Native budworm

The Victorian Department of Primary Industries (Victoria DPI) is presently monitoring native budworm numbers caught in pheromone traps in various regions across Victoria. This provides an indication of the pest risk potential for particular areas and crops. The following information and budworm numbers for September 20^th - October 1^st have kindly been provided by Ashley Wallace (Victoria DPI).

Region	Trap Sites	Moth count 7 days	Moth count 10 days*	Crop & Growth Stage	Comments
Week ending Monday 1/10/07
Mallee	Walpeup Berriwillock	24 0	34 0	Field peas Lentils	Dry -
Wimmera	Brim	430	614	Field peas, flowering	Very windy
North Central	Kerang Elmore	125 30	179 43	Faba beans Canola	- -
North East	Cobram	150	214	Canola, podding	Very windy
Week ending Thursday 27/9/07
Wimmera	Warracknabeal Kaniva	362 770	517 1,100	Faba beans Canola, late flowering	- Dry & windy

*10 day counts are projected; based on 7 day counts.

Moth numbers have generally decreased since the last report; however there have been slight increases at Elmore, Walpeup and Warracknabeal. Trap numbers at Dunkeld were not available for this edition. The drop in numbers is probably due to increasing moth mortality, or may reflect movements into other areas where plants are more attractive. Adult native budworm moths generally live between 2-4 weeks, during which time they move between plants, feeding on nectar from flowers.

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. 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 dry warm conditions means 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. Listed below are some tips for effective 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.

Click here for information on native budworm management and click here for images. For further information, refer to PestFacts Issue No. 9.