U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Soil Management Research: Morris, MN
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                                    Software
                People

                    Staff Listing
                                    CareersSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Midwest Area Morris, Minnesota Soil Management Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Forcella, Frankitem
                                            Archer, Daviditem
                                            Spokas, Kurt
  Submitted to: Meeting Abstract
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 2/9/2007
                                    Publication  Date: 2/9/2007
                                    Citation: Forcella, F., Archer, D.W., Spokas, K.A. 2007. Canada Thistle Phenology: Emergence, Growth, Anthesis, and Death of Shoots [Abstract]. Weed Science Society of America. Available: http://www.wssa.net.Interpretive Summary:
                                Technical Abstract: Natural and experimental populations of Canada thistle (Cirsium arvense) were monitored at separate sites in western Minnesota, USA, for two and four years, respectively. Both populations responded similarly to environmental cues, except during the "establishment" year for the experimental population. Otherwise, shoots consistently reached 20, 40, and 60% relative emergence at about 250, 400, and 600 GDD (base temp. = 0 deg C at 5-cm depth). Thereafter, shoot emergence could not be predicted reliably across sites and years. Heights of the tallest shoots consistently reached half their maximum heights at the summer solstice (21 June), but absolute heights varied annually. Shoot mortality during the summer was 25% of the total emerged shoots, and its initial occurrence coincided with flower bud development. Appearance of the first visible flower bud preceded the summer solstice by 10 d, and first anthesis followed 20 d later. Canada thistle phenology is affected by site-specific factors: microclimate, which is variable; and photoperiod, which is not. Both factors can be used alone and in combination to predict aspects of Canada thistle development.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov