Investigate seeding rate and date interactions with ergot in hybrid fall rye.
Ergot infection caused by the pathogen Claviceps purpurea (Fr.) is a significant issue in rye. In the harvested grain, ergot sclerotia downgrade grain quality significantly because of their alkaloids, which are highly toxic to humans and animals. Reduced grade has a negative impact on the price received by rye producers. A maximum of 0.05% net weight of ergot bodies is only allowed for the #1 class of rye. When hybrid and open pollinated varieties of rye were pushed for higher yields, the level of ergot in the harvested grain increased significantly. This was attributed to increased tillering and most likely an extended period of flowering. With fungicides not being effective, and research on genetic resistance constrained by lack of known sources of major genes, one possible option to control ergot infection is to ensure full, uniform rye stands which may reduce the length of flowering and maximize the rate of pollen shed. The primary objective of this project is to find the optimal seeding rate and seeding date combination for realizing higher yield with reduced ergot infection in fall rye by prairie producers. Multi-location (Lethbridge and Lacombe) and multi-field season (2018, 2019 and 2020) performance trials composed of one hybrid fall rye (KWS Guttino) and one open-pollinated cultivar (Hazlet); three seeding dates based on crop insurance deadlines (10 days earlier crop insurance deadline; exact crop insurance deadline date; 10 days later than the crop insurance deadline), and four seeding rates (100 seeds/m2, 250 seeds/m2, 400 seeds/m2 and 550 seeds/m2) were conducted. Data were generated for agronomic traits, yield components and factors that could influence ergot infection. Particularly interesting result was the change in length of flowering (difference between 1%-initiation and 99%-end of flowering, with increasing the seeding rate leading to a shorter window of flowering and increased spikelet fertility. Increased seeding rate significantly decreased ergot infection, potentially due to a shorter period flowering. Specifically, increased seeding rate (@250 seeds/m2 or 400 seeds/m2) and earlier planting date (10 days earlier than the crop insurance deadline) in both Lethbridge and Lacombe sites were found to contribute to highest yields and lowest ergot percentage.