trees which have blown over by the wind and when the larvae mature two years afterwards, a major outbreak occurs and vast numbers of beetles attack nearby standing trees. The blue spruce is susceptible to several needle casting diseases which cause the needles to turn yellow, mottled or brown before they fall off. Various rust diseases also affect the tree causing yellowing of the needles as well as needle fall. Canker caused by Cytospora attacks one of the lower branches first and progressively makes its way higher up the tree. The first symptom is the needles turning reddish-brown and falling off. Meanwhile, patches of white resin appear on the bark and the branch eventually dies. Rooting habits Blue spruce seedlings have shallow roots that penetrate only 6.4 cm (2.5 inches) of soil during the first year. Although freezing can't damage much in blue spruce, frost will cause seedling loss. Shadows in late spring and early autumn minimize this frost heaving loss. Despite the shallow roots, blue spruce is able to resist strong winds. Five years before transplanting, the total root surface area of 2-meter-high trees was doubled by pruning the roots of blue spruce. It also increases the root concentration in drip irrigation pipeline from 40% to 60%, which is an advantage in landscape greening. Cultivars Common cultivars (those marked have gained the Royal Horticultural Society's Award of Garden Merit): 'Glauca Globosa' – shrub from in height 'Fat Albert' – compact perfect cone to of a silver blue color 'Glauca Pendula' – drooping branches, spreads to about wide by tall 'Sester's Dwarf' – denser foliage than the species, slowly grows to about tall 'Hoopsii' 'Koster' 'Baby Blue Eyes' 'Baby Blue' Uses The Navajo and Keres Native Americans use this tree as a traditional medicinal plant and a ceremonial item, and twigs are given as gifts to bring good fortune. In traditional medicine, an infusion of the needles is used to treat colds and settle the stomach. This liquid is also used externally for rheumatic pains. Early people used their wood for building. Gallery Distributed soil types and topography Blue spruce generally exists on gentle uplands and sub irrigated slopes, in well-watered tributary drainage, extending down intermittent streams, and on lower northerly slopes. Blue spruce always grow naturally in the soils which are in the order Mollisols, and the soil will also be in the orders histosols and inceptisols in a