Pests to look out for

Australian plague locust (Chortoicetes terminifera) nymphs have hatched in New South Wales and several regions of Victoria, with further hatchings still expected in some parts. The spring nymphal population is much smaller than that of spring 2010 and is unlikely to produce a significant swarm infestation in any region. In New South Wales the only high density population is in the Savernake–Oaklands area, in the Riverina district. The fledging of nymphs now expected could produce small areas of high-density adults. According to the APLC, sporadic hatchings may have been more widespread in the Wagga–Cootamundra and Lockhart–Jerilderie–Corowa areas, which could result in a moderate increase in adult numbers.

In Victoria, there have been reports of isolated hatchings near Yarrawonga, Cobram and Warracknabeal in the North Central region, and near Meringur in the Northwest. Further hatchings are likely in some locations around Horsham, Stawell, Ararat and Hamilton. Localised high density nymphs and some bands are likely to form in these areas.  Sporadic hatchings could be more widespread in the Bendigo–Kerang, Boort–Charlton, St Arnaud–Horsham and Yarrawonga-Shepparton areas, resulting in low–medium density nymphs and possible small bands. For more information on the current locust situation, refer to the APLC website.

Armyworms (Family: Noctuidae) can be problematic to crops and grasses at this time of year. They sometimes feed on the remaining green material just below the maturing head of cereals, causing heads to fall. Ripening barley crops are generally worst affected. Agronomist, Jim Cronin (Earth Ag), has reported armyworm caterpillars around Forbes, in the Central West Slopes and Plains district of New South Wales. Armyworms have also recently been observed in a few crops in the Western district of Victoria. The first visible sign of armyworm caterpillars is often their green to straw-coloured droppings, about the size of a match head, found on the ground between cereal rows. Armyworm caterpillars are fat and smooth, and can be distinguished by three parallel white stripes on the collar just behind their head.

Cereal aphids have recently been found in numerous cereal crops in the Victorian Mallee and the South West Slopes district of New South Wales. Although numbers have been relatively low there is still time for aphids to build up in some regions prior to harvest. Feeding damage and potential yield losses from cereal aphids will depend on many factors. Losses are generally more severe when crops are moisture stressed, whereas sufficient moisture availability may enable crops to withstand moderate-high aphid populations with little or no yield penalty.

Rutherglen bugs (Nysius vinitor) are native insects that attack a wide range of weeds and crops. They are well adapted to dry warm weather and are often most damaging to moisture stressed plants. Adults can also become a grain contaminant when in high numbers. Highest numbers of Rutherglen bugs are often observed along crop perimeters. Numbers will increase with the warmer weather conditions and can reach damaging levels very quickly. Monitor crops closely, particularly canola, linseed and sunflowers.