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Association of a second phase of mortality in cucumber seedlings with a rapid rate of metalaxyl biodegradation in greenhouse soils

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Al-Sa'di, A.M., Drenth, A., Deadman, M.L., Al-Said, F.A., Khan, I. and Aitken, E.A.B. (2008) Association of a second phase of mortality in cucumber seedlings with a rapid rate of metalaxyl biodegradation in greenhouse soils. Crop Protection, 27 (7). pp. 1110-1117.

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Article Link: http://dx.doi.org/10.1016/j.cropro.2008.01.007


A study was undertaken from 2004 to 2007 to investigate factors associated with decreased efficacy of metalaxyl to manage damping-off of cucumber in Oman. A survey over six growing seasons showed that growers lost up to 14.6% of seedlings following application of metalaxyl. No resistance to metalaxyl was found among Pythium isolates. Damping-off disease in the surveyed greenhouses followed two patterns. In most (69%) greenhouses, seedling mortality was found to occur shortly after transplanting and decrease thereafter (Phase-I). However, a second phase of seedling mortality (Phase-II) appeared 9-14 d after transplanting in about 31% of the surveyed greenhouses. Analysis of the rate of biodegradation of metalaxyl in six greenhouses indicated a significant increase in the rate of metalaxyl biodegradation in greenhouses, which encountered Phase-II damping-off. The half-life of metalaxyl dropped from 93 d in soil, which received no previous metalaxyl treatment to 14 d in soil, which received metalaxyl for eight consecutive seasons, indicating an enhanced rate of metalaxyl biodegradation after repeated use. Multiple applications of metalaxyl helped reduce the appearance of Phase-II damping-off. This appears to be the first report of rapid biodegradation of metalaxyl in greenhouse soils and the first report of its association with appearance of a second phase of mortality in cucumber seedlings.

Item Type:Article
Keywords:HPLC; ITS rDNA; Oomycetes; P. aphanidermatum; P. spinosum Ridomil; biodegradation; biological survey; climbing plant; fungal disease; growing season; mortality; seedling; Asia; Eurasia; Middle East; Oman; Cucumis sativus; Pythium; Pythium aphanidermatum; Pythium spinosum.
Subjects:Plant pests and diseases > Pest control and treatment of diseases. Plant protection
Plant culture > Vegetables
Live Archive:17 Nov 2008 06:29
Last Modified:03 Sep 2021 16:43

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