Every December, I put together a Year in Review post about things that have happened during the previous 11 months. First up is our annual review of the pests, diseases, and abiotic problems in the landscape. 2021 opened without the services of our arborist and tree trimmer Nick. After conference, it was decided to put landscape and tree consultations back on my plate, which I wholly accepted.
I have often wanted to be a county horticulture extension agent, but I have been blessed with the work I do here at Grimm’s Gardens. Consulting on landscape problems has been a pleasure to me, because it puts me in a position to use knowledge I have gained over the last 15 years of study.
What does abiotic disorders mean? Well, these are landscape and plant problems not created by insects, diseases, or living organisms (except humans). Abiotic disorders may include improper planting, spray damage, or environmental stresses. So what landscape problems were more prevalent in 2021?
- Aerial spray damage on trees
- Improper tree planting and mulching
- Emerald Ash borer
- Red Currant Blister Aphid
- Fall Armyworms
- Japanese beetle
Landscape Problems on Trees
There were 4 major issues of tree problems which I observed in 2021. These were chemical damage, improper planting and mulching, emerald ash borer, and Japanese beetles.
Chemical Injury on Trees
In the 10 plus years I have worked at Grimm’s Gardens, I have never seen so many problems with trees from aerial spraying. I consulted 10 times in 2021 on chemical injury to trees in the landscape, after they were sprayed or drifted on from neighboring crop fields. What does this say to me? I have observed that the main issue is that chemical application companies are spraying improperly.
Mostly, this has to do with spraying at the wrong times, or in the wrong weather. I understand that they must switch chemicals to keep weeds from becoming resistant to herbicides, but they should read the labels more carefully and spray at the optimal time beforehand. The worst issue was with 100 year-old bur oaks that were over-sprayed by planes, killing the leaves and weakening the tree to the point where secondary pests killed them. It could have been avoided by closing the spray 100 yards sooner and not dropping chemical over the house and landscape.
Other spray issues are with drift, which is mostly caused when chemicals become volatile and float through landscapes onto plants. I saw whole landscapes, including the lawn, killed from chemical drift.
Improper Planting and Mulching of Trees in the Lanscape
Another thing I see a lot of in the landscape are improperly planted trees. What do I mean by improperly planted trees? Trees that are planted too deep. This is the hardest thing to correct on any tree planted more that 2 years previous. But we can correct recently planted trees. Trees should be planted with the root flare at or above ground level.
If that root flare is planted below ground level, the soil above the flare will be touching the trunk of the tree and can lead to depleted oxygen intake, mold and fungal issues, rot and decay, and a shortened life span.
When mulching your planted tree, be sure to keep the mulch 2 to 6 inches from the trunk of the tree, and slope it gently away from it. A mulch ring should extend to the drip line of the tree canopy, and extended as the tree grows. Competition from grass is the biggest hindrance to the growth of tree roots and trunk diameter. When mulch is against the trunk of the tree, it promotes fungal growth and decay, and allows for stem-boring insects to hide near the base.
Emerald Ash Borer
Even though at a county level EAB has not moved into any new counties in Kansas in 2021, it is closer to spreading and has caused much more damage than in 2020. I got my first live look at emerald ash borer, both adults and larvae in Atchison County, KS. First, while working in the city of Atchison, I observed both the larvae and its damage in still living green ash trees on city property. Then, I discovered the live, adult beetles emerging from a tree south of Effingham, KS.
This destructive pest continues to eat away (literally) at our native ash trees. Here in Northeast Kansas, we have mainly green and white ash trees, but in terms of overall canopy, I estimated we have 10 to 15% of our tree diversity in ash trees. That means that when EAB gets through our counties as it moves westward, we will lose up to 15% of our tree canopy.
These will continue to be a problem. While the severity and numbers were down in 2021, we still saw a significant amount of Japanese beetles. The worst problem was on peach, cherry, and apple trees, as well as on flowers and vegetable. Japanese beetles love the fruit and leaves of fruit trees. I am amzed by the eating habits of these annoying beetles.
To control Japanese beetles, the program of attack has not changed. The use of trap crops in home landscapes (such as common evening primrose) paired with handpicking into a bucket of soapy water works well. Also, if it is possible to cover dwarf fruit trees with an insect-proof fabric, this works well. I used a fabric cover on my dwarf apple tree and kept all the beetles off it.
If you live in the country, rent or get some ducks and turkeys to roam your gardens. Then love beetles, bugs, flies, and other pesky insects. In my own garden, my ducks helped to keep down the Japanese beetles, especially when they were emerging from the ground. Chemicals should be a last resort when dealing with any insect pest, as cultural and biological controls are healthier.
Other Landscape Problems
While 2021 was not a banner year for diseases and landscape problems overall, we did see some ongoing and new problems. There will always be landscape problems, but some years are worse than others.
While not typically thought of as a landscape problem, algae is certainly a pest if you have ponds, streams, waterfalls, or water features. It has become more of an issue as the availability of chemicals to combat it has changed. 2021 was definitely a problem year for algae, especially in water features.
We manage several large water features with streams and pondless waterfalls, and clearing the algae without the aid of harsh chemicals is difficult. Hand removal works best, but requires weekly to bi-weekly management. Algae growth occurs most often when there is an abundance of nitrogen or nutrient rich water in conjunction with hot, sunny days. We had plenty of heat and sun this summer and algal growth was abundant.
Red Currant Blister Aphid
This was a new to me problem this spring and summer, mainly in the nursery. I noticed several of our red currant bushes with a reddish puckering on the upper surfaces of the leaves. Upon inspection, I saw aphids feeding on the undersides of the leaves. A quick treatment of insecticidal soap and the aphids were gone.
Even though the damage done by the aphids is cosmetic and does not affect flowering and fruiting of currants, it is important to identify your pest, and control it until natural enemies can take over. If you look at your high pest populations, especially with aphids, you can usually find natural beneficials feeding on them. Lady beetle larvae, lacewing larvae, and others feed on aphids and help reduce pest populations.
Wow! Fall armyworms were very severe this year, after more than 5 years of almost complete absence from the area. These caterpillars are destructive turf and grass pests. The eggs are laid in masses by a drab brown moth, then hatch and eat voraciously on lawns, crops, and golf course turf. Because they cannot overwinter in our area, the adult moths fly south after emerging in the fall.
Fall armyworms can be controlled with an insecticide (such as spinosad) sprayed directly on them as they are feeding. This is the easiest way to get rid of them for most homeowners and turf specialists. If you live in the country, again, let out your chickens and ducks, they will go crazy for the caterpillars.
As long as we are plant people, there will be landscape problems. But by careful cultural and biological practices, we can reduce the problems we will see in our own landscapes. Remember, before you apply any chemical curatives to your landscape, correctly identify the pest of problem, and check for natural predators or remedies at work.