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 »
Over the last week or so we have received a number of enquiries about how best to manage new egg-lays, and populations of small larvae, in chickpea crops that are close to dessication and senescing. Of most concern are crops that still have reasonable areas of green crop in them, and what the likelihood of damage is if the weather… Read more »
Over the past couple of weeks there have been numerous reports of armyworm in both barley and wheat. The appearance of armyworm in wheat raises a number of questions: 1) Do they behave the same way in wheat as in barley in relation to the type of damage they cause 2) what is their damage potential and is there an… 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 »
Grubs in winter cereals are not unusual at this time of year, and already there have been reports of high numbers (up to 20/m2) in Central Queensland wheat (Figure 1). More grubs can be expected in southern districts as the season warms up. The two most likely larvae (grubs) found in winter cereals are the corn earworm, Helicoverpa armigera, and… Read more »
Cereal aphid numbers have increased rapidly over the past 3 weeks as the temperatures have increased. Whilst low numbers of aphids have been present in many crops (wheat and barley) for some time, it was not until a couple of weeks ago that numbers reached levels of concern to agronomists and growers. Until the last few seasons, cereal aphids have… Read more »
David Murray, Toowoomba Farm hygiene is an important component of integrated pest management (IPM), particularly when it comes to managing pests such as cotton aphids and Cotton Bunchy Top (CBT) disease. Recent surveys of cotton-growing areas indicate the presence of aphids and CBT, and wetter conditions through the coming winter could favour the growth of weeds that are… Read more »
While there was a hefty presence of corn earworn or cotton bollworm, Helicoverpa armigera, in the early and middle part of the 2007-08 season, pest activity has declined in recent weeks and for the most part they appear to pose no major risk. What is diapause? This is the time of the year when a proportion of mature larvae going… Read more »
In the last week, reports from the Downs are suggesting that silverleaf whitefly (SLW) numbers have increased rapidly, and now there are a number of fields that have a population at or exceeding the treatment threshold. This posting has been compiled from information and discussion with Richard Sequeira (Principal Entomologist, Emerald) and Paul Grundy (Senior Entomologist, Ayr) who have considerable… Read more »