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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 25th – October 1st 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.

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