Tree foliage

This paper establishes toxicologically-safe levels for total residues of parathion, azinphosmethyl, methidathion and their oxons on tree foliage and reports these levels in terms of absorbance units as determined by the rapid field method. Safe levels for a new insecticide, chlorthiophos, are also proposed based on preliminary residue data. Chemical structures of the four insecticides mentioned above are shown in figures 1, 2, 3 and 6. 

Safe Levels for Parathion, Azinphosmethyl, Methidathion and Their Oxons on Tree Foliage... 

Table II gives a procedure for establishing safe levels for total dislodgeable thion + oxon residues on tree foliage.

Table I. Establishment of Safe Levels on Tree Foliage (in ug/cm ) Using the Results of Dermal Dose-ChE Response Curves and Field Reentry Studies according to Knaak et al. (3)...

Present methods for the detection and population survey of spruce budworm rely on the sampling of egg masses on tree foliage. Pheromone traps could probably detect moths at lower densities than the present method and this information could be used to prevent or decrease the development of an epidemic infestation of spruce budworm. However, a great deal of work is still required to correlate trap capture with moth population densities and with damage to trees. 

This paper reviews observations on the deposition of spray drops on trees, foliage, and the floor of coniferous forests. 

Toxic effects produced on a lepidopteran species by ingestion of enniatin complex do not appear to have been noted previously. With such properties, the enniatins could affect populations of spruce budworms in the field if produced in sufficient quantity by F. ave-naceum on budworm-infested foliage. Definitive quantitative field data on enniatins and other fungal toxins associated with host-tree foliage, both insect-free and budworm infested, remain to be collected. Preliminary attempts to isolate enniatins from detached and autoclaved foliage of Abies balsamea inoculated with FA 120 were inconclusive. 

Juinchang, R., Freedman, B., Coles, C., Zwicker, B., Holzbecker, J., Chatt, A., 1995. Vanadium contamination of lichens and tree foliage in the vicinity of three oil-tired power plants in eastern Canada. J. Air Manag. Assoc. 45,461 64. 

Particulate sulphates are not thought to be a damaging agent unless hydrolysed to sulphuric acid while lodged on the plant/ tree foliage. 

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