Jaime-Garcia Ramon, Cotty Peter J
United States Department of Agriculture-Agricultural Research Service and Division of Plant Pathology and Microbiology, University of Arizona, Tucson 85721.
Plant Dis. 2004 Dec;88(12):1366-1371. doi: 10.1094/PDIS.2004.88.12.1366.
Aspergillus flavus causes aflatoxin contamination in both cottonseed and corn. Corn-cotton rotations are common in South Texas, where reduced tillage frequently results in long-term residence of corncobs on soil surfaces. Corncobs are colonized by A. flavus either prior to harvest or while in the soil. This study sought to determine the potential of corncobs as sources of inoculum for cotton and corn in South Texas. A. flavus communities in corncob and soil samples were collected during the planting seasons of 2001 to 2003 from 29 fields extending from Calhoun and Victoria Counties in the north to the Rio Grande Valley. In order to assess persistence of A. flavus in corncobs, A. flavus communities in corncobs and soil were contrasted every 2 to 3 months in four fields throughout the 3-year study. To assess seasonal variation, similar contrasts were performed in two fields on a biweekly basis. The results indicate that corncobs are major sources of A. flavus inoculum. Corncobs from the previous season contained, on average, over 190 times more A. flavus propagules than soil from the same field, and 2-year-old corncobs still retained 45 times more propagules than soil. There was no significant difference in the incidence of A. flavus strain S on corncobs and soil. The quantity of A. flavus in corncobs decreased with corncob age (r = 0.54; P = 0.002).
黄曲霉会导致棉籽和玉米受到黄曲霉毒素污染。在得克萨斯州南部，玉米-棉花轮作很常见，那里少耕常常导致玉米芯长期留在土壤表面。玉米芯在收获前或留在土壤中时会被黄曲霉定殖。本研究旨在确定得克萨斯州南部玉米芯作为棉花和玉米接种源的潜力。2001年至2003年种植季节期间，从北起卡尔霍恩县和维多利亚县、南至里奥格兰德河谷的29块田地采集了玉米芯和土壤样本中的黄曲霉群落。为了评估黄曲霉在玉米芯中的持久性，在为期3年的研究中，每2至3个月对4块田地的玉米芯和土壤中的黄曲霉群落进行对比。为了评估季节变化，在两块田地中每两周进行一次类似的对比。结果表明，玉米芯是黄曲霉接种源的主要来源。上一季的玉米芯平均含有比同一块田地土壤中多190倍以上的黄曲霉繁殖体，两年的玉米芯仍比土壤中多保留45倍的繁殖体。玉米芯和土壤上黄曲霉菌株S的发生率没有显著差异。玉米芯中黄曲霉的数量随玉米芯年龄的增长而减少（r = 0.54；P = 0.002）。
