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S.-S.T. Hua, J.L. Baker, and M. Flores-Espiritu

California is the major state for producing almonds, pistachios, and walnuts, with a total market value of $1.6 billion. Both domestic and export markets of these nuts presently allow a maximum level of aflatoxin B1 contamination in the edible nuts to be 20 ppb. Even very low degrees of infection of the nuts by A. flavus can result in aflatoxin levels above the mandatory standards. Biological control to reduce the population of and to inhibit the biosynthesis of A. flavus in orchards may be useful to decrease infection and thus aflatoxin content in the edible nuts. Certain saprophytic yeasts were shown to effectively compete with postharvest fungal pathogens such as Penicillium expansum and Botrytis cinerea. The potential of saprophytic yeasts to reduce aflatoxin contamination in tree nuts has not been hitherto extensively explored. A safe visual bioassay for screening yeasts antagonistic to A. flavus has been developed. The nor mutant of A. flavus has a defective norsolorinic acid reductase and blocks the aflatoxin biosynthetic pathway, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We used the nor mutant in the assay to screen yeasts strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment as well as the growth and sporulation of the fungus. Yeast strains that reduced the red-orange pigment accumulation in the nor mutant were identified and shown to inhibit aflatoxin biosynthesis of several toxigenic strains of A. flavus.

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Louise Ferguson, Patrick Niven, Andrea Fabbri, Lara Dallo, Walter Bentley, Paul Metheney, and Vito Polito

77 POSTER SESSION 10 (Abstr. 90-621) Tree Fruits/Nuts: Culture & Management

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Bruce W. Wood

87 ORAL SESSION 15 (Abstr. 099–106) Culture and Management–Tree Fruits/Nuts

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Michael W. Smith and William D. Goff

locations without notable depredation when pecans are on the ground is to dislodge the nuts from the tree and leave them on the ground 1 d or more to dry. Otherwise, harvest procedures are completed the same day that the nuts are shaken from the tree

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Michael W. Smith

measured, and a random 40-nut sample was collected from each tree. Nut samples were collected from field-run nuts (before cleaning to remove light weight nuts) and kernels (cotyledon) rated for necrosis symptoms using a 1–4 scale ( Fig. 1 ) on each kernel

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Brad G. Howlett, Samantha F.J. Read, Maryam Alavi, Brian T. Cutting, Warrick R. Nelson, Robert M. Goodwin, Sarah Cross, Trevor G. Thorp, and David E. Pattemore

cultivars A4 and 246 was affected by the transfer of self-pollen from other trees of the same cultivar compared with that from bagged racemes with no pollination. Few to no final nuts developed in these treatments. Evidence for the potential benefit of self

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Lenny Wells

emitters and 1.2 m from the base of the tree on each sampling date at the same time that stem ψ was measured for each tree. A 50-nut sample was collected from each tree for analysis of individual nut weight and percent kernel. Nuts were shelled and

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Timothy L. Grey, Keith Rucker, Lenny Wells, and Xuelin Luo

survival, water use efficiency, and growth is a common practice ( Faircloth et al., 2007 ). This reduces the time required for pecan trees to begin bearing nuts and producing the first commercially viable yield ( Smith, 2011 ). Indaziflam is an alkylazine

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Patrick J. Conner

collected from each tree to measure nut quality. Nut volume was determined by water displacement. Specific gravity is the average nut volume/average nut weight. Nuts were shelled and percentage edible kernel was calculated by weight. The fluctuation in yield

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Ute Chambers, Vaughn M. Walton, and Shawn A. Mehlenbacher

cultivars are bred for various traits, including precocity, high nut yield per tree, round shape, thin shells, and easy pellicle removal. Kernels 11 to 13 mm in diameter are ideal for processing, whereas larger nuts (14 to 23 mm or larger) are desired for