Keeping a Top Watch for Grain Growers
Australia is free of many of the major agricultural pests, diseases and weeds that are present in south east Asia and some Pacific countries. Their introduction into Australia could devastate plant and animal industries.
AQIS has developed the Northern Australia Quarantine Strategy (NAQS) in response to this issue. NAQS carries out surveys of high-risk areas of northern Australia for signs of newly-arrived exotic pests. This work acknowledges that, despite the rigour of Australia’s normal border quarantine operations, some exotic pests and diseases will inevitably reach our shores through events beyond our control. These events include illegal vessel landings in remote areas, bird migrations, and wind currents between Australia and nearby countries.
How does NAQS help the grains industry?
NAQS employs a team of scientists and operations staff whose work includes:
- ongoing surveys of the northern coastline from Broome to Cairns, and of neighbouring countries, to monitor for target pests, weeds and diseases;
- surveillance and inspection of goods being moved between islands of the Torres Strait, and between Torres Strait and the mainland; and
- through the NAQS public awareness program, Top Watch, raising quarantine awareness among residents of northern Australia to encourage early reporting of potential quarantine threats and travelers.
Monitoring for grain pests and diseases
NAQS monitors for many exotic pests, weeds and diseases of concern to the grains industry. A few of these are described below.
Rice tungro disease: Tungro is one of the main diseases of rice in Asia, present in Indonesia, Malaysia, Thailand and the Philippines. In April 1999, NAQS also detected one of the viruses responsible for tungro in the Indonesian province of Irian Jaya, on the island of New Guinea. NAQS is monitoring for the possible spread of tungro to Queensland, which could occur by infectious leafhoppers being carried on the strong annual winds blowing from Irian Jaya towards Queensland’s far north. Early detection of tungro would be vital to prevent its spread further south into rice growing areas.
Downy mildew: The fungi Peronosclerospora sacchari, P. sorghi and P. philippinensis can cause downy mildew disease of maize. P. sorghi also causes downy mildew of sorghum.P. philippinensis is potentially the most destructive disease of maize. It has forced maize cultivation to be abandoned in some areas of the Philippines. P. sorghi could be brought to Australia through spores carried by wind from nearby countries, P. sacchari via infected sugarcane material and P. philippineses via infected seed. The proximity to Australia, combined with the presence of host plants in northern Australia, make early detection vital to an effective national response.
Stem borers: Certain stem borer species (in the Chilo, Scirpophaga and Sesamia genera) are priorities for NAQS surveillance because they cause severe damage to grain crops including sorghum, maize, millet and rice.
A number also damage sugarcane. The larvae attack shoots or stems of host plants, which kills the plants or inflicts severe production loss. The most likely pathway into Australia is via infested plant material. As well as surveying for these pests, NAQS promotes awareness and maintains vigilance towards illegal importation of plant material.
Stewart's bacterial wilt of maize: This disease can cause total loss of sweet corn crops. It has spread via contaminated seed from America to many countries including Malaysia. NAQS looks for signs of this disease to ensure early detection and response in the event of its inadvertent introduction.
Witchweeds: The exotic witchweeds are among the worst weeds of the world, causing up to 40 per cent yield losses in severely-affected crops. These root parasites are the major weeds of maize, sorghum and grains in Africa.
A witchweed (Striga. asiatica) was inadvertently introduced to the USA about 50 years ago and cost many millions of dollars to eradicate. Australia is the only country in south east Asia that is free from the witchweeds S. asiatica and S. angustifolia. Australia does has native witchweed species and one of them has proved troublesome on Queensland sugarcane. However, they have not parasitised any of the Australian grain crops. NAQS monitors for exotic witchweeds and other target weeds during regular surveys of land across northern Australia and in neighbouring countries.