Airblast Experiment, 1988

Experimental sprays were applied to 2-tree plots in a randomized block design consisting of 2 replicates of ‘Yorking,’ 2 replicates of ‘Stayman,’ and 1 replicate of ‘Golden Delicious.’ Experimental sprays were applied with a Friend Airmaster ‘309’ at 25 gal/acre per alternate side spray (50 gal/acre, both sides) driven at 2 mph. Rates for treatments are listed as amounts/acre/both sides spray. Spray dates for the alternating side treatments were 22 Apr (Danitol treatments only, Orthene was added, complete spray); 23 and 27 May; 6, 13, 20, and 28 Jun; 5, 13, 22, and 28 Jul; 4, 11, 18, and 25 Aug; and 1 Sep. Lannate + Imidan was substituted on 23 and 27 May for the Lorsban + Lannate and Penncap M treatments and on 25 Aug and 1 Sep for the Lorsban + Lannate treatment only. Penncap M was substituted for the Danitol treatments on 6 Jun; 13, 22, and 28 Jul; 4, 11, 18, and 25 Aug; and 1 Sep. Savey was added to the Danitol treatment on 28 Jun and 5 Jul. Swat was added to the Larvin treatment on 6 Jun and to the Larvin, Larvin + Lorsban, and Penncap M treatments on 13, 20, and 28 Jun. Vendex 4 L (475 ml/acre) was added to the one side of all treatments except the Danitol treatments on 13 Jul. On the Lorsban + Lannate treatment, the rate of Lorsban was increased to 908 g/acre and Lannate was dropped on 13, 22, and 28 Jul. Effectiveness against the aphid complex was evaluated by counting the aphid-infested leaves/10 terminals and the aphids on the most infested leaf/terminal. The effectiveness of the sprays against WALH was evaluated by counting the nymphs on 25 leaves/tree. STLM was evaluated by a 5-min count of mines around the periphery of test trees. Effectiveness of the test chemicals against ERM was evaluated by counting mites several times during the season on samples of 25 leaves/tree, 125 leaves/treatment. The effect of sprays on S. punctum was evaluated by 3-min counts of adults and larvae around the periphery of test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after 1 Jul and samples picked on 22 Aug and 20 Sep. Apple samples averaged 181 fruits/replicate and 905/treatment. Pest pressure was heavy throughout the season. Russet ratings are based on 30 ‘Golden Delicious’ apples/replicate, 30/treatment. Fruits were rated as 1 (no russeting), 2 (light russeting), 3 (moderate russeting), or 4 (severe russeting). Possible ranges were 30-60 (none to light), 60-90 (light to moderate); 90-120 (moderate to severe).