As canola sets and matures pods, and spring temperatures rise, there are a number of caterpillar pests that are active in this crop. Along with helicoverpa there are diamondback moth larvae (Plutella xylostella) and cabbage white butterfly larvae (Pieris rapae) in crops. It is critical that you can distinguish the species, and be familiar with their respective thresholds, in order… Read more »
There have been a number of reports of mirid infestation in cotton on the Central Highlands and at St George. Recent research has focused on the development of plant-based thresholds that should make it easier to make decisions about mirid control.
Armyworm in barley and wheat. A number of reports of armyworm in crops have been received over the past couple of weeks. Numbers range from 30 to 50 per square metre (extreme) to a more typical 5 to10 larvae per square metre. Assessing larval density is done using a sweep net, bucket or beating a section of row into a… 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 »
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 »
Revised thresholds for helicoverpa in flowering/podding mungbeans are based on a rate of damage of 35 kg/ha per larva per square metre in podding crops. The new thresholds are nearly double the old threshold of 1/m2, and make allowances for variations in control costs and crop value. For a typical scenario with pesticide control (including aerial application) costing $40/ha and… Read more »
The new economic threshold for Helicoverpa in vegetative soybeans is 8 larvae per sqare metre and replaces the old 33% defoliation threshold. The new threshold is based on field trials conducted by John Rogers (formerly with DPI&F at Kingaroy). These field trials show that approximately 7.5 larvae per square metre can be tolerated with no yield loss, but that severe… 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 »
A comprehensive overview of Helicoverpa management in chickpea can be found in the DPI&F brochure Helicoverpa management in chickpea (2007). Key management decisions The following is an excerpt from the Helicoverpa management in chickpea brochure, and deals specificially with determining whether an infestation of helicoverpa warrants control – based on the economics of potential yield loss vs cost of control…. Read more »
