Dying Leaves and Growths at Thorn Bases of Hawthorn Tree #152547 - Ask Extension

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Dying Leaves and Growths at Thorn Bases of Hawthorn Tree #152547

Asked September 13, 2013, 2:15 PM EDT

I recently notice dying leaves on our 6' tall American Hawthorn tree. After closer inspection I notice strange ulcer like growths with orange-peach colored hairy coverings at the base of many of the thorns. Please see attached photo of pruned branch with growths.

Montgomery County Virginia

Expert Response

From the photo, iIt looks like you have (Gymnosporangium globosum), cedar-hawthorn rust

Here is a publication from the Missouri Botanical Garden
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advi...

Also another publication from NC Cooperative Extension
http://randolph.ces.ncsu.edu/2010/05/what-are-those-orange-things-in-my-tree/

Do you have cedars, junipers or other evergreens in your yard?  This rust fungus needs both the hawthorn, apples, crabapples, and cedars to survive.

See the control suggestions in the publications above (Missouri Botanical Garden):  

  1. Prune. Prune out cankers associated with cedarquince rusts from landscape junipers and deciduous host plants. The spread of cedar-quince rust can be limited by reducing the infested plant parts. This is practical if a few plants are infected and the number of galls per plant is limited.
2. Co-exist. Live with the disease. It may disfigure plants when twigs are infected.
3. preventive fungicide. Use preventive fungicides labeled for use on quince and other hosts. Fungicide sprays are aimed at protecting developing twigs and branches from infection during the time the galls on the junipers are orange and gelatinous. This usually lasts for several weeks and fungicide applications are not necessary once the galls become dry and inactive. Always read and follow label directions. Pesticides registered for use include captanchlorothalonil (Daconil), mancozeb, sulphur, thiram, and ziram.
4. Avoid planting susceptible plants together. Do not plant junipers close to susceptible varieties of apples, crabapples, or quince.
5. Resistant varieties. Remove and replace diseased plants with resistant varieties.Apples: ‘Redfree’, ‘Liberty’, and ‘William’s Pride’.
Organic Strategies:  Strategies 1, 2, 4 and 5 are strictly organic approaches. Of the fungicides listed in Strategy 5, consult the Organic Materials Review Institute (OMRI™) for appropriate organic sulfur products.
Feel free to bring in a sample to your local Virginia Cooperative Extension office for full confirmation. 

To confirm this diagnosis, bring in a sample to your local Virginia Cooperative Extension office.  We are located at 755 Roanoke St. in Christiansburg, VA. 

Kelli Scott Replied September 17, 2013, 11:13 AM EDT

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