Evaluating performance of three types of carbon seed coatings on seedling development

Abstract

Sagebrush Steppe native plant restoration faces many hurdles to success, including extreme temperature and precipitation variability and non‐native plant invasions. Multi‐year preemergent herbicides are an option for annual grass control, but also prevent germination of native seeded species. Seed enhancement technologies have been recently developed and tested to shield native seeds from herbicide effects using activated carbon, giving them a competition‐free window to germinate and develop. Several issues need to be addressed to scale these technologies appropriately to contend with the massive spatial extent of sagebrush (Artemisia tridentata spp.) steppe restoration needs, such as the ability to produce seed enhancement technologies at high volume and making them compatible with existing rangeland seeding practices. In this lab study, we evaluated the efficacy of traditional herbicide protection pellets (HPPs) versus smaller commercial coatings at protecting native seed from the preemergent herbicide imazapic. We then tested house‐made coatings against those produced by Germains Seed Technology. Finally, we tested to see if the order of seeding and spraying affects the efficacy of high carbon industrial coatings and HPP technologies. Though no technology achieved complete protection, commercial seed coatings were able to achieve results comparable to HPPs with roughly 60% less activated carbon and 80% less dry materials; this smaller size is expected to reduce cost and simplify logistics of handling, storage, and delivery at scale. We also found no difference in the effectiveness of commercial seed coatings whether seeding happened before, or after spraying.