<Dd> A diseased patch of vegetation or individual plants can be isolated from other, healthy growth . Specimens may be destroyed or relocated into a greenhouse for treatment or study . Another option is to avoid the introduction of harmful nonnative organisms by controlling all human traffic and activity (e.g., AQIS), although legislation and enforcement are crucial in order to ensure lasting effectiveness . </Dd> <Dd> Farming in some societies is kept on a small scale, tended by peoples whose culture includes farming traditions going back to ancient times . (An example of such traditions would be lifelong training in techniques of plot terracing, weather anticipation and response, fertilization, grafting, seed care, and dedicated gardening .) Plants that are intently monitored often benefit from not only active external protection but also a greater overall vigor . While primitive in the sense of being the most labor - intensive solution by far, where practical or necessary it is more than adequate . </Dd> <Dd> Sophisticated agricultural developments now allow growers to choose from among systematically cross-bred species to ensure the greatest hardiness in their crops, as suited for a particular region's pathological profile . Breeding practices have been perfected over centuries, but with the advent of genetic manipulation even finer control of a crop's immunity traits is possible . The engineering of food plants may be less rewarding, however, as higher output is frequently offset by popular suspicion and negative opinion about this "tampering" with nature . </Dd> <Dd> (See: pesticide application) Many natural and synthetic compounds can be employed to combat the above threats . This method works by directly eliminating disease - causing organisms or curbing their spread; however, it has been shown to have too broad an effect, typically, to be good for the local ecosystem . From an economic standpoint, all but the simplest natural additives may disqualify a product from "organic" status, potentially reducing the value of the yield . </Dd>

Which diseases do microorganisms cause in plants and animals