Biomedical subjects
Publications and source records attributed to R A Taber.
Twelve isolates of Pithomyces spp. from Texas were tested for sporidesmin toxin production, using both high-performance and thin-layer chromatography techniques. None of the Texas isolates produced the toxin under the conditions used. A control toxigenic New Zealand isolate, Pithomyces chartarum strain C, was grown simultaneously under the conditions tested and was found to produce sporidesmin in all cases.
Explore the source record for details and available documents.
Peanuts grown under dryland conditions where drought stress occurred accumulated more aflatoxin before digging than peanuts grown under irrigation. Kernels became more susceptible to Aspergillus flavus and A. parasiticus invasion when the soil moisture in the pod zone approached levels at which moisture moved from the pod into the soil and the kernel moisture dropped below 31%. Isolation frequencies of these aspergilli from fresh-dug kernels were lowest in 1968 (maximum of 3%). In 1967 and 1969, maximum percentages of 100 and 74, respectively, were noted. Kernel infestation was correlated with degree of aflatoxin contamination. Dryland fresh-dug kernels contained a maximum of 35,800 parts per billion aflatoxin while a maximum of 50 parts per billion was detected in kernels from irrigated plots. In 1969 A. flavus infestation was as high as 59% in peanuts from irrigated plots; however, no aflatoxin was detected. Absence of aflatoxin in these samples is attributed to the higher kernel moisture content which reduced the aflatoxin-producing potential of A. flavus. Statistical analysis of the data revealed no significant differences in degree of fungal infestation, production levels, and grade factors between any fungicide treatments.
Accumulation of aflatoxin in Spanish peanut kernel samples from different geographical areas in Texas during 1966, as detected by the thin-layer chromatographic method, was relatively low. Analysis of samples obtained from growers using artificial drying equipment (forced air and supplemental heat), when windrow conditions were unfavorable for rapid drying, suggests that this practice reduces the possibility of aflatoxin accumulation. In general, peanuts harvested from land planted to peanuts the previous year were more highly infested with fungi and contained more aflatoxin than peanuts grown on land planted with rye, oats, melons, or potatoes the previous year. Aflatoxin incidence tended to decrease from south to north Texas. These findings verify previous research observations that moist tropical climates are conducive to fungal infestation and aflatoxin accumulation. Detection of aflatoxin in sound mature kernels (kernels screened for minimal size) indicates that the practice of screening for removal of small immature kernels and removal of obviously damaged kernels does not completely eliminate aflatoxin contamination.
Explore the source record for details and available documents.
Seventy-eight samples of farmer stock peanuts, representing peanuts grown in nine different geographical areas during 1964, were assayed for aflatoxin and examined for associated microflora. Only two samples contained more than 50 ppb of aflatoxin. Infestation by members of the Aspergillus flavus-oryzae group varied from 35 to 100% of the kernels per area and from 1 to 100% of the kernels per sample. Aflatoxin production by individual isolates ranged from 0 to 349,143 ppb under the test conditions employed. In general, the isolates produced 8 to 10 times more B(1) than B(2), and no isolate producing aflatoxins G(1) or G(2) was found. The importance of proper postharvest handling of peanuts is emphasized by the prevalence of isolates of A. flavus-oryzae capable of producing aflatoxins on farmers stock peanuts.
Explore the source record for details and available documents.
Explore the source record for details and available documents.