Burkholder Plant Health Care Year in Review

This pest can cause severe damage to cherry laurel, skip laurel, and flowering cherry/plum. White prunicola scale also infests privet, lilac, boxwood, and holly. This area has three generations of this pest per year, with the third being particularly explosive in September. The insect creates a white, fuzzy coating on plant stems and can cause significant yellowing and branch death when populations are high.

Boxwood leafminer, a type of fly larva, has become the most common destructive pest for boxwoods. These larvae feed on the leaves, causing them to brown and eventually fall off. This year, psyllids and spider mites were also active, leading to a decline in the quality and appearance of boxwoods across the region.

Additionally, boxwoods are susceptible to several diseases, with volutella blight being the most common. This disease is particularly harmful to plants weakened due to pests or environmental factors.

Soil diseases, especially phytophthora, can remain inactive for many years but cause significant damage when soil moisture is high. These diseases have many hosts, affecting plants like the following:

• Boxwood
• Laurel
• Azalea
• Rhododendron (seen in image above)
• Pieris
• Holly
• Dogwood

The infection destroys fine roots and progresses through the underground water transport system, causing above-ground symptoms that resemble drought stress. A second soil/root disease has emerged in the last few years, with particularly severe damage in holly, especially Japanese holly. Although symptoms of these two diseases are similar and the diseases thrive in similar conditions, management recommendations are completely different, so thorough identification is required for effective management.

Eriophyid/rust mites are causing significant damage to plants such as privet, cypress, hemlock, and spruce. These tiny mites make detection difficult, leading to damage before homeowners notice their presence. Another species of eriophyid mite is responsible for spreading the rose rosette virus, which causes extensive damage to roses.

Due to the challenge in detecting these pests, eriophyid rust mites have caused damage to plants for many years. However, effective tools are now available to control these mites on privet and conifers. As a result, we have observed a remarkable recovery of previously mite-damaged plants.

The following species of weeds are invasive to Pennsylvania and can harm homeowner’s landscapes.

• Canada Thistle (shown above)
• Bindweed
• False Buttercup/Celandine
• Yellow Nutsedge

In this area, deer are likely the greatest hurdle to establishing new landscape plants, maintaining attractive architecture on mature plants, and ensuring full flowering in ornamental plants that are also feeding targets for deer.

Many landscape plant species are attacked by deer, but the worst are:

• Hosta
• Evergreen Azalea
• Rhododendron (especially PJM)
• Wintercreeper
• Rose
• Hydrangea
• Flowering Cherry/Plum/Apple
• Tulip

Even with clear preferences for some plants, feeding damage from deer extends deep into the list of local landscape plant species. To combat this problem, we have developed our deer repellent blend, combining effects of feeding repellents, predator signals, and behavioral deterrents. We began using this repellent in 2022, which has proven effective, with good to excellent results throughout the spring/summer and fall/winter seasons. We strictly adhere to a re-treatment interval of 60 days or less.

Two critical factors for healthy landscape plants are soil moisture and nutrition. Optimal soil moisture and nutrient levels ensure healthy, resilient plants. Burkholder Plant Health Care samples soil on participating properties and applies prescription soil amendments each season for healthy plant growth.

Maintaining ideal soil moisture levels to ensure your landscape plants thrive is vital. Generally, ideal soil moisture levels range between 20% and 60% but vary depending on the soil type and the specific plant species. The middle ground of 40% is a good target to aim for.

Soil moisture levels that are consistently lower than 20% or greater than 60% can be equally damaging to root systems, so it’s essential to calibrate your landscape watering routine accordingly. We will begin monitoring soil moisture levels during each field visit to client properties to simplify watering recommendations.

Soil nutrition is a crucial consideration for the health of the plants in your landscape. With sufficient nutrients like nitrogen, phosphorus, potassium, and micronutrients, as well as a solid foundation of proper pH levels and soil structure, your plants can reach their full potential regarding maturity, health, and strength. Poor soil conditions can also make your plants more vulnerable to pest problems and
damage from environmental stress.

All properties should have soil analyzed, and many will need to focus on managing and correcting soil nutrient levels. This can make the difference between having healthy plants that require little maintenance and constantly dealing with plant health issues. At Burkholder Plant Health Care, we take soil chemistry seriously. We sample the soil on participating properties every three years and apply prescription soil amendments in each growing season’s spring (March) and fall (October).

Our Burkholder Plant Health Care Year in Review would be incomplete without mentioning a few achievements of our team.  These include:

• Formal identification (with Penn State Insect Identification Lab) of Philoeosinus canadensis
• Full-season management plan for roses
• Rescue treatment for eriophyid mite damage
• Formal identification (with Penn State Insect Identification Lab) of Zeuzera pyrina

Learn more about these accomplishments in our new article.

If you are a current or past client of Burkholder Plant Health Care, thank you for trusting us with the care of the structure and biology of your landscape plants. If you have not brought our services onto your property and are interested in an assessment of the condition of your landscape plants, just let me know (starker@burkholderphc.com). All of our initial evaluations, sampling, and diagnostics are free for current or past clients of Burkholder Brothers. For more information about the Burkholder Plant Health Care Year in Review, give us a call.