Cantonwine E G, Culbreath A K, Stevenson K L
Former Graduate Student.
Professor.
Plant Dis. 2007 Jul;91(7):822-827. doi: 10.1094/PDIS-91-7-0822.
Epidemics of early leaf spot, caused by Cercospora arachidicola, of peanut (Arachis hypogaea) are delayed in strip-tilled compared to conventionally tilled fields. This effect may be due to applications of glyphosate used to kill the winter cover crop in strip-tilled fields and/or the presence of cover crop residue at the soil surface of strip-tilled fields. Preplant herbicide (no herbicide, glyphosate, and paraquat), reciprocal residue (plus residue in conventionally tilled plots and minus residue in strip-tilled plots), and added straw mulch were evaluated to determine their effects on early leaf spot epidemics (AUDPC based on incidence and severity, and final percent defoliation) in conventionally tilled and strip-tilled plots. Additional experiments were conducted to characterize the effects of mulch (straw, fumigated straw, and plastic straw [Textraw]) treatments on disease, and to study tillage effects on disease in nonrotated peanut fields. Glyphosate and paraquat had no effect on AUDPC values or defoliation. The addition of straw to conventionally tilled plots significantly reduced disease levels. Cover crop and straw treatments had no significant effect on disease in the strip-tilled plots. AUDPC values were highest in the bare soil plots, lowest in the straw and fumigated straw plots, and intermediate in the plots with Textraw. Fewer initial infections were detected in the Textraw plots compared to the bare soil plots based on results of a trap leaf experiment. Strip-tillage did not consistently suppress early leaf spot epidemics in nonrotated fields. These results show that the presence of cover crop residue is partly responsible for the early leaf spot suppression observed in strip-tilled fields. Cover crop residue may interfere with the dispersal of primary inoculum from overwintering stroma in the soil to the plant tissues.
由落花生尾孢菌引起的花生早期叶斑病，与传统耕作的田地相比，在带状耕作的田地里发病时间会延迟。这种影响可能是由于在带状耕作的田地里使用草甘膦来杀死冬季覆盖作物，和/或带状耕作田地的土壤表面存在覆盖作物残茬。对种植前除草剂（不使用除草剂、草甘膦和百草枯）、互作残茬（传统耕作地块添加残茬，带状耕作地块去除残茬）以及添加秸秆覆盖物进行了评估，以确定它们对传统耕作和带状耕作地块中早期叶斑病流行情况（基于发病率和严重程度的曲线下面积以及最终落叶百分比）的影响。还进行了额外的实验，以表征覆盖物（秸秆、熏蒸秸秆和塑料秸秆[Textraw]）处理对病害的影响，并研究在非轮作花生田中耕作对病害的影响。草甘膦和百草枯对曲线下面积值或落叶情况没有影响。在传统耕作地块中添加秸秆显著降低了病害水平。覆盖作物和秸秆处理对带状耕作地块中的病害没有显著影响。曲线下面积值在裸土地块中最高，在秸秆和熏蒸秸秆地块中最低，在使用Textraw的地块中处于中间水平。根据诱捕叶实验结果，与裸土地块相比，使用Textraw的地块中检测到的初始感染较少。在非轮作田地中，带状耕作并不能始终抑制早期叶斑病的流行。这些结果表明，覆盖作物残茬的存在部分导致了在带状耕作田地中观察到的早期叶斑病抑制现象。覆盖作物残茬可能会干扰初次接种体从土壤中越冬子座向植物组织的传播。
