European case study on seed treatments and seed-borne disease control using seed treatments
by Bill Clark* and Valerie Cockerill**
* Broom’s Barn Research Centre, Higham, Bury St Edmunds, Suffolk IP28 6NP
** Official Seed Testing Station for Scotland, SASA, Roddinglaw Road, Edinburgh EH12 9FJ
This is the final report of an 8 month project (RD-2008-3461) which started in July 2008. The work was funded by ENDURE (through the EU Framework 6) and a contract for £15,366 from HGCA.
Seed-borne diseases are important problems in many crops in European agriculture. In cereals, serious diseases like bunt (Tilletia tritici), loose smut (Ustilago nuda), net blotch (Pyrenophora teres) and leaf stripe (Pyrenophora graminea) occur regularly but are kept at a relatively low level because of systematic and intensive use of seed treatments. In conventional agricultural systems, seed-borne diseases could develop as serious problems if programmes with reduced pesticide inputs are initiated because of EU legislation. In organic farming, bunt (Tilletia tritici), for example, could be a major problem in the production of seeds. Due to the reliance on effective chemical methods, few developments have been made in the non-chemical area of seed-borne disease control. Research into alternative non-chemical seed treatments for use in organic systems has indicated a range of possible approaches, but to date most of these do not give sufficiently high levels of control to offer credible alternatives to existing chemical control methods. In some countries the use of resistant varieties is an important factor in an integrated strategy to control seed-borne diseases. There are resistance genes available but often we do not know their occurrence in modern varieties. It is clear from the data presented here that there is considerable variation amongst the countries surveyed of the perceived threats posed by individual seed-borne diseases. Perhaps as a consequence, there is also a wide range of thresholds that are applied in order to control the diseases. Some of this variation may be explicable in that there will be considerable variation in the amount of spring and winter cropping in these countries and this will affect the occurrence and severity of some seed-borne diseases. Some of the variation in thresholds and perceived threat from seed-borne diseases is related to climatic conditions. In most countries there is little interpretation of thresholds, i.e. they are applied strictly. In the UK there is more of a tendency for advisers to use the advisory thresholds but adapt them depending on individual farm circumstances. Why this is the case is not obvious, but is perhaps linked to the predominance of independent crop advisers in the UK, whereas in most EU countries there are state or government advisers who may apply thresholds more strictly. The use of farm-saved seed is common in many countries with typically 40-50% of crops grown from non-certified seed. It is clear that there is no agreement on European standardisation of thresholds or in the approaches to the use of seed treatments. This is in contrast to the high degree of standardisation of seed testing methodologies that are employed in EU countries. This has been achieved via the International Seed Testing Association (ISTA) which has a clear role in seed testing procedures. ISTA has developed and published standard procedures in the field of seed testing and has member laboratories in over 70 countries. It produces internationally agreed rules for seed sampling and testing, accrediting laboratories, promoting research, and providing international seed analysis certificates, training and dissemination of knowledge in seed science and technology to facilitate seed-trading nationally and internationally. It is possible that in the future it could have an influence in the area of seed treatment thresholds.
More news from: HGCA (Home-Grown Cereals Authority)
Published: December 22, 2011