Native budworm building up

Agronomist, Paul Parker (NSW DPI), has reported in-flights of native budworm (Helicoverpa punctigera) around Young and Wagga Wagga, in the South West Slopes of NSW. Paul says moths have recently been observed across a variety of crop types. Consultant, John Robertson (Agwise Services), also reports native budworm in numerous crops around the Wimmera and southern parts of the Mallee, Victoria. John revealed that some crops which are flowering will require chemical control. Although moths have mostly been observed, John also reported the presence of a low number of small caterpillars (<10mm in length).

Adult native budworm moths generally live between 2-4 weeks, during which time they move between plants, feeding on nectar from flowers. They lay eggs on many types of native and introduced vegetation, including crops such as field peas, canola, lupins, lentils and chickpeas. Female moths can begin laying eggs as early as three days after emergence, with each female capable of producing up to 2,000 eggs in a few days.

Eggs generally hatch after 1-3 weeks, but this can be sooner under warm weather conditions. However, many eggs do not hatch due to predation from natural enemies, or because they are dislodged from plants by heavy rain and/or strong winds. Once on the ground, young larvae are unlikely to survive, therefore, high moth counts do not necessarily result in high caterpillar numbers.

The following budworm information and pheromone trapping numbers for September 25^th – October 1^st have kindly been provided by Victoria DPI. Pheromone trapping data provides an indication of the pest risk potential for particular areas and crops. However, there is no substitute for growers checking their crops and measuring actual numbers of caterpillars picked up in sweep net counts.

Region	Trap Sites	Moth count 7 days	Crop & Growth Stage	Comments
Mallee	Walpeup Berriwillock	190 276	Peas – podding Lentils – flowering	Preceding week - hot/windy, no rain
Wimmera	Nhill Warracknabeal Brim Wycheproof	67 151 462 256	Faba Beans Vetch - flowering Beans - flowering Peas	Preceding week - hot/windy, no rain. Late crops -struggling
North Central	Kerang	73	Faba Beans	3.5mm rain
South West	Hamilton	223	Peas – flowering	22mm rain

 

Over the last 7-10 days, trap operators have recorded high levels of native budworm activity across many areas of Victoria. Moths were most likely carried in from parts of central Australia on northerly winds during the preceding week. There have also been recent reports of spraying in early maturing lentils, peas and some bean crops in the Wimmera district of Victoria.

The dry, warm conditions, coupled with recent frost damage, means that growers should carefully consider the yield and economic potential of the crop before spraying. Sampling of crops to determine the abundance of caterpillars is essential. The quickest and easiest method to sample most crops is to sweep with an insect net.

Tips for sweep-netting:

• Take sets of 10 sweeps. Repeat five times across the paddock. Each set of 10 sweeps should be taken from different representative areas of the crop. 

• For each set of 10 sweeps, count the number of larvae and record their size. After five sets of sweeps, calculate the average number and size of larvae.

For further information on the native budworm, refer to PestFacts Issue No. 9. For native budworm management guidelines and information on thresholds, click here.