SA sheep producers are being warned to remain vigilant about worms and blowflies in their flocks in coming weeks.
Recent rain has extended the growing season in many areas, but it is a double-edged sword with warm, moist conditions posing a heightened risk of breech and body strike, as well as a carryover of worms.
Flystrike products were in short supply before Christmas as growers rushed to protect their flocks, but the forecast of another 20 millimetres or more across the state this week is likely to exacerbate concerns.
Barber’s Pole worm, which can cause anemia and lead to death, has already been found across SA, including the Eyre Peninsula – where it is rarely seen.
Pro Ag Consulting sheep consultant Colin Trengove said worm egg testing at $25 to $30 each was a cheap and effective tool to ensure drenching occurred only when necessary, thus delaying the onset of drench resistance.
Dr Trengove, who writes a monthly SA snapshot for the WormBoss website, says there have been reports of numbers of black scour worm, Trichostrongylus, and brown stomach worm, Teledorsagia, “jumping up” in the past few weeks.
This rise corresponds with significant rain and animals grazing the green pick close to the ground.
He recommends producers closely monitor several mobs, especially their young stock and consider drenching when worm egg numbers rise above 100 eggs per gram of sheep faeces.
They should ensure they have a clean paddock for any mobs which are summer drenched.
“Especially at this time of the year, if you do need another drench within three to four months, make sure you use a different drench group,” he said.
“We have had dry summers in the past few years so worms have not carried over, but this year it could catch people out, especially if the autumn break comes earlier than May.”
Elders livestock production advisor Brendan Voss says he has already seen more cases of Barber’s Pole worm in the South East than in 2016.
“Unlike winter worms, it doesn’t always cause scouring, but it is a blood-sucking worm which drops protein levels and causes a condition known as bottle jaw,” he said.
“It can lead to rapid weight loss. They (Barber’s Pole worm) can multiply rapidly, too, laying about 10,000 eggs a day compared to the winter worms, which lay 50 to 200 eggs/day – so if you are a week behind with your control, it can really get hold of the flock.”
“Last year it was so dry during summer all the worm eggs were desiccated, but this year there is still plenty of cover and patches of green.”
Mr Voss commended growers for being proactive with their flystrike prevention, using jetting fluid and backlining products in spring, after “seeing the writing on the wall”.
He said some growers were also bringing their autumn shearing forward.
“We are not seeing a huge fly wave like 2010-11,” he said. “But it is ideal conditions for flies and if people have not managed things well, there is scope for it to get out of control.”
Tarlee sheep producer Glen Tilley says they have treated a few unshorn Merino lambs for blowflies, but knew of one farmer that had 20pc of his early-shorn crossbred lamb flock affected.
“We like to think it is less of an issue when breeding plain-bodied sheep, but extreme weather years like this one, you can get caught, especially with any sheep with wool on them,” he said.
Mr Tilley said many mixed farmers still finishing harvest were not focused on their sheep flocks, which could be a potential issue, while others were reluctant to treat lambs due to meat and wool withholding periods for the chemicals.
He said they would do a worm egg count on their weaners in the next few days.
