Native budworm

Agronomist, Warwick Nightingale (Landmark), has observed native budworm (Helicoverpa punctigera) in crops around Wagga Wagga, in the south west slopes of NSW. Native budworm is a major pest of all pulses, lucerne, sub clover and annual medic seed crops. They also attack canola and all cereal crops.

Native budworm larvae can be up to 40 mm long with substantial colour variation (shades of brown, green and orange). They usually have darkish strips along the body and bumpy skin with sparse, stiff black hairs. Newly hatched larvae (approximately 1.5 mm in length) are light in colour with dark brown heads and spots, and as they develop they become darker in colour.

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 4^th -10^th have kindly been provided by Victoria DPI. For further information on the native budworm, refer to PestFacts Issue No. 9.

Region	Trap Sites	Moth count 7 days	Moth count 10 days	Crop & Growth Stage	Comments
Mallee	Ultima Walpeup Berriwillock Werrimul	64 3 105 81	91 4 150 115	Lentils - flowering Peas - podding Lentils - flowering Lupins - finished flowering	8-22 mm rain. Cooler conditions
Wimmera	Nhill Warracknabeal	32 -	45 248	Faba beans - flowering Vetch - flowering	22 mm rain. Ave temp. 20°C
North Central	Kerang Elmore	18 95	26 135	Faba beans Lupins - early flowering	15mm rain

Trap operators have recorded high levels of budworm numbers around Victoria, although the level of activity seen is highly variable between regions. This suggests moths have been carried in from parts of central Australia on recent northerly winds. From the 10-day counts, the Mallee remains below threshold levels, however, the high trap count for Warracknabeal suggests the Northern Wimmera could be approaching threshold levels in some areas.

Thresholds are a guide to the level of moth activity (trap counts) required for one egg to be laid on approximately 5% of field pea plants in a given crop. When these thresholds are exceeded, growers are advised to be more vigilant about grub activity. For the Northern Mallee, the threshold trap counts are 400 moths (cumulative 10-day moth tally), and for the southern Wimmera the threshold is 180 moths (cumulative 10-day moth tally). The difference between the thresholds corresponds to the generally higher level of moth flight activity in the Mallee, which is due to the warmer evening temperatures. For other districts thresholds are relative, e.g. around Birchip the threshold level is approximately 300 moths.