Bowhall Red Maple - Acer rubrum 'Bowhall'

A lovely Morton Arboretum quintet of Bowhall red maples is 52 years old.

The seeds of Red Maple are quite popular with squirrels and birds. This tree if often confused with red-leaved cultivars of Norway Maple. Fall color is not reliable but ranges in any given year from red to orange to yellow. It can be spectacular in some years.

Bowhall Red grows best on moist sites in full sun. It has no other particular soil preference except chlorosis may develop on alkaline soil where it also grows poorly. It is well-suited as a street tree in northern and mid-south climates in residential and other suburban areas but the bark is thin and easily damaged by mowers. Irrigation is often needed to support street tree plantings in well-drained soil in the south.

Roots can raise sidewalks as Silver Maples can but they have a less aggressive root system and so they make a good street tree. Surface roots beneath the canopy can make mowing difficult. Red Maple is easily transplanted and usually develops surface roots in soil ranging from well-drained sand to clay. It is not especially drought-tolerant, particularly in the southern part of the range, but selected individual trees can be found growing on dry sites. This trait shows the wide range of genetic diversity in the species. Branches often grow upright through the crown forming poor attachments to the trunk. These should be removed in the nursery or after planting in the landscape to help prevent branch failure in older trees during storms.

Select branches with a wide angle from the trunk and prevent branches from growing larger than half the diameter of the trunk. Graft incompatibility on grafted trees can cause branch failure in wind storms. Preference should be given to trees produced on their own roots. [2]

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Bowhall Red Maple

Red Maples
A number of other cultivars are listed. Due to graft-incompatibility problems which cause the tree to break apart, preference should be given to cultivars produced on their own roots. In the northern and southern end of the range, choose cultivars with regional adaptation.

Some cultivars are: `Armstrong' - upright growth habit, almost columnar, somewhat prone to splitting branches due to tight crotches, 50 feet tall; `Autumn Flame' - 45 feet tall, round, above average fall color; `Gerling' - densely branched, broadly pyramidal, about 35 feet tall when mature; `October Glory' - above average fall color, excellent tree, retains leaves late, 60 feet tall; `Red Sunset' - above average orange to red fall color, does well in the south in USDA hardiness zone 8, probably the best cultivar for the deep south, oval, 50 feet tall; `Scanlon' - upright growth habit; `Schlesinger' - good fall color, rapid growth rate; `Tilford' - globe-shaped crown.

Pests
Leaf stalk borer and petiole-borer cause the same type of injury. Both insects bore into the leaf stalk just below the leaf blade. The leaf stalk shrivels, turns black, and the leaf blade falls off. The leaf drop may appear heavy but serious injury to a healthy tree is rare. Aphids infest maples, usually Norway Maple, and may be numerous at times. High populations can cause leaf drop. Another sign of heavy aphid infestation is honey dew on lower leaves and objects beneath the tree.

Aphids are controlled by spraying or they may be left alone. If not sprayed, predatory insects will bring the aphid population under control. Scales are an occasional problem on maples. Perhaps the most common is cottony maple scale. The insect forms a cottony mass on the lower sides of branches. Scales are usually controlled with horticultural oil sprays. Scales may also be controlled with well-timed sprays to kill the crawlers.

If borers become a problem it is an indication the tree is not growing well. Controlling borers involves keeping trees healthy. Chemical controls of existing infestations are more difficult. Proper control involves identification of the borer infesting the tree then applying insecticides at the proper time. Twig borers can cause die-back of the terminal 8 to 12 inches of small-diameter branches. This is usually not serious and does not require control measures, but it can be a problem on young trees in the nursery.

Diseases
Scorch may occur during periods of high temperatures accompanied by wind. Trees with diseased or inadequate root systems will also show scorching. When trees do not get enough water they scorch. Scorch symptoms are light brown or tan dead areas between leaf veins. The symptoms are on all parts of the tree or only on the side exposed to sun and wind. Scorching due to dry soil may be overcome by watering. If scorching is due to an inadequate or diseased root system, watering may have no effect.

Nutrient deficiency symptoms are yellow or yellowish-green leaves with darker green veins. The most commonly deficient nutrient on maple is manganese. Implanting capsules containing a manganese source in the trunk will alleviate the symptoms. Test soil samples to determine if the soil pH is too high for best manganese availability. Plants exposed to weed killers may also show similar symptoms. [2]

Bowhall Red Maple

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References

Bowhall Red Maples, Morton Arboretum accs. 587-58*1 - 4, photographed October 12, 2009 by Bruce Marlin
Edward F. Gilman and Dennis G. Watson, University of Florida IFAS Extension, ENH203, "Acer rubrum 'Bowhall'" (.pdf)