Figure 1 Toba Hawthorn in full bloom. Source: Cashman Nursery Plant Finder
The Toba hawthorn (Crataegus x mordenensis) is best suited in full sun or partial shade.
It is highly adaptable to both dry and moist growing conditions, but will not tolerate standing water.
Growth has been successful in a range of soil types and varying levels of pH. This hawthorn's growth averages to be 12-15 feet tall at maturity, under ideal growing conditions can live to be up to 40 years old.
REGION OF ORIGIN
The Toba hawthorn was developed at the Morden Research Station in Manitoba, Canada. Cultivated as a cold hardy ornamental to be used for landscaping it is the hardiest of the hawthorns and is hardy to zone 3b.
Figure 2 Hardiness Zones of the US. Source: USDA Agricultural Research Services
Figure 3 Toba Flower. Source: Cashman Nursery Plant Finder
Ideal as a yard or street tree it is often used as an ornamental to accent hedges or shrubs. Its short stature is ideal for growing under powerlines on a boulevard. Toba hawthorn will have showy white flowers with pink overtone in mid spring, with green foliage to accompany throughout the season it has little to no fall color in its leaves. Fruit is a glossy red pome that is present from early to late Fall. The hawthorn produces fruit annually. There are several bird species that will eat the fruit of the hawthorn.
The Toba is an interspecific hybrid, meaning that it is bred from two different species in the same genus. This often renders the offspring sterile, but there is a potential for fertile offspring. The hawthorn has perfect flowers, meaning that both the male and female reproductive parts are in the same flower (hermaphroditic).
Propagation of the Toba hawthorn can be done by one of two ways, either through root grafting or stratification of the seed. This isdone either by immersing seeds in acid and then warm treating them for a period of time. There are some species of hawthorn that only require a warm temperature treatment.
Planting would be ideal on the southern or western sides of your yard. This would provide the required full to partial sunlight throughout the day.
Growth for the Toba hawthorn tree occurs seasonally, spring through fall.
Figure 7 Pruning Guidelines. Source: Lowes.com – How to Prune Trees and Shrubs
Planting should occur in early spring as balled-and-burlapped. If you are planting from bare root these trees should be “sweated” into leaf before planting. This is due to the potential for late bud breaking.
Any maintenance or seasonal pruning should take place in late winter after there is any risk of extreme cold.
PEST AND DISEASES
Figure 8 Fire Blight. Source: Texas Plant Disease Diagnostic Lab
The hawthorn is susceptible to many issues, some of which are: Fireblight, Leaf Blight, Rusts, Leaf Spots, Powdery Mildew, Scab, Aphids, Borers, Western Tent Caterpillar, Apple Leaf Blotch Minor, Lace Bugs, Leaf Rollers, Apple and Thorn Skeletonizer, Plant Hopper, Scales, and Two Spotted Mite.
Treatments appropriate for any known issues should be administered accordingly.
Figure 9 Apple and Thorn Skeletonizer. Surce: Washington State University
Dirr, M. A. (2009). Manual of woody landscape plants their identification, ornamental characteristics, culture, propagation and uses. Champaign: Stipes Publ.
Toba Hawthorne. (2016). Retrieved February 21, 2019, from http://www.thetreefarm.com/hawthorne-toba
Hawthorn. (2015, August 10). Retrieved from http://www.agr.gc.ca/eng/science-and-innovation/agricultural-practices/agroforestry/shelterbelt-planning-and-establishment/selecting-trees-and-shrubs-species/hawthorn/?id=1345839317164