Herbicides
There are no registered herbicides for broad-leaf weed control in biserrula. Our research has shown biserrula has particular sensitivity to Broadstrike®, Spinnaker®, Raptor® and MCPA, so weed control before sowing is crucial for the successful establishment of biserrula. Grass weeds can usually be controlled with a selective herbicide. Spray-topping with glyphosate or paraquat can decrease biserrula seed production by up to 85% and is not recommended in the first year of establishment.
Grazing
Photosensitisation
In recent years several outbreaks of photosensitivity have occurred in sheep grazing Casbah biserrula pastures, although the overall incidence was low. In Western Australia, most reported cases of photo-sensitivity have occurred between August and October, the period when spring pasture is green and growing rapidly.
Photosensitivity can arise for a number of reasons and is not peculiar to biserrula. It occurs when photodynamic chemicals in the bloodstream actively sensitise the skin to sunlight. Sunburn-like changes generally occur around the ears, muzzle, tail and backline. The affected areas start to swell and in severe cases the skin can be sloughed off leaving raw sores. Animals are considerably irritated by the condition and will rub affected areas profusely.
Photosensitivity in biserrula is not normally life-threatening. If the condition is picked up early and animals are moved away from sunlight, they normally recover quite well. In severe cases long term scaring can result.
Management
DAFWA is investigating the connection between biserrula and photosensitivity. Current analysis suggests the condition is not a function of liver damage and it is unclear whether the new biserrula cultivar Mauro predisposes sheep to photosensitivity. Until more is known farmers should adopt a cautious approach to the management of sheep grazing biserrula, particularly when this plant makes up a high proportion of the pasture.
Providing an alternative feed source such as hay or straw may be beneficial. Lambs and bare-shorn animals should not be grazed on paddocks where biserrula makes up more than 30% of the pasture. Sheep should be observed regularly for the early signs of photosensitivity including swelling of the ears, eyelids and muzzle and sheep seeking out shade. Suspect animals should be removed from the pasture as soon as any of these signs become evident.
Harvesting
Harvesting biserrula with a grain harvester is possible, but major modifications to the drum are required. Biserrula is generally successfully harvested with specialist suction harvesting equipment (600-800 kg/ha of seed).
Production and marketing
Casbah is a public variety and can be freely bought and sold. Mauro is protected under the Plant Breeders Rights Act 1994 .