As temperatures start to warm up there are a number of insect pests becoming active and causing crop damage. This post provides an overview of current and potential issues for field crops.
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 (http://thebeatsheet.com.au/sampling-2/); or use the ready reckoners in this article. MANAGEMENT OF SORGHUM MIDGE How to count… Read more »
Calculating the economics of control is critical to making a decision about if and when Helicoverpa populations in chickpeas require treatment. This season, for the first time, growers and agronomists have access to an on-line calculator to help them make these decisions. The calculator overcomes the need to try and remember the formulas in the field. Best of all,… Read more »
Implications for management in grains and pulses The insecticide resistance monitoring program for Helicoverpa aims to measure resistance frequencies of field populations collected from Central Queensland through to the Riverina area of NSW. Field collections of Helicoverpa eggs are reared in the laboratory and larvae are tested with doses of insecticide that are known to kill susceptible insects. Survivors 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.
As winter crops finish up and approach harvest, there are a couple of pests that still have the potential to cause some concerns. Armyworm and helicoverpa in barley, wheat and oats. There have been a number of reports of armyworm activity across the northern region in isolated pockets. Armyworm has the capacity to lop heads in barley, wheat and oats… Read more »
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 »
With some chickpea crops being sprayed out, rather than harvested, there are reports of helicoverpa larvae surviving on crop residues. The survival of larvae, particularly large late instar larvae, poses a threat to subsequent crops that may be sown directly into the chickpea residues. It is important to check for surviving larvae under the chickpea residues before the next crop… Read more »
While soybeans are more likely to be attacked by helicoverpa from flowering onwards, severe infestations can occur as early as the seedling stage. In recent years, severe early infestations have been reported on the Downs and in the coastal Burnett with the affected crops experiencing significant yield losses. The latest published thresholds for helicoverpa in vegetative soybeans (Rogers and Brier,… Read more »
However, in some years, very high pest activity results in more severe cob damage, with larvae often tunnelling into the sides of cobs. In such cases grain samples may contain fungus-affected grains and mycotoxins, causing a downgrade in the quality of harvested grain.