雜草種類具有其特殊適應力，能合理應付激烈變化之環境而繁衍子代。例如雜草種子或地下器官具有休眠期，且多能適應土中溫度及氧氣。本演講乃由雜草種內變異及雜草相變遷之觀點介紹，認識雜草對自然變遷及受人類行為干擾之環境的反應之重要性。此等基本資料之認識實為新時代雜草防治技術所不能缺。種內變異論及(1)生態型之分化，(2)適應型(cline)之分化，(3)種內對殺草劑感受性之變異。雜草相之變遷論及(1)多年生雜草之增多，(2)水生雜草之異常繁殖，(3)抗殺草劑雜草系統之演進。將來之防草技術若僅著重於避免作物生產之「為害」是不足的。我們必須認清包括人類之生態系中之農業的重要性。如此我們之防治雜草技術才能考慮農業生態環境。殺死所有雜草在防除上並非絕對需要，但能考慮防治之經濟平準更重要。為了建立新時代之雜草防治，我們需了解雜草及作物之生理及生態之基本資料。雜草相之變遷及特性，雜草與作物競爭之機能。新的雜草防治技術要點為巧妙互用化學、栽培、物理及生物之綜合防治法。最後要強調的是需大力推行雜草科學之教育。

A weed can be said to have an excellent diversity of itsown species in responding so rationally to serious changes of theenvironment as to leave its progenies for succeeding years. Forexamples , weeds have a period of dormancy in their seeds orunderground organs and many of them possess an adaptive measureto soil environment such as moisture and oxygen levels.In this presentation, the importance of recognition of the statehow a weed responds to and changes with the changes in naturaland manrs disturbing enviroments is introduced from a view of theintraspecific variation and community shift of weeds , as listedbelow. These can be a fundamental data for establishment of aweed control technology suitable to new era.lntraspecific variation; 1) differentiation of ecotypes, 2) c1 inaldifferentiation, 3) intraspecific variation in herbicide susceptibility.Community shift of weeds; 1) increase of perennial weeds , 2)unusal propagation of aquatic weeds , 3) evolution of herbicide 、resistant strains.For the coming technology in weed control , it is not enoughto simply eliminate "pest" for crop production. We must clarifythe standpoint of our agriculture in the ecosystem where man isinvolved , so that we may place the concept of weed controltechnology into the agroecosystem. It is not necessary to eradicateweeds completely , but to control the pest below a permissiblelevel. ln order to establish the concept of weed control suitableto new era , we require basic information in physiological andecological properties of weeds and crops , property and shift ofweed community , mechanisms of competition between crop andweed , mode and mechanism of a herbicide action in crop andweed. A key in new weed control technology is integratedcontrol systems which chemical control , cultural or physicalcontrol , and biological control all available to us are sophisticatedlycombined into. Also , we have to throw energy into theeducation in weed science.