Single-leaf pinyon

Botanical name

Pinus monophylla

Type

Native evergreen pine

Height

Typically 20 to 40 feet

Needles

One per bundle, retained about 5 to 12 years

Elevation

About 3,280 to 9,186 feet overall (USFS)

Rainfall

Grows where precipitation is about 8 to 18 inches

Single-leaf pinyon is a common sight on hillside lots near Dayton, Virginia City and the east side of Washoe Valley. It is slow, tough and a poor fit for a house wall.

How do you identify single-leaf pinyon?

Look at the needles: each bundle has one stout, rounded, gray-green needle, unusual among pines. The crown is short, rounded and often multi-stemmed. The cones are round and contain large edible seeds that people gather and birds cache. Bark is thin and furrowed.

• One needle per bundle
• Short, rounded, bushy crown
• Round cones with large seeds
• Thin, furrowed bark

Where does it grow by elevation?

The Forest Service gives about 3,280 to 9,186 feet. That covers Dayton (4,400 feet), Virginia City (6,200 feet), the foothills around Washoe Valley (5,100 feet) and the Carson Range. The Virginia City NOAA station records about 12 inches of precipitation a year, in the pinyon range of 8 to 18 inches, while Reno-Tahoe International Airport at 4,410 feet records about 7 inches. Hardiness zones are 6b to 7b. It is a hillside tree more than a valley-floor yard tree.

What goes wrong with pinyon?

Drought and insects. The Forest Service reports pinyon needle scale weakens trees, making them vulnerable to fatal attacks by pinyon ips beetles, and that a large die-off in Utah contributed to the decline of the species' Great Basin range after 1987. Drought strongly limits seedlings and saplings. A crown that turns yellow, then red, is the sign. See bark beetles in pines and pine needle scale.

Slash matters. FEIS notes that removing slash larger than 3 inches generally keeps ips populations from reaching epidemic levels. Fresh pruning debris and cut wood left on a lot can feed beetles, so we haul the debris away.

Fire: thin bark and retained dead branches make mature trees vulnerable, and they survive low-severity surface fires but die in severe fires. Pinyon with brush under it will carry fire to the crown. See defensible space and fire mitigation.

What does an arborist check on a pinyon?

We look at the crown color, pitch tubes and boring dust on the trunk, and how much brush and dead wood sits under the tree. We also look at how close the tree is to the house, a deck, vents and wires, since fire behavior is the larger risk on a hillside lot.

When is pruning, and when is removal, the answer?

Pinyon grows slowly and needs little. Dead branches can come off any time of year; otherwise, conifers are usually pruned in early spring and summer. Raising the lowest limbs and removing dead wood reduces ladder fuel. Do not remove large amounts of live crown.

Removal is the usual answer for a dead pinyon, a tree infested to the point that the crown is mostly red, or a tree close enough to a house, deck or vent that fire would reach it. A group of pinyon on a building lot is a lot clearing job. A certified arborist assesses the job on a free estimate; our debris haul-away is part of the work. For firewood, call the office.