Rosemary wilting disease and its management by soil solarization technique in Iran
Wilting disease on Rosemary (Rosmarinus officinalis), an ornamental-medical plant, was studied from 2007 - 2009 in Mashhad, north-east Iran. Different Rosemary fields in this area were visited and root samples of the infected plants and soil around the roots were collected and transferred to laboratory. Samples were cultured on CMA, PDA and WA media and isolated fungi were identified. Three fungal pathogens including Phytophthora citrophthora, Rhizoctonia solani and Fusarium oxysporum were determined, whereas Helicotylenchus spp. was also associated. Pathogenicity tests proved that they were wilting pathogens, although P. citrophthora was the major pathogen in the field and glasshouses. This is the first report on Rosemary disease in the country. The disease caused losses from 30 – 60% in the fields where the suitable conditions allowed the disease to build up. Soil solarization technique was carried out to control pathogens before planting of seedlings. Application of this method reduced population density of P. citrophthora and F. oxysporum from 1300 - 1800 cfu –g/soil to 500 - 700 after 4 weeks and then 200 - 300 cfu (colony forming propagules) after 6 weeks. Solarization is a simple, economic and effective technique in managing Rosemary wilting disease before plant planting in new established orchards.
Key words: Rosemary, Phytophthora citophthora, wilting, Iran.