Submitted to: Mycopathologia
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2002
Publication Date: 5/1/2004
Citation: Timper, P., Holbrook, Jr., C. C., Wilson, D. M. 2004. Relationship between pod galling from root-knot nematodes and aflatoxin contamination in peanut [abstract]. Mycopathologia. 157:496.
Technical Abstract: A field study was conducted to determine whether aflatoxin levels in peanut, Arachis hypogaea, were correlated with pod and root galling caused by the peanut root-knot nematode. The experiment was conducted under a rain-out shelter containing 24 cement plots (each 2 x 2 m) with the following treatments: root-knot nematodes alone (RKN), Aspergillus flavus (Af) alone, RKN + Af, and no nematodes or fungus. Each treatment was replicated six times. Peanut seedlings, either infected with RKN or uninfected, were transplanted into half the plots. Inoculum of Af was sprinkled over the plant canopy at mid bloom. Drought was induced after pod set by covering plots during rain with a fiberglass shelter. Pod- and root-gall indices were determined for all plants in the plot and averaged. Pods from each plot were bulked, shelled, and a subsample of kernels was used to determine aflatoxin concentration and percentage colonized by Af. In plots treated with Af, aflatoxin concentrations were 850 to 1800 ppb and were unaffected by the presence or absence of nematodes. However, in plots without added fungus, aflatoxin concentrations were 2 ppb in plots without nematodes and 1800 ppb in plots with nematodes. There was a correlation between aflatoxin concentration and pod-gall index: with increasing pod galling, there was an increase in aflatoxin concentration (P=0.001, r=0.82). Colonization of kernels by Af also increased with increasing pod galling (P=0.04, r=0.42).