Issue: February 3, 1997

Lawn toadstools


Last year I had a lot of toadstools in my lawn. I'm worried about my grandchildren touching them and being poisoned. What can I do to get rid of the toadstools?


What can you do to prevent toadstools? Nothing. Toadstools are the structures that some fungi use to reproduce by producing spores. However, you don t need to worry so much. Your grandchildren cannot be poisoned by touching the toadstools. To be poisoned, they would have to ingest, that is chew and swallow, the toadstool. Then to be poisoned, the toadstool would have to contain poisonous substances. Relatively few poisonous mushrooms have been found in New Mexico. That being said, it is still wise to avoid eating wild mushrooms unless you are very competent at identifying mushrooms.

Don't try to use fungicides or other products to prevent toadstools. This would not be effective and is unnecessary as most of the toadstool fungi are not harmful to the lawn or other plants. However, these fungi are beneficial in decomposing lawn thatch, dead roots, and other organic material. Without the fungi, dead organic material would accumulate and their nutrients would not be recycled to be used by other living things.

You can reduce the number and frequency of mushrooms by removing thatch and other organic matter to feed the fungus. Proper lawn care, avoiding over-fertilization and irrigation, and removal of the thatch should reduce the presence of fungi and toadstools. Just remember that they can not harm you or anyone if you only touch them.

Pretty lawn and dead trees


My neighbor installed a new lawn irrigation system last year. Her grass looked better than ever, but her shade tree died. I want to have a pretty lawn, but I don't want to loose my shade trees. What happened? Can I avoid this and have both a pretty lawn and trees?


It is possible that there is no relationship between the death of the tree. Perhaps an herbicide was used incorrectly before the lawn was installed. However, the process of trenching and installing the irrigation system could have damaged the trees roots.

One of the common problems with installing irrigations systems is a poor understanding and consideration of the extent and shallow nature of tree roots. As interest in water- conserving landscapes grows, the problem can actually be even worse, but it need not be. Trees, water conservation, and attractive turf areas are not mutually exclusive. Irrigation systems can be installed to maintain trees in a water-conserving landscape.

The most likely cause of your neighbor's tree problems was that the trenching to install the irrigation pipes cut the roots of the trees. While some tree root damage must occur when trenching, it can be minimized and the trees can survive. Do not trench on all sides of the trees within the drip line of the tree. When you must trench near the tree, dig the trench directly toward the tree (radially), rather than tangentially. If you trench radially and take care to avoid tree roots, you will minimize the number of major roots which are cut.

Tangential trenching will maximize the amount of root injury.

Irrigation following installation of the irrigation system is important. If roots were cut when the irrigation system was installed, it will be important to provide additional water until roots can be regenerated to replace those lost. After the roots have re-established, irrigation providing water to moisten the soil to a depth of two to three feet in the vicinity of the drip line should be sufficient. Irrigation every ten days to two weeks during the growing season should be sufficient. During the dormant season, irrigation should be needed once a month or less if the soil is moist. However, if there has been no precipitation, it may be necessary to irrigate during the winter.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!