By Kristen Nelson, Colorado Master Gardener

The summer solstice has passed, and the long hot days of summer are upon us. Monitoring lawns, trees and gardens is a daily activity as we head into July and August. Walk-abouts are opportunities to notice any unusual or unexpected changes in our landscapes.

For those problems that are difficult to diagnose, consider contacting Colorado State University Extension Master Gardeners who are skilled in plant identification and diagnosis of diseases. They can determine what caused the change and recommend interventions to keep your trees, lawns and gardens healthy. If you see something unusual and want help diagnosing what’s going on, send an email to: MGDiagnotics@arapahoegov.com.

To help us help you, please provide the name of the plant, if you know it. Also, include statements on when you first noticed the problem and whether the problem is on one type of plant or across many kinds of plants. Attach three photos: 1) a close-up of the plant showing the area of concern, 2) the whole plant, and 3) the plant in the context of the yard or landscape. If you add your zip code, Master Gardeners can track emerging horticultural issues.

The top summer diagnostic topics arriving via email are below. Perhaps you have noticed these problems in your landscape also.

Emerald Ash Borer (EAB). Last year, Emerald Ash Borer spread to Arapahoe County. Infested trees were first identified in an area bordering Littleton, Greenwood Village and Centennial. The Emerald Ash Borer creates D-shaped exit holes in the bark of all species of North American ash trees, including green and white ash trees, which are common in Colorado. There are several treatment options that can prevent EAB infestations or save a tree after detection of an infestation.

Brown needles or brown leaves on trees. Repeated hot, dry and windy days can stress evergreens and deciduous trees, causing their needles or leaves to turn brown. Trees need adequate watering in the summer, as well as in the fall and winter. Adequate watering keeps trees healthy and vigorous so they can fight off insects and diseases. Placing mulch around trees is beneficial because it reduces water evaporation. Keep mulch 6″ away from the trunk of trees.

Lawn problems andpatchy lawns are frequently caused by improper lawn care, such as poor watering practices, dull mower blades, and fertilizer burn. There are two fungal diseases that infect Kentucky bluegrass, the predominate species of most lawns. Necrotic ring spot is a fungus that infects the roots and turns them black. The lawn may exhibit circles of brown grass with centers of green grass. Another common fungal disease is Ascochyta leaf blight. This disease develops rapidly during hot dry spells and appears as large irregularly shaped patches of straw-colored grass. 

Lawn Weeds are frequently a symptom of an environmental issue, such as compacted soil, too much water, too little water, or thick thatch. An integrated approach to weed management using cultural, mechanical, chemical and biological practices can produce positive results. Controlling bindweed is a good example of how an integrated approach of good lawn care, hand pulling weeds, herbicide application and bindweed mites yields better results than a single action.

CSU Extension hosts several websites with online garden publications, yard & garden information and  horticultural webinars. The posted information is available to help gardeners and homeowners with their landscaping. If you need extra help diagnosing a problem or answering a horticultural question, contact us because we’ve got you covered! You can drop off samples at CSU Extension Arapahoe County, 6934 S. Lima St., Suite B, Centennial, CO 80112.