The use of methyl bromide and carbendazim for the control of lettuce big‐vein disease

Abstract

Lettuce seedlings raised in peat blocks placed on contaminated soil subsequently developed lettuce big‐vein disease symptoms when grown in pots of sterilized compost. Incorporation of 0.01 g carbendazim per 4.3 cm3 peat block reduced the number of plants with disease symptoms but did not prevent root infection by Olpidium brassicae, the vector of the big‐vein agent. Similar results were obtained when seedlings propagated in the absence of big‐vein disease were grown in pots of contaminated soil but carbendazim was less effective when the treated blocks were planted in contaminated field plots. Methyl bromide applied at 500, 750 or 1000 kg/ha temporarily controlled the disease but re‐contamination occurred and was complete after three consecutive crops. Bromide residues in lettuce heads reached 9240 μg/g dry tissue in the first crop but fell to a maximum 772 μg/g by the third crop. Bromide residues in soil fell to natural levels over this period.

Applied Plant Virology

“…Injection of methyl bromide into contaminated field soils has been successfully used to control big-vein disease of lettuce, which is transmitted by Olpidium brassicae (White, 1980(White, , 1983Campbell et al, 1980). The disease may also be controlled by incorporating carbendazim (methyl-2-yl-benzimidazole carbamate) into peat-blocks used for lettuce transplants, prior to transplanting in big-vein contaminated soil (White, 1983).…”

Control of lettuce big‐vein disease by application of fungicides and crop covers

“…The findings here confirmed previous reports: the tested fungicides carbendazim and fluazinam were effective in reducing O. virulentus levels. These fungicides have known effects of reducing the abundance of zoospores, and specifically those of Olpidium spp., in the soil (White, ; Fletcher et al ., ). However, the presence of MLBVV, and therefore of LBVD symptoms, was not affected.…”