(A12) APPLE: Malus domestica Borkhausen, 'Delicious', 'Golden Delicious', 'Yorking' Codling moth (CM): Cydia pomonella (Linnaeus) European red mite (ERM): Panonychus ulmi (Koch) Lesser apple worm (LAW): Grapholitha prunivora (Walsh) Predatory Mite (SP): Stethorus punctum (LeConte) Predatory mite (AF): Amblyseius fallacis (Garman) Obliquebanded leafroller (OBL): Choristoneura rosaceana (Harris) Oriental fruit moth (OFM): Grapholitha molesta (Busck) Redbanded leafroller (RBL): Argyrotaenia velutinana (Walker) Spirea aphid (SA): Aphis spiraecola Patch Spotted tentiform leafminer (STLM): Phyllonorycter blancardella (F.) Tarnished plant bud (PB): Lygus lineolaris (Palisot de Beauvois) Tufted apple bud moth (TABM): Platynota idaeusalis (Walker) White apple leafhopper (WALH): Typhlocyba pomaria McAtee Larry A. Hull Penn State Fruit Res. & Ext. Center Biglerville, PA 17307-0330 Phone: (717) 677-6116 (Ext. 215) Fax: (717) 677-4112 Email:
[email protected] AVAUNT ADJUVANT STUDY, 1999: A study was designed to evaluate the effectiveness of adding various adjuvants to the insecticide Avaunt. All treatments were applied to single-tree plots in a randomized block design consisting of 2 replicates of 'Delicious', 1 replicate of 'Golden Delicious' and 2 replicates of 'Yorking' with buffer trees between plots. All trees were planted to a spacing of 20 x 30 ft and were 15 yrs old. Experimental sprays were applied as complete sprays with a Durand-Wayland airblast sprayer calibrated to deliver 100 gpa at 2.4 mph. Applications dates for all materials are given as a footnote to all tables. A routine schedule of fungicides (Benlate 50DF, Dithane 75DF, Nova 40WP, and Ziram 76WP) was maintained throughout the experiment. The effect of the sprays on WALH was evaluated by counting the number of nymphs/25 injured leaves/tree. Effectiveness of the treatments on SA was evaluated by counting the number of aphid-infested leaves/10 top actively growing shoots, and the number of aphids/most infested leaf, where a rating scale (0-4) was used instead of counting live aphids (see table footnotes for scale). The number of aphid natural enemies was determined by counting the number found in a 3 min examination of each replicate tree. Effectiveness of the test chemicals on ERM and AF was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 125 leaves/treatment. The predator, S. punctum was observed by making 3-min counts of adults and larvae around the periphery of the trees. STLM was evaluated by counting the number of tissue-feeding mines present during a 5 minute examination around the periphery of each plot tree. OFM shoot injury and apples showing frass was assessed by determining the number of injured shoots per tree or apples with frass in a 5 min examination for each. OBLR shelters were counted in a 5 min examination of each plot tree on 13 Jul. TABM shelters were counted in a 5 min examination of each plot tree on 27 Jul. All larvae were collected and returned to the laboratory for identification. Effectiveness of chemicals on all fruit feeders was assessed by scoring for injury dropped apples on 29 Jun, 12 and 28 Jul, and 11 Aug and picked samples of 35 and 75 fruit per replication on 28 Jul and 8 Sep, respectively. Russet evaluations were made on Golden Delicious fruits (35 per replicate). Each replicate (3) was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>51% russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of % of surface russeted) are 0-30 (none to raised lenticels) 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface, 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to >51% russeted surface). Treatment means were separated using Fisher's Protected LSD Test at the P = 0.05 level. Pest pressure was high throughout the season. All Avaunt plus adjuvant treatments appeared to have some effect on reducing WALH populations with the adjuvants Dynamic and Damoil showing the most effect (Table 1). Only Avaunt plus Damoil demonstrated much activity on STLM populations. There appeared to be little effect of the treatments on the spirea aphid and its predators (Table 2). ERM populations were variable and somewhat inconclusive (Table 3). Populations of AF were high on all plots (Table 4). All Avaunt treatments reduced the number of apples showing evidence of internal worm injury in Jun, but the reduction was only fair (Table 5). Control of the internal lepidoptera complex (CM/OFM/LAW) in all fruit samples was only rated as fair for all Avaunt treatments (Table 6). The Avaunt plus Damoil treatment gave the highest percentage of clean fruit, again rated as only fair. A high percentage of the internal worms collected were CM.
