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Ali A. Ramin, P. Gordon Braun, Robert K. Prange, and John M. DeLong

Biofumigation by volatiles of Muscodor albus Worapong, Strobel & W.M. Hess, an endophytic fungus, was investigated for the biological control of three postharvest fungi, Botrytis cinerea Pers., Penicillium expansum Link, and Sclerotinia sclerotiorum (Lib) de Bary, and three bacteria, Erwinia carotovora pv. carotovora (Jones) Bergey et al., Pseudomonas fluorescens Migula (isolate A7B), and Escherichia coli (strain K12). Bacteria and fungi on artificial media in petri dishes were exposed to volatiles produced by M. albus mycelium growing on rye seeds in sealed glass 4-L jars with or without air circulation for up to 48 hours. The amount of dry M. albus–rye seed culture varied from 0.25 to 1.25 g·L–1 of jar volume. Fan circulation of volatiles in jars increased efficacy and 0.25 g·L–1 with fan circulation was sufficient to kill or suppress all fungi and bacteria after 24 and 48 hours, respectively. Two major volatiles of M. albus, isobutyric acid (IBA) and 2-methyl-1-butanol (MB), and one minor one, ethyl butyrate (EB), varied in their control of the same postharvest fungi and bacteria. Among the three fungi, IBA killed or suppressed S. sclerotiorum, B. cinerea, and P. expansum at 40, 25, and 45 μL·L –1, respectively. MB killed or suppressed S. sclerotiorum, B. cinerea, and P. expansum at 75, 100, and 100 μL·L –1, respectively. EB was only able to kill S. sclerotiorum at 100 μL·L –1. Among the three bacteria, IBA killed or suppressed E. coli (K12), E. carotovora pv. carotovora, and P. fluorescens at 5, 12.5, and 12.5 μL·L–1, respectively. MB killed or suppressed E. coli (K12), E. carotovora pv. carotovora, and P. fluorescens at 100, 75, and 100 μL·L–1, respectively. EB did not control growth of the three bacteria. This study demonstrates the need for air circulation in M. albus, MB, and IBA treatments to optimize the efficacy of these potential postharvest agents of disease control.

Open access

Meredith L. Bliss and Harlan K. Pratt

Abstract

Gas samples from the central cavities of 3 cultivars of muskmelon fruits (Cucumis melo L.) were resolved by gas chromatography into at least 12 organic volatile fractions. Harvesting of ‘Top-Mark5 and ‘PMR-455 cantaloupe up to 12 days before normal abscission did not reduce the final concentration of volatiles attained. Production of volatiles by cantaloupe was inhibited while still attached to the parent plants, but no evidence for inhibition by the parent plant was obtained in ‘Honey Dew’, nor was the final concentration of volatiles reduced by early harvest. High concentrations of exogenous ethylene applied to harvested melons accelerated the onset of production of the organic volatiles but did not significantly affect their ultimate concentrations. Exogenous ethylene altered the relative amounts of at least 2 fractions. The production of volatiles is closely coordinated with the other aspects of ripening, but the control mechanisms appear to be different.

Free access

Nobuko Sugimoto, A. Daniel Jones, and Randolph Beaudry

measuring headspace concentrations of organic volatiles Anal. Chem. 69 364 372 10.1021/ac960820n Bartlem, D. Lambein, I. Okamoto, T. Itaya, A. Uda, Y. Kijima, F. Tamaki, Y. Nambara, E. Naito, S. 2000 Mutation in the threonine synthase gene results in an over

Open access

Alejandra Ferenczi, Nobuko Sugimoto, and Randolph M. Beaudry

commercial solid-phase microextraction device for measuring headspace concentrations of organic volatiles Anal. Chem. 69 364 372 doi: https://doi.org/10.1021/ac960820n 10.1021/ac960820n Bartley, I.M. Stoker, P.G. Martin, A.D.E. Hatfield, S