The Christmas freeze of 2022 provided an opportunity to see how Tangos, Sugar Belle, and Owari satsumas were influenced by rootstocks. This is a report of the impacts on Tangos. Since January of 2023, I have conducted ratings on how much foliage was retained after the freeze, which trees developed freeze cracks, diameter of limbs lost, and how much of the canopy was lost due to the freeze. I have been rating trees and removing limbs since March. I am wrapping up those ratings as the 2023 harvest season is about to begin. Rootstocks did have an influence on cold-hardiness. Below is a chart summarizing the ratings of each Tango/Rootstock combination. Each combination was repeated 9 times and the average of those 9 trees was used to compile this data. I ranked the rootstocks based on canopy loss from least to most. Trees on US-1516 had the least canopy loss at 8%. US-812 and UFR-17 rated 2nd and 3rd with least canopy lost. US-1516 also had the least number of trees with freeze cracks and had the highest percentage of foliage retained after the freeze. US-1516 also had the smallest diameter of limbs removed and 5 of 9 of the trees has no limbs lost greater than 10mm which is less than half an inch in diameter. On the other end of the spectrum, trees on US-852, Rich 16-6, and US-1279 had the most canopy removed. One might have expected Rich 16-6 to have performed better since it is a pure trifoliate. One reason that it may not have performed better was that 7 of 9 of these trees were replaced a year later with larger trees as these trees were smaller than the others when they were planted. However, the two oldest trees on Rich 16-6 that were growing well and not replaced had significant cold damage. The average canopy loss for all the trees was 30%. US-1516 was the clear winner in providing cold-hardiness in the Tango trial. US-812 and UFR-17 also performed well compared to the others. UFR-7 appears to have the most fruit of any of the rootstocks, but I can’t be sure until after harvest. Most trees have very little fruit this year. Up until last year there was little to no cold-damage to the Tango’s and they have endured temperatures down to 20 degrees in their two previous winters.
