Tag Archives: thresholds

Recognising caterpillar pests of canola.

Melina Miles   September 22, 2014   Comments Off on Recognising caterpillar pests of canola.

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 »

Spring pests of winter cereals

Melina Miles   August 30, 2013   Comments Off on Spring pests of winter cereals

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 »

Helicoverpa and midge management in sorghum

Melina Miles   December 20, 2012   Comments Off on Helicoverpa and midge management in sorghum

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 »

An economic threshold calculator for Helicoverpa in chickpeas

Melina Miles   October 5, 2012   Comments Off on An economic threshold calculator for Helicoverpa in chickpeas

  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 »

Latest helicoverpa thresholds for mungbeans

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 »

New Helicoverpa thresholds in vegetative soybeans

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 »

Thresholds and changing sorghum crop value

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 »

Helicoverpa management in chickpea – a refresher

adminmelina   October 8, 2008   Comments Off on Helicoverpa management in chickpea – a refresher

A comprehensive overview of Helicoverpa management in chickpea can be found in the DPI&F brochure Helicoverpa management in chickpea (2007). You can read or download a copy of the brochure at the DPI & F website at www.dpi.qld.gov.au/fieldcrops. Click on the link to Helicoverpa management in chickpea where you will find the brochure. Key management decisions The following is an… Read more »