Species that actively recruit seedlings
Perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) are two perennial grasses which actively recruit seedlings.1,2 Much less success has been experienced with phalaris (Phalaris aquatica) and tall fescue (Lolium arundinacea previously Festuca arundinacea).3,4
This eLearning module focuses on ryegrass and cocksfoot as there is solid research-based evidence surrounding seedling recruitment with these species. Information on other species, at this stage, is anecdotal.
Success with perennial ryegrass and cocksfoot appears to be associated with their ability to establish as a seedling. They are more ‘aggressive’ after germination, enabling them to compete successfully against other emerging weeds. Strategies tested by Agriculture Victoria (AgVic) and the South West Prime Lamb Group (SWPLG) near Hamilton, Victoria, in separate non-comparative projects, found seedling recruitment of perennial ryegrass to be highly effective (Table 1). The strategies demonstrate the wide variation in results, while showing each proved beneficial.
Table 1: The average number of perennial ryegrass seedlings/m2 in mid-July following normal practice (control) and a recruitment strategy
The additional seedlings established in the SWPLG experiment led to an increase in perennial ryegrass composition in September of 52%, compared to 23% in the control (Joseph, 2017). This result is consistent with comparable seedling recruitment studies in New Zealand.6
Phalaris and tall fescue seedlings are less aggressive and tend to be smothered before they can establish. Where phalaris and tall fescue seedling recruitment has occurred, it has mainly been on disturbed roadsides, in tree plantations and along drainage lines during wet summers, and in the absence of weed competition (annual plants have died out). Research into conditions for successful phalaris seedling recruitment in established pastures found it occurred in the second half of February to early March, when there was 15 continuous days of moist soil and soil temperatures were approximately 20ºC, which results in faster seedling growth.4
Three things to remember about seedling recruitment:
- Achieving success is challenging and it is not something which should be attempted every year.
- Maximising seed head emergence is the most crucial step for optimal establishment of new plants.
- There is a cost due to the paddock being unavailable for grazing for an extended period.