Foliage spray

Chapman, Pearce, and Avens (4, 20) investigated the relation between chemical composition and insecticidal efficiency of various dormant and foliage spray oils against several common insect pests of deciduous trees, and found it to be positive. They concluded that an oil which is highly paraffinic in character is the most desirable type. Saturated narrow-cut petroleum fractions were used by Pearce, Chapman, and Frear 21) in a study of the influence of molecular weight and structural constitution on the insecticidal efficiency of such oils to eggs of the oriental fruit moth, Grapholitha molesta (Busck). Correlations between efficiency and various properties were compared on the basis of composition. The value of paraffinicity was illustrated, and the importance of other properties was indicated. 

Comparisons were made with odorless kerosene and conventional summer tree spray oils. All applications in these studies were made to the point of runoff (200 to 400gallons per acre). As shown in Table II, emulsions of the isoparaffinic oil were safe at concentrations far in excess of the usual 1.5% maximum recommended for foliage sprays. 

Solid urea containing 0.8—2.0 wt% biuret is primarily used for direct application to the soil as a nitrogen-release fertilizer. Weak aqueous solutions of low biuret urea (0.3 wt% biuret max) are used as plant food applied to foliage spray. 

Perhaps most remarkably, the maximum vapor concentration observed for the systemic root soak followed by gel capsule treatments was over 150 ng/m (day 12), while for foliage spray it was only 50 ng/m (day 1). This in itself confirms the postulated evaporative loss route for systemic insecticides, and suggests that it is far more pronounced than indicated by the chamber study. Calculation of vapor fluxes from multiple air sample data—and thus quantitation of vapor losses—has not yet been completed. 

Figure 11. Carbofuran residue in high volume air samples taken above rice paddies treated by foliage spray (0) or by foliar spray followed by granular broadcast treatment (A) (51) (each point = 8 hr of sampling at 623 L/min)...

Ferreira, G.A.L. Seiber, J.N. Volatilization of three N-methylcarbamate insecticides from rice plants following root-soak systemic and foliage spray treatments. 

Leaves with notched edges. Cause Black vine weevils. The wingless, A", brownish black adults feed on the foliage spray leaves several times with pyrethrin for major infestations. The small, C-shaped, white grubs of these weevils feed on the roots and weaken the plant drench the soil around the base of the plant with a solution of parasitic nematodes. 

Water-soluble copper compounds are in any case unsuitable as foliage sprays, due to their strong scorching effect. The phytotoxity of water-insoluble copper compounds is weaker, and is to be expected when more soluble copper compounds are formed than needed. Phytotoxicity is caused by the copper(ll) ions penetrating the plant cells. Fortunately, the translocation of copper(II) ions is moderate in plants, so that only local damage occurs and the whole plant is not killed. 

In normal foliage spraying with benomyl, the pH of the aqueous suspension is close to neutral, so that the conversion time on the plant and in the plant fluids is probably of the same order of magnitude as under aqueous neutral or slightly acid conditions. However, in the suspension applied the persistency of benomyl is incereased by rapid drying of the spray, which prevents further decomposition of the active substance. 

The most well-known heterocyclic derivative is diazinon which has widespread application as a contact insecticide and acaricide (see below). It is used against flies and a wide range of sucking and leaf-eating insects. Soil half-life is about 3-6 months, whereas that of malathion is about 1-2 weeks. It is utilised both as a foliage spray and in soil granule formulations. Diazinon can be used for seed treatment. 

In areas with low soil Se, applications of Na2Se03 to soils or as a foliage spray are proposed for correcting Se nutritional deficiencies. However, in view of the toxic properties of Se salts, these practices should be carefully controlled and the addition of Se to soil, at 10 g ha" affected its contents in grains of barley and oats, from 0.019 to 0.26 mg kg" and from 0.032 to 0.44 mg kg", respectively (Table 6.9 Gupta and Gupta 2000). 

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