Orange hair like growths-poplar tree

Asked November 19, 2017, 11:26 AM EST

Orange hair like growths have sprung out of branches on a live (cotton less) cottonwood tree. What are they and can they be eliminated safely?

Pinal County Arizona

3 Responses

To find the most appropriate individual to answer your question, what state and county do you reside? Thanks! Ruth

I live in pinal county in Arizona.


It looks like your poor little cottonwood has a case of Cytospora canker! Cytospora Canker (fungus – Cytospora chrysosperma) primarily affects weak trees and occurs mainly on stems. Cankers first appear as slightly sunken areas on the smooth bark of branches and trunks. Cankers generally develop in an elliptical pattern and enlarge until stems are girdled and killed. During moist weather, reddish threads of fungus spores ooze from pimple-like fruiting bodies on cankered areas.

Fungicides are not very effective against the Cytospora canker, so prevention is key to controlling the disease.

Control measures:

1) Remove all dead and dying branches on affected trees. If cankers are confined to twigs or branches, diseased bark and discolored wood may be removed with a sharp knife by cutting back 1 to 2 inches into surrounding live, healthy tissues. Whenever possible, the wound should be shaped into a vertical oval or ellipse with rounded ends. Avoid leaving branch stubs. Do not prune or work around trees when the bark is wet as this helps to spread the fungus. Pruning tools should be sterilized between cuts by swabbing them with 70 percent rubbing alcohol or fresh household liquid bleach (1 part of bleach to 9 parts of water). Remove and burn or bury all affected parts as soon as possible. Severely cankered trees cannot be restored to good health and should be cut down and burned because they are a source of infection for other trees.

2) Some trunk cankers, if less than halfway around the stem, can be successfully removed by careful surgery of all diseased bark and the underlying discolored wood. This work is best done by a licensed and experienced arborist.

Prevention measures:

The Cytospora canker doesn't attack healthy undamaged bark, so prevent mechanical injuries to roots, trunk and limbs and reduce insect damage.

1) Treat all bark and wood injuries promptly. Cut away all loose or discolored bark. Clean, smooth, and shape the wood into an oval or ellipse with rounded tips and its long axis oriented vertically. Swab the wound surface liberally with shellac or 70 percent alcohol. Many arborists then coat the wound with a tree wound dressing or paint. The use of commercial tree paints is not generally recommended as their effect is largely cosmetic.

2) Keep plants growing vigorously by (a) proper applications of a balanced fertilizer in mid to late autumn or early spring based on a soil test; (b) watering deeply (soil moist 10 to 12 inches deep) during hot, dry weather (repeat at 10-day intervals as long as the drought continues); (c) proper pruning; and (d) winter protection of young tree trunks using strips of burlap or special tree wrapping paper to prevent sunscald and bark injury.

3) Prune only in dry weather, during or after the tree blooms; the tree will be more vigorous and able to defend against the fungi and the fungi need water to carry them to a new host. Make cuts as smooth as possible and close to the trunk, and disinfect pruning tools after each use to prevent spreading the fungi. Keep the inner bark as dry as possible to discourage the fungi by removing bark from already damaged areas and not applying any dressings to pruning wounds that might keep the damaged area moist. Prune lower branches to encourage more air flow to keep the bark drier.

4) Avoid all unnecessary bark wounds. Keep the trunk base as dry as possible and free of grass, weeds, or other debris that might attract rodents.

Tree selection measures:

1) Plant tree species that are resistant to the fungus. Avoid planting susceptible varieties such as Lombardy, Simon and Siouxland poplars – Rio Grande is resistant.

2) Grow varieties of poplars that are well adapted to the area and planting site.

3) Select only vigorous, disease-free nursery stock.

We wish you the best!