Diamondback Moth in Turnip Crops

Monitor crops closely for any early caterpillar or moth activity

By DNRE - 11th December 2002 - Back to News

"Many farmers have had trouble this year with Cabbage Moth (also called Diamondback moth, Plutella xylostella) in forage brassica crops, both in Gippsland and South West Victoria," says Frank Mickan, Pasture and Fodder Conservation Specialist, NRE, Ellinbank.

These moths are only up to 12 mm long, dark brown (male) or tan (female) coloured with three white diamond-shaped patterns markings on each wing forming a diamond shaped pattern when the wings are held together at rest. The larvae or caterpillars are up to 12 mm long, pale green and tapered at each end and wriggle violently when touched. They have a one-month life cycle over summer and as each female can lay over 150 eggs, damage from the hungry caterpillars becomes obvious very quickly.

With fodder crops being of even greater value this summer due to higher alternate fodder prices, it is even more important to monitor crops closely for any early caterpillar or moth activity so that damage can be reduced by spraying.

Some important points to consider when spraying:

The caterpillars feed on the underside of leaves or burrow into the plant, so be sure to check the underside of the leaves and in the crown/base of the plants. This makes effective spraying difficult and may account for some farmers’ comments that the sprays are not working so well. Another reason for this comment is that farmers may be using sprays not registered for cabbage moth control. This means that the insecticide is either not suitable for use, or the caterpillars or moths have built up a resistance to the particular chemical being used.
Avoid spraying just before rain so the chemical is not washed off. The insecticides are contact sprays and must hit the caterpillar or be eaten (via the sprayed plant). Two plus hours rain-free period should suffice.
Use of Poison Schedule 7 (Dangerous poisons, restricted use chemicals) products is only allowed by authorised users, ie. Commercial Operator Licence, holder of an Agricultural Chemical User Permit (ACUP), exempted QA system accredited or supervised by authorised user and accurate written records of their use for two years.
Resistance to synthetic pyrethroids has been occurring over the last few years and, AT ALL TIMES, use chemicals in accordance to the label recommendations.

There are several products registered for use against Cabbage Moth in Victoria and many will also treat the other main pest of our forage brassicas, the larger Cabbage White Butterfly. They are products containing diazinon (grazing withhold usually 14 days), the synthetic pyrethroid esfenvalerate (grazing withhold 2 days) and the Poison Schedule 7 chemical parathion-methyl (with a 14 day grazing withhold). Continue to monitor the crop closely over summer, so that action can be undertaken before damage levels become high. Monitoring will also pick up where control hasn’t been as effective using one chemical, so that others can be tried.

In managing dairy cows, farmers may have to stagger spraying for different areas of the crop to allow for the grazing withhold period whilst not compromising cow nutrition. A major change in the cows diet, such as completely withdrawing crop from the herds diet for 2-14 days (depending on product) can cause dietary upsets and reduced milk production. With forage crop providing 20%-30% of the cows diet on many farms over summer, grazing management issues will also need to be taken into account when planning for crop treatment.

EAST GIPPSLAND AERIAL SPRAYING PROGRAM

During November, staff from NRE’s Pest Plant and Animal team have been involved in coordinating the aerial spraying of weeds, mainly blackberries, in some of the more remote areas of East Gippsland.

Local Landcare groups have taken a lead role in organising the spraying and this season approximately 90 hectares were treated in the Dargo area. Around Swifts Creek, 120 hectares were treated and another 130 hectares were treated in the Buchan area.

Trevor Whibley, Catchment Management Officer, Bairnsdale said that by all accounts, everyone is very happy with the way the program went.

"I feel that the local Landcare groups and local coordinators deserve a pat on the back for their efforts in bringing about a successful joint program," Mr Whibley said.

With landholder support and NRE coordination, the aerial spraying of weeds by helicopter in steep and otherwise and inaccessible terrain appears to be a cost-effective way of controlling weeds in these remote areas.

WELFARE OF HORSES

There are welfare codes for keeping all domestic animals. The codes effecting horses are one of the most important due to the intense and personal nature of the bonds that form between people and their horses. The code of practice can be found in full on the NRE website. Access the NRE home page (www.nre.vic.gov.au), select Plants and Animals, then Animal Welfare and Management, next select Legislation and Codes of Practice, then Codes of Practice for Animal Welfare, then scroll down the page to Horses.

Horses are kept under a variety of conditions, from extensive grazing in unfenced wilderness to intensive housing in individual stalls. The Code of Practice recognises certain basic needs of horses, irrespective of the husbandry system, including:

Readily accessible food and water to maintain health and vigour
Freedom of movement to stand, stretch and lie down
Regular exercise
Social contact with other horses or people
Accommodation that neither harms or causes undue strain, and provides adequate protection
Protection from disease, and regular inspections to assess the need for attention to feet, teeth, and parasite control
Rapid identification and treatment of lice, injuries and disease.

Prospective purchases and breeders of horses should be aware that proper feeding, maintenance and training of horses represents long-term responsibilities.

Source: http://gippsland.com/

Published by: news@gippsland.com