Blackgrass (Alopecurus myosuroides) is an annual grass weed also known as twitch grass, black twitch or slender meadow foxtail. It grows to a height of approximately 90cm and is a prolific weed in Britain, common in winter cereal crop production. Blackgrass flowers between the months of May-August, shedding its seeds before the harvest of the main crop. Blackgrass has caused significant reduction in crop yield. According to Dr Stephen Moss of the UK Weed Resistance Action Group, a population of 12-25 plants/m2 can reduce crop yield by as much as 0.8 tonnes/ha (https://www.fwi.co.uk/academy/lesson/blackgrass).
Blackgrass is a challenging weed for many British farmers. A recent survey by Syngenta UK (an agrochemical and seed company) showed that growers ranked the effects of this weed as a 9.7 on a scale of 1-10. Only less than 2% of growers said it had negligible effect on their farms (https://www.syngenta.co.uk/news). Growers control blackgrass mainly using herbicides, but there is the increasing concern of herbicide resistance developed by this weed.
Recently, there have been success stories with growers using non-chemical methods. During the Groundswell June 2016 No-Till Show and Conference in Hertfordshire, UK farmers reported a reduction in blackgrass germination when they adapted practices with minimal soil disturbance (https://www.groundswellag.com/news).
A news article from the Farmers Guardian Magazine1 outlined Mr Steve Townsend’s (a soil and tillage specialist) advice to growers at the Groundswell No-Till Conference. Townsend said that in order to control blackgrass, British farmers must first understand what conditions make favourable for their growth and germination. According to him blackgrass thrives well in anaerobic (poorly drained), wet, cultivated and sour (acidic) soils; further noting that due to continuous cultivation, British soils have become low in carbon content. Continuous soil disturbance encourages oxidation of soil carbon and subsequent loss of carbon to the atmosphere. Adapting the no-till system minimizes soil disturbance and soil carbon loss leading to improved soil drainage. Minimal soil disturbance will also leave blackgrass seeds on the soil surface; as incorporating them into the soil promotes germination in the next growing season. Townsend also recommended using cover crop residues like mulching and shading to suppress and discourage the germination of blackgrass seeds.
1. Kellet, A (2016, August 19) Make sure your soil conditions are set up to beat black-grass. Farmers Guardian Magazine. Retrieved from https://www.groundswellag.com.
Feature Image: Image of blackgrass seed head growing alongside wheat. Source: https://www.syngenta.co.uk/news/product-update/uk-growers-getting-grips-black-grass