Karl Mierzejewski

Conventional application equipment: aerial application

Chemical control of insects, diseases and weeds began in earnest with the introduction of organic pesticides in the 1940s. Chemical pesticides offer a powerful control method and, until recently, their use had been overemphasized to the detriment of research and development of cultural and biological control methods. Impacts on non-target organisms and emergence of resistance to chemical pesticides prompted the development of biopesticides as well as the implementation of integrated pest management, where pesticides are used compatibly as one of many control methods.

Bacillus thuringiensis field applications: Effect of nozzle type, drop size, and application timing on efficacy against gypsy moth

Abstract In a series of recent studies, we evaluated the influence of delivery systems, drop size and application timing on the efficacy of aerially applied Bacillus thuringiensis against gypsy moth infestations. Use of different nozzle systems including Micronair, Flat Fan or Twin Jet, did not appear to result in significant differences in Bt coverage efficiency, foliage protection or population reduction. Nor was there any significant difference in population reduction when Bt was applied at two different drop sizes with volume median diameters of 110 and 163 μm. The efficacy of different formulations on larval populations were similar when used against the younger 1st and 2nd instar but differed when treatment was delayed until the population matured to the 3rd and 4th instar stages.

Deposition of Aerially Applied BT in an Oak Forest and Its Prediction with the FSCBG Model

Abstract Data are provided from 17 single-swath aerial spray trials that were conducted over a fully leafed, 16-m tall, mixed oak forest. The distribution of cross-swath spray deposits was sampled at the top of the canopy and below the canopy. Micrometeorological conditions were measured above and within the canopy during the spray trials. The USDA Forest Service FSCBG (Forest Service-Cramer-Barry-Grim) model was run to predict the target sampler catch for each trial using forest stand, airplane-application-equipment configuration, and micrometeorological conditions as inputs. Observations showed an average cross-swath deposition of 100 IU cm−2 with large run-to-run variability in deposition patterns, magnitudes, and drift. Eleven percent of the spray material that reached the top of the canopy penetrated through the tree canopy to the forest floor. The FSCBG predictions of the ensemble-averaged deposition were within 17% of the measured deposition at the canopy top and within 8% on the ground beneath the...

Effects of droplet density and concentration on the efficacy of bacillus thuringiensis and carbaryl against gypsy moth larvae (Lymantria dispar L.)

Abstract The feeding behavior of gypsy moth larvae exposed to two pesticide deposits (Bt and carbaryl) on oak leaf disks was monitored to determine the relationships between its efficacy and application parameters (droplet density and pesticide concentration). A range of pesticide concentrations and droplet densities (from 9 to 149 droplets/cm2) was used to simulate high and low application rates produced by different methods of application in the field. The LD50 and the LC50, appeared to be affected by the spatial distribution of the deposit on the leaf surface. Both Bt and carbaryl showed a decreasing LD50 at increasing time after spray. The LD50 of Bt decreased from 14.1 BIU/liter to 3.1 BIU/Iiter between 48 and 144 hours after spray. The results show that feeding inhibition by Bt is more closely related to concentration than to droplet density and dose per unit area with the highest feeding inhibition occurring at 10 BIU/liter at 9 droplets/cm2. With carbaryl, an increase in both concentration and dro...

Statistical comparison of the AGDISP model with deposit data

Abstract An aerial spray Agricultural Dispersal (AGDISP) model was tested against quantitative field data. The microbial pesticide Bacillus thuringiensis (Bt) was sprayed as fine spray from a helicopted over a flat site in various meteorological conditions. Droplet deposition on evenly spaced Kromekote cards, 0.15 m above the ground, was measured with image analysis equipment. Six complete data sets out of the 12 trials were selected for data comparison. A set of statistical parameters suggested by the American Meteorological Society and other authors was applied for comparisons of the model prediction with the ground deposit data. The results indicated that AGDISP tended to overpredict the average volume deposition by a factor of two. The sensitivity test of the AGDISP model to the input wind direction showed that the model may not be sensitive to variations in wind direction within 10 degrees relative to aircraft flight path.

Efficiency of deposition of pesticide droplets on flat cards and spheres

Abstract The mass flux of a cloud of droplets heading towards a collector can be decomposed into its horizontal and vertical components. While only the vertical mass flux contributes to droplet deposition on a flat card by the mechanism of sedimentation, both flux components contribute to deposition on a sphere by both mechanisms of inertial impaction and sedimentation. Calculated collection efficiencies decrease as wind speed increases for cards but as wind speed increases for spheres, a minimum collection efficiency is reached at a certain wind speed. The average collection efficiencies, as measured in the field trial portion of this study, are highly linearly correlated with wind speed for cards. For spheres, however, no correlation was found between the average collection efficiency and wind speed.

A model for the prediction of the evaporation rate of pesticide droplets aerially sprayed from aircraft

Abstract A model was developed to predict the evaporation rate of pesticides that are sprayed aerially. Deposit data collected from Bacillus thuringiensis (Bt) spray field trials and analyzed by washoff and image analysis methods were used to test the model. Results showed that the model with a mode based on the theoretical evaporation formula of a droplet of pure water tended to overpredict the evaporation rate of Bt by 11 % on average.

Comparison of calculated evaporation rates of water droplets with those of pesticide droplets measured in a wind tunnel by Dennison and Wedding (1984)

Abstract Calculations, based on Fuchs’ (1959) formula, of evaporation rates of water droplets freely falling through air are compared with those of water‐based pesticide droplets measured by Dennison and Wedding (1984) in a wind tunnel. Results indicate that calculations of evaporation rates of water droplets, are not significantly different from measurements of that of water‐based pesticide droplets under conditions of 20 °C and 20% relative humidity, but different under other measurement conditions.