A plant disease control agent used to improve the heat tolerance and disease resistance of cabbage, tomato or melons, such as powdery mildew, yellow leaf roll, virus disease, vine blight, wilt or bacterial wilt. The formula is 10% to 80% by weight of plant extracts, and the solvent is water, wherein the plant extracts are octagonal plant extracts, clove essential oil, cinnamon oil, purple basil flower water or any two or more of the above Plant extracts.一種植物病害防除劑，用以提升白菜、蕃茄或瓜類的耐熱性以及抗病能力，例如：白粉病、黃化捲葉病、病毒病、蔓枯病、萎凋病或青枯病，配方由重量百分比為10%~80%的植物萃取液所組成，且溶劑為水，其中該植物萃取液為八角屬植物萃取液、丁香精油、肉桂油、紫羅勒花水或上述其中任二種以上之植物萃取液。
