On the Darling Downs there have been a number of reports of common armyworm causing significant defoliation in sorghum, corn and millet. Jimbour grower John Alexander treated a severely defoliated sorghum crop two weeks ago. Millet and corn crops in the same area have also been affected. Although patchy, the outbreaks have the potential to cause significant yield loss if… Read more »
As crops come into head and start to fill grain, sorghum midge and helicoverpa will start to infest crops. Making a decision about when control is warranted is made somewhat easier with the availability of economic threshold calculators now available on the Beatsheet Blog (https://thebeatsheet.com.au/sampling-2/); or use the ready reckoners in this article. MANAGEMENT OF SORGHUM MIDGE How to count… Read more »
Since early November, large numbers of Rutherglen bug (RGB) have been migrating into cropping regions from northern NSW through to Central Queensland. Whilst the exact origin of the bugs is unknown, it is likely that they are being carried on storm fronts from inland regions where they have bred up over winter and spring on native host plants that are… Read more »
As the earlier plantings of sorghum progress through flowering, moderate to high Helicoverpa pressure means that many crops have caterpillar numbers over threshold. Nucleopolyhedrovirus (NPV) is one of the main insecticides used to control Helicoverpa larvae in sorghum, however prevailing conditions play an important role in the speed and level of control achieved with NPV.
Helicoverpa populations have started with a bang this season. One or more larvae per plant are common in pre-flowering sorghum, corn and cotton. However, early flowering sorghum crops are carrying up to 10 larvae per head. Corn and sorghum (monocot crops) host only Helicoverpa armigera, not H. punctigera – which has implications for control. Some key issues relevant to dealing… Read more »
Growers and consultants need to revise the thresholds used for important insect pests of grain sorghum such as corn earworm and sorghum midge in light of lower prices currently being offered. With new crop grain sorghum prices below $200 per tonne, the break even cost of control means that higher pest numbers (density) are needed before control becomes economic, compared… Read more »
Every year caterpillars of the corn earworm (helicoverpa), Helicoverpa armigera, cause losses to sorghum crops. Regular inspection during flowering is important to detect caterpillar infestations and properly time control measures. Pre-flowering heads of grain sorghum are very attractive to egg-laying moths of the corn earworm. On any individual head, most eggs are laid prior to the start of flowering, as… Read more »
As many of the early sorghum crops reach physiological maturity, and approach harvest, questions are being asked as to whether it is necessary to control large populations of nymphs in these crops. More specifically, whether these RGB will cause any damage to the maturing grain between physiological maturity and harvest. Photo: Dave Murray (BigBug) out looking at a sorghum… Read more »
Adam Hardy Senior Entomologist, Queensland Department of Primary Industries and Fisheries, Toowoomba. Photo: Adam Hardy (right) and Bernie Franzmann inspecting midge rating trials. Over the last decade sorghum midge have not caused many headaches for sorghum growers. However, staggered sorghum plantings mean that sorghum midge are likely to be found building up in numbers in later planted sorghum… Read more »
Rutherglen bug infestations of grain sorghum This season we are seeing large infestations of Rutherglen bug (Nysius vinitor) (RGB) in sorghum crops from Central Queensland to the Downs, and further south. The large infestations are most likely a result of storm activity and the growth of weed hosts on which they breed up. RGB are very mobile, with large numbers… Read more »