May 20, 2013: Bhutan 2013 Rust Surveys – Rust incidence lower than 2012, leaf rust widespread but yellow rust localized

Posted on by May 20, 2013

IMG_0548

Rust surveys were coordinated and undertaken by the National Plant Protection Centre, Department of Agriculture, Ministry of Agriculture and Forest, Semtokha, Thimpu, Bhutan in collaboration with the Durable Rust Resistance in Wheat (DRRW) project during the period 25th April – 3rd May 2013. Surveys were undertaken in the western (Paro, Punakha valleys) and central (Bumthang) wheat growing areas. A total of 31 sites were surveyed. leaf rust was the most widespread disease, being recorded at 45% (n=14) of the sites surveyed. Leaf rust was observed in all the areas visited but incidence and severity was highest in the Punakha area. Two newly released lines from Nepal, being evaluated at Bajo Research and Development Centre, were susceptible to leaf rust and this may indicate exposure to different races of leaf rust in Bhutan.

Surprisingly, given the regional context and seemingly favourable climatic conditions in 2013, yellow rust was only found at very low incidence in Bhutan. Yellow rust was only observed at 8 sites on the survey and all but two of these sites only had trace amounts of disease. One site – Susuna in southern Paro – had exceptionally high incidence and severity of yellow rust. With a single field (1-2 ha) of an unknown improved variety exhibiting 100% incidence and 60-70% severity. Neighbouring fields of local cultivars appeared virtually disease free.

No positive observation of stem rust was obtained on the field survey. As on the previous survey in 2012, flag smut (Urocystis agropyri) was observed at two locations. These locations differed from those recorded in 2012. Current observations confirmed the presence of this disease at low frequency in Bhutan.

aecia

Considerable attention was given to Berberis species on the Bhutan rust survey. Berberis sp. were extremely common in all the wheat growing areas visited. From field observations it was considered likely that up to 8 different species of Berberis were present along the survey route. Efforts to conclusively identify these different species are on-going. Two distinct species of Berberis were found to be infected with aecia, with infected bushes observed at 4 unique locations (including the Susuna site with high incidence of yellow rust. Infected Berberis were also observed at this location in 2012). Several aecial samples and rust samples were collected on the survey and are currently undergoing analysis.

 


May 20, 2013: Pakistan – 2013 Rust survey summary update

Posted on by May 20, 2013
Pakistan Yellow Rust Severity 2013 vs 2012

Pakistan Yellow Rust Severity 2013 vs 2012

Very extensive rust surveys were undertaken throughout the main wheat growing regions of Pakistan during February-April 2013. The survey were coordinated by Dr. Atiq ur Rehman Rattu, NARC, Islamabad but were undertaken by a wide range of different institutes within Pakistan. Surveys in 2013 covered 232 locations throughout Pakistan, an increase of nearly 50% on the previous year. All three rusts were encountered on the surveys, but stripe (yellow) rust predominated being recorded at 53% (n=124) of the locations. Leaf rust was the second most widely observed rust in 2013, recorded at 33% (n=77) of the locations. stem rust was observed at 15% (n=34) of the survey locations in 2013.
Conducive climatic conditions for rusts, especially stripe (yellow) rust, occurred in Pakistan in 2013 and these conditions were mirrored in many other countries in the CWANA region. These favourable conditions were reflected in an increased frequency (compared to 2012) of high (>40%) or moderate (>20%) severity ratings for  all three rusts in Pakistan in 2013. This increasing trend of higher severity was particularly pronounced for stripe (yellow) rust. Distinct spatial distribution patterns were observed for each of the three rusts in 2013, highlighting the distinct environmental niches present in the Pakistan wheat growing areas. Stripe (yellow) rust predominated in the cooler northern-central wheat areas of Punjab, North-west Frontier, and Azad Jammu and Kashmir. Leaf rust was the most cosmopolitan rust distributed from north to south, but with higher occurrence in the central to southern areas. Stem rust was concentrated in the warmer southern regions of Sindh, with only isolated observations in the southern Punjab and one report of stem rust from a trial at Chakwal in the north. Extensive sampling of all three rusts was undertaken in Pakistan in 2013, with over 170 samples collected, and race analysis is on-going.

April 30, 2013: Study published confirming the presence of Sr31 virulent races of stem rust in Tanzania

Posted on by July 2, 2013

A paper by Hale, Mamuya and Singh (2013) has just been published in Plant Disease which confirms and documents the presence of three Sr31 virulent races of stem rust in Tanzania. The three races – TTKSK, TTKST, TTTSK – are all members of the Ug99 race group and all three races are previously known from neighbouring Kenya. This study confirms and details the initial findings posted in April 2011. All samples described in the study were collected in 2009, although there are some indications that Sr31 virulence may have been present in Tanzania since at least 2006. The authors recommend that future surveys and systematic race monitoring efforts should be undertaken in Tanzania.

Apr 17, 2013: Pakistan Rust Situation Update

Posted on by April 20, 2013

Based on initial reports from the field, a preliminary summary of the current rust situation in Pakistan is presented. More detailed reports will follow once survey data is compiled and analysis has been undertaken.

Like other countries in the region, Pakistan experienced conducive climatic conditions for rust development in the 2012/13 season. These conditions favored yellow (stripe) rust which was widespread. Localized, severe outbreaks were observed on older susceptible cultivars e.g., Sehar-06, but other major cultivars remained resistant. Surveillance teams covered all the major wheat growing areas and at least 100 samples of yellow rust are currently under-going race analysis. As in India (see March 20th report), no major epidemics of yellow rust were observed and all indications are that Pakistan will harvest a bumper wheat crop this season.

Both stem and leaf rust were also relatively widespread. stem rust was reported from late planted commercial fields in the southern Punjab. Over 40 stem rust samples and 30 leaf rust samples are currently under-going race analysis. However, with the Pakistan wheat crop now at maturity there is little chance of damage due to stem rust.

Apr 14, 2013 – Science magazine: Global research to control stem rust disease saves wheat farmers losses worth US $1.12 billion per year

Posted on by July 12, 2013
Photo credit: Yue Jin, USDA

Photo credit: Yue Jin, USDA

New press release published on the CIMMYT web site

A study just published in Science by scientists from the University of Minnesota, CSIRO, the University of Sydney, the University of Queensland, and CIMMYT shows that research to control the wheat disease known as stem rust during 1961-2009 has added 6.2 million tons annually to world wheat harvests, worth US $1.12 billion per year at 2010 prices.

However, the emergence of Ug99, a virulent stem rust race first detected in Uganda in 1999, instigated a major problem for farmers. The disease is capable of killing wheat plants and small grain cereals, but more typically reduces foliage, root growth, and grain yields. After years of keeping stem rust at bay, Ug99 has spread from Africa to Iran, and the race is on to identify resistant genes, introduce these into locally adapted wheat varieties, and get the finished product into the hands of farmers.

Investments in breeding for resistance to stem rust have declined in recent decades, making the potential impact of Ug99 even more harmful, as most popular varieties are susceptible to the disease. A paper published in Science on 12 April 2013 presents the results of a global stem rust assessment study, which asked: Is increased investment needed for wheat stem rust research to avert crop losses from current and future strains? Using novel, probabilistic risk assessment methods, including climate suitability model s and long-term global loss data the authors estimated the economically justifiable investment in research and intervention strategies to avert future losses from stem rust.

The study found that, had there not been investment in stem rust research and ensuing effective global control during 1961-2009, losses in wheat production would have amounted to 6.2 million tons annually, or 1.3% of the total harvest. This equates to losses of US $1.12 billion per year at 2010 prices, or enough wheat to satisfy almost the entire annual calorie deficit of sub-Saharan Africa’s undernourished population. Whilst much lower than previous estimates, the losses are sizeable for the effects of just one disease on a staple food crop. This new study represents a major advance in disease-risk assessment as it accounts for variability of disease-induced crop losses over space and time.

The study concludes that “maintaining yield growth rates necessary to meet anticipated future demands will require a sustained effort to develop wheat varieties that are resistant to contemporary races of rust. This requires an investment strategy that supports sustained research programs geared to identifying and addressing ever evolving stem rust threats.” This investment strategy should amount to an economically justifiable US $51 million per year, according to the authors. Whilst this is double the value invested in recent decades, such measures are essential if we are to stop the spread of Ug99 and other new races of stem rust and improve food security for the millions of wheat-dependent consumers in developing countries.

To read the full paper in Science, click here

For more information, contact: Philip Pardey, University of Minnesota

Mar 20th, 2013: Yellow Rust Situation Update in Punjab & Haryana States, North-west India

Posted on by March 25, 2013

Indian Districts reporting yellow rust – 14 March 2013

The Directorate of Wheat Research (DWR) in India have issued a series of advisories about yellow rust occurrence in North-west India in recent weeks. Full details can be found on the DWR web site with repeat postings on the Rust Tracker India page. Staff at DWR and other agencies in India are congratulated for these prompt and regularly updated advisories on the current yellow rust situation and the timely provision of control advice issued to farmers in the region. Despite the appearance of yellow rust in some areas, many analysts are predicting another bumper wheat crop for India in the current season.

First reports of yellow rust were obtained in January 2013 from Punjab state. Yellow rust was first reported from the village Mehindpur (near Chidouri, Saheed Bhagat Singh Nagar) in Punjab on January 9, 2013. In mid-January another report of yellow rust was received from the village of Surewal in Ropar district, Punjab. At the end of January (30-31st) two yellow rust foci were observed in the village of Madhubas (Radaur, Yamunanagar district) in Haryana state. In general, during January 2013 very extensive, India-wide, wheat disease surveys coordinated by DWR only revealed very minor occurrences of yellow rust (see DWR Wheat Crop Health Newsletter, Feb 2013).

By late February, yellow rust had spread and increasing levels of disease were reported from Haryana state. On 26th February, 474 hectares of wheat were reported to be infected in the Sadhaura and Jagadhri blocks of Yamunanagar district, Haryana. High incidence and severity (up to 60S) of yellow rust were reported from Sarawa village (Sadhaura block, Yamunanagar district) with the following varieties showing susceptibility; Super 172, WH 711, HD 2851, and Raj 3765. Variety HD 2967 was also observed to be susceptible (30S) in Jaroda village (Jagadhri block, Yamunanagar district). Further spread of yellow rust was reported by DWR on 14th March, with reports obtained from Yamunanagar, Ambala, Kurukshetra, Karnal, Panipat, Panchkula, Kaithal and Sirsa districts of Haryana. Yellow rust is reported to be severe in varieties; Super 172, WH 711, HD 2851, HD 2894, Raj 3765.

Current reported district-level occurrence of yellow rust in North-west India (up to 14th March 2013) with approximate timings are illustrated in Map 1. However, future spread of disease is not a certain outcome and will depend on several additional factors, including; conducive climatic conditions (temperature and moisture being critical), efficacy of control measures, growth stage and resistance of commercial cultivars.

Feb 27th, 2013: Latest version of Mehtaensis newsletter published by DWR, Flowerdale, Shimla: Comprehensive updated information on rusts in India and South Asia

Posted on by February 27, 2013

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 by Dr. S.C. Bhardwaj, Mehtaensis contains a detailed summary of all the rust activities and race analysis results from India and neighbouring South Asian countries during the period Aug 2012 – Jan 2013. The executive summary is reproduced here:

“All the rusts of wheat were observed in Summer Crop of Nilgiri hills (Tamil Nadu) and Leh (Jammu & Kashmir) whereas black rust was not observed in Dalang and Kinnaur areas of Himachal Pradesh. Owing to the dry weather there was no record of rusts except for mild brown rust in Karnataka.

Analysis of 213 samples of rusts of wheat and barley indicated that there was no occurrence of new pathotypes. Pathotype 40A followed by 40-1 of black rust, 46S119 followed by 78S84 of yellow rust and 77-5 followed by 104-2 of brown rust were predominant in wheat growing areas of India and neighboring countries. To identify the rust resistant lines, characterizing resistance genes, confirm the presence of resistance genes and genetics of rust resistance 1811 lines of wheat were subjected to multipathotype evaluation. National repository of 126 pathotypes of different rust pathogens was maintained, nucleus bulk inocula were supplied to 38 Scientist/centres in public and private sectors. Wheat disease monitoring nursery was a organized for planting at 45 locations. Evaluation and advancement of 34 cross combinations is being undertaken.” Mehtaensis 33(1) January, 2013

Feb. 10th, 2013: Eritrea – First report of race TTKSK (Ug99) but non Ug99 race group isolates predominate

Posted on by February 19, 2013

Photo credit: W Khoury, FAO

Surveys undertaken by Dr Asmelash Wolday of NARI  in the highland wheat growing areas of Eritrea during October 2012 found all three wheat rusts (stem, leaf and yellow) to be widespread. Stem rust was the predominant rust observed on the surveys. Stem rust was recorded at 77 of the 102 survey sites (75%), with moderate or high (>20%) severity recorded at 45 of the 77 confirmed sites (58%). leaf rust exhibited a similar distribution pattern, being observed at 51 out of the 102 survey sites (50%). Moderate or high (>20%) severity of leaf rust was observed at 48 of the 51 sites (94%) where leaf rust was present.  Yellow rust was also recorded at 51 out of the 102 survey sites (50%), with moderate or high (>20%) severity observed at 41 out of the confirmed 51 sites (80%).

Stem rust samples collected on the surveys were analysed using SNP marker diagnostics by Dr Les Szabo at the USDA-ARS, Cereals Disease Lab, Minnesota. A total of 23 samples were tested, with 1 sample being  positive for the Ug99 race group stage 1 assay and postulated to be race TTKSK in the stage 2 assay. This is the first time that race TTKSK has been reported in Eritrea. The majority of the samples tested (n=18) were found to be non Ug99 races and for 4 samples inconclusive results were obtained.

Dec. 20th, 2012: Russian Federation: Important new study on wheat stem rust in the central region of the Russian Federation published

Posted on by December 21, 2012

A major new study entitled “The wheat stem rust pathogen in the central region of the Russian Federation” has just been published in the journal Plant Pathology. The study was led by Dr E.S Skolotneva from the Dept of Mycology and Algology, Moscow Lomonsov State University, Russia and gives very valuable information on the race composition of the population of Pgt in the central region of the Russian Federation during the period 2000-2009. A total of 387 isolates of Pgt were analyzed during the study period using North American differential sets (16 genotype set 2000-2006; and 20 genotype set  2007-2009). Samples were obtained from cereals (wheat and barley), grasses (Elytrigia, Agropyron, Festuca, Dactylis, Phleum and Lolium spp.) and barberry. Forty-five races of Pgt were identified as a result of the study. Major changes in race composition were observed over the study period. M-group races, especially race MKBT, pre-dominated during the early years of the study (2000-2002) but thereafter T-group races (race TKNT and race TKNTF) have dominated. After 2005, race diversity fell and only 3 races (TKNTF, TKNTC and TKSTF) were detected in samples collected during 2007-09. It was postulated that  airborne inoculum from the south may have been a possible factor behind the observed changes in race composition, as a similar group of T races have concurrently been detected in Turkey.  The authors considered that the local population of  Pgt was sexual based on the relatively high diversity of races isolated from various hosts and the absence of correlation between  virulence attributes and molecular markers.  No Ug99 race group members were detected in the Russian Federation. Effective resistance genes were Sr11, Sr9b, Sr17, Sr31 and Sr24.

Dec. 10th, 2012: Turkey: Key study on stem rust races in Turkey published

Posted on by December 21, 2012

A new study entitled “Determination of Puccinia graminis f. sp. tritici races of wheat in Turkey” has been published in the Turkish Journal of Agriculture and Forestry. Dr Zafer Mert from the Central Research Institute for Field Crops (CRIFC), Ankara led the study. Extensive surveys throughout the wheat growing regions of Turkey were undertaken in 2007 & 2008. From these surveys a total of 40 stem rust isolates were obtained and race analysis, using the North American 20 genotype differential set, was carried out. A total of 21 different stem races were identified over the 2 year period. Race TKTTC was the most common race identified. Unpublished studies by Dr Mert and the  CRIFC research group have revealed the continued predominance of race TKTTC in Turkey in 2011 & 2012. The study indicates that pathogenic variation of Pgt in Turkey is high and the common occurrence of Berberis spp. was noted by the authors, although no direct evidence for a functional role  was demonstrated in the current study. No Ug99 race group members were detected in the study. Resistance genes; Sr24, Sr26, Sr27 and Sr31 were all found to be effective against all Pgt races present in Turkey.