Submitted to: Aflatoxin Workshop
Publication Type: Abstract only
Publication Acceptance Date: 10/13/2003
Publication Date: 12/1/2003
Citation: Parfitt, D.E., Almehdi, A.A., Ly, S.B., Campbell, B.C., Hua, S.T. 2003. Application of yeast in the field for biocontrol of aspergillus flavus [abstract]. Aflatoxin Workshop. p. 81. Interpretive Summary:
Technical Abstract: Prior work in Dr. Hua's lab has shown that selected yeast strains can competitively inhibit the growth of Aspergillus flavus. Yeast will be an ideal biocontrol agent, since the strains are selected from naturally occurring isolates. Issues of potential human toxicity should be much less than with other biologically active agents, such as competitive fungi. However, we do not know whether these strains can survive outside, particularly in the hot dry climates of California where pistachio is grown. The present series of experiments were undertaken to begin to explore the extent to which inhibitory yeast strains can survive in the open environment. Yeast at concentrations of 105/ml, 106/ml, 107/ml, and 108/ml were sprayed on individual >Kerman= pistachio trees in a replicated randomized design. Three spray dates were tested at the various concentrations. Three reps of 20 nuts were harvested from each tree at three dates and assayed for yeast survival. Effects of concentration of sprayed yeast, duration of protection, and number of spray treatments were evaluated. Preliminary analysis of the results suggest that differences in time of application during the season appeared to have a much larger effect on the residual nut yeast level than the concentration of yeast applied. High levels of residual yeast were found on the nuts at the later spray dates and higher concentrations of spray.