Phomopsis Tip Blight
From mid-April through September, Phomopsis tip blight can damage new growth and tender branch tips of junipers. Older foliage is resistant to infection, which means that most blighting occurs on the terminal 4 to 6 inches of the branches. The infected branch tips turn a dull red or brown and finally an ash-gray. Small gray lesions often girdle the branch tips and cause blighting of the foliage beyond the diseased tissue. You can actually see the small black fruiting bodies in the lesions with a hand lens.
The Phomopsis fungus spores are produced all summer long, so infection can take place whenever young foliage is available and moisture or humidity is high. These conditions most commonly occur in the periods April through June and late August through September.
If conditions are such that repeated infections occur in early summer, you may see: abnormal bunching and discoloration of the foliage, stunting of young trees or shrubs, or, in severe cases, plant death.
To reduce the severity of Phomopsis tip blight on existing plantings: increase spacing between plants to improve air circulation, avoid wounding the plants, especially in the spring and fall, and maintain adequate fertility, but do not over fertilize. Water plants in early morning so that the foliage will dry as the day progresses. Avoid night watering. Prune out diseased branch tips during dry summer weather and destroy them. But avoid excessive pruning or shearing, as this encourages new succulent growth, which is most susceptible to Phomopsis blight. Fungicide applications, at 7 to 21-day intervals, may be needed to control the disease on susceptible junipers when the plants are rapidly growing in the spring. The Extension Office has a list of fungicides rated for Phomopsis tip blight.
If you are purchasing new junipers, select those that show resistance to this disease and space the plantings so that there is good air circulation. Call the Extension Office for a list of junipers that are resistant to Phomopsis tip blight.