LV EN RU DE FR

Weeds and Weed Management

Course developer

Prior knowledge

Biol1001, Botany

Course abstract

The aim of the study course is to learn the biological characteristics of weeds, recognize different weed species and their seeds, understand the impact of weeds on agricultural production, as well as learn different weed control methods.

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 gain the knowledge and skills necessary to plan and improve weed control measures in various conditions and crops. They will develop the competence to analyse the overall weed control situation on the farm, which will be important in the future when working as farmers or agricultural consultants.

Learning qutcomes and their assessment:
1. Able to recognize and identify weed species, their seedlings and seeds, determine their biological properties – 3 colloquia.
2. Familiar with weed biology, ecology and invasive weed species in Latvia – 1st test.

3. Able to determine, justify and characterize the most appropriate weed control method depending on the biological properties of the weeds – 2nd and 3rd tests.

Course Content(Calendar)

1. Introduction: Course Structure, Expectations, Assignments.
Weed Biology and Ecology
2. The Concept of Weeds: definitions of Weeds. Definitions of Weediness. Definitions of Weed Management.
3. Classification of Weeds: common System of Classification - based upon the number of cotyledons. Classification according to their life cycles - annuals, biennials, perennials. Weeds as cultural artefacts.
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 banks: dormancy and longevity, germination requirements.
7. Invasive weed species, alien invaders: principles of invasiveness, environmental implications. Problems with introduced plants in Latvia Heracleum sosnowskyi 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 - weed biology and ecology.
Principles of weed management
10. Biological control: what is biological weed control, biological control methods - inoculative or classical and inundative or mass exposure to agents - 2 h.
11. Mechanical weed control.
12. Cultural weed control and management practices: primary soil tillage, secondary soil tillage, timing, seedbed technique, night tillage, pre-emergence harrowing, post-emergence 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 - principles of weed control.
Integrated practices
15. Principles of integrated weed management - 2 h.
16. Weed control in organic systems.
The test 3 - integrated weed control.

Laboratory works:
1. Biological classification of weeds and identification of weed species according to weed herbarium (81 species) in Latvian and Latin or English and Latin (collections) - 4 h.
2. Preparation and identification of weed seed collection (40 species) (collections) - 2 h.

3. Identification and acquire of seedlings (collections) - 2 h.

Requirements for awarding credit points

Credit points are awarded if 3 tests are successfully written and individual homework is presented in person. Weed colloquia (plants, seeds and seedlings) must be answered and passed.

Description of the organization and tasks of students’ independent work

Literature studies.
Learning colloquia on weeds (plants, seeds and seedlings).
Preparation for tests.

Homework - a summary of scientific and professional literature research for a seminar on one of the course topics, coordinated with the teaching staff. Presentation of the developed homework up to 10 slides.

Criteria for Evaluating Learning Outcomes

Test scores must be successfully assessed (minimum of 4 points each). Homework must be written, submitted and presented within the study course, being able to answer questions. Laboratory work must be completed according to instructions. Weed colloquia (plants, seeds and sprouts) must be answered and passed.

Compulsory reading

1. Haft M. (1983). The arable weeds of Europe with their seedlings and seeds. BASF United Kingdom Limited. P. 494.
2. Handbook of Weed Management Systems. (1995). Edited by Albert E. Smith. Marcel Dekker, Inc. 741 p.
3. Hatcher P. E., Froud-Williams R. J. (2017). Weed Research. Expanding Horizons. 432 p.
4. Kroģere R. (2021). Laukkopības praktikums.
II daļa Tīruma nezāles. Jelgava: LLU. 37 lpp. (elektroniski)
5. Lapiņš Lapiņš D., Kažotnieks J. (2000). Laukkopība. Ozolnieki, LLKC, 247 lpp.
6. Priedītis N. (2014). Latvijas augi. Gandrs, Rīga, 888 lpp.

7. Radosevich S. R., Holt J. S., Ghersa C. (1997). Weed Ecology: Implications for Management. John Wiley and Sons. 589 p.

Further reading

1. Aldrich R. J., Kremer R. J. (1999). Principles in Weed Management. Wiley. 472 p.
2. Håkansson S. (2003). Weeds and Weed Management on Arable Land: An Ecological Approach. CABI Publishing. 288 p.

3. Jaschke P., Witschel M., Krämer W., Schirmer U. (2019). Modern Crop Protection Compounds. Third, Completely Revised and Enlarged Edition Vol. 1: Herbicides. Willey VCH Verlag GmbH & Co. KcaA. 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