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The Japanese Black Pine - What Did Happen? |
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| Since the 1940's the Japanese black pine, Pinus thunbergii has been
one of the most widely planted trees in seashore landscapes on Long
Island. This evergreen tree has been valued for its ability to withstand
salt spray and its usefulness as a wind. break and/or screen. Although it
is so widely planted that it seems a natural feature of the landscape, the
Japanese black pine is actually an exotic ornamental on Long Island,
introduced from Japan and Korea where it is native. For about the last 10 years, Japanese black pines on Long Island have been dying in relatively large numbers, particularly on the North and South Forks. Fire Island and particularly Fair Harbor's old stands of Black Pine have not been spared. Some seem to have survived though. The trees most susceptible to problems seem to be 15 to 20 or more years in age. Initially the trees which were most often seen dying were those exposed to the harshest growing conditions. Usually they were receiving little maintenance and they were growing in very sandy soils, often exposed to the rigors of a seashore location. There seemed to be a correlation between trees growing in stressful conditions and those that were dying.
In the late 1970's, the black turpentine beetle, Dendroctonus terebrans,
was discovered attacking Japanese black pines on the South Fork of Long
Island. At that time personnel from Cornell Cooperative Extension -
Suffolk County and the Long Island Horticultural Research Laboratory in
Riverhead developed information and control suggestions for this pest. In
more recent years, these beetles have been frequently observed in Japanese
black pine on the North Fork of Long Island and further west, at least to
the SUNY at Stony Brook campus. These insects have also been reported on
Pinus rigida, the native pitch pine, in a few isolated cases. The boring
of the black turpentine beetles causes resin to flow, harden and produce
the characteristic pitch tubes, which are usually seen on the lower 4 to 5
feet of the trunk. The larvae, which feed on the inner bark, may
completely girdle the tree. Although pitch tubes are a good indication of
black turpentine beetle attack, they will not be apparent if the beetles
have attacked below the soil line, as is occasionally the case. Recently
the beetles were found in the major roots of a Japanese black pine on the
SUNY at Stony Brook campus, even though no pitch tubes were visible on the
main trunk above ground. Up until recently these two factors have been looked upon as primary cause for the death of Japanese black pine which were at least 15 to 20 years of age and situated in the often stressful sites of the shore landscapes. Affected trees turn a lighter green color, eventually turning brown and dying. This symptom progression would often take place within a few months. |
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Picture 2. We stages of the black turpentine beetle actual size approximately one-quarter inch. |
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Figure 5. The pinewood nematode, Bursa phelenchus xylophilus and one of its insect vectors, Monochamus carolinensis (The male nematode shown is 0.73 mm long, whereas the insect is over 1 1/4" long.) Drawing courtesy of Pine Wilt Disease, B24 . SR282, University of Missouri - Columbia. |
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