Pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), can reduce the yield of field pea [Pisum sativum (L.) (Fabales: Fabaceae)] and faba bean [Vicia faba (L.) (Fabales: Fabaceae)]. Adults feed on the foliage and larvae feed on root nodules and nodule-associated Rhizobium Frank (Rhizobiales: Rhizobiacea) bacteria. In this study, we developed a data-based nominal threshold for pea leaf weevil in faba bean. We further tested the efficacy of insecticidal seed treatment and foliar insecticide (thiamethoxam and lambda-cyhalothrin, respectively), and nitrogen amendment for pea leaf weevil control using a multi-year field plot study at two sites in Alberta, Canada. Pea leaf weevil feeding damage significantly reduced faba bean yields. Thiamethoxam reduced adult and larval damage, and protected faba bean yield, while neither lambda-cyhalothrin nor a nitrogen amendment was effective in protecting yield. The percentage of seedlings with feeding on the terminal leaf had a negative relationship with yield and was used to estimate a nominal threshold near 15% of seedlings with terminal leaf damage. Since lambda-cyhalothrin is not effective in managing pea leaf weevil on faba bean, there is a need to research additional integrated pest management strategies to reduce prophylactic insecticidal seed treatments.

Lygus bugs and Botrytis fungal pathogen, the causal agent of chocolate spot in faba bean, can cause necrotic spots on faba bean seeds, thereby reducing market value. The mid-pod stage is the most susceptible stage for chocolate spot development and Lygus infestation in faba beans. Therefore, we hypothesised that the concomitant presence of Lygus spp. and Botrytis spp. might increase seed necrosis. Hence, the study was conducted to determine (i) the spatial and local distribution of chocolate spot and Lygus spp. in central and southern Alberta, and (ii) the association of chocolate spot disease severity and Lygus abundance. Chocolate spot and Lygus were present in all the counties surveyed. Chocolate spot had a negative association with Lygus abundance, but only the latter was significantly associated with seed necrosis. Botrytis spp. were frequently isolated from seeds despite the lack of expression of chocolate spot on the foliage. No significant effect of Lygus abundance on Botrytis isolation from seeds was found. Therefore, seed quality losses can occur both due to the fungal pathogen and the insect, which likely occupy different niches influenced by microclimate. Economic thresholds and management strategies will be required to keep insect populations and disease progression under check.

The Redekop Seed Control Unit is an integrated reversible cage mill with a blade system added, but the effects of this addition on harvest weed seed control efficacy and chaff flow are not known. Volunteer canola control when processed by a cage mill with either eight fan blades or four fan blades plus four cutting blades at 5 and 10 Mg hr-1 was tested. Blade configuration in combination with chaff feeding rate did not affect volunteer canola control which remained above 99%. If the blade system allows for reduced energy requirements, it will be a useful development in integrated mill systems.

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