The problem of crop protection has changed dramatically since 1945. There is now a whole arsenal of chemicals with which to combat agricultural pests and diseases, but this development has itself many drawbacks. Such sophisticated techniques are available only to a minority of farmers; in most parts of the world the standard of crop protection remains abysmally low. In addition, modern crop protection methods have been criticized for relying too heavily on chemical control. Biological controls, both natural and contrived, have been neglected. In some cases involving misuse of agricultural chemicals, crops must be protected from the very measures intended for their protection. Meanwhile previously localized pests and diseases continue to spread worldwide.