Issue: June 28, 2008
I am at wits end trying to diagnose the yellowing of my lawn. I thought it was under-watered, but increased watering did not help. I checked for grubs, but the roots are healthy, so I do not think that is the problem. This spring it did not get the usual care (no fertilizer, etc.). Should we have our soil tested? Perhaps it is a mineral deficiency.
We live in Corrales, NM, and we are having problems with our lawn this year. We seeded the lawn with fescue last year. It was beautiful, but this year we are having problems. We have been watering sufficiently and fertilizing. We did not aerate this year because it was too late. Is it ever to late to aerate? We have dry spots, some yellowing. This year in Corrales, has been so dry, all my flowers and trees, are not doing well like last year, do you have others writing to you about this.
Yes, others are experiencing some of the same problems. Each of you has considered some things that are important and eliminated some potential problems. This has been a challenging year. It remained cool in many parts of the state, and then suddenly became hot. Grasses did not have time to adapt to the change. This may be one cause of the problem.
This has been a very windy year. Wind causes problems as well. It is difficult to properly irrigate a lawn if the wind blows strongly while you are irrigating. Non-uniform application of water may explain some of the problem, as may the fact that wind dries the lawn and other plants very rapidly. Irrigate in the early morning when there is less wind and the air and soil are coolest.
You should not need to irrigate every day if you moisten the soil to a depth of about 8 inches when you irrigate. Waiting two or three days between irrigations will help prevent disease problems. You will need to dig a test hole to see if you are moistening the soil deeply enough and to determine how long to irrigate to moisten to the 8 inch depth. Different soils require different quantities of water to moisten to that depth. Sandy soils need less water, but dry more quickly while silt and clay soils will hold more water and dry more slowly. If you have been irrigating very shallowly and frequently, gradually change the frequency and depth of irrigation over a period of two weeks.
Check to see if your irrigation system is part of the problem. Use empty soup or tuna cans to measure the quantity of water applied to each part of the lawn. Put some cans in yellow areas; put others in the green areas. If they do not receive equal quantities of water, you will need to have your irrigation system repaired, or avoid irrigating when the wind is blowing.
A soil test is a good idea. If the soil is deficient in nutrients, or if the soil alkalinity or salt levels are too high, the lawn will not look as good as it should. When you collect the soil samples, take different samples from the green areas and the yellow areas. Your local NMSU Cooperative Extension Service has a publication to guide you in the process of sampling the soil and sending the soil to a testing laboratory. These publications are also available at the NMSU College of Agriculture web site given below.
There are other factors to consider, but these are the ones to check first. If this does not help, let me know and we will discuss other possible problems and their solutions.
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: email@example.com, office: 505-865-7340, ext. 113.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!