Italian stone pine (Pinus pinea), native to the coastal area of the Mediterranean, is a large, needle-leaved conifer that can grow to a height of 100 feet but usually tops out at 40 to 45 feet. Also known as parasol pine, Roman pine and umbrella pine, it is appreciated for its umbrella shape and edible pine nuts. This handsome evergreen is drought-tolerant, rarely bothered by deer and is not highly susceptible to many diseases. There are two diseases it is susceptible to, though, and a certain care requirement which, if not done correctly, can cause droopy branches.
Italian stone pines are hardy in U.S. Department of Agriculture plant hardiness zones 7 to 11, although they may suffer winter damage from cold winter wind in USDA zone 7. The branches will not droop because of it, but the needles will turn brown. Their branches tend to be weak and prone to breaking from high winds and winter ice storms, a common condition in trees that grow quickly. Stone pines thrive on the West Coast, especially in California where temperatures do not fluctuate severely. Tolerant of saltwater spray, the pine isn't picky about where it lays down its roots and will grow in acidic and alkaline soils. The species, however, is considered invasive in a few areas in California and in South Texas.
Overwatering the Italian stone pine deprives the tree roots of much needed oxygen, especially in slow-draining soil, and can cause the roots to rot. Once the roots rot they are no longer can absorb needed water for the tree. While these trees can survive long periods of drought, they will show physiological signs of drought stress. Both overwatering and underwatering can cause the tree branches to droop. Young trees should be given 5 gallons of water once each week for the first year or two. A more mature Italian stone pine with a 20-foot wide canopy should be given about 240 gallons of water once per month, which is the equivalent of running the hose for about 50 minutes. Run the water uniformly over the soil starting a few feet away from the trunk and extending to 5 to 10 feet beyond the edge of the canopy.
3. Root Rots
Phytophthora root rot is one of the few diseases Italian stone pines are susceptible to. Stress from too much or too little water, or stress from excessively high temperatures, increases their susceptibility to this fungal disease. The branches will droop, and its needles will turn yellow, orange or red and drop. Unfortunately, the tree will die from this disease. The fungal spores will continue to live in the soil after the tree is removed. Do not plant anything that is susceptible to this disease in the area, and be careful not to transfer the soil to other areas on shoes or gardening equipment.
4. Pitch Canker
Pitch canker is another fungal disease that can infect Italian stone pines. It is transmitted by cone beetles (Conophthorus radiata), deathwatch beetles (Emobius punctulatus) and engraver beetles (Ips spp.). Lesions caused by this disease girdle the tree’s stems, branches and roots. The girdled branch tips droop because moisture cannot get to the branch ends beyond the girdled area. Resin or pitch oozes from the lesions and sunken cankers, which can also develop as a result of this disease. There is no special care that can help the tree recover, however, with proper watering, the tree may recover on its own. An arborist can remove infected branches to improve the tree’s appearance, and in doing so should properly dispose of the branches, lest disease spread to other plants.
- Missouri Botanical Garden: Pinus Pinea
- Invasive Plant Atlas of the United States: Italian Stone Pine
- University of Florida IFAS Extension: Stone Pine
- Cal Poly -- Urban forest Ecosystems Institute: Italian Stone Pine
- The University of Arizona Cooperative Extension: Pines of Arizona
- North Carolina State University: Watering Shrubs
- Missouri Botanical Garden: Phytophthora Root Rot of Conifers
- University of California Cooperative Extension: Pitch Canker