Department of Botany and Plant Pathology, Central Oregon Agricultural Research and Extension Center, Oregon State University, Madras, OR 97741.
Division of Agriculture and Natural Resources, Agricultural and Natural Resources Intermountain Research and Extension Center, University of California, Tulelake, CA 96134.
Plant Dis. 2024 Jan;108(1):118-124. doi: 10.1094/PDIS-04-23-0688-RE. Epub 2024 Jan 3.
White rot, caused by , is a serious disease that causes significant yield losses in production. The pathogen persists in soil as sclerotia, which germinate in response to sulfur compounds in root exudates. This study was aimed at investigating the potential of early-terminated bait crops to reduce densities of sclerotia in soil. In growth chamber experiments with white onion ( cultivar 'Southport White Globe'), red onion ( cultivar 'Marenge'), sweet onion ( cultivar 'Walla Walla'), and bunching onion ( cultivar 'Parade'), termination of all four Alliums at the first- and second-leaf stages reduced soil sclerotia populations by up to 62 and 76%, respectively. Examination of soil samples collected 4 weeks after crop termination indicated that sclerotia populations in bait crop treatments remained low when seedlings were terminated at the first- and second-leaf stages. In contrast, crop termination at the third-leaf stage resulted in an increase in sclerotia counts due to the pathogen reproduction on the bait crops. The reduction in sclerotia populations in soil due to early crop termination was also observed in replicated field trials. Greater reductions in sclerotia counts were observed when plants in these experiments were terminated chemically as opposed to mechanically. In-furrow fungicides did not reduce sclerotia numbers under the conditions tested. This study demonstrates the potential for early termination of bait crops to help reduce white rot inoculum in soil.
白腐病由引起，是一种严重的疾病，会导致生产中的产量损失。病原体以菌核的形式存在于土壤中，当根分泌物中的硫化合物发芽时，菌核就会发芽。本研究旨在调查早期终止的诱饵作物降低土壤中菌核密度的潜力。在白洋葱（品种“Southport White Globe”）、红洋葱（品种“Marenge”）、甜洋葱（品种“Walla Walla”）和大葱（品种“Parade”）的生长室实验中，所有四种葱在第一和第二叶期终止生长，可分别将土壤中的菌核种群减少 62%和 76%。在作物终止后 4 周收集的土壤样本检查表明，当幼苗在第一和第二叶期终止时，诱饵作物处理中的菌核种群仍然较低。相比之下，在第三叶期终止作物会导致菌核计数增加，因为病原体在诱饵作物上繁殖。在重复的田间试验中也观察到由于早期作物终止导致土壤中菌核种群减少。在这些实验中，当植物被化学而非机械终止时，菌核计数的减少幅度更大。沟施杀菌剂在测试条件下没有减少菌核数量。本研究表明，早期终止诱饵作物有助于减少土壤中的白腐病接种体。
