Greetings,
I just wanted to share with you some of the slides and information I presented this past Tuesday via zoom in case you haven’t had a chance to attend the meeting. You may also consider reading my previous blog post on blossom thinning (https://blogs.ext.vt.edu/tree-fruit-horticulture/2020/03/28/apple-blossom-thinning-general-overview-and-updates/) and the factsheet on the Virginia Cooperative Extension webpage (https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/spes/spes-134/SPES-134.pdf) if you want to get a better idea about the science and application of chemical thinners, e.g. 6-BA, NAA and ethephon.
Table 1: Chemicals and plant growth regulators labeled for fruit thinning in Virginia
There are two forms of Refine, Refine 3.5 and Refine 6.25. The later contains a higher concentration of NAA.
Table 2: Thinning chemicals and rates recommended for petal fall-5 mm fruit diameter
Carbaryl can be applied as a carbaryl only thinning spray between petal fall and 5 mm fruit diameter, but it will be less effective as fruits are getting bigger.
Table 3: Thinning chemicals and rates recommended for 6 mm-15 mm fruit diameter
Table 4: Chemicals and rates recommended for rescue thinning applications (at 16-25 mm fruit diameter)
Sherif M. Sherif, Assistant ProfessorVirginia Tech, School of Plant and Environmental Sciences,AHS Jr. Agricultural Research and Extension Center
595 Laurel Grove Road, Winchester, VA 22602
Tel. 540-232-6035, Email: ssherif@vt.edu