SUMMER WEEDS SURVEY
Identify and define composition, distribution and population of summer weeds establishing in paddock in the wheat belt.
Project lead organisation
Summer weeds continue to be highly prevalent and reported as an issue by multiple RCSNs. Summer weeds are given a generic label when the reality is that they are extremely diverse both spatially and temporally. Anecdotal reports suggest the summer weed spectrum is changing with many species emerging that are not well understood by growers. Species identification is critical to achieving successful management outcomes. Whiles previous summer weed surveys have concentrated on roadside weed composition, actual in-paddock weed flora is not well understood.
Controlling summer weeds has a positive impact on the soil moisture and nutrient profile which has a direct result on subsequent crop yield and profitability. Llewellyn et al (2016) Western region. In addition to this is the cost of control.
Adoption of summer weed control is high with 88% of growers in this region using herbicides to control weeds during summer.
In the Geraldton RCSN meetings held in February 2018, most members believed that correct identification of summer weeds and their management was a significantly important local issue. It was identified that new species of summer weeds are becoming more prevalent and control of summer weeds is becoming problematic and costly. Kwinana West and Esperance RCSN members also identified the impact and management of summer weeds as a significant issue. The suite of summer weeds present in a paddock and property can comprise many species which often changes over a season through staggered germination.
Between January and April 2020 197 paddocks were surveyed for relative abundance and distribution.
There were 49 broadleaf and 14 grass species excluding volunteer crop and pasture species. The number of summer broadleaf species for each Agzone ranged from 19 to 31 species while grasses ranged from 2 to 9 species. Agzones 2, 4, and 5 have the highest number of species.
The most common and widespread summer broadleaf weeds across the cropping belt are mintweed, paddy melon, Afghan melon, caltrop, wild radish, mallow and wild turnip. Capeweed was the most numerous broadleaf weed however it was the third most widespread after mintweed and paddy melon. Flatweed (Hypochaeris radicata) was found in all Agzones at low densities. The most common summer grass weeds are stink grass, button grass and small burrgrass while annual ryegrass was the most numerous and widespread grass species overall.
The same paddocks will be surveyed during the 2020-21 summer.
Results and Reports