April 28, 2016

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Pinus banksiana – Jack Pine/Scrub Pine

Jack pine, a Minnesota native, is a fast growing (when young), short-lived (60-80 years), pioneer species. Pioneer species are typically the first trees to arrive following a forest disturbance such as a fire. As such, pioneer species like jack pine and trembling aspen tend to be the first trees to reforest an area and tend to tolerate hotter drier conditions that also may exist on the site following a disturbance.
Medium tree height: 35-50′
Canopy spreads: 20-30′, Oval crown
Flowers: Monoecious
Drought Tolerance: Intolerant
Shade Tolerance: Intolerant
Soil pH Tolerance: Intermediate to high pH
Poor Soil Drainage: Intolerant to flooding
Salt Tolerance: Tolerant to salt spray and Tolerant to soil salts
This two needle pine grows well on dry, sandy soils. The tree isn’t considered a beauty very often with its persistent cones, retention of dead lower limbs and often crooked trunk. The dark colored, scaly, ridged bark doesn’t help with this scruffy appearance.Look for 3/4 to 1 1/2 inch needles that are in widely forked pairs ( V shaped ). The individual needles themselves are often twisted when viewed from the end. The blunt, resinous buds are small in comparison to some pines and the color is a pale brown.The cones on jack pine are described as serotinous – typically, they stay closed until heated by a fire. This trait is somewhat variable from region to region. The cones are often attached in pairs and point towards the end of the twig or branch to which they are attached.Jack pine is seldom considered a good looking tree, sometimes interesting in form, but seldom an good landscape specimen. Jack pine tends to retain dead branches along the lower trunk and also hangs on to its serotinous cones. These traits tend to give the trees a scraggly, rough look. The species is native to the Anoka Sand plain, but it is not a widely planted tree.
Disease Management
Brown spot, Mycosphaerella dearnessi Fungi Most pine, esp. Scots and ponderosa. Spots that enlarge to bands and encircle the needle develop in late July and August. Diseased needles often have
dead tips. Killed needles drop late in the fall.
Nurseries should use seedlings from resistant trees; allow for adequate spacing and avoid shearing and other operations when foliage is wet.  CHEMICAL: Mancozeb.
needle blight(also called red band), Mycosphaerella
Fungi Two-and three-needled pines are affected but most common on Austrian pine. Chlorotic spots appear on infected needles in fall and winter. Spots spread, turn
red/brown and girdle needles causing the distal end to die. Black fruiting bodies break through lesion surface in spring. Defoliation can be severe.
Remove the lowest whorl of branches on young trees. Clean out debris and weeds in
and around trees. Space plants for good air circulation. Avoid planting in low-lying areas with poor drainage.
Growers should shear trees during dry weather.  CHEMICAL: Bordeaux (8-8-100). Can be toxic to new needles.
Lophodermium seditiosum
Fungi Two-and three-needled pines, esp. Austrian red and Scots pine. Current season
foliage develops yellow spots which turn brown with yellow margins in late fall and spring. Black, elliptical fruit bodies mature in or just beneath the epidermis in late summer. Needles brown and drop. Twigs die back. Spores
are released during late summer/early fall rains with most infection occurring in August and September.
Improve air circulation with thinning and pruning: cool moist environments favor infection.  CHEMICAL: Nurseries should apply mancozeb plus a spreader sticker or chlorothalonil. Make 3-4 applications starting July 1.
Pine needle rust, Coleosporium sp. Fungi Two-and three-needle pines develop light-colored blisters which burst open to release
yellow/orange spores in early summer. These spores infect the alternate hosts aster and goldenrod and NOT pine.
Damage is seldom detrimental. Remove or mow
goldenrod and aster plants in the immediate vicinity. CHEMICAL: None recommended.
Pine-oak gall rust or eastern gall rust, Cronartium quercuum Fungi Two-and three-needled pines are susceptible. The alternate host is red oak. Globose swellings up to 10 inches in diameter form on pine branches. Yellow/orange
powdery-appearing spores form on the gall surface in early summer.
Remove galls on pine branches preferably before
spring. CHEMICAL: None recommended. However, if the situation warrants, mancozeb may be applied when yellow pustules form on pine galls.
Pine-pine gall rust or western gall rust, Endocronartium
(Peridermium) harknessii
Fungi Two-needled pines, especially mugho, ponderosa, red and Austrian pine. There is no alternate host. Rough, globose galls
appear on branches and trunk. Yellow/orange powdery spores form on the gall
surface in early summer.
Remove galls on infected trees. Remove all trees with galls for a distance of 300 yards around nurseries and cull infected seedlings. CHEMICAL: Mancozeb when yellow spores are present on galls.
Shoot (Diplodia) blight, Sphaeropsis sapinea Fungi New shoots are invaded and killed in the spring, usually before needle expansion is complete. Needles turn brown; resin soaking is common. Dieback may progress into main stem. Fruiting bodies form at the base of infected needles, on
twigs and on second year cones. Austrian pine is extremely susceptible after
reaching cone-bearing age.
Keep landscape trees well watered and stress free. Thin forest stands. Avoid shearing
during wet weather or high humidity. Plant less susceptible pine species. CHEMICAL: Benomyl, thiophanate-methyl. Begin when new growth starts. Use a spreader sticker. Also Bordeaux.
White pine blister rust, Cronartium ribicola Fungi Five-needled pines are susceptible (eg. eastern white pine, limber pine). Elongate cankers with abundant pitch flow develop
on trunks and branches causing branch dieback or a flagging. White blisters containing yellow/orange spores break through the cankered areas in the spring.
Spores produced on pine infect the alternate host, Ribes species.
Minimize use of white pine on sites with high blister, rust hazard ratings. Avoid planting currants and gooseberries in the vicinity of white pine. Remove the lower branches on large trees. Scout trees annually for a flagging suggestive of early infection and remove infected branches. CHEMICAL: Triadimefon.
Jack pine has an extensive range across North America. Visit website with “Silvics of North America; Volume 1 Conifers” to look at range maps and to compare the range of Jack Pine to other pines such as Red Pine and Eastern White Pine.  (USDA Forest Service)                                      (View “Silvics of North America)

“Christmas Tree Pest Manual” (USDA Forest Service) (View Manual)