. Agricultural plant pest control : a study manual for commercial and governmental pesticide applicators . Weeds; Pests. The length of time the herbicide residue remains depends on the herbicide used, the rate of apphcation, and the soil moisture and texture. H Basics of Herbicide Selectivity It is important to understand how herbicides kill plants, why a herbicide is phytotoxic to one species and not another, and how herbicides can be used to best accomplish the results desired. Selectivity is relative. The most important factors that affect herbicide selectivity are: 1) structural difference
. Agricultural plant pest control : a study manual for commercial and governmental pesticide applicators . Weeds; Pests. The length of time the herbicide residue remains depends on the herbicide used, the rate of apphcation, and the soil moisture and texture. H Basics of Herbicide Selectivity It is important to understand how herbicides kill plants, why a herbicide is phytotoxic to one species and not another, and how herbicides can be used to best accomplish the results desired. Selectivity is relative. The most important factors that affect herbicide selectivity are: 1) structural differences in plants, 2) differences in absorption, 3) differences in translocation, 4) physiological differences, and 5) herbi- cide concentration. Combinations of these factors can be used to improve herbicide selectivity. ? Structural differences among plants permit selective applications. The narrow, upright leaves of a cereal plant lack the exposed leaf surfaces of a broadleaf plant. Water droplets can stick only to a small portion of an upright leaf surface. On the other hand, a broadleaf plant has a wide leaf surface which extends parallel to the ground and will hold more spray and therefore be affected more by the herbicide. Another important structural difference is the location of the growing point of the plant. The growing point of many grasses is pro- tected because it is located at the base of the plant. Contact sprays may injure the leaves of the grass plant but not contact the growing point. Broadleaf plants have exposed growing point at the tips of the shoots and in the leaf axils. The growing point is therefore more accessible to the herbicide. Waxiness, hairiness or pubescence of a plant may prevent spray droplets from adhering to the leaf. If the chemical droplet adheres to the leaf hairs without contacting the leaf surface, it will not be absorbed. On the other hand, hairs may collect and hold greater amounts of droplets, preventing the spray from running off the lea
Size: 1503px × 1662px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionamericana, bookl, booksubjectweeds
