Can watering at night cause mold or fungus in grass lawns?

Asked February 5, 2015, 1:56 PM EST

Can watering at night cause mold or fungus in grass lawns? Are there any problems with mold or fungus on the front range? (Castle Rock Colorado)

Douglas County Colorado

1 Response

Generally, no. There is reduced risk with night watering if applied at a time when the lawn is wet with dew anyway (roughly 9pm - 9am). If on the other hand you extend the period of wetness by watering at 7pm or 10am, fungal diseases are more likely to result. If you have an automatic sprinkler system, set it to come on sometime between 10pm and 6am. There is usually less wind and better water pressure then.

Yes, there are a few fungal diseases common in lawns along the Front Range - Necrotic Ringspot, Dollar spot, Ascochyta leaf blight, leafspot-melting out, slime mold, powdery mildew and others. Many of these fungal diseases are triggered by cultural practices other than excessive watering (though that may contribute) - such as too little water, mowing too low, too much fertilizer, too little fertilizer, excessive shading, poor air circulation through the lawn, etc.

You may want to have a look at these lawn care fact sheets from CSU