Horsetail is well known as one of the hardest weeds for any crop producer to manage. There are actually more than 15 species of horsetail to be found in BC, and most problematic one is Field Horsetail (Equisetum arvense). It is a prehistoric perennial plant, typically a couple of feet in height. It has whorls of stick-like leaves growing at the joints. The plants are found in patches, and likely every individual will be connected by one massive, creeping, tuber-bearing root system which can exist very deeply in the soil. In the Summer 2018 edition of the BC Berry Grower magazine, Dr. Jichul Bae, a weed scientist at the Agassiz Research and Development Centre, said that the rooting structure, called a rhizome, can reach three meters deep into the soil. These features make it really tough to control. Cultivating chops the rhizomes into small pieces, each of which will regenerate. Herbicides will not easily stick on the thin and waxy leaves.
Dr. Bae has done work previously in cultural and mechanical weed controls, as well as “living mulches”. He believes the use of living mulches may be used more in helping to manage horsetail in highbush blueberries. Such non-chemical controls may be necessary, as one of the main herbicides that growers have used, Amitrol, no longer has registration in any crop but Spruce bareroot nursery stock only.
Other chemicals that have some effect on horsetail are the following (NOTE: always check the label for crop-specific instructions. The following are comments about products that have some effect on horsetail. These are not recommendations).
Casoron G-4 is a granular herbicide. It is quite effective at controlling down into the roots, but should not be used every year. 2,4-D has some limited foliar effects. These are phenoxy class products, are not registered in blueberries. Aim EC can be used in conjunction with glyphosate prior to planting some crops. Callisto and Sandea have limited and short-term control on horsetail.
As always, do not hesitate to contact us to find out more about your option to control horsetail in your field.