Variation in size and distribution patterns of granules of a blank hexazinone formulation were studied in both ground and aerial applications. Granule size ranged from 2.5 to 93 mg with 90% of the granules between 5 and 35 mg. The granule size frequency among weight classes did not change within a 5-m wide test swath from a truck-mounted applicator, indicating no impact on the distribution of active ingredient. The ground applicator did not produce a uniform deposition of granules. Average granule depositions were 11 ± 5 kg/ha and 16 ± 8 kg/ha for the target rates of 20 and 40 kg/ha, respectively. Aerial application with a helicopter-mounted bucket spreader produced a 27-m wide effective swath. Average deposition rates were 19 ± 5 kg/ha and 39 ± 9 kg/ha for the target rates 20 and 40 kg/ha, respectively. The optimal sample sizes for aerial application were estimated to be 27 and 50 samples for 40 (±10%) and 20 (±10%) kg/ha rates, respectively, with 90% certainty.

A small -plot, pneumatic applicator was developed to apply either granular herbicide formulations or liquid herbicides impregnated on commercial dry fertilizer to field research plots. Pre-weighed herbicide samples poured into a stainless steel, motor-driven belt, cone seeder are automatically sput into four subsamples in a four-outlet rota seed distributor run by a 12-volt electric motor, and delivered to four plastic venturi chambers. A gasoline engine-powered leaf blower forces air through a 10-cm diam polyvinylchloride (PVC) pipe to the input sides of the venturi chambers. The forced air stream carries the herbicide samples through 2.5-cm diam flexible plastic tubing to four deflector shields mounted 61 cm apart on a fiberglass boom. The applicator uniformly delivers granules up to 400 kg/ha in a 2.5-m wide swath.