The Last Malus tschonoskii
This summer saw the removal of the last Malus tschonoskii on campus. As part of our mission to display great plants for Delaware Valley gardeners, we trial new introductions and cultivars of plants. Beginning in the 1980s, Scott Arboretum participated in the National Crabapple Evaluation Program led by Professor Les Nichols of Penn State University. This program evaluated readily available crabapple cultivars in various locations throughout the United States based mainly on disease resistance and aesthetic autumn appeal.
Malus tschonoskii was among the over 50 species and cultivars evaluated for 4 years during the 1990s. It was confirmed that the Tschonoskii crabapple is highly susceptible to fire blight. Fire blight is caused by a bacteria (Erwinia amylovora) which attacks the blossoms or flowers and then moves up twigs into the branches. It creates a burnt appearance on the flowers, foliage, and twigs. Plants in the Rosacea family (i.e. roses, apples, and pears) are highly susceptible to this disease.
With the last specimen of Tschonoskii crabapple wholly succumbing to fire blight, it was removed from the collection as unsuitable for gardens in the Delaware Valley. This study did reveal that Malus ‘Donald Wyman’, Malus Molten Lava®, and Malus ‘ Indian Magic’ are great crabapples for disease resistance, flower display, fall color, and great plants for Delaware Valley gardens. To experience more crabapples, visit the Scott Arboretum crabapple collection located below Cunningham Fields.