Dial-a-Garden Message

for the Week of Monday, June 8, 2009

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

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

The evapotranspiration rate for the last seven days is 1.3 inches in the Grand Valley, for Kentucky bluegrass. Divide this into a couple of applications for best results.

An upcoming event will be of great interest to wildflower enthusiasts. On Tuesday, June 30, naturalist and wildflower field guide author Katherine Darrow will be speaking at 6:00 p.m. at the Mesa County Central Library. Her topic is “From Sagebrush to Tundra: Western Colorado Wildflowers from the Bottom to the Top” and the presentation is free. Sponsors are Eagle County Extension and the Western Colorado Gardening Foundation.

A lot of area honeylocusts have been hit hard by the honeylocust plant bug this year. The feeding activity of this insect causes distinct distortion of the young leaves and may cause twig dieback. A severe infestation may warrant treatment; permethrin will control this pest without increasing spider mite problems. Check to be sure the insect is still present before you treat; this plant bug has only a single generation each year, but peak damage usually occurs at around this time. Avoid carbaryl (Sevin) as this tends to worsen spider mite infestations, which can cause premature leaf drop in honeylocusts during the summer. A fact sheet on the insects and mites that trouble honeylocusts is available at www.ext.colostate.edu/pubs/insect/05571.html or give us a call at 244-1836 to receive a copy by mail.

It is time to begin monitoring for squash bug, the insect that does so much damage to our squash plants every year. You’ll have best results if you can find the insect and treat before egg laying begins. A treatment of a pyrethroid insecticide around the base of the plant is recommended; repeat two weeks later for best control. An organic option is to dust diatomaceous earth around the base of the plant; this will need to be repeated following irrigating. If you treat before the plants start producing flowers, you can avoid concerns about residual chemicals. Squash bugs prefer winter squash; a resistant variety of winter squash is Waltham butternut. Plant it this month to harvest in October.

Lawns that have had problems with annual white grubs in the past should be treated in mid-June with a long-residual product containing imidacloprid. If you wait until the damage is apparent, later in the summer, the grubs will be more mature and largely resistant to the insecticide. Annual white grubs can do significant damage to lawns in Western Colorado. They feed on lawn roots, and the affected areas of turf will pull up easily indicating that they have been at work. More information is available at http://www.ext.colostate.edu/pubs/insect/05516.html or by calling the Master Gardeners at any of our area offices.

Small annual weeds can become large annual weeds very quickly now. Annuals need to be controlled before they release their seeds for next year’s crop. Mowing may help but it won’t completely prevent seed formation as many annuals will still produce seed at the new lower height. Cutting the root a couple of inches below the soil surface is sufficient; it’s not necessary to get the entire root out with annual weeds. If you prefer to spray, do it during the cooler part of the day and be sure the wind isn’t blowing. It’s painfully easy to get herbicides onto non-target plants when it’s hot or windy.

The downtown Grand Junction Farmer’s Market starts this Thursday at 5:00, and the Master Gardeners will be staffing the Mesa County booth. Stop by and learn about our exciting programs, and what’s new at the Gardens and Arboretum. If you have plant questions or samples, we’ll do our best to provide answers, or just stop by to say hi!

Give us a call with your yard or garden questions; the Master Gardeners are here to help. You can reach us in Mesa County at 244-1836, in Delta County at 874-2195, and in Montrose and Ouray Counties at 249-3935.

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