33 are completely resistant against black and brown rusts while FLW32 has resistance to black rust and adult plant resistance against yellow and brown rusts. Work on standardization of doubled haploid production in wheat using maize pollination induced chromosome elimination was initiated. Offseason nursery was used for selection and generation advancement of 325 wheat lines. Under frontline demonstration of wheat variety, HS542 was planted in five adopted villages (12 farmers) of Tehsil Arki (Solan district of Himachal Pradesh).”
The latest version of the Mehtaensis newsletter (a 6 monthly newsletter named after Prof. K.C. Mehta) has just been published by the DWR, Regional Station, Flowerdale, Shimla. Compiled and edited by Dr. S.C. Bhardwaj, O.P. Gangwar, Pramod Prasad and Hanif Khan 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 July – Dec 2014. The executive summary is reproduced here:
“During the off season/summer crop (2013-14) all the rusts of wheat were observed at Wellington (Tamil Nadu), Dalang (Himachal Pradesh) and Ladakh (Jammu & Kashmir). Yellow and brown rusts were first observed on 12th of September and 6th of October, respectively on wheat disease monitoring nursery (WDMN) at Shimla. Scientists from PAU, Ludhiana have observed (19.12.2014) the occurrence of yellow rust of wheat in a farmer’s field in village Daroli Upper near Anandpur Sahib in Punjab. The spot has been chemically treated to eradicate the focus of infection. During the period about 135 samples of wheat rusts were collected/received. So far 38 samples of all three rusts of wheat have been analysed.
Only two pathotypes each of black {34-1 (10G13) and 40A (62G29)} as well as yellow rust {46S119 and 46S117 (new pathotype)} of wheat were observed till date. Brown rust, pathotypes 77-5 (121R63-1), 77-11 (125R28), 104-4 (93R57) and 162-1 (93R47) were identified in Himachal Pradesh samples. In samples from Tamil Nadu only 77-9 (121R60-1) and 77-10 (377R60-1) were observed.
Seedling resistance test (SRT) of more than 1070 lines of wheat and barley, including AVT, NBDSN and EBDSN entries have been done against different pathotypes of three rusts of wheat and barley. Analysis of polymorphism among brown rust pathotypes based on SSR marker analysis and their infection types on brown rust differential sets and the clustering in the same was done in the form of dendrogram.
Forty five different crosses were attempted for inheritance studies and gene transfer for rust resistance. More than fifty populations/selections were analyzed for seedling resistance against suitable rust pathotypes and were transplanted in the field for advancement of generations for genetic analysis and gene pyramiding studies.
Repository of pathotypes of different rust pathogens of wheat, barley, oat and linseed was maintained and inoculum of wheat and barley rusts was supplied to 39 centers/Scientists.
For monitoring the occurrence/spread of different diseases of wheat, WDMN and SAARC-WDMN were planted at different locations”. Mehtaensis Vol. 35 (1). ICAR. Indian Inst of Wheat and Barley Research, Regional Station, Flowerdale, Shimla 171 002 H.P. India
Rust surveys were carried out in all the four key wheat growing regions of Kenya: South Rift, Mount Kenya region, Central Rift and North Rift. The surveys were conducted by experts from the Kenyan Agricultural Research Institution (KARI). A total of 296 farms were sampled. Stem rust was detected in 196(66.2.0%), yellow rust in thirty-one (10.4%) and leaf rust in eight(2.7%) of the farms with disease severity ranging from trace to 80S, 50S and 40S respectively. The rusts were detected in all the wheat growing regions. Stem rust infection ranged from TR to 80S with infection in South Rift (69.6%) North Rift (55.8%), and maximum infection in Central Rift (92.2%) and Mount Kenya region (57.7%). Yellow rust infection ranged TR to 60S with minimum infection in North Rift (7.4%) ,South Rift (8.9%) and maximum infection in Mt. Kenya region (15.5% and Central Rift (11.8%). Leaf rust infection ranged from trace to 50S with minimum infection in Mount Kenya region (1.4%, Central Rift (3.9% and maximum infection in North Rift was (5.3%).
Commonly grown varieties :Robin, NJRBWII, KSMwamba and Kwale . Robin was popular in Central Rift( 47.1%), Mt.Kenya region(43.7%), South Rift (41.8%) and North Rift (12.6%) of the sampled fields.Variety NJRBWII occupied the largest area in North Rift (63.2%).
The area planted with NJRBWII increased in 2014 the North Rift compared to 2013 in the same region and the area under Robin increased in the other three regions. Variety Eagle 10 still occupied a very small area in all the regions except in the South Rift(19.5%) of the sampled fields.
The general observation was that the adoption of Robin was coming up very fast, but unfortunately the variety has broken down to apparently new race of stem rust yet to be defined. Only those farmers who sprayed following the right recommendations harvested/will harvest the crop. Those who did not spray or sprayed without following the proper recommendations lost the crop to the disease.
Secondly, the disease pressure was very high in all the regions but the majority of the farmers sprayed to keep the inoculum load low( South Rift,North Rift,Central and Mt.Kenya region).
The latest version (Vol 34, July 2014, No. 2) of the Mehtaensis newsletter (a 6 monthly newsletter named after Prof. K.C. Mehta) has just been published by the DWR, Regional Station, Flowerdale, Shimla. Compiled by Dr. S.C. Bhardwaj, O.P. Gangwar, P. Prasad and Hanif Khan with technical assistance from: S.B. Singh, Subodh Kumar (Mehtaensis July 2014 Vol.34No.2). Mehtaensis contains a detailed summary of all the rust activities and race analysis results from India and neighbouring South Asian countries during the 2013/14 season. Reported highlights are summarized as follows:
There was no major outbreak of wheat rusts in India during 2013-14. However, sporadic incidence of yellow rust of wheat was observed at some locations in Northern India. Stem (Black) rust of wheat was reported on indigenous experimental wheat material planted in Uttarakhand and barley material in Karnataka. During the year 1625 samples of different rusts of wheat and barley were received/collected for pathotype analyses. Analyses of more than 1209 samples revealed that the wheat rust population analyzed is avirulent to Yr5, Yr10, Yr11, Yr12, Yr13, Yr14, Yr15, Yr24, Yr26, YrSp and YrSk (yellow/stripe rust); to Sr26, Sr27, Sr31, Sr32, Sr35, Sr39, Sr40, Sr43, SrTt3 and SrTmp (black/stem rust); to Lr24, Lr25, Lr29, Lr32, Lr39, Lr42 and Lr45 (brown/leaf rust). Predominant pathotypes were; (i) yellow/stripe rust: 46S119 (74% of samples) and 78S84 (18.5% of samples); (ii) brown/leaf rust: 77-5 (121R63-1=THTTM) predominant, followed by 104-2 (21R55=PHTTL); (iii) black/stem rust: pathotype 11 (79G31=RRTSF) was predominant followed by pathotype 40A (62G29=PTHSC). One new pathotype each of the three wheat rusts were identified, however all were less virulent than those already described. Virulence on Sr31 (Ug99 type of pathotypes) was not identified anywhere in India, Bangladesh, Bhutan and Nepal.
Fig. 1. Wheat stem rust at Dinajpur, May 2014 (Photo credit: Dr P.K. Malaker WRC, Dinajpur)
Extensive annual rust surveys were undertaken throughout the wheat growing areas of Bangladesh during February-March 2014. The surveys were coordinated by Dr P.K. Malaker of the Wheat Research Centre (WRC), Dinajpur, but implemented by several collaborating stations, including; Dinajpur, Joydebpur, Jamalpur, Jessore and Rajshahi. A total of 230 different locations were covered by the survey teams. 2014 was a favourable year for wheat rusts in Bangladesh. It was exceptional in the respect that all three rusts were recorded on the survey. Leaf rust was the most frequent with much higher disease pressure than in previous years. Leaf rust was very widely distributed, being present throughout the wheat growing regions of Bangladesh. Almost 90% of the sites surveyed (n=197) recorded leaf rust, and 50% of these had high or moderate severity. Highest severity was recorded in the north-west and western wheat growing areas of Bangladesh (Map 1). The popular variety ‘Prodip’ was notably susceptible to leaf rust.
Stem rust was putatively recorded at two widely separated locations in Jamalpur and Jessore and later, clear symptom (Fig. 1) of the disease with susceptible reaction was observed at WRC, Dinajpur. Only low severity and incidence were recorded. The disease was observed on few lines in the rust trap nurseries from ICARDA, but not in any other cultivars or lines. The symptoms
Map 1. Leaf Rust Severity 2014 (red dots = high severity, orange dots = mod severity, yellow dots = low severity)
and urediospore morphology were examined at WRC, Dinajpur and ascertained to be of stem rust. Samples were collected and are undergoing race analysis at DWR Regional Station in Shimla, India. These would probably represent the first stem rust records from Bangladesh in three decades. Yellow rust was recorded only at WRC, Dinajpur. The disease was found on the rust susceptible check variety Morocco in a trial plot. Yellow rust is infrequent in Bangladesh, but does occur sporadically.