Effect of cogongrass [Imperata cylindrical (L.) Beauv.) extract as a botanical herbicide on the growth of itchgrass [Rottboellia exaltata (L.) L. F.] in maize (Zea mays L.) plants

Weeds are one of the plant pests commonly found in maize fields. The weed often encountered in maize fields is Rottboellia exaltata at Tarakan City, Indonesia. This will have an impact on reducing the productivity of maize plants, So it is necessary to take measures to control the R. exaltata weed. To control R. exaltata in maize plants, a botanical herbicide derived from Imperata cylindrica is employed. This research aims to determine the influence of I. cylindrica extract as a botanical herbicide on the growth of R. exaltata in maize plants. The study utilizes a Completely Randomized Block Design with one factor and four replications. The treatments are as follows: P0=Control, P1=20% concentration of I. cylindrica extract, P2=40% concentration of I. cylindrica extract, P3=60% concentration of I. cylindrica extract, P4=80% concentration of I. cylindrica extract, and P5=100% concentration of I. cylindrica extract. The observed parameters include the height of R. exaltata weed, the number of leaves on R. exaltata weed, the percentage of leaf damage on R. exaltata weed, the percentage of leaf damage on maize plants, the height of maize plants, the number of leaves on maize plants, the fresh weight of R. exaltata weed, and the dry weight of R. exaltata weed. The data analysis involves Analysis of Variance (ANOVA) with a confidence level of 95%. If the ANOVA results indicate significant differences, the analysis is further conducted using Duncan's New Multiple Range Test (DMRT) Test. The research results show the study establishes the efficacy of 100% I. cylindrica extract, especially in the P5 treatment, in inhibiting R. exaltata growth. It significantly reduced weed height by 29.59%, leaf number by 27.68%, offspring by 30.69%, and caused leaf damage of 25.83% in the weed and 32.92% in maize. Additionally, it decreased the fresh and dry weights of the weed by 18.89% and 23.43%, respectively.