Phoma species cause needle dieback on western hemlock, western redcedar, and several pine and spruce species in bareroot and, particularly, container nurseries (Figure 59). Cotyledons, lower needles, and buds are affected by this soil-borne fungus, resulting in defoliation. Infected needles become chlorotic, turn golden brown, and are cast. Other symptoms include dieback or tip blight which progress down the stem. Symptoms develop in the fall through early spring following the first growing season.
In bareroot seedbeds, cultural practices such as mulching, which reduces soil splashing, help reduce pathogen dispersal. Decreasing sowing densities improves air circulation and results in drier foliage, which inhibits the disease. Although Phoma losses in British Columbia have not justified soil fumigation, it has been used in western U.S. nurseries.
Kliejunas, J.T., J.R. Allison, A.H. McCain, and R.S. Smith, Jr. 1985. Phoma blight on fir and Douglas-fir seedlings in a California nursery. Plant Disease 69: 773-775.
James R.L. 1980. Engelmann spruce needle and twig blight at the Coeur d'Alene Nursery, Idaho. U.S. Dep. Agric. For. Serv., North. Reg. Rep. 80-21.
|
Other Fungi |
Insects |
Environmental |
|---|---|---|
|
Colletotrichum blight |
|
Chemical burn |
|
Principal, locally grown hosts |
Host age and season when damage appears |
|
Nursery type and location |
|
|
|
|---|---|---|---|---|---|---|
|
Bareroot |
Container |
|||||
|
Age |
Season |
Coastal |
Interior |
Coastal |
Interior |
|
|
All pines and spruces, western hemlock, and western redcedar |
1+0 |
Fall through following spring |
Yes |
Yes |
Yes |
Yes |
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Figure 59. Phoma pycnidia (at arrow) on stem of spruce germinant.