Going, Going, Gone!
Written by: Tony Arnoldi, Board Certified Master Arborist WI-0102B
Posted: 2018 | Disease Treatment | Plant Health Care | Summer | Tree and Shrub Care
This slot in our Summer issue of the Seasonal Report Newsletter I usually reserve for the “curve-ball” issue that nature usually pitches in most every year – something unusual, pronounced, difficult, or extremely noteworthy that we need to recognize and deal with. For 2018 the winner is monster levels of needlecast infection, and the speed at which this surge of fungal deterioration is overtaking our prized Spruce trees!
Needlecast fungus has been written about here periodically, and most recently in the winter issue of the Seasonal Report. So I will only take a moment to refresh the biology of the problem.
The fungal spores are released into the air from fallen, diseased needles of the previous year. These spores are carried by wind for some distance and land on the soft, new growth that emerges in spring. If the new needles are also moist, the spores can then stick to and infect those needles; however, if the needles are dry, the spores bounce off and do not infect. What matters here is the frequency and duration of needle-wetting events. The more times the needles are moistened, the greater the infection. Infected needles will be killed (brown-out) over the course of a full year or more, and will then fall off. The loss is first seen to occur on the innermost needles, and will progress over the years toward the tips of the branches, where the most recently produced needles are. Once the disease has killed even the tips, the branch is completely dead. Because shade helps the fungus, the lower branches, and other shaded portions of the tree go first. The fungus mostly responsible on Spruces is Rhizospheara.
Of course, every spring has its wet weather and Rhizosphaera is always brewing at some “normal” level. What is different this time is the sheer numbers of trees showing the infection and the speed at which it has progressed from last year. This is the greatest increase in one year that I can remember. The reason for this is again the wetness of the previous two springs – 2017 was a record for precipitation, and this year we had a prolonged wet spring as well. These two back-to-back wet springs seem responsible.
In observing the progression of the needle-loss, the trees can quickly get into the position of only having 1 or 2 years of needles left on a majority of the branching. When this occurs, the opportunity to intervene is narrowed considerably. If there are green needles left on the tips, a spray program can be initiated that will prevent the majority of the infection on the current year’s needles. This spray program consists of 2 or 3 sprays per year, starting in spring. Several years of spray program utilization is necessary to protect and collect sufficient needles to have beauty return, but return it will with the sustained effort.
So this is an alert and call to action. If your Spruces have deteriorated, but still retain green ends on most of the branches, success can be yours. Many spruces have been needlessly cut down. Please contact your Wachtel Certified Arborist for an assessment of your trees to see if recovery can be obtained. In this way, your Spruce evergreens can resume providing their year-round beauty to your landscape.
Related Newsletters
Seasonal Needle Drop of Evergreens
Knowing that seasonal needle drop is normal, is the first step to determining what may be happening. The Certified Arborists at Wachtel Tree Science are always available to help you make sure.
Are your Evergreen Trees Stressed?
One of the largest stresses for trees is drought conditions that make trees more susceptible to attack by insects.
Are Your Evergreens Looking a Little “Off” Lately?
One of the most common ailments for our evergreens is a class of diseases generally referred to as “needle cast”. There are several species of needle cast fungi that can infect pines, spruces, or fir trees. These fungi cause the inner needles to fall off prematurely resulting in trees that appear thin and/or “sick”.