Slaters

Agronomist, Brad Jackson (Tyler's Hardware & Rural Supplies), has found slaters in a canola crop, near Rupanyup, in the Wimmera district of Victoria. The paddock was a vetch paddock last year and contains quite a lot of trash. The highest numbers of slaters are being found on heavier black soils hiding underneath stubble. Brad says there has been no damage to emerging canola seedlings, which are still at the cotyledon stage. The paddock will continue to be monitored closely.

Slaters will occasionally attack broad-acre crops, and in some instances can cause serious damage. One particular species, the flood bug, is known to be a significant pest in isolated areas of northern New South Wales, and was recently reported attacking canola. Feeding by slaters results in uneven rasping-type damage that can appear as ‘windows’ of transparent leaf membrane. Entomologist, Peter Mangano (DAFWA), says loss of canola seedlings from slater damage can occur over a prolonged period from cotyledon emergence through to the six-leaf stage. The slater species observed by Brad is not the flood bug; it is probably Porcellio scaber or a closely related species. Porcellio scaber is usually grey in colour, curls up into a ball when disturbed, and is commonly found in home gardens.

It is important to remember that the presence of slaters within a paddock (even in high numbers) does not necessarily mean a pest issue. Slaters typically feed on decaying organic matter and only rarely feed on crop seedlings. There appears to be a strong correlation with minimum tillage and stubble retention. Monitor crops closely before deciding on the best course of action. In the past, some growers have used methiocarb baits or high rates of chlorpyrifos sprayed late in the evening (or at night), when slaters are most active.