False wireworms

Agronomist, Bob Ronald (Landmark), has reported canola crops with false wireworm feeding damage. The affected paddocks are located north of Corowa and near Oaklands, in the Riverina district of New South Wales. Bob says the paddocks were at the 2-3 leaf stage, and that in the worst affected parts, there are numerous bare patches. These patches are patchily distributed across the paddocks. Canola seed will be broadcast across the worst affected parts. Chemical control is not warranted as the feeding damage across paddocks is sporadic and generally not severe.

False wireworm larvae are relatively fast moving, have a pair of prominent spines on the last body segment and vary in colour from cream-yellow to brown-grey. They generally grow between 10-50 mm long, and have a hardened cylindrical body. False wireworms attack germinating seeds and chew on seedling stems and roots, weakening the plant or ring-barking the plant.

Bob says plants could be seen chewed off at the ground level, with entire crop rows missing in parts. The damage appeared to be more prevalent on lighter soils types, which were mostly sandy red soils. The affected paddocks were sown with an imidacloprid seed dressing and contained some trash from the previous years crop. Neighbouring paddocks that were burnt earlier in the season were not affected.

False wireworms (F: Tenebrionidae) attack a variety of crops including cereals and canola, and are mostly found in paddocks with high amounts of stubble and trash. There are a large number of false wireworm species, which are similar in appearance. The most common broad-acre pests in Victoria and New South Wales are the grey false wireworm, the eastern false wireworm, the bronzed field beetle and the vegetable beetle. Control options (including chemical control) vary depending on species. Unfortunately, identification can be difficult to the untrained eye. For comprehensive information on wireworm identification, biology and management, see pestIQ.