Evaluation of Blossom Thinning Spray Timing Strategies in Apple
In the eastern USA and several other apple-growing regions, apple blossom thinning using lime sulfur is a relatively new crop load management strategy. This study sought to evaluate how application timing of lime sulfur + stylet oil blossom thinning sprays would influence thinning efficacy and crop...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-09-01
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| Series: | Horticulturae |
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| Online Access: | https://www.mdpi.com/2311-7524/7/9/308 |
| _version_ | 1797519088270966784 |
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| author | W. Chester Allen Tom Kon Sherif M. Sherif |
| author_facet | W. Chester Allen Tom Kon Sherif M. Sherif |
| author_sort | W. Chester Allen |
| collection | DOAJ |
| description | In the eastern USA and several other apple-growing regions, apple blossom thinning using lime sulfur is a relatively new crop load management strategy. This study sought to evaluate how application timing of lime sulfur + stylet oil blossom thinning sprays would influence thinning efficacy and crop safety of ‘Gala’ apples. This project occurred at two locations in the USA, Winchester, Virginia, and Mills River, North Carolina, during the 2019 growing season. Two main timing strategies were assessed: (1) model-guided sprays with the pollen tube growth model (PTGM), (2) fixed spray intervals with the first spray applied at a specified percentage of open bloom (20% vs. 80%), and the second spray applied at a reapplication interval (48 h vs. 72 h). Model-guided and 20% open bloom + 48-h treatments reduced fruit set and increased fruit weight, diameter, and length at both sites. Treatments with a delayed first spray at 80% open bloom or a more extended second reapplication of 72 h were generally ineffective. There was no conclusive evidence that lime sulfur + stylet oil blossom thinning spray timing influenced russet incidence/severity or leaf phytotoxicity. This study demonstrated that effective and safe blossom thinning can be obtained from applying two sprays at 20% open bloom and 48 h thereafter or using the PTGM. |
| first_indexed | 2024-03-10T07:37:14Z |
| format | Article |
| id | doaj.art-e7664a7e359b468babd25c84d5c08856 |
| institution | Directory Open Access Journal |
| issn | 2311-7524 |
| language | English |
| last_indexed | 2024-03-10T07:37:14Z |
| publishDate | 2021-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Horticulturae |
| spelling | doaj.art-e7664a7e359b468babd25c84d5c088562023-11-22T13:21:32ZengMDPI AGHorticulturae2311-75242021-09-017930810.3390/horticulturae7090308Evaluation of Blossom Thinning Spray Timing Strategies in AppleW. Chester Allen0Tom Kon1Sherif M. Sherif2Alson H. Smith, Jr. Agricultural Research and Extension Center, School of Plant and Environmental Sciences, Virginia Tech, Winchester, VA 22602, USAMountain Horticultural Crops Research and Extension Center, Department of Horticultural Science, North Carolina State University, Mills River, NC 28759, USAAlson H. Smith, Jr. Agricultural Research and Extension Center, School of Plant and Environmental Sciences, Virginia Tech, Winchester, VA 22602, USAIn the eastern USA and several other apple-growing regions, apple blossom thinning using lime sulfur is a relatively new crop load management strategy. This study sought to evaluate how application timing of lime sulfur + stylet oil blossom thinning sprays would influence thinning efficacy and crop safety of ‘Gala’ apples. This project occurred at two locations in the USA, Winchester, Virginia, and Mills River, North Carolina, during the 2019 growing season. Two main timing strategies were assessed: (1) model-guided sprays with the pollen tube growth model (PTGM), (2) fixed spray intervals with the first spray applied at a specified percentage of open bloom (20% vs. 80%), and the second spray applied at a reapplication interval (48 h vs. 72 h). Model-guided and 20% open bloom + 48-h treatments reduced fruit set and increased fruit weight, diameter, and length at both sites. Treatments with a delayed first spray at 80% open bloom or a more extended second reapplication of 72 h were generally ineffective. There was no conclusive evidence that lime sulfur + stylet oil blossom thinning spray timing influenced russet incidence/severity or leaf phytotoxicity. This study demonstrated that effective and safe blossom thinning can be obtained from applying two sprays at 20% open bloom and 48 h thereafter or using the PTGM.https://www.mdpi.com/2311-7524/7/9/308appleblossom thinninglime sulfurpollen tube growth modelcrop load management |
| spellingShingle | W. Chester Allen Tom Kon Sherif M. Sherif Evaluation of Blossom Thinning Spray Timing Strategies in Apple Horticulturae apple blossom thinning lime sulfur pollen tube growth model crop load management |
| title | Evaluation of Blossom Thinning Spray Timing Strategies in Apple |
| title_full | Evaluation of Blossom Thinning Spray Timing Strategies in Apple |
| title_fullStr | Evaluation of Blossom Thinning Spray Timing Strategies in Apple |
| title_full_unstemmed | Evaluation of Blossom Thinning Spray Timing Strategies in Apple |
| title_short | Evaluation of Blossom Thinning Spray Timing Strategies in Apple |
| title_sort | evaluation of blossom thinning spray timing strategies in apple |
| topic | apple blossom thinning lime sulfur pollen tube growth model crop load management |
| url | https://www.mdpi.com/2311-7524/7/9/308 |
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