NEIGHBORHOOD GARDEN FOR DECEMBER 8, 2007

******************************************************************

PINE WILT (PART 2: REPLACEMENT TREES)

BY GEORGE EDGAR

          Over the past 20 years PINE WILT has killed so many Scots or SCOTCH PINE (Pinus sylvestris) trees in the Midwest that Extension Specialists and arborists in many Midwest states no longer recommend planting this once popular species as a landscape or windbreak tree. Some experts even predict that we will not have any Scots pine trees in eastern and central Nebraska within 5 to 10 years. No cure has been found so far. High value trees can be protected with a series of trunk injections of Greyhound (abamectin is the active ingredient). This is a preventative treatment and very expensive.

          In researching information for this article I looked at many sources and found the most useful information from the Nebraska Statewide Arboretum. Justin Evertson of NSA has a good article on “Less Common Conifers”. He says, “Throughout much of the Great Plains, just a handful of species make up the majority of evergreens planted. This lack of diversity is starting to be a real problem in areas where diseases are decimating both Scots or Scotch pine and Austrian Pine.” (Botanical Bits February 2004). He also recommends that we plant native trees that know how to survive in Nebraska.

          The trees listed below are from an NSA article, “GreatPlants Gardener 2005 Plant Descriptions for the Eastern Great Plains” and includes trees that Justin mentions:

·        Cedar, Eastern Red (Juniperus virginiana) - an upright evergreen that tolerates wide range of soils and climate; ‘Canaerti' is a great cultivar with tufted foliage; 'Taylor ' is an outstanding GreatPlants selection from central Nebraska noted for its narrow, upright habit (Height=40’-50’, Spread=8-20’)

·        Fir, Douglas (Pseudotsuga menziesii) – one of the noblest conifers; unique cones are adorned with “tails”; not as drought tolerant as spruce; fails on dry, poor soils; injured by high winds. (Height=50 ft.)

·        Fir, balsam (Abies balsamea) – nice fragrance; 'Canaan' is a variety that should be tried more.

·        Fir, concolor (Abies concolor) – one of the most beautiful evergreens; bright blue new growth eventually makes for soft, blue-green needles; should be planted more. (Height=30-50’, Spread=20-30’)

·        Fir, Fraser (Abies fraseri) – very similar to balsam fir, not quite as hardy, needs consistent moisture. (Height=40’-60’) (Very slow growing and hard to grow in Nebraska.)

·        Fir, Korean (Abies koreana) – deep purple cones amid short, green needles with white banding underneath; heat tolerant, but prefers cooler areas.

·        Fir, Nikko (Abies homolepis) – glossy, green, 1” needles on a fairly narrow tree holding its pyramidal shape in old age; fairly wind tolerant, except in dry, winter winds.

·        Pine, Bosnian (Pinus heldreichii) var. leucodermis – similar to Austrian pine; worth a look. (Height=20’-40’)

·        Pine, Jack (Pinus banksiana) – extremely cold hardy; gnarly growth habit. (height=30’-40’)

·        Pine, Lacebark (Pinus bungeana) – beautiful mottled bark; avoid windy, exposed sites. (Height=40’-50’)

·        Pine, Limber (Pinus flexilis) – native to Kimball county; very flexible branches are plume-like with twisted blue-green needles; for well-drained, dry soils only. (Vanderwolf is a good cultivar/variety and readily available. (Height=40’, Spread=20’)

·        Pine, Ponderosa (Pinus ponderosa) – reliable native with long needles and beautiful bark; for well-drained dry soils; avoid over watering. (Height=50’-60’)

·        Pine, Red (Pinus resinosa) – attractive reddish bark; very cold hardy and drought tolerant.

·        Pine, White (Pinus strobus) – tolerates wetter conditions than most pines; nice long, soft needles. Rapid growing, pyramidal shaped when young, becoming umbrella-shaped with age. (Height=75’, Spread=30’)

·        Spruce, Black Hills (Picea glauca var. densata) – a variety of White Spruce. Nice alternative to blue spruce; short, dark green needles; likes to be kept moist; tolerates tough sites and conditions; extremely hardy. (Height=30’-50’, Spread=15’-25’)

·        Spruce, Norway (Picea abies) – beautiful weeping habit and attractive long cones on this durable tree from Europe; dislikes windy, dry sites. (Height=50’-70’, Spread=30’-40’)

·        Spruce, Serbian (Picea omorika) – arching, ballerina effect on branches; deep green with white undersides; adaptable; (Height=50’-60’, Spread=20’-30’)”

Other more familiar trees that you should look at include:

 

·        Spruce, Colorado Blue (Picea pungens var. glauca) – a majestic tree that is used quite often as a specimen tree, but beautiful. (Height=60’, Spread=25’)

·        Spruce, Colorado – (Picea pungens) - Similar habit as Colorado Blue Spruce but having deep green foliage. (Height=60’, Spread=25’)

·        Spruce, White-(Picea glauca) - Alberta Spruce is another variety as is the Black Hills Spruce. Likes full sun, well drained soil, medium to dry moisture. (Height=40’-60’, Spread=10’-20’)

          For more information about trees and shrubs, you can reach the Nebraska Statewide Arboretum on the internet at “http://arboretum.unl.edu”. At this web site you can get more information on the trees listed. They also have links to colored pictures of the trees mentioned. I want to thank Justin Evertson for permission to use his articles in this series.

          You can also contact your County Extension Educator or go on line to www.ianrpubs.unl.edu. On the left hand side you can type in the name of a disease or the name of a tree then click on search. A list of publications will appear. You can read those you want and/or download them to your computer or print them for your files.

          Or you can go to www.nfs.unl.edu. This is the web sight for the Nebraska Forestry Service which is a division of the University of Nebraska-Lincoln. In the upper left hand corner in the search box type in “pine wilt” or the name of the tree you want information about. A list of publications will appear. You can read those you want and/or download them to your computer or print them for your files.

          In Part III, I will give suggestions on how to go about selecting a new tree for your landscape or a replacement for your Scots pine. I will also give tips on how to plant the tree selected.        

Copyright 2007