Effects of various ecological factors on the germination of two crop and pasture weed species, Vulpia bromoides and Vulpia myuros

Vulpia species (silver grasses), including V. bromoides and V. myuros, are native to the Mediterranean, Middle East and Eurasia, but have become dispersed worldwide. These two species reduce the grazing quality of pastures, frequently co-occur and are often associated with poor-quality acidic soils. This study investigated two species, Vulpia bromoides and V. myuros. Germination trials tested the effects of seasonal temperature, light,pH, moisture, salinity, pre-germination heat shock and smoke, and seed burial depth. Vulpia bromoides germinated well regardless of temperature or light (>80%, all conditions), whereas V. myuros preferred lower temperatures and absence of light (97%, 7/17oC in 24-h dark). Under different culture conditions, the two species germinated well across the pH range 4 to 10 (>85%). Reduced moisture, pre-germination heat shock and smoke, and increased burial depth reduced germination and emergence of both species. Preventing germination of these species in pastures must begin before or during winter. Fire may be useful for control, butsufficiently high temperatures must be achieved to kill seeds. Tillage to bury seeds, prior to pasture renovation, may prevent germination of seeds.