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<p class="MsoNormal"><span style="font-size:11.0pt">Dear all,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Please join us in <a href="https://map.arizona.edu/107">
<b>Marley 230</b></a> <b>at 4:00 PM</b> <b>today </b>for a seminar presented by Dr. Connel Ching'anda, School of Plant Sciences, University of Arizona.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Zoom link: <a href="https://arizona.zoom.us/j/84253432688">
https://arizona.zoom.us/j/84253432688</a> (password: <b>SPLS2025</b>).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Refreshments will be provided in the Marley Lobby at 3:30 PM.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Title: Factors influencing biocontrol efficacy and mycotoxin contamination risk in Texas corn<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Abstract:</span></b><span style="font-size:11.0pt"> Grain corn is an important crop in Texas valued at over $1.2 billion. However, mycotoxin contamination is a perennial problem in Texas that results in
significant economic losses for corn growers. Aflatoxin produced by <i>Aspergillus flavus</i> and related species and fumonisin produced by
<i>Fusarium</i> <i>verticillioides</i> and <i>F. proliferatum</i> are the two major mycotoxins contaminating corn in Texas. Recommended mycotoxin mitigation tactics include minimizing biotic (insect injury, disease) and abiotic (drought, soil fertility) stresses
to the corn crop. In addition, biological control using naturally occurring non-aflatoxigenic
<i>A. flavus</i> genotypes to outcompete aflatoxin producers is an effective strategy to limit aflatoxin contamination, but there is no biocontrol for fumonisin. Climatic conditions where corn is grown vary in Texas, ranging from cool and dry conditions in
the north to warmer and wetter conditions in the south. In general, cool temperatures (20-25</span><span style="font-size:11.0pt;font-family:"Cambria Math",serif">¢J</span><span style="font-size:11.0pt">) favor fumonisin contamination while warmer temperatures
(25-35</span><span style="font-size:11.0pt;font-family:"Cambria Math",serif">¢J</span><span style="font-size:11.0pt">) favor aflatoxin production. Though some factors contributing to aflatoxin biocontrol efficacy and mycotoxin risk and have been previously
characterized, knowledge gaps still exist that limit the ability of corn growers to mitigate crop losses due to aflatoxin and fumonisin contamination. Thus, the objectives of the current study are to 1) elucidate area-wide, multi-year effects of applying single-strain
versus multi-strain aflatoxin biocontrol products; 2) compare the size and composition of mycotoxigenic fungal communities among different agroecological regions in Texas; 3) identify biotic and abiotic factors that influence growth of mycotoxigenic fungi
and severity of mycotoxin contamination; and 4) collect field data to contribute to development of predictive models for mycotoxin contamination risk. In 2024, fields located in different regions of Texas with variable biocontrol application histories were
sampled. Fields treated with single- and multi-strain products all had high frequencies of biocontrol genotypes in soil and on the crop at harvest, but frequencies of individual genotypes within the multi-strain mixture varied from field to field. High frequencies
of biocontrol genotypes in fields that did not receive an application in 2024 suggests biocontrol strains displace aflatoxigenic
<i>A. flavus</i> in both treated and non-treated fields and persist in soils for several years. Fumonisin-producing
<i>Fusarium</i> spp. and <i>A. flavus </i>were the most frequent kernel-infecting fungi, but incidence varied among different regions of Texas. Likely due to biocontrol applications, aflatoxin concentrations in grain were generally low (below the FDA action
level of 20 ppb), while fumonisin concentrations were frequently above the FDA advisory level (2 ppm) in central and northern regions of Texas. Both Aspergillus and Fusarium ear rot severity correlated with ear injury caused by insect feeding. In addition,
mycotoxin concentrations correlated with insect feeding style with aflatoxins correlated with chewing injury while fumonisin correlated with piercing injury. Relationships between soil factors, weather variables, mycotoxigenic fungal populations, and severity
of mycotoxin contamination are currently being evaluated and will be used for development and validation of models to predict aflatoxin and fumonisin contamination risk in Texas. A better understanding of factors influencing the long-term efficacy of aflatoxin
biocontrol applications and mycotoxin contamination risk will allow corn growers to make more effective and economical mycotoxin management decisions.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt;font-family:"Courier New";mso-ligatures:none">===============================================================<br>
</span><b><span style="font-size:20.0pt;font-family:"Vladimir Script";mso-ligatures:none">Zhongguo Xiong</span></b><span style="font-size:10.0pt;font-family:"Courier New";mso-ligatures:none"> <br>
School of Plant Sciences BIO5 Institute<br>
BIO5 Email: <span style="color:blue"><a href="mailto:zxiong@arizona.edu"><span style="color:blue">zxiong@arizona.edu</span></a></span>
<br>
Phone: (520)-621-9869<br>
Forbes 303, P.O. box 210036 Fax: (520)-621-7186<br>
University of Arizona <br>
Tucson, AZ 85721-0036 <span style="color:blue"><a href="http://ag.arizona.edu/~zxiong"><span style="color:blue">http://ag.arizona.edu/~zxiong</span></a></span><br>
===============================================================</span><span style="font-size:11.0pt;mso-ligatures:none"><o:p></o:p></span></p>
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