Throughout his career, Kerr was a prolific plant breeder. He developed the ‘Kerr’ applecrab, ‘Almey’ ornamental crab, ‘Toba’ Hawthorn, ‘Sutherland’ caragana, as well as a number of willows, poplars, elders, flowering almonds, hazelnuts, cherry-plums, apricots and cherries. He had a special interest in chrysanthemum breeding and developed a number of cold-hardy cultivars including ‘Sutherland Pink’, ‘Cree’, ‘Early Autumn’ and ‘Popeye’. His ‘Royalty’ crabapple was selected as one of Canada’ Centennial trees in 1967. The beautifully landscaped grounds at the Sutherland station were a beacon for growers and gardeners alike, where Kerr freely shared his knowledge and enthusiasm for cold-hardy plants. Kerr wrote extensively about various aspects of horticulture and his network of growers was such that he was instrumental in the establishment of the Saskatchewan Nursery Trades Association. Kerr was bestowed with many awards and honors over the course of his career including an honorary Doctorate from the University of Saskatchewan.
Kerr retired in 1966 when the Sutherland Forest Nursery Station was closed. The federal government donated the land to the City of Saskatoon, which converted it into the Saskatoon Forestry Farm and Zoo. The roots of the zoo began with Kerr, who was also an avid conservationist. He rescued many injured or orphaned wildlife which he kept on the grounds of the station: his rescues included pheasants, racoons, coyote pups, bear cubs and even a talking magpie. His love of animals inspired the formation of the Saskatchewan Wildlife Federation. Kerr valued the relationship between flora and fauna. He wrote: “The importance of trees in making our homes more pleasant and inviting should not be overlooked. Who wants to live on a treeless farm or in a treeless town? Not matter how nice the house may be it is not a home until there are trees around it. The relationship of trees to the abundance and variety of birds and wildlife is of major importance.”