BSPP News 30 Spring 1997 - Online Edition

The Newsletter of the British Society for Plant Pathology
Number 30, Spring 1997

On Their Travels

A visit to St Lucia, West Indies
Windward Island Banana Development and Exporting Company

With the free weeks in summer 1996 between graduation and starting a Ph.D.,I went to St Lucia to get some practical experience. I was met by Dr UlrikeKrauss at St Lucia's Hewanorra International Airport after an uneventful flightfrom London. The drive from the airport to the guest house, my home for the nextnine weeks took us virtually the length of the island. It was immediatelyevident that St Lucia was lacking in flat land but definitely not in rain. Infact the island receives between 1500 and 3000 mm of rain per year depending onrelief, not the 30,000 mm I saw stated on a sign in the rain forest. St Lucia isa tropical island paradise with rain forest covering the mountainous interiorand agriculture covering the more accessible tracts of land. Bananas are themajor agriculture product and are produced mainly on small holdings.

On the first full day on the island I spent reading up on banana crown rotdisease, the most important of the post-harvest diseases. The following day Igot to see the research station I had heard much about. This is the secondlaboratory Dr Krauss has had since coming to St Lucia three years ago. The firstlab was washed out to sea during a tropical storm a couple of years ago; verylittle was recovered. Her present lab lacks an adequate electricity supply,which is a little frustrating as the lab is fitted with an air conditioning unitbut the current is insufficient to run it. Consequently all sterile work wasdone first thing in the morning, before the fan was turned on and started todistribute spores and dust.

The work I got involved in was the screening of mycoparasites using abioassay. This involved the production of hundreds of banana skin discs andinoculating with different combinations of pathogen and presumptive mycoparasitespores. After a few days the quantity of necrosis was assayed to determine thecontrol offered by the mycoparasite. Some time was spent on looking at themechanism of mycoparasitism microscopically. After cutting numerous samples forexamination I was informed that I would make a good substitute for a microtone.A few field trials were undertaken while I was there. This generally meant mesitting cross-legged on the floor with several boxes of exceptionally rottenbananas and measuring the rot.

On a couple of harvest days we went out into the field. Banana production inSt Lucia is markedly different to that of the central American dollar bananaproducers. There are 23,000 banana farmers on this island, which isapproximately equal in size to the Isle of Wight. Some farmers have as little ashalf a acre. With farmers scattered over this mountainous isle and theinfrastructure mediocre, the level of extension is low. This results in avariety of practices. In terms of crown-rot control the wrong fungicide isfrequently used, and if the recommended one is used then the concentration isoften questionable. Being out on extension exposes the difficult situation thefarmer faces. A common reason for the wrong fungicide usage turned out to be thecorrect fungicide was not available. The greatest problem with crown- rot isthat the farmer never sees it. Crown-rot, being a post-harvest disease, is notseen in the field, so a mental picture of it does not exist. Because it is notseen, it can easily be acquired and cost cutting practices can develop.

The island has more than just bananas and I did try and see more of theisland, including the ?drive through volcano' which you can no longer drivethrough. An amusing time was being involved in a parrot survey. The St Lucianparrot is indigenous to the island and a survey of them was scheduled while Iwas there. We got early one morning to reach a good vantage point looking overthe rain forest. This was all well before the 6 am sunrise. During dawn and duskthe parrots are most active. However, it rained during the whole survey period,we got drenched and the parrots stayed in bed: not a single one was spotted! Isuppose being in a rain forest in the hurricane season, this was to be expected.

By spending nine weeks working with a specific disease I feel I have gainedmuch. Things taught at college could at last be put into practice. While there Isaw, in part, the specific problems facing a small island state with dependenceon a single crop. In short I thank BSPP for partly financing this trip, whichhas aided in my training as a phytopa thologist.

Paul Matthews

Fusarium head scab: Global status and future prospects

Paul Nicholson and David Parry were fortunate to be invited to a trulyinternational gathering of researchers interested in Fusarium earblight, or head scab, at CIMMYT in Mexico City from 13-18 October 1996.

After the longest flight either of us had ever endured, we were whiskedthrough to sprawling suburbs of Mexico City to the oasis of CIMMYT. What ismore, we had to suffer the indignity of staying in a palatial Spanish- stylemansion with its own swimming pool and tennis courts. Of course we were much toobusy to take advantage of such extrava gances.

The primary reason for our meeting was the apparent increase in Fusariumear blight in many cereal growing areas of the world. There were 22 inviteddelegates from 17 countries together with another dozen or so resident CIMMYTpersonnel and we were trying to exchange ideas and build up a global picture ofthe significance of the disease and improve our methods of control.

Most delegates were associated in some way with breeding for resistance,although there were several mycotoxin experts and a few presentations concerningfungicides. We were obviously deemed to be an important group as theintroductions included a statement by the director of CIMMYT, Prof. T.G. Reevesand the Austrian Ambassador, Dr Kurt Henkel. Why the Austrian Ambassa dor youmay well ask. The original concept for the meeting was developed by Prof PeterRuckenbauer who is the Director of the Institute of Crop Production & PlantBreeding at the University of Vienna, and he and his colleagues, together withDr Jesse Dubin and Lucy Gilchrist at CIMMYT, were responsible for organising themeeting. At all times Jesse, Lucy and the rest of the well oiled CIMMYT machineensured the smooth running of the meeting and attended to the various needs ofthe participants.

Resistance breeding & mycotoxins

The first morning consisted of a series of presentations by Ruth Dill-Macky(University of Minnesota), Lucy Gilchrist (CIMMYT, Mexico City), Martha Diaz(INIA, Uruguay), and Maria Theresa Galich (INTA, Argentina) as an overview ofspecific breeding pro grammes in contrasting locations. We then moved on to thefirst talk on the importance of mycotoxins by Anne Desjardins who reported somevery interesting research on mutants of Fusarium species which lackedthe gene responsible for mycotoxin synthesis. Bob Bowden from Kansas StateUniversity followed on with sexuality and diversity in Gibberella zeaeand Paul finished this session with some of his work on the development andapplication of quantitative PCR to Fusarium ear blight.

The next, large session was on screening and breeding progammes in a rangeof countries. Jeannie Gilbert (Canada), Hermann Buerstmayr (Austria), Peidu Chen(China), Jackie Rudd (South Dakota), Tomohiro Ban (Japan), Akos Mesterhazy(Hungary), Ravi Singh (Mexico), Irina Ablova (Russia), and Radshey Pandeya(Canada) all related their progress in searching for resistance sources andtrying to achieve the most appropriate techniques for inoculation. I was quitesurprised about the degree of consistency in both these areas. Frontana andSumai 3 kept coming up as the most promising, and best studied sources ofresistance to the disease.

Much debate centred around disease screening methods but the consensus wasthat spray inoculation of conidia at anthesis and point inoculation of spikeletsat a similar growth stage were the best methods to assess resistance to initialinfection and colonisation (Type 1 and Type 2 resistance respectively). ElenaKlechkovskaya from the Ukraine then presented a paper on control and this wasfollowed by a review of the signifiance and control of the disease by David.

The following day we were up early and onto a coach bound for the CIMMYTfield station at Toluca, a mere 2800m above sea level and famous as the sourceof the A2 mating type of Phytophthora infestans. After a quiet tripthrough Mexico City during rush hour (they are such careful and courteousdrivers) we arrived at the relatively cool but sunny field station and wereshown the nurseries for wheat breeding. This was followed by lunch consisting ofhuge barbequed cow sides washed down with beer. An enjoyable field trip if everthere was one!

International collaboration

The next day, after hearing more about mycotoxins from Akos Mesterhazy(Hungary) and Maya Pinero (Uruguay) were were asked to assemble in the boardroom and sit in countries, a bit like the United Nations, to draw up acollaborative research proposal (fight over funds). This actually turned out tobe a good natured affair and we did indeed get some reasonable ideas downrelating to our priorities. for funding. The main emphasis was the need to findand incorporate sources of resistance to the disease in well adapted wheatcultivars, but we also recognised the need to integrate resistance varieties ina strategy for control which included fungicides where these were available. Theproposal will be put to CIMMYT for funding by donor governments.

I think we both learned a lot from this meeting, particularly relating tothe interna tional significance of the disease. Time after time speakers wouldstart their talks with some sort of significance statements. For example theCanadian delegate started his paper by stating that in their region this yearthey had just lost $1 billion as the result of yield losses and mycotoxincontamination of wheat. I also think we realised how fortunate we were workingin the UK despite our research funding problems. The Ukrainian delegate had notbeen paid for 6 months and she was not sure whether she would have a job at allupon her return.

Both of us had some time after the meeting for a little sight seeing andwere astonished at the geographical and cultural diversity which exists inMexico. Seeing ethnic Indians worshipping the sun on top of the 3000 old sunpyramid on a Sunday morning was a mild contrast to morning prayer in our localAnglican church (David).

We would like to thank the organisers and all those involved in the meetingfor their invitation to attend and their hospitality. We would also like tothank the British Society for Plant Pathology most sincerely for theircontribution towards the cost of this trip.

David Parry

Harper Adams Agricultural College, Newport, Shropshire

Paul Nicholson

John Innes Centre, Norwich