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The gorgeous evergreen plant, like other plants, suffers from pest infestations and severe diseases yearly.
Recognizing and understanding the different pests and diseases that tend to afflict every plant is the greatest solution for pests and diseases. This will assist you in determining the best way to handle it.
As a result, in this article, we will educate you on the pests and diseases that might infest your boxwood plant on any long island, as well as the best ways to control and treat them.
The Most Common Boxwood Pests & Diseases
Evergreen plants known as boxwood (buxus) are frequently cultivated as hedges. The plants require little maintenance and can flourish in locations with at least four hours of direct sunshine.
Despite all the care, they continue to have insect and disease infestations, including:
1. Boxwood Leafminer (Monarthropalpus flavus)
The most harmful pest for boxwood is the gall midge (fly). Its symptoms include leaf drop, blistering, and yellowing which is a clear indication that larvae feed inside the leaves.
From mid-May to early June, adult flies develop and produces their eggs in freshly sprung spring vegetation. But before emerging, they cut a little opening on the underside of the leaves through which the pupae grow.
With their empty pupal cases emerging from the leaves, the brilliant orange adult flies are frequently seen in great numbers and up to 17 larvae eat inside the leaf, spend the winter there, and emerge as pupae the following spring. Every year, one generation usually emerges.
You should try and cultivate resistant breeds to control leafminers; for sensitive types of breed, time foliar sprays for adults in spring or for young miners in early to midsummer.
Furthermore, fall or early spring is the perfect time to apply systemic insecticides to the soil. These pesticides should be directed toward the leaf’s outermost layer and they should include a penetrating surfactant.
2. Boxwood Mite (Eurytetranychus buxi)
Boxwood mite is a spider mite that feeds on the upper surface of plants, leaving little white scratches or dots. Leaf drops and pale foliage might occur as a result of severe injury.
Little amounts of damage don’t often have a big impact on the look of these landscape plants, but they can be unpleasant in nurseries on plants that are being produced for sale.
Steadily increasing populations of boxwood mites and harm are frequently related to systemic (soil) application of imidacloprid, which is often used to control leafminers or psyllids. So, you must Inspect treated plants for mites.
Boxwood mites can be maintained by water blasts that remove them from the leaves, or you can use miticides as well as horticultural oil. Whichever one you opt to use, just ensure that you administrate them in early May.
Read Also: Major Gardenia Pests And Problems
3. Boxwood Psyllid (Psylla buxi)
The boxwood psyllid is a leafhopper-like pest that feeds on fresh foliage and causes it to cup, twist, and stunt. When the leaves grow, they become galled, partially enclosing and sheltering the psyllids within.
Nymphs may also feed on older, more developed leaves, producing visible white wax and honeydew that falls into the leaf beneath, where sooty molds grow.
On certain cultivars, the damage is mild and often unnoticed (e.g., B. sempervirens ‘Suffruticosa’), mainly in landscape settings, but even small degrees of damage is undesirable in nurseries.
Plant-resistant cultivars or a dormant-stage oil spray that targets the egg stage for vulnerable boxwood. B. x ‘Glencoe’ (‘Chicagoland Green,’ B. microphylla ‘Fiorii,’ B. sempervirens ‘Arborescens,’ and the hybrids ‘Green Mountain’ and ‘Green Velvet’ have all been identified as kind of resistant.
Foliar pesticide treatments can be applied when nymphs are present. Coverage on deformed foliage may be challenging, thus products with translaminar action may be useful. So, therefore you can add a surfactant to improve the wetting and coverage.
4. Boxwood Webworm (Galasa nigrinodis)
This moth pest, commonly known as the boxwood leafier, webs or links leaves together on boxwood. Damage to boxwood foliage appears to be minor and is usually limited to the inside of the foliage.
Caterpillars can be spotted among the twigs the webbing and fallen dead leaves. The rust-brown moth has the appearance of a leaf-footed insect and is active from June to September.
Pachysandra, a local insect is said to be the original host but turns out to be Osmanthus as the actual host.
However, the infestation of boxwood webworms has not yet been linked to dieback or other visible harm.
5. Boxwood Erineum or Bud Mite (Eriophyes canestrinii)
This is another pest that tends to affect boxwood which is mostly on long islands. This boxwood erineum has been causing new growth distortion, as well as felt-like erineum galls on leaves, and flower ‘blasting.’ It is caused by an eriophyid mite and has only been discovered on Long Island on indoor-grown boxwood.
6. Volutella Blight (Pseudonectria buxi, syn. Volutella buxi)
Volutella Blight causes the leaves on diseased branches to lose their green color and turn a pale tan or brown. This fungus kills leaves that remain on the plant for months, whereas leaf loss is common in Calonectria boxwood blight. A hand lens will reveal the fungus growing on the undersurface of leaves or stems in white or orange cushions called sporodochia. With time, the cushions will turn peach or salmon-colored (light orange). While within a plant, V. buxi matures into bigger wood.
The disease can develop at temperatures ranging from 50 to 95 degrees Fahrenheit, even though it prefers 68 to 77 degrees Fahrenheit and grows slowly at freezing or high temperatures.
If Volutella infection is discovered, prune out infected stems below the afflicted region while sterilizing pruners with 70% ethanol between cuts.
To alleviate environmental stress, consider improving winter protection and irrigation management.
Drought stress is commonly blamed for the Volutella attack. Leafminer control may reduce Volutella canker by minimizing foliage injury.
Only prune or shear plants that are not drought-stressed in dry weather.
Thinning is preferred over shearing because it allows light and air to enter deeper into the hair.
7. Macrophoma Leaf Blight (Dothiorella candollei)
Dothiorella candollei, which causes Macrophoma leaf blight, is one of the most visible fungi that destroys boxwood leaves.
In dead parts of the leaves, D. candollei develops little circular black fruiting structures (pycnidia). As a result, infected foliage is covered with black “dots” containing fungal spores.
This disease is not a hazard to boxwood in and of itself: the fungus infiltrates stressed boxwood tissue.
If you see a Macrophoma leaf spot, remove the damaged part of the plant. Boxwood should be protected against environmental stress and pest infestation.
Macrophoma leaf blight will be less common in stress-tolerant cultivars so ensure that you pick cultivars that are not prone to winter or drought damage.
Also, try as much as possible to avoid overwatering and exposing roots to compacted soils to keep root systems healthy.
8. Phytophthora Root Rot (Phytophthora spp.)
The earliest sign of Phytophthora root rot, produced by one of the several species of oomycete (water mold) in the genus Phytophthora, maybe a loss of shine in the canopy.
The leaves turn a lighter green, then a reddish brown or pale straw tint. The roots soften and brown, and the outer cortex of the root easily peels off when touched. Weak bark and cankering near the soil line are also recently considered. Infected boxwood will die from this infection.
If Phytophthora root rot is identified on boxwood in the landscape, remove the affected plants and replace them with a Phytophthora root rot-resistant shrub.
To prevent disease transmission, use fungicides throughout nursery production.
Planting should be avoided on thick, poorly draining soils.
Boxwood can be cultivated in raised beds or containers if the soil drainage is inadequate. Overwatering and deep planting should be avoided.
Although there are no chemical treatments for many diseases, they can be avoided by planting properly.
FAQs
1. What Is Systemic Insecticide For Boxwoods?
Acephate (Orthene) applied in mid-May (about 3-4 weeks after the adults emerge.) can be applied to control the larvae developing in the new leaves.
From February to early April, the systemic insecticide imidacloprid (Merit) can be applied around the base of the shrub.
2. How Do You Treat Boxwood Dieback?
Proper diagnosis is critical to distinguish boxwood dieback from diseases with similar symptoms, such as Phytophthora root rot.
If found in the landscape, then diseased boxwood plants should be removed and destroyed.
Pruning tools used on diseased plants should be disinfected with a 10% bleach solution.
3. How Do You Prevent Boxwood Blight?
To prevent the spread of blight spores, avoid pruning when foliage is wet. Increase airflow by pruning up the lowest branches on surrounding trees and large shrubs. Spread mulch around your boxwoods and maintain soil fertility to help keep your plants growing vigorously.
4. What Causes Brown Leaves On Boxwoods?
Boxwoods, like other plants, can show drought stress by the browning of foliage.
Drought stress is the most severe in newly-planted landscapes where the plants are suffering from transplant shock, those without irrigation or rainfall for a long period, or those grown in very warm temperatures.
5. What Fungicide For Box Hedge?
If you have a problem with box blight, the fungicides tebuconazole (Provanto Fungus Fighter Concentrate) and tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect) carry label recommendations for use against this disease and can be applied up to six times per year.
6. Does Neem Oil Help Boxwood Blight?
You can spray the leaves with insecticide to kill the plant or try for an organic option such as neem oil.
You may also notice phytophthora root rot, a fungal infection. The fungus kills the roots, so the plant has a harder time taking in moisture and nutrients, and eventually begins to die back.
7. What Is The Best Insecticide For Hedges?
Pesticides including Cypermethrin or Deltamethrin are the most effective. So, if you have them, always ensure that you spray them onto the plant in May or June, and make sure you read the instructions before use.
Conclusion
We believe this article was useful and that you now know how to spot boxwood pests and diseases, especially if you reside on Long Island or plan to visit such a site someday.
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