Host suitability of grain sorghum and sudangrass for Pratylenchus brachyurus

ABSTRACT: Nowadays, the root-lesion nematode Pratylenchus brachyurus (Godfrey) is a major pest of soybean in Brazil, mainly in areas using double cropping with maize or cotton, which are suitable hosts for P. brachyurus. A great effort has been made to find cash crops for P. brachyurus management. Grain sorghum [Sorghum bicolor (L.)] was classified as a non-host for P. brachyurus but based on a single trial. It would be a valuable option as a culture for double cropping with soybean, as it is profitable and can be used in root-lesion nematode management. Sudangrass (S. bicolor var. sudanense) is not directly profitable, but Brazilian farmers favor it because it can produce pasture, green chop, silage, or hay under unfavorable hydric conditions. However, no information is available regarding the suitability of sudangrass for P. brachyurus. Thus, the current study aimed to assess the suitability of grain sorghum and sudangrass for P. brachyurus in two glasshouse trials. The first trial tested sudangrass and grain sorghum ‘DKB 510’, ‘Dow 740’, ‘Dow 822’, ‘DKB 599’, and ‘AG 1040’. The second trial retested sudangrass and grain sorghum ‘Dow 740’ and ‘DKB 599’. The results demonstrated that sudangrass and grain sorghum were suitable hosts for P. brachyurus. These results, in addition to those obtained for other types of sorghum, emphasize that S. bicolor and sudangrass should be avoided in fields infested with P. brachyurus, as they increase the nematode population.

摘要：现如今，短尾根腐线虫（Pratylenchus brachyurus (Godfrey)）是巴西大豆生产中的主要害虫，在采用玉米或棉花与大豆复种的种植区域危害尤为严重，因为玉米与棉花均为该线虫的适宜寄主。针对该线虫的防治，学界已投入大量精力探寻适宜的经济作物。此前有研究将高粱[Sorghum bicolor (L.)]归类为该线虫的非寄主，但该结论仅基于单次试验数据。高粱作为大豆复种作物极具应用价值，不仅种植收益可观，还可用于根腐线虫的防治。苏丹草（S. bicolor var. sudanense）本身无法直接产生经济效益，但巴西农户仍偏好种植，因其可在水分条件不利的情况下生产牧草、青饲、青贮饲料或干草。然而目前尚无关于苏丹草是否适于短尾根腐线虫寄生的相关研究报道。为此，本研究通过两项温室试验，旨在评估高粱与苏丹草对短尾根腐线虫的适宜性。第一项试验测试了苏丹草以及‘DKB 510’、‘Dow 740’、‘Dow 822’、‘DKB 599’与‘AG 1040’五个高粱品种。第二项试验重复测试了苏丹草以及‘Dow 740’与‘DKB 599’两个高粱品种。试验结果表明，苏丹草与高粱均为短尾根腐线虫的适宜寄主。结合其他高粱类型的相关研究结果，本研究结论强调：在受短尾根腐线虫侵染的田块应避免种植双色高粱与苏丹草，因其会导致线虫种群数量显著上升。