Photo by Vic Johanson
Rosthern 18 originated with the Rosthern Experimental Farm, Saskatchewan, Agriculture Canada, and was selected in 1936 and tested under this name. However Rosthern 18 was never officially released for commerce.
The tree is vigorous, round topped, with good wide-angled branching habit. It is very hardy, but susceptible to fire blight. This apple tastes better if it is left on the tree longer. It seems to me it would make a good cooking apple and due to its extreme hardiness and good annual production it may be a better overall variety than its reputation suggests. Note: This apple will taste bitter to some. Both the skin and flesh are green.
Our Rosthern 18 died and we have not replaced it.
Here is a description of the original cultivar. We don't know how to explain the differences: The tree is vigorous, upright and spreading, and moderately productive. It is hardy to Zone 2a, and resistant to fire blight. The fruit is medium size 4.5 cm - 5.0 (1 3/4-2" ) in diameter, oblate, and matures in mid September. The skin is greenish-yellow with striped red or almost completely washed red. The flesh is white, fine textured, pleasant but somewhat astringent. It is good for fresh eating, good for cooking and stores well for 8 weeks. This is the description of the original cultivar which is now difficult to find.