Control Efficacy of Natural Products on Broadleaf and Grass Weeds Using Various Application Methods

Abstract

Synthetic herbicides have negatively impacted biological organisms and human health. Thus, nonsynthetic herbicides for weed control are needed in organic and conventional agriculture. Nonsynthetic products such as vinegar and detergents are increasingly becoming popular in crop disease treatment, as well as controlling insects and weeds. Therefore, the objective of this study was to determine the herbicidal efficacy of various nonsynthetic products using different application methods. Various nonsynthetic products were applied to grass and broadleaf weeds at 1%, 3%, 5%, and 10% concentrations to test their herbicidal efficacy, and two plant extracts were used as adjuvants. In addition, the inhibitory effects of selected brown rice vinegar and effective microorganisms (EM) powder soap on grass and broadleaf weeds were compared to the inhibitory effects of other vinegars and EM powder soaps. Of the nine various natural products tested, brown rice vinegar and EM powder soap at 5% concentrations were the only applications to completely control grass and broadleaf weeds in Petri dish bioassays. In greenhouse conditions, the shoot fresh weight of Eclipta prostrata, Solanum nigrum, Persicaria hydropier, and Portulaca oleracea was completely inhibited when soil applications of EM powder soap at 10% concentrations were used. EM powder soap was more effective in controlling grass and broadleaf weeds than brown rice vinegar. In addition, brown rice vinegar and EM powder soap did not appear to last long in soil. Two-time application methods were more effective in controlling all weed species than one-time application methods. However, no synergism effects were observed when brown rice vinegar and EM powder soap were combined with other natural products. Brown rice vinegar and EM powder soap did not show adjuvant effects when combined with plant extracts, which can sometimes create better contact with or penetration of the weeds. Thus, weeds growing alongside transplanted vegetable crops can be effectively controlled with brown rice vinegar and EM powder soap by using soil applications in row, either individually or combined together and with either one or two applications.