Formulation selection, and investigation of azadirachtin-A persistence in some terrestrial and aquatic components of a forest environment

被引:0
|
作者
Sundaram, KMS
Sundaram, A
Curry, J
Sloane, L
机构
[1] Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ont. P6A 5M7
来源
PESTICIDE SCIENCE | 1997年 / 51卷 / 01期
关键词
volatilization; rain-washing; foliar residues; residues in water; persistence in soil and litter;
D O I
10.1002/(SICI)1096-9063(199709)51:1<74::AID-PS606>3.0.CO;2-J
中图分类号
S3 [农学(农艺学)];
学科分类号
0901 ;
摘要
Five commercial formulations of azadirachtin-A (AZ-A) Margosan-O(R), Azatin-EC(R), Neem-EC(R), RH-9999 and Neemix(R) 4.5, were investigated for their volatilization and washoff potential in laboratory studies. Prior to the investigation, RH-9999 (a wettable powder) was mixed with water to provide an end-use formulation containing 35.6 g AZ-A kg(-1), while the remaining four formulations were investigated without dilution, Volatilization and washoff of AZ-A occurred more from white spruce foliage than from wax-coated glass plates. Neem-EC provided the lowest amount of loss, whereas Margosan-O provided the highest. Physical properties and atomization behaviour of the five formulations indicated that Azatin-EC was highly viscous and caused phase separation in droplets collected on glass plates after atomization in a rotary atomizer. RH-9999, despite its low viscosity, caused phase separation in droplets because of the heterogeneity of the wettable powder formulation. Based on the minimum loss of AZ-A due to volatilization and washoff from spruce foliage, and on the minimum potential for phase separation in droplets after atomization in a rotary atomizer, Neem-EC was considered to he the most appropriate choice for use in field studies to investigate environmental persistence and fate of AZ-A in terrestrial and aquatic matrices of a forest ecosystem. The Neem-EC formulation was sprayed at 40 and 80 g AI ha(-1) over single spruce trees and on litter and soil plots selected in a mixed-wood boreal forest in Ontario, Canada. In addition, outdoor aquaria containing stream water and sediment were also fortified with the formulation at 400 and 800 g AI ha(-1). Persistence of AZ-A was evaluated using one-year-old spruce needles, current-year shoots, spruce bark, litter, soil, stream water and sediment. The duration of persistence varied from 3 to 6 days in terrestrial matrices, whereas it ranged from 8 to 13 days in water, and 2 to 3 days in sediment. The half-life (DT50) values ranged from 10.7 h (for soil) to 71.6 h (for spruce bark) at the lower dosage rate, and from 18.8 h (for litter) to 76.2 h (for bark) at the higher dosage rate. The DT50 value for stream water was about 35 h regardless of the dosage rate applied. The data indicated that AZ-A was appreciably labile and short-lived in different forestry matrices, with low DT50 values.
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页码:74 / 90
页数:17
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