CREJ - Property Management Quarterly - February 2015
Last year brought some unexpected surprises and exciting opportunities. As we move into the new year, Swingle is predicting emerald ash borer and- the November 2014 freeze will have a major impact on Colorado landscapes. Therefore it’s vital that property owners and managers think about how their community will be affected. Emerald ash borer. Discovered in September 2013, emerald ash borer is a wood-boring insect that attacks all ash trees growing in Colorado. At its most infant stage (larvae), the insect will bore into the tree, making “S” shaped galleries just below the bark. The damage caused by the insect deprives the tree of much-needed water and nutrients. EAB has yet to be found outside of Boulder, but during this past summer some important developments transpired. First, the entire city of Boulder is now thought to be infested with EAB and under quarantine through the Colorado Department of Agriculture. Boulder County does not have the waste facilities for wood debris from infested trees, so all wood must be taken for disposal to either Larimer, Weld or Jefferson counties, which are currently under quarantine. Additionally, Boulder is a highly mobile community with a busy university and daily commuter traffic. This leads to the likelihood of the insect breaching the quarantine area. Second, many trees throughout several city blocks are symptomatic of borer infestation and sadly have begun dying. Symptoms include dead branches, thinning leaves at the top of the tree, sprout growth near the base and “D” shaped exit holes present on the bark. It’s estimated that EAB has been feeding on Boulder ash trees for six years. EAB is unquestionably the worst urban landscape disaster to reach North America and is now ready to take off in Northern Colorado communities. EAB has killed over 50 million trees, and kills 99 percent of the ash trees it comes in contact with. When EAB was first discovered in Michigan in 2002, the federal government tried to eradicate the insect by taking down healthy trees around infested areas. This, however, was unsuccessful. There is no proven way to stop the spread. Every year since 2002, the insect has spread. It is now in 21 states, but eventually will end up in all 48 continental states because, while the insect flies less than a mile per year, it is an excellent hitchhiker, traveling across state lines on firewood and vehicles. The insect is stealth and by the time its presence is known, it’s likely too late to treat the tree. The next discovery will certainly be within the next 18 months. If the borer is discovered outside of Boulder, immediate action will be needed to save Colorado ash trees. Property mangers should work with a certified expert to identify ash trees on their property, evaluate for infestation and receive treatment options. Any detection of EAB symptoms should be reported to the Colorado Department of Agriculture. November freeze. Mild temperatures during the fall of 2014 came to an abrupt end in mid-November. The high temperature Nov. 10 was 64 degrees Fahrenheit. The night of Nov. 12, the recorded low temperature was -13 degrees Fahrenheit. This represents a 77-degree change in temperature in three days – the third-greatest temperature drop ever recorded in Denver since 1872. When the freeze hit, many plants still had foliage, and even more had not fully hardened off for winter. The process of hardening off is when the sugar concentration of the cells changes in the foliage – essentially lowering the freeze temperature. The plant cells were not far enough along in the process, and simply froze and ruptured, similar to frozen pipes. The freeze disrupts the water-conducting tissues in the tree or shrub, desiccating the plant tissues in the dormant season. Initially we thought plant injury would not appear until spring 2015. But after just a few weeks, the south sides of our spruce and pines turned a bleached, straw color and junipers turned bronze. Many shrubs, fruit trees and, especially, roses are also showing freeze damage. The twigs are brown and shriveling. Brown leaves still clinging to trees may indicate damage. A skilled arborist can check the buds and the tissue below the bark of young shoots to see if the plant is viable. Managers should have dead twigs and branches pruned and provide consistent watering to the landscape, even during the winter months. We will have to wait for spring to see how these damaged plants respond. What can you expect? A continual loss of foliage on evergreens throughout the spring, and leafy plants may fail to leaf out or do so sporadically. Pine wilt nematode. In states just east of Colorado, thousands of Scots and Austrian pines have been lost due to pine wilt. This tiny, wood-boring insect (pine sawyer) spreads a wormlike animal, called a nematode, to healthy pine trees. The nematode multiplies and clogs up water-conducting tissues in the tree. The insect is more stealth than EAB, and typically infestation is difficult to recognize until the tree rapidly dies in the late summer or early fall. Even when the tree dies, there are no visible signs of insects, nematodes or disease. The insect has been found in areas of Colorado such as Lamar, Greeley, Fort Collins, Parker, Aurora, Centennial, Highlands Ranch, Denver, Englewood, Littleton, Longmont, Loveland and Grand Junction. Pine wilt predominantly affects Austrian, Scotch and mugho pine trees. In 2012, during an unusually hot summer, experts saw an uptick in tree mortality. The good news is that 2013 and 2014 both had moderate summer temperatures, as well as above normal rainfall, which dampened the pine wilt nematode’s destruction. In 2014, Swingle did diagnose a few trees with pine wilt, so the nematode is still out there. If there is a hot spring, there is the potential to see many pines die in the fall of 2015. Japanese beetle. For those from the eastern United States, you might be very familiar with this insect, because its origination began there. Japanese beetles need consistent soil moisture to mature, especially in the winter. During the 2013 and 2014 winters, Colorado had an abundance of moisture, which resulted in an uptick of Japanese beetle activity in the 2014 summer. Property managers and owners should look for green beetles feeding on the foliage of garden plants and vegetation. They tend to feed on roses, Virginia creeper (vine), linden trees and many other ornamentals. Japanese beetles won’t kill your plants, but will make them very unsightly. The available spray treatment for the Japanese beetle won’t eradicate the insect, but can help to control it. Two sprays should adequately manage the insect because it stops feeding on foliage in early August. If this winter continues with consistent moisture, be on the lookout for Japanese beetles in early July.