Weed Suppression

From Mulching to Herbicides: Choosing the Right Weed Management Tactics for Your Farm

Weed Management

Weed management can be a daunting task for growers, and it’s not uncommon to view them as an inevitable presence. Unfortunately, the cultivation methods you use for your cash crop may create favorable conditions for specific weeds to thrive. It’s important to incorporate multiple weed-management strategies to mitigate this problem, and each strategy should be carefully selected based on your unique situation. Your choice of tactics will also vary depending on factors like available equipment, time of year, and required labor. There are two main types of weed management: seedling-focused and seed bank-focused. Seedling-focused management prioritizes controlling weeds during the “critical period” when competition significantly reduces yields. However, for long-term management, additional strategies are needed because if weeds survive this stage and set seed, the problem can be even more challenging to control in the following season. Seedbank-focused management prioritizes reducing seed rain and minimizing labor and competition from weeds in successive seasons. The seeds of many common agricultural weeds have a “half-life” of only a year, so by preventing them from going to seed, you can significantly reduce the viable seeds in the topsoil’s seed bank every year. While long-term management focused on preventing seed rain can have significant effects, it can also require much manual labor.

DIY Weed Prevention

To prevent weeds from growing, covering bare soil is crucial. Mulching and winter cover crops are two of the most popular methods. To eliminate specific weeds, crop rotation with a tailored successor crop is effective. Although many farms rely on herbicides, the prevalence of herbicide-resistant weeds is increasing, and some herbicides have been shown to have negative effects on the soil’s microbial community. Polyethylene sheeting can also reduce weed coverage and increase soil nitrate levels, but mulching has been shown to have higher soil quality and microbial activity. When implemented correctly, mulching can also have a significant impact on weed coverage and seed germination.

DIY Weed Removal

Whether you prefer natural approaches or more traditional methods, there are several ways to remove weeds from your garden. Here are some options to consider:

  • Eco-Friendly: The most environmentally-friendly method is to remove weeds by hand. However, this can be time-consuming for larger fields.
  • Mechanical: For larger fields, mechanical means of weed suppression may be more practical.
  • Preventing Spread: Be careful not to spread weed seeds to other areas when removing them by hand.
  • Corn Gluten Meal: Corn gluten meal is an effective way to prevent weed seed germination. However, it can also prevent other seeds from growing, so use it only after desired plants have germinated.
  • Ground Cover: Mulching, ground cover plants, newspaper, cardboard, and landscape fabrics are all effective methods to smother weeds.
  • Chemical: Vinegar, boiling water, herbicidal soap, salt, and weed torches are all effective chemical methods. Be sure to use salt sparingly, as it can render soil uninhabitable for several months.
  • Cover Crops: For larger fields, consider planting cover crops in the fall to improve soil health and provide nutrients in the spring.

FURTHER READING

Establishing Winter Cover Crops. Oregon State University Extension Service. https://extension.oregonstate.edu/crop-production/soil/establishing-winter-cover-crops

Cover Crops. Oregon State University Extension Service. https://forages.oregonstate.edu/fi/topics/cover-crops/species

Coleman, E. The New Organic Grower. (1989). Chelsea Green Publishing.

Gilman, S. Organic Soil-Fertility and Weed Management. (2011). Chelsea Green Publishing.

Fredrikson, L., Skinkis, P., and Peachey, E. (2011). Cover Crop and Floor Management Affect Weed Coverage and Density in an Establishing Oregon Vineyard. HortTechnology. https://doi.org/10.21273/HORTTECH.21.2.208

Isik, D., Kaya, E., Ngouajio, M., and Mennan, H. (2009). Weed suppression in organic pepper (Capsicum annuum L.) with winter cover crops. Crop Protection. https://doi.org/10.1016/j.cropro.2008.12.002

Brown, B. and Gallandt, E. (2018). A Systems Comparison of Contrasting Organic Weed Management Strategies. Weed Science. https://doi.org/10.1017/wsc.2017.34

Reiss, A., Fomsgaar, I., Mathiassen, S., Stuart, R., and Kudsk, P. (2018). Weed suppression by winter cereals: relative contribution of competition for resources and allelopathy. Chemoecology. https://doi.org/10.1007/s00049-018-0262-8

Hazrati, H., Fomsgaard, I., and Kudsk, P. (2020). Root-Exuded Benzoxazinoids: Uptake and Translocation in Neighboring Plants. Agricultural and Food Chemistry. https://doi.org/10.1021/acs.jafc.0c04245

Pannacci, E., Lattanzi, B., and Tei, F. (2017). Non-chemical weed management strategies in minor crops: A review. Crop Protection.