NUTRITIONAL IMPROVEMENT OF ROSE TO MANAGE PERONOSPORA SPARSA, CAUSAL AGENT OF DOWNY MILDEW

Abstract

The downy mildew (Peronospora sparsa), is one of the most important diseases of rose in Colombia, causing losses up to 8%. The objective of this research was to determine a preventive control of the disease, through the improvement of the nutritional balance of the plant. The first phase, involved the effect of different concentrations of N, K, Ca, B and Mn, on the incidence and severity of the disease, and in the second one, the evaluation of the best five treatments of the first phase. The treatments were applied to the varieties Charlotte, Classy and Malibú during 4 weeks, using a splitting plot design with six replications. After one month the plants were inoculated with the fungus at a concentration of 3x10⁴ sporangia mL-1 .The results of the area under the disease progress curve (AUDPC), showed that the plants of Charlotte with 200 ppm of Si had the lowest expression of the disease. In Classy, the best treatment was the standard solution, demonstrating that the effects of the treatments depend of the variety. Charlotte and Malibú showed susceptibility, while Classy, partial resistance to the disease.