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Herbicide Deposition on Leaf Surfaces

Published online by Cambridge University Press:  12 June 2017

F. Dan Hess  and
Richard H. Falk
F. Dan Hess
Affiliation:
Biol. and Biochem. Res., Sandoz Crop Prot. Corp., 975 California Avenue, Palo Alto, CA 94304
Richard H. Falk
Affiliation:
Dep. Bot., Univ. California, Davis, CA 95616
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Abstract

Leaf surface morphology and physical characteristics of herbicide deposits on leaf surfaces can influence herbicide performance. Leaf surface topography, the degree and type of epicuticular wax formation, and the presence, type, and distribution of trichomes all influence the distribution of a given herbicide formulation sprayed onto a leaf surface. Depressions above anticlinal cell walls accumulate herbicide, thus lessening uniform distribution. As the amount of particulate wax increases, the size of individual spray drop deposits on the leaf decreases, thus resulting in reduced coverage. In many instances the presence of trichomes reduces optimal epidermal coverage by intercepting spray drops before they reach the epidermal surface. Adjuvants reduce the adverse influence of leaf topography, epicuticular wax, and trichomes on herbicide distribution, but their use usually does not yield an even coating over the entire leaf surface. Many herbicides, in pure form, are solids (i.e., crystals) rather than liquids. For most applications, herbicides are dissolved, dispersed, or emulsified in a water-based spray solution. After spraying, water and any solvents evaporate from the leaf surface and herbicides often return to their solid crystalline form. In the few cases that have been studied, less herbicide is absorbed when present on the leaf surface as a solid rather than as a liquid. In many instances, greater effectiveness of a postemergence herbicide may be obtained if attention is given to optimizing the distribution and physical form on sprayed leaf surfaces.

Keywords

Leaf surface morphologyherbicide formulationadjuvantscanning electron microscopy
Type
Special Topics
Information
Weed Science , Volume 38 , Issue 3 , May 1990 , pp. 280 - 288
Copyright
Copyright © 1990 by the Weed Science Society of America 

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References

Literature Cited

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