Climate change and the fight against plant diseases

Earlier this month, Dr Adrian Newton from the James Hutton Institute spoke about the implications of climate change for pathogen defence in plants, at the Society for General Microbiology Spring Conference in Harrogate, North Yorkshire, UK.

He explained, “The communities of microbes on plants are complex and include harmless and beneficial organisms as well as those that cause disease on plants and humans. We need to understand the dynamics of complex microbial communities and their interactions to be able to predict the likelihood of disease”, reported ScienceDaily.

Dr Newton explained, “Climate change adds an extra layer of complexity to an already complex agro-ecological system. Higher temperatures, increasing levels of carbon dioxide, water limitation and quality may all affect existing plant microbes as well as favouring the appearance of new microbes. This may increase the incidence of some diseases and reduce the incidence of others.”

As co-author of ‘Climate change, plant disease and food security: an overview’, published in Plant Pathology’s special issue, ‘Climate change and plant diseases’ in February, Newton used Fusarium head blight (FHB) as a case study to illustrate the point. Chakraborty and Newton (2011) explained that pest and disease management has helped to double food production in the past 40 years, but pathogens still claim 10-16% of the global harvest. In recent decades, FHB has re-emerged as a disease of global significance, causing yield loss and reduced grain quality, resulting in price discounts with an estimated cost of $2.7 billion in the northern great plains and central USA from 1998 to 2000.

FHB severity is affected by climate and atmospheric composition changes. Rainfall, humidity, and temperature changes all influence the main strain of FHB, including the quantity of the harmful mycotoxin produced by the fungus. An increase in the number of crops containing potentially dangerous levels of mycotoxin and the risk of epidemics of this fungal disease, is expected across the UK over the next few decades, according to mathematical modelling.

More Plant Clinics for Sierra Leone

 Sierra Leone April 2011 035

Plant clinics have taken off in Sierra Leone and are a permanent feature of the extension landscape backed by the Ministry of Agriculture, Forestry and Food Security. However they are trying to extend the numbers of plant clinics so as to make them more accessible to farmers and to this end, CABI with funding from COOPI (an Italian NGO) has recently trained 15 plant doctors and 15 plant nurses enough for one plant clinic for each chiefdom within Kono district.

Kono district is the heart of the Sierra Leone diamond mining area but despite the potential riches underground the population remains extremely poor. Phil Taylor and Wade Jenner went to Kono to train new clinic staff from 30 May – 14 April.  Module one of ‘How to be a Plant Doctor’ was taught over 5 days and COOPI provided all the plant clinics with a camera as well as tables and chairs, umbrella for shade and advertising banner and megaphone. In addition each trainee was given a bicycle so as to improve their mobility and enable them to reach more remote regions.

It is intended that Modules 2 and 3 are to be taught in the coming months to further increase the help they can offer farmers.

Along with Uganda and Kenya the Sierra Leone Plant Clinics are participating in the trial of electronic data retrieval whereby the record sheets are scanned and emailed to CABI prior to being read by computer software and the data installed in a spread sheet.

Wheat rust and climate change – a possible connection

A possible link between wheat stripe rust and climate change was observed by researchers meeting at the International Wheat Stripe Rust Symposium, which convened in Aleppo, Syria last week.

The symposium organised by the International Center for Agricultural Research in the Dry Areas (ICARDA) aimed to review the current global status of wheat stripe rust epidemics that have severely affected crop yields in Central and West Asia, the Middle East and North and East Africa in recent years. More than 100 scientists and policymakers from 31 countries participated and an important feature of the meeting was to share experience and approaches to manage wheat rust through breeding and control strategies in affected countries in Asia and Africa.

Recently, severe epidemics of stripe (yellow) rust have been reported in Morocco, Ethiopia, Uzbekistan, Tajikistan, Kyrgyzstan, Turkey, Azerbaijan, Afghanistan, Iran, Pakistan, India, and Syria. “Some of the countries affected by rust epidemics have invested very little in agricultural research and development,” said Hans Braun, director of the Global Wheat Program at the International Maize and Wheat Improvement Center (CIMMYT) in Mexico. At the meeting, he challenged policymakers to recognize the link between scientific research and food security and to invest more heavily in agricultural research. “To combat the problem of wheat rusts, farmers in these regions need to adopt new varieties of wheat that have durable resistance to both stem and stripe rust,” said Ronnie Coffman, vice chair of the Borlaug Global Rust Initiative.

Climate change, in terms of rising temperatures, and the timing and increasing variability of rainfall, is contributing to the spread and severity of rust diseases, said the press release. Emerging races of rust are showing adaptations to extreme temperatures not seen before. Scientists around the globe are working on monitoring and surveillance of stem rust and stripe rust to insure rapid detection and reporting so farmers, policymakers, and agricultural research centres can respond more quickly to initial outbreaks.

Wheat rust has been a problem for many decades, as reported in various papers in the CAB Abstracts database (Newton, 1922; Tehon, 1927; Zekl, 1934; Naoumova, 1935; Beilin, 1938; and Roche et al., 2008). Interestingly, the paper by Beilin, published in 1938 in the Bull. Acad. Sci. in 1938 and abstracted in CAB Abstract in 1939, discussed the problems related with developing hardy wheat cultivars with resistance to drought, without paying attention to their response to diseases; and how the climatic conditions exacerbated the disease spreading.

Beilin reported that Russian breeding work at the time had been concerned mainly with the development of hardy, prolific and drought-resistant wheat varieties with no focusing on their response to smut and rusts. As a result, the most popular standard wheat varieties then were highly susceptible to various rusts, including Puccinia, graminis, and the climatic conditions of the main area under winter wheat permitted overwintering of the rusts. The relatively high day temperature in June and abundant rainfall and dew in May and June facilitated their rapid development. The use of susceptible varieties under these conditions and the absence of correct crop rotations led to severe rust epidemics, lowering the quality of the grain and reducing the yields in some years and districts to about half the normal.

The ICARDA press release also reported that new rust resistant varieties are in the pipeline at international and national agricultural research centres. Breeders are selecting for other important characteristics including improved yield performance, drought tolerance, and regional suitability. 

Country preparedness for outbreaks of wheat rust involves such issues as the availability of resistant varieties that are known to and accepted by farmers, the availability of sufficient quality seeds of new varieties for farmers to use, and the availability, accessibility and affordability of effective fungicides and capacity of farmers to use them.

In most cases, the bottleneck to getting resistant varieties into the field in time to protect local harvests is local capacity and the ability of national programs to rapidly multiply seeds and deliver them to market. Improving country capacity requires long-term planning, funding, and getting farmers involved earlier in the variety selection process, says the ICARDA press release.

Link to the symposium website

Link to press release

Further Reading
    1. Beilin, I. G. (1938) Recent Wheat rust epidemics in North Caucasus and factors favouring their outbreak and development. Bull. Acad. Sci. U. R. S. S. 1938 1938 No. 5-6 pp. 995-1016 pp.
    2. Naoumova, Mme N. A, (1935) Dependence of the development of yellow rust of Wheat on meteorological factors. Summ. sci. Res. Wk Inst. Pl. Prot. Leningr., pp. 64-65 pp.
    3. Newton, M. (1922) Studies in Wheat stem rust (Puccinia graminis tritici). Trans. R. Soc. Canada, 3rd series, Section V 1922 Vol. 16 pp. 153-210 pp.
    4. Roche, R.; Bancal, M. O.; Gagnaire, N.; Huber, L. (2008) Aspects of Applied Biology, No. 88 pp.
    5. Sache, I.; Suffert, F.; Huber, L. (2000) A field evaluation of the effect of rain on wheat rust epidemics. Acta Phytopathologica et Entomologica Hungarica, Vol. 35 No. 1/4 pp. 273-277.
    6. Tehon, L. R. (1927) Epidemic diseases of grain crops in Illinois, 1922-1926. The measurement of their prevalence and de-structiveness and an interpretation of weather relations based on Wheat leaf rust data. Illinois Dept. Registr. and Educ. Div. of Nat. Hist. Survey, Bull, Vol. 17 No. Art. 1 pp. 1-96 pp.
    7. Zekl, F. (1934) Causes of wheat rust. Deutsche Landwirtschaftliche Presse, Vol. 61 No. 32 pp. 397 p.

Update: Plant Health News (27 Apr 11)

Here’s a taste of some of the latest news stories about plant health:

If there’s another news story you’d like to highlight, please post a comment.

Update: New Pest & Disease Records (20 Apr 11)

We’ve selected a few of the latest new geographic, host and species records for plant pests and diseases from CAB Abstracts. Click on the links to view the abstracts.

To view all search results for new geographic, host and species records for plant pests and diseases, click here (>28,000 results)

If there’s another new record you’d like to highlight, please post a Comment.

Update: Plant Health News (13 Apr 11)

Here’s a taste of some of the latest news stories about plant health:

If there’s another news story you’d like to highlight, please post a comment.

Plant Clinics boost fight against diseases and pests

“Plant clinics boost fight against diseases, pests” – this was the title of a story that appeared in the newspaper Business Daily last week. It was one of many positive articles that were written after a group of journalists were taken to visit some Plant Clinics in Kenya.

The article includes examples where the Plant Clinics have helped farmers in Kenya.

Karanja Kinyanjui, a farmer from Kikuyu District, who supplies Nairobi’s Wakulima Market says he spent Sh10,000 on pesticides prescribed by agro-vets for his potatoes and spinach to no avail. Following this, diagnosis from the plant doctors encouraged him to spray wood ash onto his crops, which, within a week wiped out the disease.

“It still pains me to imagine that the agro-vets fleeced me of my meagre earnings,” he said.

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