Alaska Pioneer Fruit Growers Association


July 9, 1997

Dwight Bradley


Following up on an idea of Bob Boyer’s, I did a small but promising experiment with IRT plastic in the orchard over the summer. I had two apparently identical Norland trees, both on Antonovka rootstock, which were grafted in 1995 an bought as 1-year whips in 1996 from Lawyer. A control tree was grown with ordinary care, which in my orchard amounted to a couple of watering during June and July, and an occasional weeding around the base of the tree (the orchard is in sod as opposed to being clean-cultivated). The test tree was placed in the center of a 4-foot square of IRT plastic, slit on one end to get it around the tree and held down by rocks. I watered it at the same time as the control tree. The dark gray plastic transmits infrared radiation and hence allows the soil to heat up more that it normally would. The results:


Height, May 1997 52² 55²
Height, Sept 1997 68² 62²
Blossoms? 5-10 5-10
Fruit 5 none


The IRT tree grew 16² compared to 7² for the control tree, and although both trees had a handful of blossoms, only the IRT tree set fruit. Furthermore, it turned out that the IRT tree had some serious sunscald injury, so it actually overcame a severe initial handicap! Specifically, a sunscald blister nearly girdled the tree an inch or two above ground level (I didn’t notice this until shortly after starting the experiment).


In summary, anecdotal evidence suggest that IRT could really make a difference. Next summer, I’ll put IRT around some more trees and thus be able to decide whether this year’s results were a fluke or real.