Native budworm

Native budworm (Helicoverpa punctigera) larvae are a major pest of a variety of crops during spring to early summer. They feed on buds, flowers, fruiting parts and seeds, attacking pulses, lucerne, sub clover and annual medic seed crops. They will also attack canola and cereals.

Agronomist, Warwick Nightingale (Landmark), has reported high numbers of native budworm moths collected from a pheromone trap near Wagga Wagga, in the South West Slopes of New South Wales. Warwick has also detected native budworm after sweep-netting in a field peas crop south-west of Wagga Wagga.

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 10th-16th have kindly been provided by Ashley Wallace (Victoria DPI).

Region	Trap Sites	Moth count 7 days	Moth count 10 days*	Crop & Growth Stage	Comments
Mallee	Walpeup Wycheproof	74 147	106 210	Field peas Field peas	- 7 mm of rain
Wimmera	Brim	690	986	Field peas	Drying winds and little rain
North Central	Kerang Elmore	295 7	421 10	Faba beans Canola, full flower	- 6 mm of rain
North East	Cobram	654	934	Canola, full flower	-
South West	Dunkeld	51 (2 days)	255	Canola, early flower	-

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

High moth numbers continue to be reported in many areas across the state, however this is highly variable. Growers in the northern Mallee are advised to be more vigilant in surveying crops for grub activity when moth numbers exceed 400 moths (10-day cumulative tally). This threshold drops to 180 moths in the southern Wimmera due to lower numbers of moth flights as a result of cooler evening temperatures. Thresholds in other districts are relative. For example, a threshold of approximately 300 moths is appropriate around Birchip. Once numbers have reached these thresholds, it can be expected that approximately one egg will be laid on 5% of field pea plants in a given crop. If grub activity is deemed to be extensive enough to cause yield losses, growers will need to consider the feasibility of spraying, considering projected yields and current climatic conditions.

Moth numbers, and the subsequent generation of grubs, will vary between regions and paddocks, so monitoring remains the best way to determine the risk they pose to individual crops. Crops should be monitored using a sweep net from early flowering and throughout podding in pulse crops. Pod inspections are also essential in order to detect small grubs and accurately determine numbers.

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