Integrated management of downy mildew of basil. (November 2020)

• Record Type: Journal Article
• Authors: Gilardi, Giovanna; Garibaldi, Angelo; Gullino, Maria Lodovica
• Is Part Of: Crop protection. Volume 137(2020)
• Publication Date: 2020-11
• Subjects: Ocimum basilicum -- Peronospora belbahrii -- Non –chemical products -- Fungicides -- Cultural practices; Plants, Protection of -- Periodicals; 632.05
• DOI: 10.1016/j.cropro.2020.105202
• Languages: English
• ISSNs: 0261-2194

Abstract

Abstract: The downy mildew of basil, which is caused by Peronospora belbahrii, is one of the most devastating basil diseases throughout the world, and management programmes with a limited use of fungicides are necessary to control it. In order to develop efficient integrated disease management programmes, the efficacy of alternative products (calcium oxide, zeolite, orange oil with ascorbic acid, potassium phosphites and bicarbonate), applied in different spray programmes in trials carried out under artificial and natural infestations with the pathogen, has been tested. Various combinations of the treatments were chosen, on the basis of the efficacy of the single products, for further testing in experiments carried out in the presence of natural pathogen infestation and under a reduced crop density. The effect of the tested programmes on downy mildew severity (% of affected leaf area), disease development ( AUDPC ) and yield (fresh weight of plants) was evaluated. Calcium oxide, K-phosphite and orange oil with ascorbic acid generally provided the most consistent disease control (58%, 40% and 26% efficacy, respectively), when used alone under severe disease pressure, compared to the inoculated control. Spray programmes based on calcium oxide, applied 2 to 4 times, in succession to one application of azoxystrobin, and under a reduced crop density, were the most efficient treatment in the presence of a natural infestation by the pathogen; this IPM programme reduced downy severity as much as 80%, providing the same effect as a conventional chemical programme based on the alternation of azoxystrobin, fluopicolide + propamocarb and mandipropamid. Highlights: Alternative products were tested alone and after fungicides against basil downy mildew in greenhouses. Calcium oxide, K-phosphite and orange oil generally provided the most consistent disease control, better than copper. Crop density was found to be a significant factor in modulating the degree of efficacy of the tested protocols. The results suggest the possibility of reducing the number of fungicide applications against basil downy mildew. Calcium oxide is a good alternative to copper salts against basil downy mildew.