Weed Science

Cooperative Extension

Program overview

The University of Delaware Weed Science Program provides continuing education on the principles of weed science, and training on effective and responsible weed control practices. UD Weed Science conducts unbiased studies for weed control of agronomic crops and commercial vegetables. Chemical, mechanical, and cultural practices are evaluated. Results and recommendations are made available to farmers and agribusinesses through publications, county and state-wide meetings, and field days throughout the year. UD Weed Science informs the agricultural community of emerging weed issues.

Weed management guides

These guides are technical bulletins that provide technical information on managing key weeds in agronomic crops and commercial vegetables. Bulletins include control of Delaware’s noxious weeds. Often the information is specific to Delaware or the mid-Atlantic Region.

Learn more about the guide in the video below.

Weed Management Guide: youtube.com/watch?v=wH5AyULjKL0

Additional Weed Management Guides

Weed science fact sheets

Factsheets for weed science

Weed science Control Factsheets

Burcucumber Control in Cropland Updated (3/19)
Canada Thistle Control in Cropland Updated (3/19)
Giant Ragweed Control in Cropland Updated (3/19)
Johnsongrass Control in Cropland Updated (3/19)
Palmer Amaranth Control in Cropland Updated (3/19)
Texas Panicum Control in Field Crops and Commercial Vegetables Updated (3/19)
Perennial Weed Control

Weed science reports

Delaware Soybean Board Reports

Additional weed management reports

Report books prior to years available online here are available in PDF format upon request. For a copy to be emailed, please contact us and specify the year(s) you would like emailed.

Glyphosate, Weeds, and Crops Series

Series of publications developed by Extension Weed Specialists on glyphosate and key weed species.

GWC-1 Facts About Glyphosate-Resistant Weeds

GWC-2 Understanding Glyphosate to Increase Performance

GWC-9 Biology and Management of Horseweed

GWC-10 Biology and Management of Wild Buckwheat

GWC-11 Biology and Management of Common Lambsquarters

GWC-12 Biology and Management of Giant Ragweed

GWC-13 Biology and Management of Waterhemp

NE-42 life history studies

Studies on the biology and ecology of key weed species in the Northeastern U.S.

Large and Small Crabgrass

Yellow and Giant Foxtail

Barnyardgrass

Galinsoga

Horsenettle

Yellow Nutsedge

Common Purslane

Quackgrass

Common Ragweed

Phillips Manual on Grass Weed Identification

Phillips Manual: Weeds of the Northeast- Identification by Basal-Leaf Characteristics

Weed control results

Annual results of the UD conducted weed control demonstrations and trials. Trials are conducted at the UD’s Thurman Adams Research Farm (UD-REC) and at various on-farm locations throughout Delaware. Compilation of these trials is the basis of UD Weed Management Recommendations. Extension recommendations are seldom made based on a single trial.

Weed science presentations and resources

Ppresentations on various topics with information specific to Delaware or the mid-Atlantic Region.

Weed science links

Related Fact Sheets

All Results

AWARENESS OF POTENTIAL PLANT TOXICITY TO GRAZING ANIMALS

Effects on animal health from consuming or contacting potentially toxic plants can range from none to death. Potential deleterious effects include tainted milk; liver or kidney damage; cardiovascular, nervous system, musculoskeletal, or gastrointestinal problems;
CONSIDERATIONS FOR HERBICIDE USE IN PASTURES

Weeds are often not desirable in pastures for many reasons. Many weeds are less palatable to animals, weeds decrease rapidly in nutritive value as they mature, and some can be toxic if consumed in large enough quantities. Weeds can also reduce the amount of desirable vegetation. Weed infestations can often be prevented by implementing cultural practices that maintain a dense cover of desirable forage where weeds find it difficult to germinate and grow.
DETERMINING THE PRESENCE OF GLYPHOSATE-RESISTANT HORSEWEED UNDER FIELD CONDITIONS

Glyphosate is the active ingredient in Roundup, Touchdown, Duramax, and numerous other brand names. If resistance is suspected in one of your fields, some questions should be asked to help determine if herbicide resistance is the reason for lack of control.
LARGE PLOT TEST-DEMONSTRATIONS FOR EVALUATING WEED CONTROL

Growers, consultants, and the agribusiness industry often ask if they can benefit from changes in their weed management practices, such as the use of a different herbicide, altering the rate of the existing herbicide, incorporating cover crops, or using a new type of cultivator. Comparing changes on separate farms, or even separating fields into halves, often can lead to erroneous conclusions because of the variations within and between fields.
LIMA BEAN FIELDS INFESTED WITH ALS-RESISTANT PIGWEED IN DELAWARE

Pigweed is one of the most wide-spread weed species in Delaware and the region, infesting vegetable crops as well as grain crops. Pigweed is capable of quickly becoming the dominant species in a field due to its high seed output, producing over 100,000 seeds per plant.
MULBERRY WEED (FATOUA VILLOSA)

Mulberry Weed or hairy crabweed (Fatoua villosa) (Thunberg) Nakai is an invasive exotic Asian species from the Mulberry family (Moraceae). First reported in Louisiana in 1964 by J.W.
PORCELAIN BERRY

Porcelain berry, Ampelopsis glandulosa var. brevipedunculata, is an aggressive weed in the Vitacea (grape) family of the eastern United States. This plant is a deciduous, woody, climbing vine or erect shrub native to Northeast Asia—China, Korea and Japan.
SWEET CORN TOLERANCE TO LAUDIS AND IMPACT

Callisto, Impact, and Laudis are all similar herbicides (HPPD-inhibiting herbicides [Group 27]) and all are labeled for use in sweet corn. Previously, sweet corn hybrids have had limited evaluation to determine tolerance to Impact and Laudis.
WEED CONTROL IN TURF

Your lawn may grow more than the beautiful grass you intended. It may also grow weeds, which prevent your lawn from looking its best. In addition to reducing the aesthetics of your lawn, weeds compete with the desired turfgrass for water, nutrients, and light. If you don’t control weeds, your lawn will deteriorate over time.