Control of Plum Curculio, 1991

Abstract

Abstract Test 1 was set up to compare effectiveness of different schedules of Asana, Guthion, and Lorsban. Treatments were arranged in a randomized block design and replicated three times on single tree plots of'McIntosh' apples. These trees were 25 years old, 4.6 m high, and planted on seedling rootstocks 5.8 × 12.5 m apart. Plots were separated by one or more unsprayed buffer trees. Sprays were applied dilute to runoff with a hand sprayer (32 kg/cm2) at pink (1 May), petal fall (14 May), first cover (24 May), and second cover (5 Jun). Fruit damage was evaluated on 14 Aug by examining 50 dropped and 100 picked apples from each tree for both feeding damage and oviposition scars. Test 2 was set up to compare effectiveness of post petal fall border row treatments versus complete sprays of Guthion in controlling plum curculio. The following treatments were compared: (1) Standard Plot—All trees in each plot were sprayed with Guthion 35 W (11.6 oz form/100 gal) at petal fall (14 May), first cover (24 May) and second cover (5 Jun); (2) Standard Petal Fall—All trees were sprayed with Guthion 35 W (11.6 oz form/100 gal) at petal fall (14 May); (3) Border Row Plot—All trees were sprayed at petal fall (14 May) with Guthion and trees along the perimeter of plots were sprayed at first cover (24 May) and second cover (5 Jun). These border sprays were applied to single trees around the perimeter of plots in Orchard 12 and to the two outer rows of trees around the perimeter of plots in Orchard 12B. Each treatment was replicated four times. Two replications were set up in rectangular 9-tree plots of 'McIntosh' apples in Orchard 12. Trees in these plots were 25 years old, 4.6 m high, and planted on seedling rootstocks 5.8 × 12.5 m apart. Another two replications were set up in rectangular 24-tree plots in Orchard 12B. Trees in this orchard were 12 years old, 3.2 m high, and planted on M111/M9 interstem rootstocks 8.5 × 4.6 m apart. Trees in Orchard 12B were planted in three 8-tree rows consisting of two adjacent 'McIntosh', 'Cortland', 'Golden Delicious', and 'Delicious' trees. Fruit damage was evaluated on 14-15 Aug by examining 50 dropped and 100 picked apples from the center 'McIntosh' tree in each plot in Orchard 12 and 50 picked apples from each of two trees (one 'Golden Delicious' and one 'Cortland') in the center of each plot in Orchard 12B.