- 28 Junie 2006
- 27 JANUARY 2006
Sclerotinia Working Group
Meeting held on 27 January 2006 at the offices of the Protein Research Foundation, Rivonia
The Chairperson, Mr GJH Scholtemeijer, welcomed everybody present at the meeting. A special word of welcome was extended to Dr T Gulya and Dr G Kong from the USA and Australia respectively.
A special word of welcome was also extended to Dr P Caldwell, Mr J Potgieter and H Van der Westhuizen after the surgery they had undergone since the last meeting.
Dr B Flett and Dr D Fourie were congratulated with the successful past Plant Pathology Congress they organised.
Mr GJH Scholtemeijer PRF Dr J de Kock PRF Mr GJ Pretorius OPOT Mr FAS Potgieter OAC Dr T Gulya USDA Mr W van Wyk PRF Mr E Theron NWK Dr P Caldwell University of KwaZulu-Natal Dr D Oelofse ARC – Roodeplaat Dr B Flett ARC – GCI Prof A McDonald ARC – GCI Prof NW McLaren University of the Free State Ms M Govender Pannar Dr D Fourie ARC-GCI Dr G Kong Department of Primary Industries, Australia Mr J Potgieter Pannar Mr H van der Westhuizen Philagro Mr N Hackland BASF Mr G Keun Secretary
Mr H Kriel Xenocor Bioworx Mr A Van Vuuren NWK Ms M Craven ARC – GCI Prof D Berger University of Pretoria Prof ZA Pretorius University of the Free State Dr G Swart Syngenta Mr J du Plessis PRF Dr R Kloppers Pannar Dr M Griessel PRF
Confirmation of agenda
The agenda was accepted with the addition of the following item:
Item 5.1 Presentation: Dr G Kong – Rust
Feedback on research
With regard to the research done by Philagro, Mr Van der Westhuizen mentioned that:
- Philagro is involved in Sclerotinia research in respect of Sunflower and Soybeans.
- Sumisclex SC is registered as a preventative spray for Sclerotinia on soybeans;
- Preventative spraying is however very costly to the producers and therefore trials were done to register the product as a corrective application as well;
- Emergency registration for the use of Sumisclex SC as a corrective spray on soybeans was granted;
- During the 2005/06 season trials will be conducted at Piet Retief and Koedoeskop;
- A wetting agent will also be included in the trials.
- A trial was started during the previous year to control the disease during the stem stage;
- Benomil registered for seed treatment and Sumisclex SC were included;
- During 2005/06 the trial will be repeated and Sumitoma will be included in the trial.
Mr Van der Westhuizen mentioned that the applications for full registration and also for preliminary registration for the pivot application were submitted seven (7) months ago and feedback was still awaited.
Dr Gulya requested more clarity on the distributorship of products by Philagro, as he was aware of a very promising chemical product that could be used on sunflower seed for controlling mildew, which was currently manufactured by LG Chemical in Korea.
With regard to Sclerotinia on soybeans in the Koedoeskop area, Mr Potgieter enquired if a cautionary should be issued to farmers. Mr Van der Westhuizen offered to phone some of the agents in the area to determine how wide spread it was and report back on the matter.
The Chairperson referred to the radio programme and specifically the news bulletin that could be used to convey such a message to farmers. The Chairperson further mentioned that if a cautionary was warranted, Mr Van der Westhuizen should get in touch with the Protein Research Foundation office to arrange such a message or even a broadcast.
Research: Soybean: ARC-GCI
During the presentation by Prof NW McLaren regarding Sclerotinia stem rot of soybean, he referred to the following:
- The cultivar evaluation that was done;
- The Sclerotinia stem rot severity in 34 cultivars;
- The ranking of the cultivars in 2003/04 and 2004/05;
- The greenhouse trials and specifically the correlation between the greenhouse and field trials;
- The differences in the results of the above and the reasons therefore;
- The interactions with disease potential and regression analysis;
- Fungicides used in the trials.
Prof McLaren mentioned that there was a problem with the inoculation technique and proposed further studies in this regard. He also proposed that the trials be repeated during the 2005/06 season.
Dr De Kock referred to the low rate of infestation, whereupon Prof McLaren mentioned that infestation in the greenhouse was high but it was not reflected in the field trials. Dr Flett mentioned that it seemed as if very specific climatic conditions were required for spores to be released to infect the plants. Prof McLaren mentioned that it was decided to use mycelium for inoculation, which might not be epidemiologically correct.
Dr Gulya inquired if overhead irrigation was used with the field trials, whereupon Prof McLaren mentioned that the field trials were irrigated and regulated during the inoculation phase. Dr Gulya mentioned that according to his knowledge, all the soybean researchers in the United States who were testing soybean cultivars for Sclerotinia resistance were using mycelium even though ascospores will be biologically more correct. He further mentioned that ascospores were very difficult to produce and the process time consuming. Dr Gulya said that whatever used, some type of irrigation system was required to provide wetness at the canopy of the plant. Frequent irrigation for the first two (2) days after inoculation to keep the canopy wet would definitely be advantageous.
The Chairperson enquired whether both mycelium and ascospores could be used for inoculation. Prof McLaren mentioned that at this stage they were comparing it to find the best technique.
The Chairperson said that one of Prof McLaren's worries was the fact that there was no correlation between the greenhouse work and field trials. The Chairperson enquired which of the results seemed to be the most acceptable. Prof McLaren said according to him the environmental changes played a role in the problems experienced.
A copy of the presentation of Prof McLaren will be attached to the minutes.
- That the contents of the presentation of Prof McLaren be noted.
Research: Sunflower: ARC-GCI
With regard to the research on sunflower done by the ARC-GCI, Dr Fourie mentioned that the trials were planted during the middle of December at Potchefstroom, Delmas and Greytown. She also referred to the various treatments used in the research.
The Chairperson enquired whether the chemicals used were different to the chemicals used by Dr Gulya. It was confirmed that there were some differences. It was also mentioned that if there were successes anywhere, such chemicals would be included in the research.
With regard to the reference made to Benomil, Dr Gulya mentioned that it was a very effective fungicide for the control of Sclerotinia, but all registrations had been stopped in the United States of America. He said that currently there was no fungicide registered for use as a spray against any disease in the United States of America, preventative or corrective. New products of BASF and Syngenta were being tested.
With regard to seed treatment, Dr Fourie mentioned that Benomil was registered for sunflower. According to information, PANNAR do treat sunflower seed with Benomil. Dr de Kock mentioned that Syngenta indicated that they were working on Switch as a seed treatment, but the progress was not known.
Dr Gulya said that currently all United States of America sunflower seed planted were treated with three (3) fungicides. He also referred to work being done in Australia and Canada on seed treatments with Benomil to minimize early seedling infection by Sclerotinia. To a question to the researchers regarding the effect of seed treatment on decreasing infection of the stem rot, Dr Griessel replied that it was very little.
- That the research done in respect of Sclerotinia on Sunflower by Dr Fourie, be noted.
- That the research done in respect of Sclerotinia on Sunflower by Dr Fourie, be noted.
Research: Soybeans: University of KwaZulu-Natal
During a presentation by Dr Caldwell she referred to the following:
- The work completed during 2005:
- Illustrated the formation of Sclerotinia by S Sclerotiorum;
- Determined the effect of action of two commercial bio-control agents on S Sclerotiorum (in vitro);
- Determined cultivar reactions to S Sclerotiorum; and
- Determined possible toxicity of various seed treatments against soybean seed germination.
- The proposed work for 2006 entail:
- Epidemiology trial;
- Bio-control in greenhouse;
- Chemical control;
- Seed treatments;
- Cultivar trial.
A copy of the presentation of Dr Caldwell will be attached to the minutes.
- That the contents of the presentation of Dr Caldwell, be noted.
- The work completed during 2005:
Presentation / Comments on Research: Dr T Gulya
During a presentation by Dr T Gulya he referred to the following:
- The areas planted during 2004;
- The sunflower specialists involved at the Sunflower Unit, Fargo, North Dakota;
- The USDA sunflower pathology research areas;
- The fact that research was not done on Sclerotinia only, but on downy mildew, on rust although not a significant problem, etc;
- Information with regard to the incidence of stalk rot and head rot and research done in respect of genetic resistance, fungicides, biological control and cultural control;
- The research was done using wild sunflower species as potential sources of Sclerotinia resistance;
- The research that was done on GMO sunflowers and specifically the transfer of the "ox-ox" gene to sunflower; and
- The funds allocated by Government to the USDA Sclerotinia Initiative. Five commodities were included, i.e. canola, dry beans, pulses, soybeans and sunflowers.
Further explanations were requested on the tillage study that was done as well as the risk assessment and research done on suppressive soils.
A copy of the presentation of Dr Gulya will be attached to the minutes.
- That the contents of the presentation of Dr Gulya, be noted.
Road Ahead – General Discussion
During the discussion of the road ahead, Dr De Kock mentioned that:
- Studies were being done on the pathogen and environment, the reaction of cultivars, chemicals including seed treatment to control the disease and techniques;
- The working group in conjunction with companies endeavoured to get registration of chemicals as quickly as possible;
- The main restriction was that there were not enough researchers;
- It be noted that enough funds was available for the research;
- It was essential to improve the contacts with other researchers in the same field; and
- There was a lack of information regarding the extent of Sclerotinia in South Africa.
The Chairperson said that Dr Fourie confirmed that she was in constant contact with Dr Gulya. He inquired if there was anything further that should be done. Dr Gulya mentioned that it was very important that the government, universities and other institutions must be involved in the matter.
Mr J Potgieter said that he was of the opinion that rust was a more severe problem with sunflower than Sclerotinia, reason being that 60%-70% of the sunflower was traditionally grown in the western part of the country. In the long run the rust will have a more harmful effect on the yields than Sclerotinia at the moment.
Mr J Potgieter further referred to the quality of sunflower and mentioned that 80% of the United States of America, market changed to the higher quality product. In Australia quality was also an issue and that was why their production was stable. He further mentioned that if the sunflower industry in South Africa wanted to survive in the long term, quality must be addressed and that was why funding of the project proposal of the University of the Free State on high oleic sunflower was important.
Mr Pretorius said that listening to the presentation and specifically the opinions on tillage / plough / soil preparation he was uncertain what the best method was to combat Sclerotinia. Dr Gulya referred to Dr Van Wyk's theory of inversion ploughing and mentioned that it was perhaps something that must be investigated further. Prof McDonald said if you had a theory, it must be proven. If proven, it became science and the problem facing world science was that governments were withdrawing from their responsibilities. In the same vein the theory of Dr Van Wyk still needed to be proved.
Presentation: Dr G Kong – Rust
Dr Kong addressed the meeting with regard to rust in Australia and mentioned the following:
- The problems experienced with rust on sunflower and the various races thereof;
- The ability of the pathogen to develop and the fact that ± 100 races were expected in 2006 already;
- The work / research done to develop strategies to prevent the development of the races;
- The reasons why the development of races were so quickly, and the fact a the number of wild sunflower populations could play a role; and
- The fact that rust was the most important disease of sunflower in Australia.
To a question of the Chairperson regarding information on the sunflower crop etc. Dr Kong replied that:
- A lot of work was done on genes and especially to get a resistant gene which could be used in the breeding programme;
- The major oilseeds crop in Australia was canola;
- Sunflower competes against sorghum and due to the yield of sorghum, the price of sunflower must be two to three times of that of sorghum to be competitive;
- Sorghum was mainly used for animal feed;
- Fungicide control was too expensive;
- A lot of work was done by prof ZA Pretorius and Pannar on rust, but it could not yet be determined whether it was the same races as in Australia;
- It be noted that there were groups interested to make use of sunflower as a basis for the production of bio-diesel, but it seemed as if the economic viability might be a problem.
A copy of the abstract of Dr Kong's presentation at the Plant Pathology Congress will be attached to the minutes.
As there were no further matters for discussion, the Chairperson adjourned the meeting at 13:30.