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Faculty

HERBERT B. SCHER, Research Engineer

Department of Biological and Agricultural Engineering
Room 2042 Bainer Hall
(530) 754-9594
E-Mail: hbscher@ucdavis.edu

Current Research

Dr. Scher worked in industry before coming to UC Davis where his research interests centered on controlled release delivery systems for pesticides. These systems included microcapsules and microparticles, granules, surfactant barriers and propesticides. Controlled release formulations have taken on added significance in recent years because of the realization that these types of formulations can (a) reduce worker exposure by means of reduction in pesticide toxicity and (b) minimize pesticide impact on the environment by reducing evaporation and leaching. Additionally, because environmental losses such as ultraviolet degradation can be reduced, less active ingredient needs to be applied to achieve biological efficacy and, therefore, further reduction of pesticide levels in the environment can be achieved. It has also been realized that controlled release pesticide formulations have the ability to improve pesticide selectivity, that is reduce crop phytotoxicity. Lastly, controlled release pesticide formulations are often useful because they can reduce physical incompatibilities when mixtures are used in spray tanks and can reduce biological antagonism when mixtures are applied to the field.

Dr. Scher became part of the UC Davis faculty in 2001. In addition to controlled release delivery systems his research interests include:

Reduction of Fines During the Spray Process and During Rebound from Surfaces for Agricultural and Consumer Products ? Fines from agricultural sprays can cause drift onto adjacent fields resulting in pesticide losses. Inhalation of fines from sprays of agricultural and consumer products can have toxic and/or allergenic consequences. Fines can be reduced by the addition of low levels of specific high molecular weight polymers to the product formulation. Reduction in fines can be correlated to the increase in elongational viscosity.

Formulation of Biopesticides to Increase Shelf Life ? Lagenidium giganteum, which has been used successfully for mosquito control and is a registered biological control agent with state and federal agencies, has had limited application due to its short biological shelf life. A water in oil emulsion formulation of Lagenidium giganteum is being developed that extends both physical and biological shelf life and at the same time can be sprayed efficiently without dilution with water to achieve optimum efficacy.

Reduction of Organophosphate Insecticide (from Dormant Spray Application) Levels in Waterways ? Organophosphate insecticides are often applied with copper fungicides in dormant spray applications. It is well known that the presence of copper can have a catalytic effect on the decomposition of organophosphate insecticides. This might be an area of inefficiency in dormant spray mixtures where the presence of copper can accelerate the decomposition of organophosphate insecticides on the tree surface and hence higher rates of organophosphate insecticides need to be applied to achieve control (hence more burden on the environment). Organophosphate decomposition rates are being studied as a function of the absence or presence of copper, pH (use of buffers) and the absence or presence of crop oil.

Representative Recent Publications

Scher, H. B., and J. L. Chen. 2000. Microcapsules containing suspensions of biologically active compounds and ultraviolet protectant. U.S. Patent 6149843.

Scher, H. B., M. Rodson, J. L. Chen, and K. S. Lee. 2000. Microencapsulated compositions. U.S. Patent 6133197.

Scher, H. B., I. M. Shirley, J. E. VanKoppenhagen, R. Follows, P. Wade, F. G. P. Earley, and D. B. Shirley. 2002. Variable release microcapsules. U.S. Patent 6485736.

Scher, H. B., and M. Rodson. 2002. Microencapsulated Acetochlor herbicidal composition. U.S. Patent 6340653.

Scher, H. B., R. J. R. Lo, J. L. Chen, J. E. VanKoppenhagen, and I. M. Shirley. 2003. Dry water-dispersible compositions of microencapsulated pesticides. U.S. Patent 6555122.

Scher, H. B., J. E. VanKoppenhagen, K. S. Lee, I. M. Shirley, P. Wade and R. Follows. 2003. Base triggered release microcapsules. U.S. Patent 6544540.

Scher, H. B., J. E. VanKoppenhagen, K. S. Lee, I. M. Shirley, P. Wade and R. Follows. 2003. Acid triggered microcapsules. U.S. Patent 6514439.

Scher, H. B, P. J. Mulqueen, N. P. Green, and C. J. Piper. 2004. Emulsions. U.S. Patent 6710092.

Giles, D. K., D. Downey, H. Scher, D. Winetzky, and T. Becker. 2004. Suppression of aerosol generation during spraying and deposition of consumer products. Atomization and Sprays. In Press.

Scher, H. B. 2004. Mechanisms of controlled release and design of test methods. Proceedings
of the Controlled Release Society – 31st Annual Meeting. In Press.

Membership in Professional Societies

American Chemical Society
Controlled Release Society

Research Support