Safe Application Rate Research Articles

Relative toxicity of phenoxy herbicides onLehistes (Poecilia) reticulatus (Peters)

Phenoxy herbicides 2,4-D, its sodium and ethyl amine salts and ethyl esters, commonly used in aquatic weed eradication programmes, were tested by acute and static bioassay investigations on a cyprinid fishLebistes (Poecilia) reticulatus under laboratory conditions. The toxicities of these different formulations are compared and reported in relative toxicity ratings. ‘Safe application rate’ and ‘safe application factor’ equations were also calculated. Median lethal concentrations at various time intervals are also reported along with respective fiducial limits and regression equations. Comparative regressions are drawn for three time intervals, 24, 48 and 96 hr.

Safe and toxic application rates of boron for cocoa (Theobroma cacao) seedlings

In a preliminary study to ascertain the safe and toxic rates of boron for cocoa seedlings, the F3 Amazon and the Amelonado varieties were treated in the glasshouse by foliar spray with 0, 5, 10, 25 and 50 ppm B as solubor. It was observed that 5 ppm B was required to raise the leaf-B of six-month old cocoa seedlings from the deficiency to the sufficiency level. The critical levels were 32.5 ppm B for Amazon and 36.3 ppm B for Amelonado. B rates in excess of 5 ppm caused chlorosis, necrosis, and in extremely high rates, the death of the seedlings.