Document generated on 09/26/2021 6:27 p.m. Phytoprotection Fusarium head blight : a re-emerging disease T.C. Paulitz Volume 80, Number 2, 1999 URI: https://id.erudit.org/iderudit/706188ar DOI: https://doi.org/10.7202/706188ar See table of contents Publisher(s) Société de protection des plantes du Québec (SPPQ)l ISSN 0031-9511 (print) 1710-1603 (digital) Explore this journal Cite this article Paulitz, T. (1999). Fusarium head blight : a re-emerging disease. Phytoprotection, 80(2), 127–133. https://doi.org/10.7202/706188ar La société de protection des plantes du Québec, 1999 This document is protected by copyright law. Use of the services of Érudit (including reproduction) is subject to its terms and conditions, which can be viewed online. https://apropos.erudit.org/en/users/policy-on-use/ This article is disseminated and preserved by Érudit. Érudit is a non-profit inter-university consortium of the Université de Montréal, Université Laval, and the Université du Québec à Montréal. Its mission is to promote and disseminate research. https://www.erudit.org/en/ Colloque / Colloquium - Saint-Jean-sur-Richelieu (Québec), Canada 9 juin / 9 June 1999 Nouveaux problèmes de phytoprotection au Québec / New plant protection problems in Québec Fusarium head blight: a re-emerging disease Timothy C. Paulitz Dept. of Plant Science, McGill University, 21111 Lakeshore, Ste. Anne de Bellevue, Québec, Canada H9X 3V9 PHYTOPROTECTION 80: 127-133 Fusarium head blight (scab) of wheat is to the spikelets, glumes, and rachis of endémie in Eastern Canada and is con- the head. Two to three weeks after sidered to be one of the most important anthesis, the first symptoms appear. disease on this crop, in terms of the Infected spikelets turn brown and sporo- potential losses and harm to consum- dochia form on the glumes. Thèse ers. The disease is caused by Fusarium orange-pink colored sporodochia con- graminearum Schwabe [teleomorph = tain masses of three to seven septate Gibberella zeae (Schwein.) Petch]. The macroconidia of F. graminearum, and same pathogen also attacks other small may cause infection on secondary tillers grains such as oats and barley; and that flower later. However, the disease causes an ear rot of maize. The epide- is considered to be monocyclic, since miology of this disease hâve been re- the secondary inoculum is formed when viewed bySutton (1982) and Parry étal. the susceptibility of the host is low, and (1995). This pathogen survives over there is little plant to plant spread from the winter on wheat and maize débris. this inoculum. At harvest, seeds infect­ The following spring, purple-black per- ed at anthesis are small, whitish col­ ithecia are formed. Thèse are the fruit- ored, and wrinkled. Other seeds can ing bodies of the sexual stage of the also be infected, although they hâve a fungus, Gibberella zeae. Asci and 4- normal appearance. The infected de- celled ascospores are formed and forc- bris is often left on the ground over the ibly ejected around the time of anthesis winter, especially in no-till or reduced of the wheat crop. In Québec, anthesis tillage situations. Perithecia can also of spring wheat occurs in late June to form in the fall, although it is unclear early July and this is when the wheat is what rôle they play in the epidemiology most susceptible to this pathogen. of the disease the following spring. G. Ascospores are considered to be the zeae is homothallic, meaning it can form most important primary inoculum of this the sexual stage by selfing. PCR-RAPD disease in eastern North America. Thèse markers and vegetable compatibility ascopores are deposited on the heads group studies show a large amount of of wheat, germinate, and infect into the genetic diversity among strains (Dusa- developing seed. Compounds in the benyagasani et al. 1999; Bowden and anthers such as choline and betaine are Leslie 1992). Perithecia are readily thought to stimulate the germination of formed in culture and in the field in the spores (Strange et al. 1978). After areas with adéquate summer rainfall, infection, the fungus continues to spread such as eastern Canada. The pathogen Note du rédacteur : le texte ci-dessus est présenté tel que soumis/Editor's note : the above text is presented as submitted. 127 has also been divided into two ecotypes, 10 years, bemg replaced by corn and Group I and II. Group I is found in arid soybeans. In the main wheat growing areas such as Australia and Eastern areas of the mid continent, Fusarium Washington and primarily causes root, head blight was considered to be a seedling, and stalk rots. It does not minor problem, surpassed by foliar form the sexual stage in culture or in diseases such as rust and Septoria. But nature, and thus does not attack the in 1993, an épidémie swept through head. Group I has recently been reclas- thèse areas and has continued for the sified as a new species F. pseudo- last 6 years. This disease has caused graminearum, based on molecular év­ over three billion dollars US in losses idence and subtle différences in the and is considered to be the most costly septatron of the macroconidia (Aoki and plant disease épidémie of the last half O'Donnell 1999). of the 20th century. This subject has been reviewed by Bai and Shaner (1994) Why is this disease so important? and McMullen et al. (1997). The impact Because the fungus produces mycotox- of this disease, along with the low grain ins in the grain which can harm animais priées of the last 2 years, has lead to and humans. The two most important numerousforeclosuresof farms in Min­ are deoxynivalenol (DON, vomitoxin) nesota, North Dakota, Manitoba and and zearalenone. A number of other Saskatchewan. There is also concern trichothecenescan also beformed. This that the disease is moving to dryer areas subject is reviewed in a book by Miller of Alberta and Saskatchewan, where it andTrenholm (1994). DON causes feed- has not been previously a problem ing refusai in animais, especially non- (Gilbert 1998). ruminant swine. Zearalenone is an estrogen-like compound that causes Why has the disease re-emerged as reproductive disorders in swine. At the a problem in thèse areas? One reason présent time, the maximum allowable is the increased summer précipitation limit of DON in grain in Canada is 1 that thèse areas hâve received since ppm for human consumption, 2 ppm 1993. Some areas hâve received dou­ for animal consumption. Levels in the ble their normal summer rainfall. Like grain are heavily monitored by eleva- most diseases, free water or moisture tors, millers, and government agencies is needed for infection. Secondly, the both in Canada and the United States. prevalence of no-till and low-till agri­ culture over the last 15-20 years has Why is this called a re-emerging dis­ increased the inoculum load of the fun­ ease? It is already endémie on wheat gus. The adoption of this technology and corn in eastern Canada, because of has been widespread, and has several the high probability of rain during the intrinsic benefits, such as réduction in susceptible period of anthesis. For soil érosion and reduced energy and example, in 1996, 85% of the winter labor costs. However, since much of wheat crop of southern Ontario was the residue is left on the surface, the destroyed by the disease, resulting in inoculum can overwinter. Many stud- losses of over $100 million (Schaafsma ies hâve shown a réduction in survival et al. 1998) During anthesis, rain show- of the pathogen if the residue is buried ers came in off of Lake Ontario and set (Khonga and Sutton 1988; Teich and the stage for the épidémie. Obviously, Hamilton 1985). However a return to there was adéquate inoculum présent, the moldboard plow is unlikely. There even though the growers practiced strip may hâve also been a loss of genetic rotation with soybeans and corn. A résistance in modem cultivars, since major épidémie on maize also occurred they were not selected against this dis­ in 1990 (Charmley et al. 1994). Howev- ease. At the présent time, cultivars are er, Québec and eastern Ontario are moderately to highly susceptible. Fi- minor producers of wheat, compared nally, there has been some spéculation to the upper Midwest of the US and that the disease has increased because prairie provinces. Most of the wheat in of the movement of corn production Québec is grown for animal feed and westward into new areas previously production has declined over the last cropped with wheat. This pathogen 128 PAULITZ : FUSARIUM HEAD BLIGHT attacks both corn and wheat, so this likely to be widely practiced because of may lead to a buildup of inoculum. the energy costs, dégradation of soil structure and érosion. In addition, if inoculum can travel a iDng distance, as MANAGEMENT suggested by Francl et al. (1999) who trapped spores at sites remote from STRATEGIES fields, then tillage may not hâve a sig­ nifiant effect. Crop rotation is another How can this devastating disease be cultural practice that could reduce dis­ managed or controlled? There are a ease. The recommendation is not to number of différent stratégies, howev- plant wheat where the previous crop er as consistent with the principles of wascorn or wheat (Martin and Johnston integrated pest management (IPM), 1982), since wheat following corn has none alone will be sufficient to provide higher levels of disease (Teich and a consistent and stable réduction of this Nelson 1984), and soybean-corn rota­ disease. tion gave less disease than corn-corn (Lipps and Deep 1991). Résistant cultîvars In the long term, this is the most eco- Chemical control nomically and environmentallyfeasible Chemical control is another option, but method of managing this disease.