Feasibility of Aerial Spraying of Southern Pine Seed Orchards¹

Abstract

Abstract A series of aerial applications were made with a helicopter and a biplane to evaluate the feasibility of using aircraft to apply 5 gallons per acre of a water-base spray to southern pine seed orchards. Application parameters were established by a mathematical model which predicts spray coverage. Data obtained on spray deposition at the canopy top and in the tree crown provide a basis for using aircraft to apply pesticides to seed orchards. More spray deposits were found in the upper tree crown than in the lower tree crown. The helicopter achieved higher quantities of deposit in the crown than the biplane. On a percentage basis, however, spray observed at each of the 3 crown levels was comparable in both aircraft. A greater number of spray drops was observed on the slash pine (Pinus elliottii Engelm.) needles than on the Ocala sand pine (Pinus clausa var. clausa (Chapm. Ex Engelm.) Vasey ex Sarg.), suggesting that higher application rates may be required to achieve comparable coverage in densely foliated pines. Under conditions similar to these trials, i.e. aircraft tank mix, drop size, foliage, meteorology, release height, and swath width, one should expect comparable results when treating southern pine seed orchards.