Leaf structure as related to absorption of pesticides and other compounds.

TLDR: The various plant environmental, and chemical factors which affect absorption are examined in this review, and a variety of pesticides is considered, as well as certain growth regulators and other substances which are not, strictly speaking, “pesticides.

Abstract: Plants are sprayed and dusted with chemicals for numerous reasons. Some of the chemicals applied to plants exert their influence simply by remaining on the foliage surface; others must be absorbed and perhaps translocated before their activity is realized. Many of the compounds used have a mammalian toxicity less than that of table salt, whereas others exceed strychnine in toxicity. Likewise, many are relatively non-phytotoxic but others kill plants readily. Possible foliar residues which may be left by various pesticides are of course influenced by both absorption characteristics and metabolic breakdown. The various plant environmental, and chemical factors which affect absorption are examined in this review. A variety of pesticides is considered, as well as certain growth regulators and other substances which are not, strictly speaking, “pesticides.” A limited consideration is also given to recent findings relating to penetration of inorganic ions, where the mechanisms involved may bear certain similarities to the penetration of some organic substances which also ionize or hydrolyze during the course of their penetration. Because of this broad coverage, space precludes detailed discussions of all aspects of absorption and of associated structural relationships. These subjects are developed quite fully in many of the reviews listed below and in the introductions to some of the specific sections in this report. Also, only foliar absorption and movement within the leaf mesophyll and veins are considered. Long distance transport in the vascular system of the stems and roots is not included, since several excellent reviews and monographs on this subject have recently been published or are in preparation.