Mushrooms are popping up on the lawn? Here’s what to do

Q: After the rain, I’ve been seeing mushrooms popping up in my lawn. Are they harmful? If so, how do I get rid of them?

Mushrooms are a normal sight after cool, rainy weather. In fact, their presence indicates that your soil contains lots of organic matter (which is a good thing). Healthy soil contains a huge variety of organisms, including fungi, that feed on decaying organic material. The fungi are always present, but if there’s moisture, they will produce fruiting bodies (mushrooms).

If you are concerned that pets or children may eat the mushrooms, you can simply pluck them out of the grass. Although most lawn mushrooms are not toxic, you should never eat wild mushrooms.

I should mention that if mushrooms appear in the middle of summer or during the dry season, you may have an irrigation leak or a drainage problem. 

Q: I heard that some fruit trees shouldn’t be pruned during the rainy season. Why is that?

Eutypa dieback is a fungal disease that affects grape vines, apricot trees, and sometimes cherry trees. Early symptoms include washed-out looking new leaves that are small and wilted. The infection will spread to and kill branches and can eventually kill the whole tree or vine.

Prune apricots and cherries in the late summer so the cuts can heal over before winter. Grapevines should be pruned in the late winter (February) while they are still dormant but after the winter rain has stopped.

When removing infected branches, be sure to disinfect your pruners, loppers, or saw with bleach, Lysol, or rubbing alcohol after each cut.

Q: When turning my compost, I found a lot of big, white grubs. Where did they come from, and are they harmful?

These are probably fig beetle larvae. Fig beetles show up in the late summer to feast on soft fruit that has been damaged (usually by bird pecks). The mature beetles are about 1 ½ inches long, metallic green, and have the unfortunate tendency to fly into windows and other fixed objects. Once they are done colliding with things, they deposit their eggs in mulch or compost. The larvae feed on decaying organic material, so they are somewhat beneficial. If their presence bothers you, just set them out for the birds.

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Los Angeles County

mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/

Orange County

ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/

Riverside County

anrmgriverside@ucanr.edu; 951-955-0170; https://ucanr.edu/sites/RiversideMG/

San Bernardino County

mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu