Working Party on Poplar and Willow Diseases

Stem breakage at Hypoxylon canker
(Photo: FAO)

Septoria, leaf spot on poplar
(Photo: FAO)


Officers of the Working Party are:

Report from 47th Session of Executive Committee  

Report from 23rd Session

 The role of the working Party

FAO-IPC is the only scientific Committee that is not only concentrating on fundamental research of poplar and willow, but also on the practical aspect of poplar culture. This is very important because poplar and willow plantations are becoming more and more important again all over the world, mainly because of the use of the wood for bio-energy. At the same time, change of climatic conditions might have a great influence on the spread and appearance of poplar and willow diseases in the near future. In addition, international transfer of plant material (cuttings, sets) will enhance the (unwanted) spread of pathogens. Because of intensive use of poplar and willow in bioenergy plantations, more and more research will be needed on diseases. Therefore, we believe that international collaboration in the field of poplar and willow diseases will be needed more than ever, and there will be important with a Working Party with a strong profile on diseases to reach and attract the right stakeholders.

Discussion has been initiated on merging or cooperation between the WP for Diseases and the WP for Insects and Pests and both WP’s agree that we should continue to have separate WP’s, at least for the coming 4 years. The close relations between the topics, however, would benefit from closer cooperation when it comes to exchange of information concerning ongoing projects and active researchers. We also agreed on planning for a joint meeting within two years.

Activity Report for 2004-2008

The activity within the WP has been low during the period, mainly because of low number of people attached. For the Executives it has been a period of reorganization and preoccupation in the business of own departments and research projects. With a new situation to be expected during next year the activities of the WP have all opportunities to develop and be revitalized.

The most notable and successful activity is the close cooperation of the WP for Diseases with the WP Environmental Applications and Production systems (output H). We have agreed to try to have joint meetings or to attend each others WP workshops.  

A joint meeting was arranged in Sweden and Estonia with WP Environmental Applications, Production Systems and Diseases in May 2005 with participants from both WP.

Participants from WP Diseases also took part in the Environmental Applications Working Party meeting in Belfast, 2006 and in Montreal, June 2007, with oral presentations.

Programme for future work 2009-2012

Specific objects during the first two years

Webpage - contacts

During the last year, the Research Institute for Nature and Forest - DGBS in Geraardsbergen, Belgium, has been approached by several private companies all over Europe to get more information and also plant material from our newly selected poplar cultivars. We believe, more and more information will be needed by the poplar industry in the near future. IPC is the best organisation for distributing both scientific and practical information on poplars and willows, including diseases. For this, the webpage for the WP must be updated and made user-friendly and easy to access – to be a portal for information and news concerning diseases. The information includes listing of active researchers in the field, an updated list of publications and ongoing projects.

Meetings - workshops

In the frame of a EU project Treebreedex, in September 2009, the Research Institute for Nature and Forest has also organised a workshop on screening and selection methods within forest tree breeding programmes. One of the topics has been development and demonstration of screening methods for disease resistance. We investigated the possibilities to hold a WP meeting at the same time, in order to give the WP participants the possibility to join the Treebreedex workshop in this important matter.  

The next Executive Committee meeting will be held 2010, in September, when IPS will organize a meeting in Orvieto, Italy. This will be an excellent opportunity for the WP for Diseases to organize a WP workshop in close proximity to get better contact with IPS participants and attract new members. The matter has also been discussed with WP for Pest and Insects to jointly plan this workshop.  

Collaboration activities

Ideas are initiated on a new international collaboration project on Melampsora rust, based on observation of a network of poplar and willow field trials with a well-defined selection of genotypes, spread all over Europe. Contacts have already been taken between the Research Institute for Nature and Forest in Belgium and several East-European countries that might be interested in participation.

Plans in short for the coming four years 

1.   Meeting for the WP during August 2010, possibly together with WP Insects and/or WP6 in  connection with the IPS meeting. Planning during 2009 for a first call before summer.

2.   Meeting /workshop in the frame of the EU-project Treebreedex in September 2009 in Belgium, on development of screening methods for disease resistance. 

3.   Update the membership list of active researchers on Poplar and Willow diseases and add to the Directory of Poplar and Willow Specialists and the IPC website. To be executed before July 2009.

4.   Routinely post an annotated bibliography of Poplar and Willow disease publications and upload these to the IPC website. A first version of publications during the last 4 years to be uploaded before July 2009.

5.   Prepare a database of Poplar and Willow disease projects and their relevant web links.

After p.3-4 are executed a questionnaire can be sent out to all researchers addressed by the topic, asking for ongoing projects in different countries; to be uploaded on the web page. They will also be asked to visit the IPC-WP website for possible additions or changes of the listings in p. 3-4.

6.   Take initiatives to coordinate a common international collaboration project on Melampsora rust. Questionnaire for interest sent out early 2009.

7.   Coordinate the chapter on diseases of the Poplar and Willow book to be finished before March 2009.

8.   Prepare a NEWSROOM, during 2009, with short notes on Poplar and Willow diseases and encourage contributors to add new information and ideas. An informal forum for fast information.


9.   Create a new network such as Forpath to be accessible through the IPC website.

10. Establish a chat room to consult pathologists on identification and discuss issues related to diseases. Requires people with competence in specific topics that agree to follow this, or somebody responsible for the chat room that will forward the tasks to the person of choice.

Both p.9 and p.10 are ideas partly overlapping each other and p.8.  Further discussion is required to find what to give priority and what the needs are.

11. Strengthen linkages with other Working Parties: Common meetings with WP6, cooperation with WP insects and Pests, meetings in connection to IPS and IUFRO sessions.


Report from 22nd Session

During the 22nd Session of the IPC, the Working Party held one technical meeting during which four scientific/technical papers were presented and discussed and several posters of Poplar and Willow disease threats and impacts were displayed and discussed in the poster sessions.

The Working Party aimed to act as a focal point for those seeking information on identifying and managing pathogens on Poplars and Willows. The focus was to disseminate information on diseases and networking with researchers and other users on their management. Specifically close linkages with breeders would be necessary on new pathogens to prepare selection strategies to be adopted in their breeding programmes. Additionally, the Working Party would provide guidance for the import/export of plant genetic material and quarantine.

Achievements from 2000-2004 included:

  • A survey of Poplar and Willow diseases was conducted through pathologists, breeders and users; the most important diseases and host species were reported for the period 2000-2004 and projected for the period 2004-2008;
  • The list of active researchers working on Poplar and Willow diseases was updated.

The results of a SWOT analysis of the current situation included:

  • Pathologists: a strongly recognized group; and
  • Strong knowledge base.
  • Low member activity;
  • Insufficient networking, particularly in the Southern Hemisphere;
  • Small number of Poplar and Willow pathologists; and
  • Low profile of the Working Party.
  • Collaboration with IUFRO Division 7 - Rusts of Forest Trees; and
  • Use of list servers to increase the profile of the Working Party.
  • Reduced funding and fewer pathologists working on Poplar and Willow diseases; and
  • Declining participation in NPCs in North America.
Lesson LearnedThe Way Forward
  • The Working Party and IPC Profiles are not sufficiently apparent; and
  • There are advantages of being proactive rather than reactive - prevention through preparedness and prediction.
  • Merging of Working Parties on insects and diseases to form a ¿Protection¿ Working Party;
  • Closer collaboration with other Working Parties in more ¿holistic¿ approaches to management;
  • Better use of list servers (e.g. Forent and Forpath) and web links to raise the profile of IPC; and
  • Posting of recent publications and, annotated bibliographies of the IPC website.

The agreed programme of work 2005-2008 included:
  • Update the membership list of active researchers on Poplar and Willow diseases and add to the Directory of Poplar and Willow Specialists and the IPC website;
  • Prepare a database of Poplar and Willow disease projects and their relevant web links;
  • Create a new network such as Forpath to be accessible through the IPC website;
  • Routinely post an annotated bibliography of Poplar and Willow disease publications and upload these to the IPC website;
  • Establish a chat room to consult pathologists on identification and discuss issues related to diseases;
  • Prepare a summary report of the survey of Poplar and Willow diseases and encourage contributors to add more complete information;
  • Coordinate the chapter on diseases of the Poplar and Willow book; and
  • Strengthen linkages with other Working Parties.

The Working Party on Poplar and Willow Diseases made the following recommendations:

  • Encourage Governments and National Poplar Commissions to recognize that, to manage Poplars and Willows in a more sustainable manner, it will be necessary to allocate more funds and resources to research disease population dynamics and interactions with host species;
  • Raise Government, National Poplar Commissions and other stakeholder awareness about the importance of issues related to import/export of plant genetic materials and quarantine; and
  • Inform Governments and National Poplar Commissions about the increasing requirements for research on disease problems caused by plant-associated bacteria in correlation with specific environmental conditions. 

Reports from prior Sessions

This working party has met regularly since its first meeting in Paris in April 1957, with attendance mainly by pathologists. Each meeting has served to exchange information about the health conditions of poplar and willow plantations in the member countries and about the work done and the results of research. An overview paper describing the activities of the working party since its formation was presented by the chairperson in 1992.

Marsonnina brunnea on poplar leaf (Photo: E.N.C.C.)At each meeting, a subject is proposed to the participants so that discussion can quickly concentrate on a common field. Joint research programmes have been agreed between pathology laboratories where mention may be made of international arrangements for studying the susceptibility of cultivars to Marssonina brunnea and a research programme on sensitivity to Xanthomonas populi.

In carrying out these programmes, pathologists have helped one another, exchanging information, techniques and sometimes their material. They have received visiting researchers who can then familiarize themselves with the methods applied. In this way knowledge of poplar and willow diseases has made rapid strides towards their control.

Apart from summary reports of the meetings, with the texts of the communications presented in an annex providing a wealth of documentation, the working party in 1981 completed a synthesis which was published under the title Les maladies du peuplier (Poplar diseases) by the National Forestry Fund set up in 1946 by France.

The leaf diseases, for example, Marssonina brunnea and, in particular, the rust diseases Melampsora spp. have been a major cause of loss of vigour in poplar plantations in many countries. Because of the high variability of the diseases, work has initially concentrated on their taxonomy. The sensitivity of 78 clones of European origin to Marssonina brunnea has been tested in France. As there was a certain divergence among the findings obtained in a number of countries, the working party has been endeavouring to find satisfactory explanations through international cooperation.

The bark parasite Dothichiza populea, which is also highly variable, has caused increasing concern to affected countries.

The gravity of risk from virus diseases was recently highlighted by the working party. Though damage attributed to air pollution may be caused primarily by physiological stress, a suggestion was made at one of the last meetings of the working party that it should become involved with this topic.

The working party has repeatedly drawn attention to the existence of physiological races of Melampsora larici-populina and M. allii-populina and to the rapid evolution of populations of these races. Although it was acknowledged that progress has been made in understanding the reaction of clones and species of poplar to the diseases, it has been stressed that more attention should be paid to the selection of clones for resistance to both pathogens. A strategy has been described for the breeding of white poplar, involving the selection of families and provenances for tolerance to frost and drought.

Two joint projects were prepared in 1994 with the Working Party on Poplar and Willow Insect Pests. The first aimed to acquire systematic knowledge on the natural resistance mechanisms of poplars and willows towards insects and diseases. The second looked for possible correlations between tree susceptibility and soil characteristics or other ecological factors, in order to determine the risk of damage by insects or diseases to a particular poplar or willow for a given site.

The following recommendations were made in 1996 for future activities:

  • the preparation of a world map of the principal diseases of poplars;
  • the extension of existing collaboration with the European Union in the evaluation of the reaction of existing clones of poplars to the main diseases to other countries and continents and harmonizing the results to make them comparable;
  • the preparation of a detailed study of the diversity of two pathogens Marssonina brunnea and Discoporium populeum.

Once again potential problems arising from the transfer of diseases from one continent to another were identified as being of high importance.

In 1999, a global Review of Fungal Diseases in Poplar was prepared by G. Cellerino.

At its formal meeting during the twenty-first session of IPC the following activities were agreed for the period 2000-2004:

  • Updating the membership list of active researchers in the pathology and entomology of Populus and Salix. It would be maintained on IPC web site and in the IPC Directory of Poplar and Willow Researchers. Researchers in this area will be asked to submit not only their contact information, but also a list of their current projects, and relevant links.
  • The working party will attempt to meet in conjunction with the IUFRO rust group between IPC meetings.
  • Active researchers will be asked to contribute to IPC web pages on 'Methods in the Pathology and Entomology of the Salicaceae' and ' WP News'.
  • Subject areas for focus and discussion at the next IPC meeting should continue to be considered. The following suggestions were made:
    (a) continuation of reports and discussions of microevolution of poplar and willow rust fungi and practical attempts to combat these developments;
    (b) active reconsideration of the common perception that species of Cytospora and Discosporium are always secondary pathogens;
    (c) discussion on the risk of spread of exotic pathogens of the Salicaceae;
    (d) development of early-screening methods for under-researched pathogens such as Discosporium.

Members submitted the following recommendations to the plenary session of the twenty-first session, which were adopted:

  • The IPC should encourage member nations to increase funding for research and training of new scientists. The establishment of international fellowships and scholarships would be particularly beneficial.
  • Detailed studies of worldwide pathogen populations, pathogen variation and host range were needed (see the reference to the global study of diseases of poplars, above). To this end, living collections of insects and pathogens of the Salicaceae were required, and since establishment and maintenance of such collections are expensive, possibly funded by the IPC.
  • The IPC should make available on its Web site, the proceedings of IPC meetings and full-text versions of archived, published material that is currently unavailable electronically.





last updated:  Monday, August 24, 2015