Although the spring weather has been cool and wet, many weeds are well on their way to flowering and developing seeds. Some plants that can be observed flowering at this time are Shepherds’s Purse, Flixweed, Dandelion, Henbit, Yellow Rocket, and Field Pennycress to name a few.

Many of the weeds flowering between April and May are perennials, winter annuals, and some cases fast growing annuals (e.g. Bedstraw Catchfly).

Weeds can be very competitive in crop production and also can be a source of poisoning to cattle, sheep and horses. Knowing what weeds you have growing in crop production fields and pastures can lead to making the right decision for control. Numerous publications exist than can aid one in making proper identification. Jerry Doll, Weed Scientist at the University of Wisconsin-Madison, made a comparison of several popular weed identification books last year. Of the numerous weed identification books available, he created his top five picks that were most suitable for upper North Central States. You can read Jerry Doll’s weed identification review on the Internet at the following web address (http://ipcm.wisc.edu/wcm/). Upon arriving at this web site, click WEEDS, then scroll down and click on "2001 Weed Articles" and search for "Weed ID Reference Comparison," May 24, 2001. I concur with Jerry Doll, no one book is the "perfect weed ID book." Three web pages that offer some useful web links to weed identification and poisonous weeds are listed below.

www.uwyo.edu/plants/weeds/links.htm
Offers over 100 links to weed science/weed ID web sites

www.noble.org/imagegallery/
Offers excellent photos of weeds, shrubs, trees, vines

http://sis.agr.gc.ca/pls/pp/poison?p_x=px
Poisonous weed link, good photos and poison symptoms

Weeds can be sent to the Department of Agronomy and Plant Genetics at the University of Minnesota for identification. There is no charge, but this service is only offered to crop producers and those people working in the agricultural service sector. See note for HOME OWNERS-WEED ID at the end of the article. Weed samples that need to be identified can be sent in two ways: (1) by mail or (2) email with attached digital photos. If using Email, enclose background information about the weed along with 2-3 digital photos. Be sure the photos are good quality and in focus so they show the main characteristics of the weed such as the whole plant, stem, leaf structure, and flower. If your are mailing a sample for identification, please follow the guidelines below.

• DO NOT place weeds in plastic bags or wrap in plastic. Plants will turn to mush in the mail.
• DO NOT tape weeds to paper or manila folders.
• Put the plants in a fold of a paper towel or newspaper. Press overnight under the weight of a heavy book and mail them in the paper. If necessary, plants can be gently folded to accommodate the envelope.
• Mail all plants samples at the beginning of the week. This will help to avoid having the plant samples sit in the post-office over a weekend.
• Send at least two samples of the entire plant that include the top growth of the plant- stems, leaves, and the flowers and/or fruits, if available. Roots are not normally needed for identification of older plants. However, if sending weed seedlings or older plants, please send the entire plant.
• Include background information about the plant: perennial, annual, biennial (if known), where found (cropland, near a wetland, edge of field, soil type, sunny/shady location, etc.)
• Include your name address, phone number, and/or email.

Mail weed samples to: Kevin Cavanaugh
Department of Agronomy & Plant Genetics
411 Borlaug Hall
1991 Upper Buford Circle
St. Paul, MN 55108

Digital photos can be sent by e-mail:    cavan008@umn.edu

Information on weed management, herbicide application, and timing can be found in the University of Minnesota Extension Service publication BU-3157-S Cultural and Chemical Weed Control in Field Crops-2002. You can view this on the web at:  www.extension.umn.edu/distribution/cropsystems/DC3157.html#cult

HOME OWNERS-WEED ID

Follow the above guidelines when mailing samples to the Yard and Garden Clinic. The Yard and Garden Clinic charges $5.00 for identification. Payment must accompany sample. Check with your University of Minnesota County Extension Office for a Master Gardener who may be able to identify the weed FREE before sending in a sample to Yard and Garden.

Yard and Garden
University of Minnesota
155 Alderman Hall
1970 Folwell Ave.
St. Paul, MN 55108