APS_April 2023

81 (2016), and return fruit set following Year 2 (2017) of a hand-thinning and summer plant-growth 729 regulator (PGR) experiment. Hand thinning (Thin) consisted of reducing all fruitlet clusters to 730 single fruitlets. The PGR treatment consisted of 150 mg∙L -1 ethephon followed by two (2016) or 731 three (2017) applications of 5 mg∙L -1 1-napthaleneacetic acid. Hand thinning and the first PGR 732 applications occurred approximately 5 weeks after ful bloom in both years, wi subsequent 733 PGR applications made on approxi ately two-week intervals. 734 Spring 2017 Bloom Density (clusters/cm 2 TCSA) Spring 2018 Fruitlet Density (clusters/cm 2 TCSA) Treatment ‘Chisel Jersey’ z ‘Chisel Jersey’ ‘Brown Snout’ Control 2.70 4.90 0.00 Thin only 2.67 4.89 0.01 PGR Only 0.43 8.52 0.00 Thin + PGR 2.45 5.98 0.12 Crop Density P=0.026 y P=0.063 P=0.218 PGR P=0.498 P=0.016 P=0.177 Crop Density:PGR P=0.783 P=0.105 P=0.252 z n=6 trees per treatment for ‘Chisel Jersey’ in both years; n=4 trees per treatment for ‘Brown 735 Snout’. 736 Table 2. Cumulative yield (2016-2018) of seven cultivars from a three-year experiment at Lyndonville, NY. Hand thinning and the 740 first plant growth regulator applications occurred approximately 4-6 weeks after full bloom in both years, with subsequent applications 741 made on approximately two-week intervals. 1-napthaleneacetic acid (NAA) was applied at 5 mg∙L -1 and ethephon (Eth) at 150 mg∙L -1 . 742 2016-2018 cumulative yield (kg/tree) Table 2. Cumulative yield (2016-2018) of seven cultivars from a three-year experiment at Lyndonville, NY. Hand thinning and the first plant growth regulator applications occurred approximately 4-6 week after full bloom in both years, with subsequent applications made on approximately two-week intervals. 1-napthaleneacetic acid (NAA) was applied at 5 mg∙L -1 and ethephon (Eth) at 150 mg∙L -1 . ri 17 Bloom Density (clusters/cm 2 TCSA) ri g 2018 Fruitlet Density (clusters/cm 2 TCSA) regulator (PGR) experim nt. Hand thinning (Thin) c nsisted of reducing all fruitl t c usters to 30 sing e fruitlets. The PGR treatment co s sted of 150 mg∙L -1 ethephon followed by wo (2016) or 1 three (2017) applications of 5 g∙L -1 1-napthaleneacetic acid. Hand thinning and the first PGR 2 applications occurred approxi ately 5 weeks after full bloom in both years, with subsequent 3 PGR applications made on approximately two-w ek intervals. 4 S ing 2017 Bloom Density (clusters/cm 2 TCSA) Spring 2018 Fruitlet Density (clusters/cm 2 TCSA) Treatment ‘Chi el Jersey’ z ‘Chisel Jersey’ ‘Brown Snout’ Control 2.70 4.90 0.00 Thi nly 67 89 1 PGR Only 0 43 8 52 0 Thin + PGR 2 5 5 98 12 Crop Density P=0.026 y P=0.063 P=0. 18 PGR 498 16 177 Crop Density:PGR 783 105 252 z n=6 trees per treatment for ‘Chisel Jersey’ in both years; n=4 trees per treatment for ‘Brown 735 Snou ’. 6 Table 2. Cumulative yield (2016-2018) of seven cultivars from a three-year experiment at Lyndonville, NY. Hand thinning and the 740 first plant growth regulator applications occurred approximately 4-6 weeks after full bloom in both years, with subsequent applications 741 made on approximately two-week intervals. 1-napthaleneacetic acid (NAA) was applied at 5 mg∙L -1 and ethephon (Eth) at 150 mg∙L -1 . 742 2016-2018 cumulative yield (kg/tree) A pple Table 1. Return bloom density of trees at a research orchard in Lansing, NY following Year 1 (2016), and return fruit set following Year 2 (2017) of a hand-thinning and summer plant-growth regulator (PGR) experiment. Hand thinning (Thin) consisted of reducing all fruitlet clusters to single fruitlets. The PGR treatment consisted of 150 mg∙L -1 ethephon followed by two (2016) or three (2017) ap plications of 5 mg∙L -1 1-napthaleneacetic acid. Hand thinning and the first PGR applications occurred approximately 5 weeks after full bloom in both years, with subsequent PGR applications made on ap proximately two-week intervals. z n=6 trees per treatment for ‘Chisel Jersey’ in both years; n=4 trees per treatment for ‘Brown Snout’. y P-values generated from analysis of a linear mixed effects model of return bloom or return fruit set, where previous fall’s crop density (fruits/cm 2 TCSA) is a covariate and PGR is an indicator variable. Each cultivar and year analyzed separately.

‘Harry Masters Jersey’ ‘Harry Masters Jersey’

‘Geneva Tremlett’s Bitter’ ‘Geneva Tremlett’s Bitter’

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‘Binet Rouge’ ‘Binet Rouge’

‘Brown Snout’ ‘Brown Snout’

‘Chisel Jersey’ ‘Chisel Jersey’

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Treatment Treatment

‘Dabinett’ ‘Dabinett’

‘Michelin’ ‘Michelin’

Control Control

17.4 z,y 17.4 z,y 11.7* 11.7*

11.5 11.5

24.0 24.0

30.9 30.9

21.1 21.1

18.0 18.0

14.6 14.6

Hand-thin (6 fruit/cm 2 ) Hand-thin (6 fruit/cm 2 ) NAA, NAA, NAA, NAA NAA, NAA, NAA, NAA Eth, NAA, NAA, NAA Eth, NAA, NAA, NAA Eth, Eth, NAA, NAA

6.1* 6.1*

17.6* 17.6*

17.3* 17.3*

13.5* 13.5*

10.9* 10.9*

8.8* 8.8*

17.6 17.6 18.3 18.3 17.6 17.6

14.5 14.5 12.6 12.6 10.2 10.2

24.4 24.4 27.4 27.4 29.2 29.2

24.5 24.5 23.5 23.5 36.4 36.4

17.1 17.1 23.1 23.1 24.0 24.0

19.2 19.2 19.9 19.9 16.2 16.2

10.2 10.2 12.3 12.3

Eth, Eth, NAA, NAA 14.9 z Significance in columns compared each treatment to the control using Dunnett’s test. * indicates significance at P ≤ 0.05. 743 y n=5 trees per treatment (25 trees per cultivar) 744 z Significance in columns compared each treatment to the control using Dunnett’s test. * indicates significance at P ≤ 0.05. y n=5 trees per treatment (25 trees per cultivar) 14.9 Significance in columns compared each treatment to the control using Dunnett’s test. * indicates significance at P ≤ 0.05. 743 y n=5 trees per treatment (25 trees per cultivar) 744