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Look out for other invertebrate pests

Aphids can be problematic to emerging crops and grasses at this time of year. The importance of many aphid species is heightened by their ability to act as vectors for important plant viruses and diseases. Aphids that arrive in crops in autumn and persist in low numbers over winter may lead to large, damaging populations that peak in late winter and early spring. However, in most years natural control by predators and parasites and adverse weather conditions keep their numbers below economic spray thresholds.

Slugs are stimulated out of their summer aestivation following autumn rains, generally in paddocks were they have previously been a problem. Although all seedling crops and pastures may be attacked, canola is particularly susceptible. Slug numbers can be monitored by placing tiles on the soil surface and counting the number under them after a few days.

Redlegged Earth Mites hatch in autumn following exposure to cooler temperatures and adequate rainfall. It takes approximately two weeks of exposure to favourable conditions (<20°C and >10mm rain) for oversummering eggs to hatch. This releases swarms of mites, which can attack delicate crop seedlings and emerging pasture plants.

Blue Oat Mites will be hatching soon following good rainfall in many areas. Blue oat mites are often mistaken for redlegged earth mites due to their similar appearance and sympatric life-cycle. However, blue oat mites and the redlegged earth mite differ markedly in their biology and tolerance to pesticides, and require separate management strategies. Blue oat mites can be identified by the red mark on their back and dark blue-black coloured body.

Cut worms can be a problem to all germinating crops. Prolonged autumn green feed in areas may allow them to develop to a large size by the time crops start emerging. Agronomist, Sandy Biddulph (Biddulph Rural Consulting), has recently observed adults of the common cutworm, commonly known as ‘bogong moths’, around Cootamundra, in the South West Slopes of NSW. Check crops, especially pulses and pasture legumes, from emergence through establishment at the base of plants; damage is often patchy.

Bryobia Mites are most active in warm conditions in autumn, spring and summer. They attack clovers, lucerne, lupins and canola. The feeding damage is characterised by a long trail of whitish-grey spots on the upper side of cotyledons and leaves.

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