Willow oak (Quercus phellos): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Quercus phellos L. in USDA PLANTS, beech family
Other names	Peach oak, pin oak and swamp chestnut oak (Silvics)
Native status, USDA PLANTS	Native in the lower 48 states
Size, Silvics	Medium to large, attaining 24 to 37 m (80 to 120 ft) in height and commonly 100 cm (39.5 in) in diameter at breast height; a straight, tall, slender trunk is common
Growth, Silvics	Known for rapid growth and long life; on good sites it makes moderately rapid growth
Green weight of the wood, NRS-38	64 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) says willow oak is found mainly in bottom lands of the Coastal Plain from New Jersey and southeastern Pennsylvania south to Georgia and northern Florida, west to eastern Texas, and north in the Mississippi Valley to southeastern Oklahoma, Arkansas, southeastern Missouri, southern Illinois, southern Kentucky and western Tennessee. It describes a tree of moist alluvial soils, commonly along water courses, with willowlike foliage, which is an important source of lumber and pulp and a favored shade tree, easily transplanted and used widely in urban areas. The climate it grows in is humid and temperate, with 180 to 190 frost-free days in the north-northeastern range and 300 in the south-southwestern range.

Flowers, acorns and growth

Silvics says willow oak is monoecious, with male and female flowers in separate catkins on the same tree, flowering from February to May about a week before the leaf buds open. Late freezes after the buds open kill the flowers and defoliate the trees; new leaves follow but a second crop of flowers is not produced. The tree produces an acorn crop almost every year, which the handbook calls important for wildlife food: ducks, squirrels, deer and turkey are named as major consumers, along with blue jays and red-headed woodpeckers.

Diameter growth depends on tree size. In unmanaged stands on good sites, trees 15 to 30 cm (6 to 12 in) across averaged 6.6 cm (2.6 in) over a 10-year span, trees in the 36 to 46 cm (14 to 18 in) class 7.9 cm (3.1 in), and trees in the 51 to 71 cm (20 to 28 in) class 7.1 cm (2.8 in). The handbook says the tree is not a rapid pruner on good sites and a very ineffective natural pruner on poor sites, and that epicormic branches tend to form if dormant buds along the stem are stimulated by a disturbance such as crown breakage, wounding, drought, flooding or suppression.

Roots

Where it grows on alluvial soils, the handbook says willow oak feeder roots are concentrated in the aerated layer above free water, where they form extensive ectomycorrhizal associations that aid uptake of nutrients and water and offer some protection against root diseases. Roots do not penetrate into the zone of free-standing water, and permanent standing water kills the root system and ultimately the tree. Root growth usually begins during early March in the soil region of best growth.

Wood

Silvics calls willow oak an important source of lumber and pulp, and says that willow oak is being used in hardwood plantations because it gives a good combination of pulping characteristics and growth rate. The Wood Handbook (FPL-GTR-282, 2021) groups it in the red oak group of the Eastern states; what it says about that group is set out once on the northern red oak page. Table 5-3b has a separate willow oak row, shown below.

Wood Handbook Table 5-3b	Specific gravity	Modulus of rupture (lbf per square inch)	Side hardness (lbf)
Green	0.56	7,400	980
At 12% moisture content	0.69	14,500	1,460

The Wood Handbook states that specific gravity is based on oven-dry weight and the volume when green or at 12% moisture content. The green weight of the wood without bark is in the NRS-38 table, the same figure used in the log weight calculator.

Diseases, insects and damage the handbook names

Silvics (1990) names these agents by the names it used.

Fire. Called a principal enemy of willow oak. The handbook says seedlings and saplings are killed by even a light burn, hot fires kill larger trees, and trees not killed immediately are often wounded and become susceptible to butt rot fungi.
Canker. A common canker on bottom-land willow oaks caused by Polyporus hispidus, which the handbook says grows rapidly, lengthening 10 to 15 cm (4 to 6 in) per year, and may cause as much as 25 percent cull in some areas.
Trunk borers. Named as perhaps the most serious insect pests because they cause serious degrade in saw log quality: the red oak borer, the carpenterworm and the living-beech borer.
Acorn losses. Squirrels, birds, hogs and insects, mainly acorn weevils, reduce the fruit crop.
Acid rain. The handbook reports that willow oak foliage showed yellow or brown necrotic zones when exposed to simulated rain of less than pH 3.2.

The guides on oak wilt and cankers cover those subjects in general.

The guide on reporting a pest in the United States and the Canada reporting page give the offices that take sightings of regulated pests. Who may apply pesticides is in pesticide licences by country.