Downy Mildew («Plasmapara halstedii») : Importance and Geographical Distribution on Sunflower in Morocco

Allal Douira, Aziz Achbani, Denis Tourvieille, Mohamed Bahsine, Mohamed Najeb Serrhini, Naïma Laamaraf
2007 Phytopathologia Mediterranea  
Downy mildew, caused by Plasmopara halstedii (Farl.) Berl. and de Toni, is a very serious disease of sunflower. Studies on the evolution of sunflower downy mildew conducted in 1996 and in 1997 showed that this disease was spreading to new sunflower-growing areas. In 1996, among 146 fields inspected, 77 (53%) were found to be infested with downy mildew. The Gharb region had the highest proportion of fields affected (60%), followed by Saïs (50%) and Loukous (41%). In 1997, 33% of the fields
more » ... ed were infested. Again, the Gharb was the most frequently infected region with 39%, followed by Saïs (32%) and Loukous (17%), the last a region where downy mildew affects fewer fields. The incidence of mildew in sunflower plants in most of the regions averaged about 3% in 1996, and exceeded the values for 1997, when it was 5%. The disease is most often randomly distributed in the field. The surveys conducted with a sample of a hundred farmers showed that the lack of rotation and the utilisation of chemically untreated seeds of sensitive varieties favoured the disease.
doi:10.14601/phytopathol_mediterr-1568 doaj:25a27ebfabf141dfa08e3d48bfb678ae fatcat:rsbjo62aafaznbiwjmfjemw6ra