It’s amazing to think a new year is already upon us. In 2015, Colorado landscapes were met with their share of challenges from unpredictable, meteorological events and pests and insects attacking our lawns and trees. Here are Swingle’s 2016 landscape predictions for the Colorado Front Range.
2016 Landscape Predictions:
GIANT CONIFER APHID:
The giant conifer aphid has long burdened Colorado landscapes. This aphid is large and can grow up to 1/4 inch in size. Adults are long-legged, generally gray and black and mostly found in pine, Douglas-fir and spruce trees.
The giant conifer aphid feeds on the sap from twigs and branches, often in large groups. Heavy infestations cause a yellowing of foliage, needle drop and occasionally cause dieback of shoots. Populations usually are highest in late spring, but continue to proliferate as the season progresses.
What is most often noticed is the large amount of honeydew produced by aphid feeding. This honeydew production attracts ants and more importantly yellow jackets. Sometimes large clusters of yellow jackets will be seen swarming in trees with heavy infestations of the giant conifer aphids. Sooty mold can also grow on the honeydew and can cause discoloration of concrete and other hard surfaces under the trees with heavy aphid infestations.
Trees with known infestations should be sprayed in late spring, early summer and again in mid-summer if the population persists. It is also important to inspect all trees, throughout the season to ensure infestations are controlled.
ELM AND WILLOW SCALE:
These insects often go unnoticed in landscapes and though adults are immobile, they still cause irreparable damage. Their damage can often be serious, causing dieback of branches and plant fatality. Scales are sucking insects similar to aphids – feeding on the sap of twigs and branches.
Sprays and injections are both used in order to manage these pests effectively. Swingle predicts the willow scale will finish off aspen trees that have been infested yearly, and that elm scale populations will continue to increase.
Another 2016 landscape prediction is the cranberry girdler, which is a species of moth found recently invading Colorado landscapes. Despite its name, the most damaging stage of the cranberry girdler is a worm-looking grub found in lawns predominantly in the Denver metro area.
The grub feeds on lawn roots just under the soil line. As its name implies, girdler grubs also feed on the base of cranberry plants girdling the plant eventually killing it. Misdiagnosis of this pest is common as the damage to lawns looks similar to drought stress.
Management of this pest is very difficult with over-the-counter pesticides. Swingle’s professionals should be called upon to identify and manage this pest in residential and commercial landscapes. There are biological controls available to commercial applicators, as well as treatments depending on the client’s preference. Lawns and other plants need to be inspected throughout the season and treated as needed. Swingle’s Advantage Plus Lawn Care Program can provide you with a healthy lawn and an expert’s eye to identify any issues that may arise.
EMERALD ASH BORER:
Last year we predicted EAB would spread beyond the Boulder limits. However, to date the destructive pest continues its residency in Boulder County, though we believe by June of 2016 it will begin to migrate.
Why do we believe this? Populations are building very rapidly in northern Boulder and hundreds of trees are dying daily. In southern Boulder, borers are being caught in traps just a few blocks inside of the city limits. The reality – borers are plenty and still very active.
Many experts agree that EAB has in fact traveled outside of Boulder, but has yet to be discovered. In northeastern Colorado, 15 to 20 percent of the urban forest is made up of ash trees. Within a decade, we believe the borer will spread to most areas of the south Platte drainage.
What does that mean for you? Sooner than later, if you have an ash tree, you need to plan ahead. Waiting to treat until AFTER the borer is discovered on your property or an adjacent property is NOT a good strategy. Remember: once the borers are found it’s likely they’ve already been there for two to three years, causing significant if not irreversible damage.
After the unexpected polar vortex in November of 2014, many trees and shrubs were damaged or died from the dramatic temperature change. Sadly the effects are still being felt in 2016.
One tree we’ll be keeping a close eye on is ornamental pear. Late in the summer of 2015, the bark of pear trees began coming loose from trunks. We suspect many of these trees may experience damage or die in the new year. Pruning dead branches and practicing good horticulture can help. We’ll know more as spring approaches.
PINE WILT NEMATODE:
Pine wilt is a fatal disease, which attacks Austrian and Scotch pine trees. The disease is caused by a microscopic worm, which quickly multiplies in the water conducting tissues of the tree – eventually clogging vessels and causing it to die. While the disease has not been severe of late, we believe its impact will not be immediately evident.
Nematodes require a warm spring to multiply rapidly, and the last two have been fairly cool and Austrian pines seems more resistant to the disease. However, it may take a few seasons before signs of infestation appear and by that time it’s often too late. Symptoms include dead branches among healthy ones.
We expect to see this disease become more pervasive – especially if we have an abnormally warm year. The time is now to have your pine trees evaluated for proper disease control.
The Japanese beetle is becoming more established in the northeastern part of Colorado. The beetle commonly feeds on turf grass, roses, Virginia creeper, crabapple, linden, elm and many others.
With the excessive moisture Colorado has received over the last few winters, the beetle grubs continue to increase in population.
Beetle grubs attack healthy lawn roots, causing brown patches to appear during the early, summer months. While brown patches can be caused by multiple reasons, they are more easily identified on trees, shrubs, and roses due to their bright green appearance on foliage. Japanese beetles, both in lawns and on trees and shrubs, require additional treatment or the damage will be irreversible.
In the Denver metro region, weather sources predict it to be a dry summer. It may seem illogical but now is the time to prepare your plants for this dry summer. Recharging the soil profile with water is critical to promoting deep root growth and this deep root growth in turn provides drought resistance come summer.
Contact Swingle to schedule an evaluation to prepare your lawn and landscape for 2016.