Seed germination and viability of herbicide resistant and susceptible Chenopodium album populations after ensiling, digestion by cattle and manure storage

Chenopodium album became a problem weed in sugar beet production, due to resistance to metamitron, a key herbicide in this crop. Dispersal of the seeds from resistant biotypes may occur due to spread by wind, animals, agricultural machinery or manure. This study examined the effect of ensiling, digestion by cattle and storage in slurry and farmyard manure on the germination and viability of the seeds of one susceptible and three resistant C.album populations. After 4weeks in a maize silo, seed viability of C.album populations was reduced drastically to 0-5%. Incubation for 24h in the rumen followed by a post-ruminal digestion in vitro of intact seeds only resulted in a small reduction in viability in one C.album population. Storage in a slurry cellar for 16weeks reduced the viability of intact seeds of the C.album populations to 25-60%. Only 0-1% of the seeds remained viable after storage in a farmyard manure heap for 4weeks. An accelerated ageing experiment showed seed persistence to be population specific and less related to seed weight. Keeping a fresh maize silo closed for at least 4weeks and heaping farmyard manure are excellent preventive measures to limit the spread of resistant C.album seeds between fields.