The effectiveness of <i>Zingiber zerumbet</i> extract on the growth of <i>Lasiodiplodia theobromae</i>, caused dieback disease on nutmeg plants

Abstract Lasiodiplodia theobromae is one of the causes of dieback disease in the nutmeg plants that can reduce crop productivity up to 70%. The use of synthetic fungicides to control L. theobromae often has a negative impact on the environment. Therefore it is necessary to control alternatives that are relatively effective and safe for the environment, such as botanical fungicides. One of the plants that can be used as botanical fungicides is the rhizome of the Zingiber zerumbet . The pathogenic fungus isolate used was L. theobromae , while the rhizome of the Z. zerumbet used was obtained from Simpang Teritit Village, Wih Pesam District, Bener Meriah Regency. The concentrations of Z. zerumbet rhizome extract used were 1%, 2%, 3%, 4%, and 5%. The results showed that the application of Z. zerumbet rhizome extract with different concentrations suppressed the growth of the fungus L. theobromae in-vitro. Application of Z. zerumbet rhizome extract with 5% concentration showed the highest inhibition of L. theobromae fungus colony growth up to 7 HSI, which was 72.79% with a colony diameter of 20.07mm. Z. zerumbet rhizome extract at 5% concentration reduced conidia production of L. theobromae , which was 11.88 x 10 9 conidia/ml.