SYMPOSIA PAPER Published: 01 January 1989

Drop Size Spectra, Spreading, and Adhesion and Physical Properties of Eight Formulations Following Spray Application under Laboratory Conditions


Three oil-based formulations, Dipel® 6L, Dipel® 8L and Dipel® 12L, and five aqueous formulations, Thuricide® 48LV, Thuricide® 64B, Futura® XLV, Dipel® 6AF and Dipel® 8AF, of Bacillus thuringiensis (B.t.) were sprayed at a dosage rate of 30 BIU per ha in a laboratory chamber using a spinning disc atomizer. The formulations were mixed with Day-Glo® fluorescent pigments to facilitate drop detection on sampling surfaces. Spray drops were sampled with Kromekote® cards and deposits were collected on glass plates. Drops were counted on balsam fir foliage of potted seedlings. Physical properties such as, viscosity, surface tension, volatility and pseudo-plastic behavior, were determined for the formulations.

Spray drops of the three oil-based Dipel formulations were completely spread on Kromekote cards and fir foliage,, The degree of spreading was influenced by viscosity and surface tension values. Drops of the five aqueous formulations were either totally spherical or hemispherical on all sampling surfaces, and the degree of spreading was related to surface tension and pseudoplastic behavior.

The data on drop size spectra indicated little influence from the physical properties of formulations. This is because of the differences in the application rates used. All the-three oil-based Dipel formulations were non-volatile and provided 100% recovery of the spray volume on the glass plates. The four aqueous formulations, except Thuricide 64B, provided lower percent recovery of the spray volume on glass plates.

Author Information

Sundaram, A
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Developed by Committee: E35
Pages: 129–141
DOI: 10.1520/STP22913S
ISBN-EB: 978-0-8031-5092-8
ISBN-13: 978-0-8031-1450-0