Activity of Phenobarbitone in controlling Marrow Powdery Mildew

Abstract

IN molecular structure, phenobarbitone resembles 6-azauracil which was shown by Dekker¹ to exhibit systemic activity against powdery mildew of cucumbers. In the experiments described here, tests of phenobarbitone and related compounds were made on young potted marrow seedlings which had been dusted with conidia by shaking over them leaves heavily infected with powdery mildew, caused by Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll. To assess systemic fungicidal performance, the seedlings, which had previously been left unwatered for 48 h, were watered with the test chemicals immediately after inoculation, at the rate of 150 ml. per pot. Foliage applications were also assessed, the plants being dipped in aqueous solutions containing the test chemical together with the non-ionic wetting agent, ‘Ethylan CP’ (0.0025 per cent v/v), at a temperature of 30° C.