APPLICATION OF NON CONVENTIONAL TREATMENTS FOR THE CONTROL OF PYTHIUM ROOT ROT ON LAMB'S LETTUCE

摘要

Pythium irregulare has been recently reported to cause root rot on lamb's lettuce (Valerianella olitoria). The aim of this research has been to evaluate the efficacy of fertilizers, biostimulants, biological control agents and novel fungicides with low environmental impact against it.Trials have been carried out in greenhouse on potted plants grown in a peat based substrate artificially infested with the pathogen. The following treatments have been applied to the substrate before seeding: potassium phosphate (Alexin 95 PS) at 2.5 g L1; acibenzolar-s-metile (Bion 50WG) at 0.1 mg L"1; metalaxyl-M (Ridomil Gold) at 0.5 ml L1; azoxystrobin (Ortiva) at 0.8 ml L'1; Trichoderma asperellum and T. gamsii (Remedier) at lg L'1; tetraconazole at 154 e 770 ml L"1; fungicide formulation 1164 at 308 and 1540 ml L"1; fungicide formulations 1145 and 1174 at 400 and 2000 ml L1; deoxycholic acid at 40 and 200 ppm; sur-natant produced by a strain of Pseudomonas fluorescens at 40 and 200 ppm.Potassium phosphite, the formulations 1145 and 1174 and deoxycholic acid at 200 ppm significantly reduced in one trial the disease, with results similar to azoxystrobin.