Dial-a-Garden Message

for the Week of Monday, July 6, 2009

Susan Rose, Horticulture Education Specialist
Colorado State University Extension Tri River Area

Thank you for calling Dial-a-Garden. This message was recorded on Thursday, July 9, 2009.

The evapotranspiration rate for the last seven days is 1.6 inches of water, for Kentucky bluegrass. It is usually best to divide this into two applications during the week. If you are not able to put 0.8 inches down at a time without it running off, you will need to cycle the application. Try watering for fifteen minutes, waiting half an hour, and watering again. You can measure the amount of water you are putting on by setting out straight-sided cans such as tuna cans in various locations.

Leaves yellowing and falling prematurely may have several causes. On willows, the problem is often spider mites. You may be able to detect some fine webbing on the undersides of the leaves, although to see the mites themselves you’ll probably need a hand lens or microscope. Bring in a sample to one of our area offices and we can check for you. Spider mites can be controlled to some extent with a strong spray of water, repeated once or twice a week; this may be the most practical solution for large trees.

When trees in the stone fruit (Prunus) genus, including ornamental plums and cherries as well as fruit-bearing species, start dropping yellow leaves in summer, check around the soil line for damage to the bark in that area. You might find a gummy substance and sawdust. The peach crown borer feeds around the base of the tree and girdles it; affected trees can fail quite suddenly. The best treatment is preventive; treat the trunk from about a foot above ground down to the soil with an insecticide labeled for borers. The time to treat is right now, and again in about thirty days.

Certain other trees, including cottonwoods, aspens, and willows, will drop their leaves when under stress. This process, called cladoptosis, conserves water by reducing transpiration through the leaves. The stress factors could include drought, excess water, compacted soil, or injury to the trunk or roots. Address any insect problems that are present, and get on a deep and infrequent watering schedule. Avoid fertilizing already stressed trees, as this can aggravate the problem. Winter watering is a very important part of maintaining tree health.

Bring in samples of your affected trees and let us take a look. Master Gardener diagnosticians meet each week in each of our offices to inspect the samples and make recommendations. In order to help us help you, please bring in as fresh a sample as possible. One that is completely dead usually can’t tell us very much, but one where the problem is active will contain information that will help. When you bring your sample in, you’ll be asked to provide additional information such as the age of the plant, where it is located, how it is watered, and any treatments it has received. All this helps us to figure out what is going on with it. Digital photos are helpful too; you may send them to me at susan.rose@colostate.edu

The Gardens at the Mesa County Extension office, located on the fairgrounds, include the Mesa County Arboretum, the turfgrass collection, the Ute ethno-botany learning garden, the adaptive and container garden, three rose gardens, our Plant Select gardens, the cactus and succulent garden, and more. They are very colorful now, and we would like to invite everyone to come enjoy this terrific resource! The gardens are open twenty-four/seven, but if you’d like more information about these and our other projects stop by Monday through Friday between 8:00 and 5:00. We’ll be glad to answer your questions!

We’re located in Mesa County on the fairgrounds at 2775 Highway 50; take the main entrance to the parking lot and turn right. We’re the building with all the gardens around it. In Delta we’re located at 525 Dodge Street, across from the courthouse. In Montrose, we’re upstairs in Friendship Hall, 1001 North Second Street. Our offices are open from 8:00 to 5:00 most days, though we sometimes need to close from noon to 1:00.

Thank you for calling Dial-a-Garden. This message will be updated next week; have a great week!

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