Non-Peer ReviewedIn recent years concern over the development of herbicide resistant weeds has lead to interest in
integrated weed management systems that seek to relieve selection pressure for herbicide
resistance by utilizing mechanical and cultural controls in addition to herbicides. The cultural
practice of increasing crop seeding rate has been identified as having potential to provide non-chemical
weed control and enhance the effects of herbicide application. The objective of this
study was to examine the interaction between increasing seeding rate and the dose response
relationship of weeds to herbicide application. Lentil was chosen to represent the crop, with wild
mustard as the weed, and fluthiacet-methyl the herbicide. The experiment was a factorial design
with four levels of seeding rate (70, 140, 280, and 560 plants m-2) and seven levels of herbicide
application rate (0, 0.94, 1.87, 3.75, 7.5, 15, and 30 g ai ha-1). The study was conducted at two
locations near Saskatoon, Sk. in 2012. Results of the experiment show that increasing lentil
seeding rate decreased the total mustard biomass when herbicides were not applied or were
applied at low rates. In addition increasing lentil seeding rate lowered the herbicide dose required
to result in a 50% reduction in mustard biomass. Doubling seeding rate from the recommended
rate to 280 plants m-2 reduced reliance on herbicide application to maintain lentil yield. These
results suggest that the practice of increasing seeding rate can work with herbicide application to
reliably and effectively control weeds, even in situations where herbicides alone may not achieve
good control
