What is Causing Yellow and Brown Tips on Junipers?

The Plant Diagnostic Clinic often receives samples and calls about junipers with browned branch tips in the spring. I have observed a lot of this damage in central Missouri starting late last winter. There are several reasons this damage may occur. In some cases, it might be weather fluctuations or other sources of plant stress such as spider mite feeding. However, many healthy-looking junipers with just the terminal 2-6 inches of branch affected, the problem is Kabatina tip blight, caused by the fungus Kabatina juniperi.

Generally, when you look closely at blight affected branch tips, there will be a distinct gray stem lesion where the dead, discolored foliage begins. Beyond that gray lesion area, the branch is usually green and healthy looking. If you have a hand lens, you might be able to see small black blisters in the grey area. Those are spore-producing bodies of the fungus, and their presence can help diagnose this disease. Often, other types of damage such as winter injury appear as a gradual yellowing and browning with no clear demarcation of tissue or grey lesion area.

Although plant pathologists believe the primary infection period is in the fall, the symptoms don’t usually become apparent until late winter. Blighted branch tips eventually fall off in May and June as new growth begins, and no new symptoms develop until the following winter. This disease does not usually cause extensive dieback or tree death, and control measures are not often necessary. However, there are some varieties that are more resistant to the disease, and by avoiding injuries to the branches in the fall, you may be able to reduce some of the infection. There are no fungicides labeled for control.

We certainly do see other juniper disease problems in Missouri, however Kabatina tip blight is seen most commonly in late winter and early spring affecting last year’s growth. For more information about the disease, you can visit our Web site at http://soilplantlab.missouri.edu/plant/diseases/juniper.htm. If you are having problems with your junipers, or with other plants, we welcome your sample submissions. You can see our Web site or contact us with questions about sample submission.

Simeon Wright
Plant Diagnostic Clinic
573-882-3019