2004 Annual Report for SW03-063
Factors Affecting Alfalfa Stand Longevity in Montana
Alfalfa managements including harvest timings, use of nurse crop at seeding, insect pests and plant diseases each have important impacts on forage yield and persistence. In northern areas, cutting or grazing should be avoided during a fall hardening period. Impact of nurse crops on alfalfa stands may impact longevity. Intensive harvest treatment significantly reduced total forage production by 20%, reduced total root mass by 33%, increased broadleaf weeds (predominantly dandelion, Taraxacum officinale) abundance by 170% and significantly increased the severity of crown and root rot symptoms.
1. An extensive survey of pests and production practices will be conducted in a
variety of Montana production areas for effects on alfalfa stand longevity.
2. Identify the impact of clover root curculio, Sitona hispidulus, other arthropod pests and plant diseases on alfalfa stand longevity.
3. Evaluate the impact of fall harvest timing on alfalfa stand longevity.
4. Evaluate the impact of nurse crops on alfalfa stand longevity.
5. Provide economic analysis of individual, recommended and non-recommended practices from the results of research plots and from cooperating producer field-level trials.
Research plots have been established at SARC (Southern Agricultural Research Center) to investigate the impact of fall harvest on stand longevity (Obj 3). Data were collected in fall 2004 and a poster presented at the Agronomy Society of America annual meeting:
Cash, S.D., R. L. Ditterline, K. D. Kephart and S. L. Blodgett. Alfalfa Stand Mortality and Production Following Intensive Late Summer Harvests. Display Presentation, Agronomy Society America Annual Meeting, Seattle, WA, 2004.
Plots were established at CARC (Central Agricultural Research Center) to investigate the impact of nurse crop on alfalfa stand longevity. Data were collected in fall 2004 (Obj 4).
County sites are in the process of being identified for the extensive survey of pest and production practices on stand longevity (Obj 1 and 2). Yellowstone County site has been visited and initial data and history collected. Other county sites will be visited in spring 2005.
Impacts and Contributions/Outcomes
Data collected from this project will identify important factors in alfalfa stand longevity for Northern Great Plains. One recent finding indicates that late summer alfalfa harvesting on 1 September significantly reduced forage yields by an average of 20%. The first year of this trial provided a useful and vivid demonstration for producers on the effects of a poorly timed late summer harvest on alfalfa. Encroachment by broadleaf weeds (predominantly dandelion, Taraxacum officinale) was observed to increase by 170%.