Decision criteria for optimizing postemergence johnsongrass control in soybean crops in Argentina

Pesquisa Agropecuária Brasileira

Daniel Tuesca¹  Eduardo Puricelli²  Luisa Nisensohn²  Delma Faccini²  Juan Papa² 

[1],Univ. Nac. de Rosario Fac. Ciencias Agrarias Zavalla,Argentina

关键词: weeds;    herbicides;    application timing;    planta daninha;    herbicidas;    época de aplicação;   

DOI  :  10.1590/S0100-204X1999000500004

来源: SciELO

【 摘 要 】

Field studies were established in Zavalla and Oliveros, Argentina, during four years in order to optimize Johnsongrass (Sorghum halepense (L.) Pers.) chemical control by means of the thermal calendar model in comparison with other criteria (weed height or days after sowing). The effect of three application dates of postemergence herbicides was determined by visual control, density of tillers originated from rhizome bud regrowth, and from crown and shoot bud regrowth, and soybean yield. Following the thermal calendar model criterion, applications during the second date afforded the best control. Weed height for the first date showed little variability between experiments but was highly variable in the second and third application dates, achieving in some cases values greater than 120 cm. For all years, no significant differences were detected for crop yield between the first and second application dates, and yields were always lower for the third date. The greatest rhizome bud regrowth was observed for the earliest application date and the highest crown and shoot bud regrowth was determined for the last application date. Parameters associated with control efficiency showed the best behaviour for the second date. However, plant height at this moment may interfere with herbicide application and the variability exhibited by this parameter highlights the risk of determining control timing using only one decision criterion.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License