[Brittany Kordick]

At this past week’s Berkshire Roundtable meeting we spent some time discussing Dolgo crabapple: its genetics, growth habit, and most importantly, its potential for use as a rootstock that might confer increased flower bud hardiness in spring freeze events. When grown in the Northeastern United States on its own roots, Dolgo reaches standard size and does not appear to have any natural dwarfing characteristics. Furthermore, numerous growers reported good vigor and size on various rootstocks.

This is in sharp contrast to my own experience with growing Dolgo on MM111 in the North Carolina Piedmont region, where the varietal exhibits low vigor and generally wimpy growth post-grafting. We usually wait several years before planting our grafted Dolgo trees in our orchard because they are so markedly un-vigorous. Once planted out, the trees continue this sluggish growth pattern and, while the crops are good sized and of great quality, our Dolgos never really catch up with the rest of our trees and resemble natural dwarf trees, sizewise. At the meeting, a grower from Ohio echoed our Dolgo experience, saying that her trees also struggle and seem stuck in low gear, low vigor growth. Again, this is in sharp contrast to the typical Dolgo experience in colder climates.

On my way home from the meeting I was struck by a thought that perhaps Dolgo needs more chill hours than our NC climate, and perhaps even Ohio’s, can provide. I had never made the connection before, but Dabinett behaves exactly the same as Dolgo in our climate, and it apparently requires more chill hours than we get here in central NC. I thought that must be it, but it turns out that Dolgo is touted as a great variety for low chill hour regions, with requirements given ranging from 400-700 hours only. We’ve already achieved well over 1,000 chill units here, as determined by the Shaltout and Unrath model, and we typically accumulate at least a few hundred more each dormant season, so there goes that theory.

I’d really like to get to the bottom of why Dolgo appears to be underperforming in our region, and to that end, would love to hear from others growing this variety in various climates. We love the fruit and would love to plant more Dolgo trees. Perhaps there’s a better rootstock pairing for this climate or it would do better as an own-rooted planting. If you’re growing Dolgo in your orchard, please share your experience!