GARDENING: Avoid lawn disease by watering at right time |

GARDENING: Avoid lawn disease by watering at right time

Curt Swift
Free Press Gardening Columnist
Leaves on a lilac notched out by the black vine weevil.
Curt Swift |

Watering before 10 a.m., as the billboards around Grand Junction remind us, certainly saves water from evaporation. However, if you’re also concerned about your lawn contracting a disease, you should be watering between midnight and 6 a.m.

Watering your lawn between 6 and 10 a.m. increases the risk of a lawn disease. Unless you have an irrigation controller, watering between midnight and 6 a.m. may be difficult unless you don’t mind getting up several times during the night. Those of you who are night owls should not have any problem with these early morning hours.

A lot of landscape contractors have been changing out sprinkler heads and raising heads to improve water coverage of the lawn. Undertaking this task can result in a much healthier lawn. Now that we are experiencing rain showers every few days you can afford to have the sprinkler system shut down for a while as you raise and straighten your sprinklers.

Next week a group of irrigation specialists from Pakistan will be visiting various farms and research facilities in Olathe and the Grand Valley to study water-efficient agriculture. The following week a group of economists from the Ukraine are spending a few days in the Grand Valley. They will be meeting and talking to growers about economics and marketing. Lance Earley, a retired CSU Extension agent and Rod Sharp, agricultural and business Management economist with CSU, will be helping me host the Ukraine group. That same week I will be leaving for Afghanistan for seven days. When I get back I will do my best to give you an update on my experiences the past two years working with agricultural professionals and farmers in Afghanistan and Pakistan.


People are still asking me about their Austrian and Scots pines. They want to know why their trees are turning brown. The literature on these non-natives indicates they prefer temperatures below 68 degrees F in the summer and are stressed at temperatures above. As the temperature continues to increase over the next few centuries, we will see even our native trees suffer. These trees will move further up into the mountains and further north. At least their progeny will. We are already seeing this northern and higher movement of insects and smaller plants due to the changing climate.


This week I sent samples of lavender essential oil to Dr. Greg Dooley at Colorado State University for analysis. He will be running tests to determine how the high altitude lavender essential oil produced in western Colorado compares to lavender essential oils produced in other parts of the world. This project, initiated by the Lavender Association of Western Colorado, has been in process for two years.

In October I’ll be attending the first U.S. Lavender Growers Association conference in Virginia to report on the essential oil research project and some of my own lavender research. It should be fun to learn about all of the new lavender farms being installed in the United States. As the lavender farms in France decline due to disease, we will see more production in the U.S. Some of the new U.S. farms are small consisting of 100 plants or less, while some new lavender farms are putting in 20,000 plants.


A couple weeks ago I was in Jefferson County conducting a workshop on herbicide damage and explaining how it is confused with physiological problems. Physiological problems are those caused by the environment — too much or too little water, soil salts, excessive soil temperatures, improper planting depth, oxygen-starved roots, etc. I was able to walk around Grand Junction and get all the photographs I needed showing these problems.

Pretty much every place in the nation, except where they have outlawed weed killers, plants show the symptoms of herbicides. Some plants exhibit such damage with their curled leaves. Some plants have leaves that curl up on the margin, while others have leaves that curl down. Sometimes the petioles twist like a pig’s tail, while other leaves show herbicide damage with the development of spots. Petioles are the stems that connect the leaf blade to the stem. Leaf spots can be caused by a disease or may be due to the concentration of the chemical causing a burn. The burn spots can also be elongated where the chemical runs down the leaf.

During this cool period, weed control is often more effective, especially for perennial weeds like bindweed, clover and dandelions. Annual weeds like knotweed and goathead (puncture vine) are best controlled in the summer. Occasionally, somebody will ask me why the herbicide they applied burned back the top of the plant but the plant recovered and grew back. This is often due to mixing too strong a solution. The label is there for a reason — for you to follow.


Teddy Hildebrandt of T4Tree and I were looking at lilac leaves the other day that had been badly notched along the edge by the black vine weevil. I think the notching provides the leaves a beautiful appearance. We need to come up with a GMO lilac that already has those notches. That way we won’t need the black vine weevil to make them. While this notching does little damage to the leaves, the notching is an indication of the amount of damage the larva are doing to the roots. The larva feed on the roots of the plants while the adult snout beetles feed on the leaves.

If you notice damage caused by this insect, and it attacks many different plants, you might want to give Teddy a call (970-640-5284) and have his team drench the roots of your plants with imidacloprid. This systemic insecticide is very effective in controlling this insect and should provide up to two years protection from future damage. If you find your plants yellowing or out of sorts, it might be due to this insect.

Dr. Curtis E. Swift is a retired horticulture agent with the Colorado State University Extension. Reach him at, 970-778-7866 or check out his blog at He owns Swift Horticultural Consulting and High Altitude Lavender.

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