Chilling Units for Honeycrisp and SweeTango apples - Ask Extension
What are the chilling unit requirements for Honeycrisp and SweeTango apples originating in MN?
Are chilling units different if cultivars coming from W...
Knowledgebase
Chilling Units for Honeycrisp and SweeTango apples #344797
Asked July 20, 2016, 6:44 AM EDT
What are the chilling unit requirements for Honeycrisp and SweeTango apples originating in MN?
Are chilling units different if cultivars coming from Washington, Missouri, NY, etc. versus MN?
I would like to gift Honeycrisp and SweeTango to family in s. Oklahoma. Would they successfully fruit? Also, are rest-breaking agents like BudPro and Dormex effective on these cultivars to boost chill hours for those areas in US with chill hour deficiencies? Thanks!
County Minnesota
Expert Response
The chilling requirement of a fruit is the minimum period of cold weather after which a fruit-bearing tree will blossom. It is expressed in chill hours. Chill hours are the number of hours between the temperatures of 32 and 45 degrees Fahrenheit.
Most apple cultivars have a chill requirement of 750 to 1000 hours. Unfortunately, because of their high chill requirements, most apple cultivars cannot be successfully grown in Arkansas, Tennessee, and Georgia. In southern parts of the United States, apple cultivars with low chill requirements (400 to 500 hours) will successfully flower and produce fruit. An apple cultivar with a low chill requirement isn't a good choice for Iowa because it will bloom earlier than most apple cultivars and the flowers will likely be destroyed by a late freeze.
In the northern part of the United States (including Iowa), cultivar hardiness is usually more important than the chill requirement.
The chill hours for Sweet Tango and Honey crisp are 800-1000.
The apple varieties recommended for Oklahoma have shorter chill hour requirements.
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1039/F-6210web.pdf
Manipulating the chill hours with a chemical each year is tricky and may be too much bother for the recipient of the gift. It will take a lot of effort to get fruit. Dormex requires a Pesticide operators license and isn't an option for someone who is not licensed. I found some suggestions for manipulating chill hours.
http://forums.gardenweb.com/discussions/1439020/dormex-for-more-chill-hours
My recommendation is to give them a tree that is adapted to their zone.
Most apple cultivars have a chill requirement of 750 to 1000 hours. Unfortunately, because of their high chill requirements, most apple cultivars cannot be successfully grown in Arkansas, Tennessee, and Georgia. In southern parts of the United States, apple cultivars with low chill requirements (400 to 500 hours) will successfully flower and produce fruit. An apple cultivar with a low chill requirement isn't a good choice for Iowa because it will bloom earlier than most apple cultivars and the flowers will likely be destroyed by a late freeze.
In the northern part of the United States (including Iowa), cultivar hardiness is usually more important than the chill requirement.
The chill hours for Sweet Tango and Honey crisp are 800-1000.
The apple varieties recommended for Oklahoma have shorter chill hour requirements.
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1039/F-6210web.pdf
Manipulating the chill hours with a chemical each year is tricky and may be too much bother for the recipient of the gift. It will take a lot of effort to get fruit. Dormex requires a Pesticide operators license and isn't an option for someone who is not licensed. I found some suggestions for manipulating chill hours.
http://forums.gardenweb.com/discussions/1439020/dormex-for-more-chill-hours
My recommendation is to give them a tree that is adapted to their zone.
