Pesticide Drift: Deposit Efficiency from Ground Sprays on Cotton1

Carbofuran residues in grasshoppers and vegetation from aerially sprayed prairie pastures: Potential effects on wildlife

“…The mean deposits of 43 1 and 64 9% of the nominal rate of application measured on filter papers in the two pastures are similar to results reported from analysis of horizontal artificial targets used to sample deposit of insecticide from multiswath application by fixed wing aircraft Applications at volumes of spray per hectare the same as ours (9 4 L/ha) have resulted in deposits ranging from 61 to 94% [19] and Days after appl icatton 42 to 44% [20] to 5 to 30% [21] of the applied rates of active ingredient Higher rates of spray (20 76 L/ha) have similarly resulted in deposits of 28 to 100% [22], 63 and 73% [23], 30 to 40% [24], and 67 to 88% [25] of the applied rates Our variability of deposit on the filter papers (1987 C V 76 4%, 1988 C V 66 5 % ) is also comparable to that found by other investigators 73 and 83% [20], 31 to 75% [25], 17 to 27% [ 2 5 ] , and 103 to 213% [21], although variability has commonly not been reported [19,22,23,26] The filter paper samplers may have underestimated de posit because horizontal artificial targets are less efficient at trapping small spray droplets than are the irregular, multifaceted, often hair-covered and serrated surfaces of natural foliage [27,28] Comparisons of insecticide deposit on hori zontal artificial targets at crop canopy height with deposit on foliage per unit area have resulted (as percentages of applied rates) in 54% on crested wheatgrass vs 42% on Teflon" discs [16,20], and 46 to 51% on alfalfa vs 61 to 94% on aluminum foil targets [19] Artificial targets have thus been less efficient than foliage in trapping spray in some experiments and more efficient than foliage in others, including our 1988 application…”

“…The amount of pesticide trapped by foliage varies with the density of vegetation, so that some fraction of the deposit is found on the substrate below the crop canopy Johnson et a1 [29] reported mean depositions of aerially applied deltamethrin on crested wheatgrass and substrate as 58 and 21 070, respectively, in one trial and 48 and 20% in a second trial Similarly, Ware et a1 [26] recovered 39% of ground sprayed DDT on cotton foliage and 34% on the substrate below the canopy in one trial and 83% from foliage vs 6% from the substrate in a second trial in which the foliage was much denser than it was in the first The amount of pest1 cide trapped by foliage alone is therefore unlikely to provide a measure of total deposit in most spray operations The deposit on the alfalfa-grass pasture was probably greater than that on the native grass pasture, as indicated by the residues detected in the filter paper samplers and grasshoppers, and by the initial residues of 19 4 pg/g predicted in vegetation by the model (Fig 2) The lower mean concentrations in foliage at 3 h postspray from the alfalfa-grass pasture (10 8 pg/g) compared to the native grass pasture (13.3 pg/g) can be explained by the diluting effect of the greater density of foliage of the former relative to the latter [30,31].…”

Decomposition and Metabolism of the Ethylene-releasing Compound CGA-15281 in Peach Orchard Soils

“…The magnitude of nontarget placement varies widely with field conditions, chemical applied, and method of application. Estimates of 17% to 61% nonplant placement on annuals (8) are, however, not uncommon. Because of the po tentially significant volume of material entering the soil zone, it is of considerable ecological interest to ascertain the fate of these compounds in orchard soils.…”

A mathematical model of aerial deposition of pesticides from aircraft.

“…Their trajectory calculations for a nonevaporating drop indicate that 15-pm particles could easily travel 610 m (2000 ft) before impact. Ware et al (12) studied aerial drift for various types of spray nozzles and concluded that most of the drift was from droplets less than 100 pm in diameter.…”