Clubroot disease caused by the fungus Plasmodiophora brassicae is one of the main
obstacles to cabbage production in many countries. Plants infected with fungus will stunt their
growth and result in very low yields. The control of clubroot disease with synthetic chemical
fungicides is reported to be less effective because fungal spores can last very long in the soil,
besides that chemical control causes many negative effects. One alternative to environmentally
friendly control is to use weed extracts that contain allelochemical compounds that function as
fungicides. Chinese Cabbage (Brassica rapa subsp. L.) is a vegetable that has high economic
value. The aim of the study was to determine the effectiveness of extracts of alang-alang, teki
grass, kirinyuh and babandotan on the intensity of clubroot disease, growth, and yield of
Chinese cabbage. The research was carried out at the Experimental Garden of the Faculty of
Agriculture and Fisheries, Universitas Muhammadiyah Purwokerto from September 2021 to
November 2021. The study was arranged using a single factor Completely Randomized Design
(CRD) consisting of 7 levels of treatment with 5-time replications. The results showed that the
weed extract treatment and chemical fungicide tested had no significant effect on plant fresh
weight, the number of leaves, plant height, stem diameter, but it had a significant effect on
disease severity, leaf area, root fresh weight, and root volume. Treatment of babandotan extract
(G4) showed the highest leaf area (10,458 cm2) which was not significantly different from
healthy plants. The treatment of giving nutmeg extract (G3) on average can reduce the severity
of the disease from 74% (moderate intensity) to 49.52% (mild intensity). Keywords: fungicide,
clubroot, Chinese cabbage.