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Plant Diseases/Pecan trees


I have a green fern looking leaf growing on pecan tree limbs, what is it and how do I get rid of it??

Sounds like it could be resurrection moss or lichens. Here is a web link with pictures of both.

Resurrection ferns are air ferns and do not harm the tree. IF the pictures on the web link fit the fern do nothing they will not harm the tree.

Lichens are an example of a symbiotic relationship between algae and certain fungi. They are capable of producing their own food. The algae associated with the fungus is a green or blue-green alga. There are three forms of lichens based on growth patterns. Crustose are species that are closely pressed against the surface of the limb or trunk of dead or live trees. Foliose forms are leaf like or prostrate but are also tightly attached to the tree. Fruticose forms are bush like, erect or hanging. Although lichens are found in most areas of Texas, they are most noticeable in areas that have extended periods of high humidity.

The effect of lichens on a tree are only slightly detrimental. The plants are epiphytes. That is they derive their nutrients from the air and not from the plant on which they are growing. Although they are not parasitized, literature reports suggest that lichens do have a slight negative effect. The main concern is that lichens give a tree an unkept appearance. Presence of lichens also is a good indicator of a thin tree canopy. This often leads homeowners to conclude that lichens are the cause and not the effect of thin foliage. The best control for lichens is maintain the tree in good condition. This will insure a dense canopy which will shade the limbs and reduce photosynthesis. Without photosynthesis, lichens are not able to manufacture food needed for growth and development.

Copper containing fungicides are suggested as possible controls for lichens. Applications of Kocide DF for the control of ball moss, have been observed to control lichens for a short period of time. Currently copper fungicides are not approved for lichen control. Because of their limited affect on a plant, chemical control is not suggested.

The best thing to do is fertilize the tree to increase the overall health of the tree. Fertilize with 10-10-10 fertilizer at the rate of 2 lbs per inch of trunk diameter scattered around the tree and watered in good . Apply just before a rain storm and you will not have to water. IF you really feel that you need to get rid of the fern spray them with Roundup, a herbicide. This should kill the fern. But it is really not necessary to the health of the tree.  

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Jim Hyland


30 years experiance in the ID and management of forest diseases and ID of landscape tree diseases.

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