Weed Management
Weeds can reduce the growth rate and affect the health of trees and shrubs you plant, as they compete for nutrients, water, and light. On this page, you’ll find information on weed management and control of trees and shrubs, including mulching, herbicides, and pesticides. Find specific tips on dealing with Japanese barberry, mulberry weed, ragweed, sowthistle, knotweeds, and more.
Weed Control and Management for Trees and Shrubs
Whether you’re a green industry professional or growing trees and shrubs in your own garden, managing weeds is essential if you want your trees and shrubs to be healthy. Successful weed control and management require a combination of cultural and preventative measures. You can supplement these measures with the effective use of appropriate herbicides.
One very common method for suppressing weeds is to apply a mulch. Mulch can also enhance the beauty of the landscape, conserve soil moisture, and act as a buffer from the damaging effects of traffic and lawn equipment. Mulching plays a key role in organic land care best management practices.
Proper mulching is one of the best ways to promote vigorous root growth and tree health because it mimics the natural environment found in forests. However, excessive or improperly applied mulch can adversely affect plants. Learning how to properly mulch your trees and shrubs is therefore essential.
Identifying Invasive Plants
When you’re looking for plants to add to your garden, avoid anything on the Pennsylvania invasive plant list. Many invasive plants have lovely flowers, make an excellent color contrast, or you’ll find them being sold at a bargain price. Be aware, however, that they spread quickly because they’re not limited by pests, diseases, or predators. They also grow and reproduce rapidly and thrive in a variety of conditions.
Some of the most common invasive plants are:
- Tree-of-Heaven (Ailanthus altissima): Native to both northeast and central China, as well as Taiwan, the tree-of-heaven is an invasive, pervasive, and problematic tree. It is allelopathic, which means it produces a toxin that inhibits the growth of other plants. Controlling the tree-of-heaven is important because it can quickly crowd out native plants. It’s important to know how to recognize it, as there are several other trees that look very similar.
- Japanese barberry (Berberis thunbergii): This is an invasive non-native woody plant that can grow 3 to 6 feet tall and wide. It can very quickly dominate woods and woodland edges, crowding out native plants and disrupting ecosystems.
- Annual sowthistle (Sonchus olearaceus): Sowthistle reproduces from seeds and the seedlings form a basal rosette low to the ground. As they grow, they can reach approximately 4 feet tall.
- Mulberry weed (Fatoua villosa): A summer annual that can grow more than 2 feet tall. You can remove it by hand before the seeds set.
- Oriental bittersweet: This is a non-native woody perennial vine that covers and kills plants by blocking sunlight, weighing down plants, and girdling trunks and stems.
- Ragweeds: These are members of the Aster family. Common ragweed can be found throughout parts of the Northeast and has historically been a problem in soybean crops.
- English ivy (Hedera helix): This non-native woody perennial vine has been known to kill the trees of branches when left to grow unchecked. When allowed to grow up a structure it can be difficult to remove because of the root-like structures it uses to anchor itself.
Herbicides Application
You should take proper care when applying herbicides near trees and shrubs. Incorrect herbicide formulations can damage non-target plants. Glyphosate, a systematic, non-selective herbicide, is easy to use but very unforgiving. Overspray can be devastating to plants around it.
Before applying herbicides, take a close look at the label to see what active ingredients it contains. Manufacturers formulate some combination products in either amines or esters. You are required to obtain certification as a commercial or public applicator if you're planning to apply restricted-use pesticides. Spray record-keeping plays an important part in an integrated pest management plan.
- Workshops
$125.00
Professional Pest Managers School
When 12/09/2024Length 7 hours, 15 minutesEvent Format In-PersonThis one-day pesticide update session provides research-based information for applicators, as well as recertification credits in categories where it can be difficult to find credits. - Articles
¿Qué licencia de pesticida necesita su empresa?
En Pensilvania, los profesionales relacionados con la industria agrícola, forestal y de jardinería que utilizan pesticidas deben conocer las leyes que regulan el uso de pesticidas en Pensilvania y saber cómo aplicarlas y cumplirlas. Esto incluye reconocer si se requiere una Certificación de Aplicador de Pesticidas (comúnmente conocida como Licencia de Pesticidas) y qué tipo y categoría de certificación deberá tener según el trabajo que realice. - Articles
Home Orchard Calendar
Calendar applies to Zone 6, in the Mid-Atlantic Region. Apples bloom generally the last week of April. Adjust timings for other regions. - Articles
Phomopsis Canker and Twig Blight in Blueberries in Home Fruit Plantings
Bushes that have been weakened by other factors usually are more prone to phomopsis twig blight and canker. In addition to twig blight and canker, the fungus causes a fruit rot. - Articles
Pests and Pesticides in Home Fruit Plantings
Can fruit crops be grown in the home garden without pesticides? The answer is yes, but fruit quantity and quality may decrease. - Articles
Applying Mulches in Home Fruit Plantings
Since most mulch materials are applied for weed control, it is important that they be in place before weeds have emerged from the soil. - Videos
Controlling Tree of Heaven: Why it Matters
Length 3:53Learn about the invasive tree-of-heaven, commonly found in Pennsylvania, and how you can use it to help control another invasive species, spotted lanternfly. - Videos
Tree of Heaven: Native Look-alikes
Length 5:06Learn the identification characteristics of the invasive tree-of-heaven and be able to distinguish it from the native look-alikes, black walnut and staghorn sumac. - Articles
Off-label Applications of Pesticides and Phytotoxicity
Extension professionals and pesticide industry representatives consistently reminded growers to read the pesticide label thoroughly and observe all precautions listed on the label. - Articles
Amines or Esters; Which Should You Use?
As the forsythia comes into full bloom and dandelions show their beauty, one thing is certain; spring is upon us. - Articles
Mulberry Weed
A weed that has been spreading in recent years in the nursery and landscape trade is mulberry weed. - Articles
Use Glyphosate With Care Near Trees!
Glyphosate is the active ingredient in non-selective, systemic herbicides sold under various trade names – Roundup, Accord, Glypro, and many others. - Articles
The Invasive Japanese Barberry
Japanese barberry (Berberis thunbergii) is an invasive, non-native woody plant that can grow 3 to 6 feet tall with a similar width. - Articles
English Ivy in the Landscape
English ivy is an evergreen with dark green older foliage that has white veins, while new growth is a lighter green color. - Videos
Tree of Heaven: Accurate Identification
Length 3:47Learn the distinguishing characteristics of the invasive tree-of-heaven that you can use to accurately identify it. - Articles
Putting an End to My Landscape Fabric Nightmare
Landscape fabric is often used in ornamental landscapes as a method to block weed growth permanently. - Webinars
Turf and Ornamentals: Right-of-Way
Length 2 hoursEarn Cat. 10 and PC credits while you learn about common invasive plants in PA, what's new in Integrated Vegetation Management, and more - Online Courses
$59.00
Weed Management for Ornamental Landscapes
Sections 6Length 8 hoursLearn how to identify and manage weeds in the northern United States using integrated pest management and herbicides. Earn PDA core and category credits. Earn PCH credits. - Articles
Tree-of-Heaven
Tree-of-heaven (Ailanthus altissima) is an invasive tree and noxious weed in PA. This article displays images to assist with identification and provides recommendations for control, including a management calendar and treatment and timing table. - Articles
Oriental Bittersweet
Oriental bittersweet (Celastrus orbiculatus) is an invasive, perennial, woody vine. This article displays images to assist with identification and provides recommendations for control, including a management calendar and treatment and timing table. - Articles
Mulching Landscape Trees
Mulches are materials placed over the soil surface to enhance landscape beauty, improve soil conditions, protect plants from foot traffic and lawn equipment, and suppress weeds. - Workshops
Rights-of-Way and Integrated Vegetation Management
Length 7 hoursThis seminar will provide vegetation managers with routine and the newest information about identification and best practices. Controls include mechanical, cultural, and chemical methods. - Articles
Which Pesticide License Does Your Business Need?
In Pennsylvania, Green Industry professionals who use pesticides need to understand the Pennsylvania pesticide laws and how to comply with them. - Articles
Introduction to Creating Healthy Landscapes
When a plant looks unhealthy or has been injured by an insect or a mite, often our first impulse is to apply a pesticide.