Pine |
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| Brown spot needle blight |
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Scots and Ponderosa pines are common
hosts. Disease development is favored by rainy weather conditions.
Symptoms on needles first become evident in late summer as reddish
brown spots with yellow borders. Later, the tips of the needles become
tan then necrotic with the base of needles remaining green. Fruiting
bodies of the fungus develop in necrotic tissue. Most needles are cast
in the fall, but some are not cast until the following growing season |
Longer needled varieties of Scots pine are more resistant. (See resistant varieties). Space trees to provide adequate air circulation. Keep down weeds. Remove and destroy fallen needles to reduce inoculum level. Apply protectant fungicide when new needles are 1/2 grown. A second application 3-4 weeks later may be needed in wet seasons. Labeled fungicides are Bordeaux mixture, chlorothalonil, Kocide 2000 or mancozeb. |
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| Dothistroma needle blight (fungus) |
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Ponderosa and Austrian pines are highly
susceptible. Scots pine is highly resistant. Early symptoms, in
September, are tan or yellow bands,often with a red border. Ends
of needles become brown with base of needle remaining green. Infected
needles may drop prematurely. Repeated attack sometimes kills tree.
In the spring, fruiting bodies are numerous,especially in the transition
zone between green and brown needle tissue. |
Space trees to provide adequate air circulation. Keep down weeds. Remove and destroy fallen needles to reduce inoculum level. Apply fungicide in mid-May to protect older needles. Follow with a second application in mid-June to protect new needles. Use Bordeaux mixture or other copper materials, or mancozeb. (See resistant varieties.) |
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| Leaf scorch (nonparasitic) | ||
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Tips of needles die back. Needles may have some banding as a result of several periods of dieback. Common on white pine in winter or periods of summer drought. | Avoid trunk damage or disturbance to roots. Keep trees well watered. An anti-desiccant used in winter may reduce damage. |
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| Mortality of established white pine | ||
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Eastern white pine most susceptible. Foliage of mature Eastern white pines from a distance appears gray-green and wilted. Twig growth slows and bark is wrinkled. The tree will gradually turn yellow and die. Symptoms may resemble Phytophthora root rot, Procera root rot and pine wilt. Condition is more prevalent in high pH soils, soils that are poorly drained and during years with heavy spring rains. | Once the decline has started it is difficult to reverse. The following action may have some benefit: adjustment of soil pH with granular sulfur, aerifying the soil in the root zone and water and fertilizing as needed. Management of the problem is best achieved through prevention. Avoid planting Eastern white pine on poorly drained sites, in soils with soil pHs greater than 6.5 and in soils with heavy clay content. Avoid root injury and soil compaction. |
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| Phytophthora root rot | ||
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Eastern white pine most susceptible. Poor growth evident for several seasons and foliage has a yellow cast. Roots become brown in cross-section and decayed. Occurs on pines growing in poorly drained sites. | Phytophthora root rot is usually managed by planting pines into sites having good drainage. In some circumstances fungicide drenches may be used, however, these are of little benefit if drainage problems are not corrected. |
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| Procera root rot | ||
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Abundant resin flow associated with base
of trunk, roots, and root collar
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Avoid planting easterrn white pine on poorly drained sites. Do not replant on sites with confirmed Procera root rot. Sanitation to remove and destroy infected trees including roots. |
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| Natural needle browning and shedding (nonparasitic) | ||
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Older needles turn yellow, then brown in late summer, early fall. Needles are shed from tree. This is a normal process in the life of the tree. Most obvious on white pine. | No control necessary. |
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| Needle rust (fungus) | ||
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Small, cream-colored and bag-like pustules on needles. Red pine very susceptible. Not found on white pine. | Usually does not require control in Missouri. |
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| Pine wilt (nematode) Bursaphelenchus xylophilus | ||
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Scots pine is very susceptible. Since 1998, we have also identified the nematode in white pine from two sites in southeast Missouri. Initial symptom may appear as dieback of scattered branches or the entire tree may look gray-green as a result of moisture stress. Tree death is usually rapid. Infestation occurs during the summer and the disease develops in a few weeks. | The only control at the present time is to remove and destroy affected trees that can serve as a source of infection for healthy trees nearby. The nematode is spread by beetles that live in dead or dying trees. See also MU publication MX 858. Some varieties may be more resistant. |
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| Sphaeropsis (Diplodia) tip blight (fungus) | ||
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Small, black fruiting bodies evident
at base of needles. Infected tips often have white resin drops at the site
of infection.
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Prune out dead branches to improve tree's appearance and reduce inoculum. Space trees to provide adequate air circulation. Apply preventive fungicide when new candles are about 2 inches long, followed by second application 10-14 days later. Labeled fungicides are Bordeaux mixture, copper materials, propiconazole (Banner Maxx), and thiophanate methyl. |
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Email: plantclinic@missouri.edu
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