BSPP News Autumn 2001 - Online Edition

The Newsletter of the British Society for Plant Pathology
Number 40, Autumn 2001 

Modern Fungicides and Antifungal Compounds - The 13th Reinhardsbrunn Symposium

Friedrichroda, Germany : 14 - 18 May 2001 

The series of the Reinhardsbrunn Symposia was established by Professor Horst Lyr in 1962 and held every three years in Friedrichroda. Systemic fungicides were originally the main topic of these Symposia but since 1980 other antifungal systems (such as biocontrol agents and induced resistance) have been introduced. This year more than 120 participants were at the symposium with more than sixty poster and talk contributions. Oral sessions covered the following areas: management and monitoring of fungicide resistance, mechanisms of fungicide resistance, biological control and host parasite interaction, current status of fungicide science, trends in control of plant disease, new fungicides and their mode of action and trends in fungicide research. 

After the introductory remarks by Professor H. W. Dehne, who has taken over the organisation on retirement of Prof. H. Lyr, the latter welcomed us and recalled happy memories from previous symposia. The first talk was by Nancy Ragsdale from the USA who described a national study to determine the future role of pesticides in US agriculture. The primary conclusion was that chemical pesticides would remain a part of pest management in the foreseeable future but a more in-depth analysis was needed. Phil Russell then gave two talks about resistance management and pesticide resistance which are major problems in agriculture, leading to loss of pest control and marketable crop, and consequent product sales and investment in developing new products. Professor Russell also talked about a study in the UK, Germany and France during 1998-2000 showing a rise in the overall sensitivity of wheat eyespot populations due to prochloraz application, leading to an increase in the field control of eyespot. 

I was most interested in the session on biological control, and gave a talk entitled "Characterisation and activity of Bacillus antagonists to Botrytis cinerea", where I presented data for isolation and selection of potential antagonists against B. cinerea and their modes of biocontrol action. Three Bacillus isolates showed very good antagonistic activity when tested under glasshouse conditions against B. cinerea. My talk received much interest and I was able discuss my work with other researchers from all over the world. 

Eftihia Tsomlexoglou under the statue of J.S. Bach in the city of Eisenach

Jos Wubber from the Netherlands gave talked about controlling powdery mildews in ornamental plants using an integrated control system that included biological control agents, i.e. the well-known biopesticide Trichodex, plant extracts and salts. He found that the combination of several of the tested products had good potential for control of powdery mildews and could be used as part of an integrated control scheme. Similar results were presented from our group by my supervisor Barrie Seddon, in a poster presentation entitled "Interaction between fungicides and the biocontrol agent Brevibacillus brevis for integrated disease control", where it was concluded that combinations of B. brevis and fungicide application are possible for disease control. Tim O'Neill presented work on evaluation of fungicide treatments against rose downy mildew (Peronospora sparsa), which has become an increasing problem of both container-grown plants and outdoor crops in the UK. The different fungicides managed to control disease to various levels only when they were applied before the first disease symptoms. Also, increased plant spacing delayed the first occurrence of disease symptoms and slowed disease epidemics. This method combined with reduced overhead watering could be used as potential components of an integrated management strategy for rose downy mildew.

Brüggemann and Kraska from Germany presented two talks about the uses of organic polymers in agricultural. Organic polymers (hydrogels) can absorb water and can be used for formulation of fungicides or biocontrol agents since the plants can take up the plant protection agent together with the water. In a field trial hydrogel/fungicide formulations were tested against powdery mildews of wheat and late blight of potato and it was found that they could control diseases.

This was a fascinating meeting and an opportunity to put my own research into perspective and establish  useful contacts as I finish my PhD.  I am grateful to the BSPP for providing me with a travel grant that helped cover my expenses in this beautiful place. It will remain an unforgettable experience for years to come. 

Eftihia Tsomlexoglou
University of Aberdeen

Diagnostics and Disease Control

Edinburgh : 30 May 2001

Some 75 delegates registered for this one-day meeting,  hosted by the Scottish Mycology & Plant Pathology Club in conjunction with the BSPP.  It brought together molecular biologists, epidemiologists and field pathologists for an interesting meeting on disease diagnostics.  The meeting explored both the development of diagnostic test systems and the practical use of such tests in crop management decision making. 

The first session focused on the general development and use of diagnostics.  The keynote speaker, Dr Emily Taylor of NIAB, described the progress being made in the use of molecular methods for seed health testing. Neil Boonham, of CSL, reflected on the range of methods appropriate for different diagnostic uses.  Alistair McCartney from Rothamsted assessed the methods being developed for detection of airborne pathogen inoculum.  Finally, Gareth Hughes (Edinburgh University) made everyone's brain hurt with an exploration of probability in relation to the practical use of diagnostic information in decision making. 

After an excellent lunch, the meeting continued with a series of papers looking at specific uses of particular diagnostic methods.  Neil Havis (SAC, Edinburgh) described work on the use of a monoclonal antibody-based test for quantification of fungicide residues in plant tissue.  Marian McEwan of SASA reviewed work on the development of a test for Tilletia tritici in seed samples.  Shautak Hussain (SCRI) described the use of molecular diagnostics for Phytophthora infestans in epidemiological investigations and lastly Tina James from SASA told us about the results of a ring test of diagnostic detection methods for potato spindle tuber viroid conducted in a series of European labs.  This highlighted the variability found in the use of diagnostic methods in different hands and usefully brought the meeting back to the points made earlier by Gareth Hughes on the interpretation of diagnostic data.

The venue for the meeting was the grand lecture theatre in the University of Edinburgh's Michael Swann building on the King's Buildings campus.  Excellent technical support with the visual aid equipment was greatly appreciated, especially with the majority of speakers using powerpoint-generated slides! 

SMPPC meetings are as much a social event as a scientific one and are an excellent opportunity to meet with friends and colleagues.  Over the years the quality of papers presented at the twice-yearly SMPPC meetings has grown so that the day 'feels like a pukka meeting but among friends' to quote one delegate.  I must thank Fiona Burnett for much of the local organisation and Moyra Farquhar for helping  with registration and delegate information.  Ian Toth produced a stylish cover for the programme and abstracts at very short notice for which I am grateful.  Lastly, the SMPPC is grateful for the continuing support of the BSPP and in particular for the contribution it has made in support of this joint meeting.

Mark J Hocart
SAC Edinburgh

8th International Workshop on Plant Disease Epidemiology

Ouro Preto, Brazil : 6 - 11 May 2001

This workshop was held in Ouro Preto, Brasil. The name Ouro Preto means 'black gold' and the town was formerly the capital of the Brasilian mineral mining state of Minas Gerais. The venue was a well-equipped hotel set in the midst of rolling hills, some 5 km outside Ouro Preto. To reach it, most of us had to fly into São Paulo or Rio de Janeiro, then take another flight to the current Minas Gerais state capital, Belo Horizonte. There we were met by the conference organisers and taken by car to the workshop venue. This warm welcome and efficient organisation typified the arrangements made by our Brazilian hosts throughout the meeting.

The topic of the workshop was 'Understanding Epidemics for Better Disease Management'. Among the 88 participants from 18 countries, membership of BSPP was well represented. Indeed, seven out of the twelve invited speakers were BSPP members, including the current BSPP President, Chris Gilligan, who opened the workshop by delivering the keynote address. The scientific programme included sessions on: theoretical epidemiology and modeling with practical applications; spatio-temporal analysis of epidemics applied to disease management; the IPM philosophy - an appraisal of the pros and cons in botanical epidemiology; dispersal of plant pathogens and vectors; injury, damage and loss - concepts and application; new tools for epidemiology applied to disease management; comparative epidemiology; molecular tools in epidemiology; disease forecast, warning systems, decision making and disease management; host-pathogen-vector- environment interactions; and a summary and conclusions session on the final morning. The isolated location selected for the meeting encouraged maximum participation in the sessions, all of which were well attended. Younger participants were given the chance to speak about their poster presentations, and take part in the ensuing discussions. Most discussions continued during the drink or lunch breaks, while we enjoyed a great variety of food and drink.

During the course of the workshop, several important topics emerged. Theoretical epidemiology continues to play a central role in developing our understanding of botanical epidemiology. Recent work in Chris Gilligan's group to include spatial and stochastic processes enables the prediction of criteria that lead to pathogen invasion and persistence. Moreover, by combining mathematical modelling with experimentation it has been possible to predict the evolution of variability within and between epidemics. By including fundamental epidemiological concepts such as primary infection and secondary infection, the dynamics of the plant and that of inoculum in compartmental models of the SEIR (Susceptible, Exposed, Infected and Removed) form, the work also offers a mechanistic approach with which to analyse, compare and predict field epidemics. An example of this approach was described by Tijs Gilles for the development of light leaf spot on oilseed rape. 

The development of reliable mechanistic models for the analysis of botanical epidemics requires experimental validation using a combination of controlled environment and field experiments. Whilst microcosm experiments are efficient, validation with field experiments is expensive. However, the potential of novel molecular techniques for rapid detection and quantification of plant pathogens, such as PCR described by Alastair McCartney, and indirect assessment of disease severity by remote sensing using GPS and GIS introduced by Forrest Nutter, provide exciting opportunities for the production of high quality spatio-temporal data.

Whilst the SEIR approach allows us a generic and mechanistic framework with which to describe disease dynamics, no similar framework yet exists to link disease dynamics with yield. Two posters of notable exception, presented by R. B. Bassanezi and A. Shoeny, were prominent in their attempts to derive relationships between disease severity and net photosynthetic rate and between the infection of wheat roots by take-all and various components of yield, respectively.

Quite a few of the discussions were about issues relating to forecasting of diseases. The scale at which forecasting systems need to be applied was an important issue. Although farmers prefer to get a disease forecast for their individual farm it is often necessary to look at a much greater scale to understand what can happen on a smaller scale. A good example of this was the poster presentation by Gerald Holmes on the spread of cucurbit downy mildew over long distances from southern Florida into more northern States. Another point of discussion was that plant pathologists are too often focussed on the development of the pathogen, but forget to look at the development of the plant. Chris Gilligan demonstrated with his work on soil-borne pathogens that there is a relationship between the amount of available susceptible root tissue and the rate of disease progress. Such relationships are also likely to exist for above ground pathosystems as well. Mike Jeger observed that only a few forecasts are based on information on the perenniation of pathogens, whilst most diseases are initiated by inoculum produced after perenniation. Clearly, this is an element that needs to be incorporated more often into forecasts. Posters presented by H. Ngugi and H. Scherm on pseudosclerotia of Monilinia vaccinii-corymbosi and by T. Gilles and B. Fitt on apothecia of Pyrenopeziza brassicae are examples of recent work addressing the factors affecting perenniation of pathogens. 

Our Brazilian hosts organised an enjoyable social programme for us. This included a barbecue, to the accompaniment of Brazilian music played by a group of our hosts. The half-day excursion enabled us to explore the historic city of Ouro Preto, with its eighteenth century houses, steep hills and cobbled streets. The Baroque church we visited was ornately decorated and reflected the wealth of the area. After walking up the steep hills several times, we were all tired by the end of the excursion! There was also a great peak behind the hotel, which was climbed by many of the participants. The challenge was to find a way across the valley. Once this was found, the top was reached after a fairly steep climb, which meant that quite a few of us had to slide down on their backs to get back to the valley. In the evenings, the participants entertained themselves playing pool billiards 'Brazilian rules', explained by our Brazilian colleague Francisco Vale.

After the workshop, Bruce Fitt visited a former PhD student, Lauriano Figueroa, who comes from Guatemala and is now Regional Manager (Fungicides) for Syngenta for Central and South America, based in São Paulo. There was an excellent view over São Paulo from his 13th floor apartment. We spent some time discussing the strategies for use of fungicides against disease problems on crops in Central and South America. 

There was a high level of enthusiasm during the discussion of possibilities for the next workshop. None of the previous eight workshops has been held in the UK, but there seems to be a strong possibility that the ninth may be held here some time after ICPP 2003 in New Zealand. We are grateful to the BSPP for contributing funds to help to ensure that UK epidemiology was well represented at the Workshop.

Xiangming Xu, HRI, East Malling
Bruce Fitt, IACR, Rothamsted
Gareth Hughes, IERM, University of Edinburgh
Doug Bailey, University of Cambridge
Tijs Gilles, HRI, Wellesbourne