OSCII Activity C.32

Integrating weed control for organic pea and lentil production

Activity summary

Organic production of pea and lentil is difficult because of weed problems. Individual weed management practices have been developed for organic lentil and pea production in western Canada. Individually, components of an integrated weed management system can increase lentil and pea yield and reduce weed problems. Research we have conducted under organic conditions has determined that the seeding rate for pea (Baird et al., 2009) and lentil (Baird et al., 2009) should be increased for weed suppression and maximum economic yield. In fact, the maximum rate examined in the experiment gave the greatest net return. However, with higher seeding rates come greater seed costs, especially in large seeded crops such as peas. Mechanical weed control can also be used to control weeds in pulses. We have found that lentil is tolerant to pre- and post- emergence rotary hoeing as well as in-crop harrowing. In field pea, the rotary hoe provided a 60% reduction in wild mustard and green foxtail biomass while increasing yields up to two-fold (Shirtliffe and Johnson, 2012).  Inter-row cultivation has been used in other crops to control weeds that are too large to control by rotary hoeing or harrowing. Optimum weed control often comes from combining multiple control methods and optimizing their application. Others have found that in cereals, the use of an inter-row cultivator was more economical than increasing seeding rate for weed control.

We have also developed an integrated organic weed control system for weeds in oat and were able to reduce weed biomass by 73% and increase oat yield by 23% only using cultural and mechanical weed control techniques (Benaragama and Shirtliffe, 2013). We anticipate that this project may be able to have even greater weed control benefits, as it will utilize inter-row cultivation. The project will build on knowledge developed by the principal researchers in the management of weeds in the area of cultural and physical weed management. As this system will not rely solely on any single method, it should be more resilient and sustainable compared to normal weed control practices.

The overall objective of this research is to develop an integrated mechanical and cultural weed control system for organic pea and lentil production. To do this, we will first determine the crop tolerance and weed control capability of inter-row tillage. Using this information, we will develop guidelines and best management practices for the use of post seeding tillage implements in organic pulses. We will then determine the economic optimum combination of mechanical weed control tactics (rotary hoe, harrow and inter-row cultivation), as well as seeding rate, to control weeds in organic lentil and pea.

This work will be done using multi-year and location field experiments and it will be done on organically managed land. We anticipate that slightly higher than normal seeding rates and a combination of mechanical weed control techniques will provide optimum weed control in pea and lentil. However, we will not know the results of this experiment until we run the experiments and take into account the cost of machinery and increasing seeding rate. This research will benefit organic pea and lentil production, reducing production risk and allowing for more pulses to be grown organically in Canada. This information will also have application for conventional farmers, and it may allow for reductions in pesticide use, as well as control of herbicide resistant weeds.

Materials and Results to Date

Activity researchers

Name Affiliation
Steve Shirtliffe, Activity Leader University of Saskatchewan
Eric Johnson Agriculture and Agri-Food Canada
Scott Research Farm
Chris Willenborg University of Saskatchewan