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The most infected needles are prematurely shed by December. Because the infected needles are within the interior of the tree, the newer needles on the outer surface of the pines are flushed green and resistant to the disease. However, the premature shedding of needles in the interior can extend outwards leading to a loss in overall growth.
Most of the breeding efforts for five-needle pine resistance are currently focused in North America, on P. strobus, P. monticola and P. lambertiana. [18] The means of resistance in rust-resistant five-needle pine varieties involve various mechanisms, such as abortion of infected leaves and slow development of canker symptoms. [7]
An elongated white scale insect, the pine needle scale feeds on the needles causing fluffy white patches on the twigs and aphids also suck sap from the needles and may cause them to fall and possibly dieback. Mites can also infest the blue spruce, especially in a dry summer, causing yellowing of the oldest needles.
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The bark of mature trees is reddish, the young trees are gray with smooth bark. [6] The leaves are needle-like, 2.5 cm (1 in) long, light blue-green, turning bright yellow before they fall in the autumn, leaving the shoots bare until the next spring. [5] The needles are produced in clusters on long woody spur shoots. [5]
For its timber, the pine species is regarded as the most commercially important tree in the Southeastern U.S. [5] [6] [7] The common name loblolly is given because the pine species is found mostly in lowlands and swampy areas. [8] Loblolly pine is the first among over 100 species of Pinus to have its complete genome sequenced. As of March 2014 ...
Western white pine is a large tree, regularly growing to 30–50 metres (98–164 ft) tall. It is a member of the white pine group, Pinus subgenus Strobus, and like all members of that group, the leaves ('needles') are in fascicles (bundles) of five, [5] with a deciduous sheath. The needles are finely serrated, [5] and 5
The tree produces spiky green fruits about the size of a golf ball, which turn brown and drop off the tree over an extended period beginning in fall and continuing over the winter.