利用Rhizoctonia solai為材料，篩選三十種冬裡作田雜草不同濃度水溶萃取液對土壤微生物之活性。其中有活性之雜草者，當水溶萃取液濃度增加，其抑制活性亦增加。紫花霍香薊(Ageratum boustonstonianum)、看麥娘(Alopocurus aequalis var. amurensis)、昭和草(Erechtites valerianafolia)及小葉碎米薺(Cardamine parviflora)等四種活性較強之雜草，再進一步測試對猝倒病菌(Pythiuma phanidermatum)、立枯病菌(R. solani)、白絹病菌(Sclerotium rolfsii)、疫病菌(Phytophthora capsici)及鐮刀病菌(Fusarium sp.)等五種土壤病菌之效果。紫花霍香薊10%(W/V)水溶萃取液對五種病原菌生長的抑制最強，對猝倒病菌可達完全抑制之效果。看麥娘對立枯病菌和疫病菌菌絲生長的抑制可達60%。昭和草對猝倒病菌和立枯病菌菌絲生長之抑制率為70及47%。30種冬裡作田雜草水溶萃取液經沙門菌斑點測試，結果濾紙圓周皆未出現菌落環，顯示此等水溶萃取物質皆不具致變性。

Aqueous extracts of 30 upland weeds were screened for activities on Rhizoctonia solani.For the extracts that showed activites, the extent of mycelial inhibition were concentration related. Of the weeds screened, Ageratum houstonianum. Alopocurus aequalis, Erechtites valerianafolia and Cardamine parviflora produced the strongest activities; The extracts of these four weeds futher tested on Pythium aphanidermatum,R, soani, sclerotium rolfsii,Phytophthora capsici and Fusarium sp.. Mycelial growth of P.aphanidermatum was completly inhibited by extract,10%(w/v) level resulted in more than 60% inhibition of mycelial of R. solani and p.capsici.Aqueous extracts of 30 weeds were tested for mutagenicity by Ames test using Salmonella spp;all results were negative.