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Phoma blight

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.

Selected References 

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.

Look Alikes

Other Fungi

Insects

Environmental

Colletotrichum blight
Fusarium
Gray mould
Sclerophoma
Sirococcus blight
Top blights and cankers

 

Chemical burn
Frost
Sunscald

Summary

Phoma blight

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
2+0

Fall through following spring

Yes

Yes

Yes

Yes

Figures

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Click on this image to see a larger version     Figure 59. Phoma pycnidia (at arrow) on stem of spruce germinant.