LV EN RU DE FR

Weeds and Weed Management

Course developer

Course abstract

Students familiarize the theoretical concept and practical knowlege of weed biology and ecology, principles of weed management. On acquire the course, student will be able to identify arable land weeds and know their life cycles and reproductive biology, relevance of weed management systems, the interaction between weed and crop. Students will have an understanding and practical skills of weed biological, cultural, chemical control methods and of integrated weed management as well as weed control in organic systems. The identify of weeds, weed seeds and seedlings students acquired during laboratory works.

Learning outcomes and their assessment

Students will obtain the knowledge and skills necessary for planning and optimization of weed control in different conditions and crops. Test No. 1. and 2.
Can identify weed species, seeds and sprouts – colloquiums.
They will raise competence to analyses the overall situation in weed management. This competence is necessary for students as future farmers or farmer advisors. Test No.3.
At the end of the course, a written exam combining theoretical and practical tasks.

Course Content(Calendar)

1. Introduction: Course Structure, Expectations, Assignments’
Weed Biology and Ecology
2. The Concept of Weeds: Definitions of Weeds. Definitions of Weediness. Deffinitions of Weed Management.
3. Classification of Weeds: Common System of Classification – based upon the number of cotiledons. Classification according to their life cycles – annuals, biennials, perennials. Weeds as cultural artifacts
4. Ecological systems:– the relationship between weeds and the environment. Characteristics and growth habits of weeds. Succession – biomes. Ecological perspective.
5. Life cycles and reproductive biology: asexual , sexual reproduction. Relevance of weed management systems.
6. Seed bancs: dormancy and longevity, germination requirements.
7. Invasive weed species, alien invaders: principles of invasiveness, environmental implications. Problems with introduced plants – in Latvia Heracleum sosnowsky Manden.
8. Weed and crop interference: definition and principles of competition, factors influencing competitiveness, models for prediction of competition, allelopathy.
9. Weed population: dispersal, community, dominants.
The test 1
Principles of weed management.
10. Biological control: what is biological control of weeds, methods used in BC of weeds – inoculative or classical and inundative or mass exposure. – 2 h
11. Cultural weed control and management practices:
12. primary soil tillage, secondary soil tillage, timing, seedbed technique, night tillage, pre-emergance harrowing, post-emergance harrowing, post-harvest tillage, direct seeding. – 4 h
13. Crop rotation in weed management: prevention, crop rotation effects, intercropping, rotation strategy, rotation crops, smother crops, cover crops, fallows, crop density, crop rotation design, cropping practices, previous crops, monoculture and crop rotation. Weediness dynamics in crop rotation. Limiting introduction of weeds. – 3 h
14. Chemical weed control: how herbicides work, herbicide groups., plant grows stages and timing of application, impact of herbicides on the environment – herbicides in soil, environmental fate of herbicides. – 2 h
The test 2
Integrated practices
15. Principles of integrated weed management. – 2 h
16. Weed control in organic systems
The test 3.

Laboratory works:
1. Biological classification of weeds and identification of weeds used Weed herbarium (79 species) in English and Latin.(4 h) (tutorial)
2. To acquire Weed Seed collection (39 species) (2 h) (tutorial)
3. Identification and acquire of Seedlings.(2 h) (tutorial)

Requirements for awarding credit points

The writen examination.
The assignment for the test include:
- Theoretical questions covered during the semester;
- The practical tasks which are based on the laboratory works.
All tests and tutorials of laboratory works should have a positive evaluation.

Description of the organization and tasks of students’ independent work

Literature studies.
Processing and presentation of results of laboratory works.
Group work during practical classes.
Preparation for tests.

Criteria for Evaluating Learning Outcomes

The assessment of thre study course examination is comulative. It is made up of the grades of the examinationtests during the semester and tutorials of laboratory works.
The grade is successful if at least 50% of the question of tests or the examination are correct.
Students who have at least „7”are not required to write a theoretical part of the examination; their grade for this part is made up of an arithmetic mean of gradēs in tests during the semester and grade of tutorials of laboratory works.

Compulsory reading

1. Weed Research. Expanding Horizons. Edited by P.E. Hatcher R.J. Chichester ;Hoboken, N: Fround-Williams.Willey. 2017. 432 p.
2. Radosevich S., Holt J., Ghersa C. Weed Ecology: Implications for Management. New York ... [etc.]: John Wiley and Sons. Inc.,1997. 589 p.
3. Handbook of Weed Management Systems. Edited by Albert E. Smith. New York etc. : Marcel Dekker, Inc. 1995. 741 p.

Further reading

1. Hakansson S. Weeds and Weed Management on Arable Land: An Ecological Approach. CABI Publishing. 2003. 288 p.
2. Modern Crop Protection Compounds. Vol. 1: Herbicides. Edited by W. Kramer, U. Schirmer, P. Jaschke, and M. Witschel. Weinheim: Willey VCH Verlag GmbH & Co. KcaA. 2012. 534 p.

Periodicals and other sources

Weed Research. An International Journal of Weed Biology, Ecology and Vegetation Management. European Weed Research Society (EWRS). Wiley Online Library. https://online library.wiley.com/journal/13653180

Notes

Piezīmes / Notes Bachelor study programme “Sustainable Agriculture”, with specialization Sustainable plant production, in full-time studies