Weed Identification and Control

Information on weed identification and control, including catsear, marestail, purple loosestrife, pokeweed, pigweed, poison ivy, crabgrass, hemlock, purslane and multiflora rose. Tips on various herbicides and integrated pest management.

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Marestail (horseweed) in Rock Springs, PA (Annie Klodd)
Managing Herbicide Resistant Marestail (horseweed) - Videos Videos
Best management practices for resistant marestail (horseweed) More
Herbicide Resistant Marestail (horseweed) in Pennsylvania
Herbicide Resistant Marestail (horseweed) in Pennsylvania - Videos Videos
Marestail (horseweed) resistant to glyphosate and Group 2 herbicides is present in PA and presents management challenges. More
Harrington Seed Destructor
Harrington Seed Destructor - Videos Videos

Harrington Seed Destructor

Annie Klodd

2:44

Penn State is involved in research on Harvest Weed Seed Control for herbicide resistant weeds. Here, the HSD is described as it operates during harvest. More
Newly emerged pigweeds in Berks Co., June 13, 2017 (Photo: Annie Klodd, Penn State)
Palmer Amaranth and Waterhemp Beginning to Emerge - News News
Palmer amaranth and waterhemp have emerged for the season in Pennsylvania. It is important to scout for these invasive weeds now, and control them before they reach 4 inches tall. More
Photo: James H. Miller & Ted Bodner, Southern Weed Science Society, Bugwood.org
Yellow Woodsorrel - Articles Articles

Yellow Woodsorrel

Tim Abbey

Yellow woodsorrel (Oxalis stricta) has foliage (composed of three leaflets) that resembles white clover or black medic. More
Photo: John D. Byrd; Mississippi State University, Bugwood.org
Yellow rocket - Articles Articles

Yellow rocket

Tim Abbey

Not all weeds get a “cool” common name, but yellow rocket (Barbarea vulgaris) is one of them. More
Photo: Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org, wild garlic,Allium vineale
Wild Onion and Wild Garlic - Articles Articles
Wild garlic (Allium vineale) and onion (Allium canadense) are perennial plants that can be a weed in turfgrass and landscape beds. More
Smooth groundcherry Physalis longifolia var. subglabrata Photo: Theodore Webster, USDA Agricultural Research Service, Bugwood.org
Smooth Groundcherry - Articles Articles

Smooth Groundcherry

Tim Abbey

Smooth groundcherry (Physalis longifolia var. subglabrata) is a perennial plant. More
Photo: Shepherd's-purse Capsella bursa-pastoris Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org
Shepherd's purse - Articles Articles

Shepherd's purse

Tim Abbey

Shepherd's purse (Capsella bursa-pastoris) is a winter annual. More
Pineapple-weed (Matricaria discoidea) Photo: John D. Byrd, Mississippi State University, Bugwood.org
Pineappleweed - Articles Articles

Pineappleweed

Tim Abbey

Pineappleweed can be either a summer or winter annual. More
Photo: John Cardina, The Ohio State University, Bugwood.org poison-hemlock Conium maculatum plant
Poison Hemlock - Articles Articles

Poison Hemlock

Tim Abbey

Poison hemlock (Conium maculatum) appears to have become more abundant over the past few years. More
Photo: Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org eastern poison-ivy Toxicodendron radicans
Poison-Ivy - Articles Articles

Poison-Ivy

Tim Abbey

Poison-ivy (Toxicodendron radicans) is a native woody, perennial vine. More
Photo: Bruce Ackley, The Ohio State University, Bugwood.org prostrate knotweed Polygonum aviculare
Prostrate Knotweed - Articles Articles

Prostrate Knotweed

Tim Abbey

Prostrate knotweed (Polygonum aviculare) is a summer annual. More
Photo: Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org common purslane Portulaca oleracea
Purslane - Articles Articles

Purslane

Tim Abbey

Purslane (Portulaca oleracea) is a summer annual that forms low growing mats of succulent stems and leaves. More
Photo: Chris Evans, Illinois Wildlife Action Plan, Bugwood.org, catchweed bedstraw, Galium aparine
Catchweed Bedstraw - Articles Articles

Catchweed Bedstraw

Tim Abbey

Catchweed bedstraw (Galium aparine) is an annual that can form dense mats of vegetation. More
Photo: Robert Vidki, Doronicum Kft., Bugwood.org henbit Lamium amplexicaule
Henbit—a Common Winter Annual - Articles Articles
Henbit (Lamium amplexicaule), like many of our common weed species, grows in many areas – lawns, landscape plantings, nursery containers, and unmanaged sites. More
Ideas On Herbicide Resistance Shared At Regional Meeting Ideas On Herbicide Resistance Shared At Regional Meeting - News
A productive discussion was had in Lancaster on the challenges, successes, and needs going forward for managing herbicide resistant weeds in the mid-Atlantic. More
quackgrass Elymus repens Stem(s) Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org
Orchardgrass and Quackgrass - Articles Articles
A number of grass species appear in lawns and ornamental beds and are considered weeds. More
Photo: Mark Czarnota, University of Georgia, Bugwood.org
Mulberry Weed - Articles Articles

Mulberry Weed

Tim Abbey

A weed that has been spreading in recent years in the nursery and landscape trade is mulberry weed. More
Photo: Karan A. Rawlins, University of Georgia, Bugwood.org
Black Medic - Articles Articles

Black Medic

Tim Abbey

Black medic (Medicago lupulina) is a spreading, low growing summer annual. More
Photo: Tim Abbey
Common Pokeweed Identification and Management - Articles Articles
Pokeweed can be a weed in landscape beds and nurseries. More
Photo: Loke T. Kok, Virginia Polytechnic Institute and State University, Bugwood.org, bull thistle, Cirsium vulgare
Bull Thistle Identification and Management - Articles Articles
Bull thistle (Cirsium vulgare) is a biennial that true to its name, has notable spines. This plant is much different than Canada thistle. More
Invasive Pigweeds: Palmer Amaranth and Waterhemp
Invasive Pigweeds: Palmer Amaranth and Waterhemp - Articles Articles

Invasive Pigweeds: Palmer Amaranth and Waterhemp

William S. Curran, Ph.D., Annie Klodd

Palmer amaranth is a species of pigweed that was recently introduced into PA and has been positively identified on more than 30 sites across the state. More
Photo: Chris Evans, University of Illinois, Bugwood.org, annual sowthistle, Sonchus oleraceus
Annual Sowthistle - Articles Articles

Annual Sowthistle

Tim Abbey

Annual sowthistle (Sonchus olearaceus) is one of the annual thistles. More
Clean the Combine to Stop Spread of Herbicide Resistant Weeds
Clean the Combine to Stop Spread of Herbicide Resistant Weeds - Articles Articles
Thorough cleaning and knowledge of the combine’s prior use can prevent the introduction of new herbicide-resistant weeds to your fields. More