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Plant Diseases/red growth on weeping willows


We have 2 weeping willows and both of them have red spines growing out of the roots and trunk. What is it and if it is harmful to the tree how do I control it?

Dear Jason, This was actually a tough question, because I haven't seen this condition personally. There are a few possibilities so let me describe them and you can see what you think your willows have.  One possibility is an insect called the poplar borer. These one-inch long insects drill into the wood of the tree and cause the tree to ooze red sap, and sometimes leave long trails of sawdust.  Also you have the fungus cytospora which causes a canker to appear on willow trees. Symptoms are yellow, black or brownish-orange discolored areas on the bark of the tree. Cankers, pimple-like black speckles, appear on the bark of the tree. The cankers produce spores, which under moist conditions, will leak from the cankers in long, orange, thread like tendrils. Controlling cytospora canker is best done by maintaining the health of your tree. Wounds caused by lawn equipment leave your tree susceptible to canker. Once canker occurs, remove all infected branches and make clean even cuts on branches that have jagged edges. Clean fresh wounds by removing diseased area, in older wounds remove loose pieces of bark. Do not apply dressings to the wounds; allow them to dry out. This would be very difficult when the affected area is the trunk.  Another cause may be a bacteria called Agrobacterium, which lives in the soil and causes galls to form on trees and other woody plants. Or, the growth may be caused by a fungi from the Cytospora and Cryptosphaeria families, both of which commonly cause cankers to appear on willow trees. Cankers are lesions of dead, cracked wood. They may also ooze with a reddish-orange substance that is composed of the fruiting bodies of the fungi. Galls, cankers and insect pests are most damaging to trees that are stressed or weak. Branches affected by boring insects, galls or cankers can be easily pruned off, but when the growth is on the trunk of the tree, treatment is much more difficult. There is no way to chemically treat galls. As for cankers, fungicide will kill the fungi that caused the canker, but the canker itself is dead wood. Trying to dig a canker or a gall out of a trunk will only further wound the tree. Boring insects can be killed with insecticide, but not when they have burrowed into the trunk and are protected by the bark of the willow.
Ok so basically, you can spray with borer spray if you think it is borers.  Fertilome makes a good one.  If it is canker or gall, you can remove as much of it as possible of the exposed parts.  Either way, this is not very good news for your trees.  You might get some help if it is a fungus by removing all the fruiting bodies of the fungus that you can, and then spraying the rest of it with NEEM.  
I am sorry for the vague answer, and the delay in getting my response to you.  If you can take a picture of it and show your local extension agent (county office) they might know definitely which of these ills is afflicting your willow.  I hope this information helps you somewhat.  Please write back if you have further questions.  Good luck, Melissa  

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Melissa Johnston


Plant diseases, landscaping, tropical plants, roses, herbs, plant care, grafting, horticulture, plant identification, anything about plants I can likely answer.


35 years experience in various plant businesses, 1984 Certified Texas Master Gardener.

Master Gardener Association of Texas charter member

none as of yet, but I have a plant q&a book I am in process of submitting.

Magna cum laude graduate of Texas A&M, 1978

Awards and Honors
Plant growing awards, highest grade for Texas Master Gardener graduates.

Past/Present Clients
Past member of and was very highly rated. Owned landscape company in the past, Almost Paradise, and was very successful despite little equipment, no help, and no advertising. Lived well for two years until 9/11.

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