Skip routine drenches in a dry spell to slow worm resistance
She says dry weather kills worm larvae, so drenching on a fixed 28-day cycle through a drought is not needed.
|October 29, 2026Listen to the full interview:
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Drenching every 28 days through a dry spell is unnecessary and risks leaving a resistant worm population.
WormWise programme manager Ginny Dodunski says drought changes the worm risk on a farm, because the larvae die when pasture dries out.
“They’re basically an aquatic organism and they have to live in a droplet of moisture, or they’re dead,” she says.
Dodunski says a dry summer and a wet summer put different pressure on stock, so a drench plan has to follow the weather. Without aggressive feed and stocking rate management through a drought, breeding stock lose condition and their immune systems go to sleep.
“We sleepwalk into a situation where we now have breeding stock that are actually in quite poor condition.”
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