Plant Sciences Commons^™

Weeds Can Poison Crops, Aik Hock Cheam

Journal of the Department of Agriculture, Western Australia, Series 4

Weeds can interfere with the growth of a crop simply by competing with the crop for nutrients, moisture and light. But some weeds also release chemicals that inhibit the germination and growth of crop plants; the technical term for this is allelopathy. Aik Cheam outlines the problems caused by two common weeds and the discusses preventative measures.

Skeleton Weed : The Current Situation, Peter Scott, Jon Dodd

Journal of the Department of Agriculture, Western Australia, Series 4

Skeleton weed is a major threat to western Australia's grain industry. This weed established itself throughout the entire eastern States wheatbelt in just over 50 years and is now found from south-east Queensland to South Australia. It was first founs in Western Australia at Ballidu in 1963, and since that time has been the subject of an ongoing and intensive eradication campaign. Peter Scott and Jon Dodd report on the present status of skeleton weed in Western Australia and outline the progress to date and future directions of the eradication campaign.

Weeds : A Curse For Native Plants In Farm Woodlands, Max Abensperg-Traun

Journal of the Department of Agriculture, Western Australia, Series 4

Weeds have a mJOR IMPct on native Australian plants, particularly in the tropical north and the agricultural regions of southern Australia.

Maz Abensperg-Traun, and his clooeagues from the CSIRO Division of Wildlife and Ecology, explainthe effects of weed invasion on the diversity of native herbaceous plants in faarm woodlands in the centeral wheatbelt of south-west Western Australia.

Wiping Out Tall Weeds, Brad Rayner

Journal of the Department of Agriculture, Western Australia, Series 4

Control of weeds is an on-going battle for farmers, with many weapons becoming increasingly expensive. A refreshing exception to this trend is the blanket wiper, a cheap but effective meens of applying herbicides to taller weeds in pasture. Brad Rayner explains how it works.

Crops In The Woolbelt : Current Options And Emerging Prospects, Wal Anderson, Ross Gilmour, Robyn Mclean, Peter Nelson, K H.M Siddique, Paul Carmody, Ian Prtichard

Journal of the Department of Agriculture, Western Australia, Series 4

It has traditionally been more profitable to grow sheep for wool in the medium rainfall parts of the south-west of Western Australia than to grow crops . Crop production has been difficult owing to the hilly terrain, the frequency of waterlogging, the high incidence of damaging frosts in some areas, the frequency of losses from diseases, difficulties with wet weather at harvest, and a lack of adapted crop varieties.

Advances over the past decade have made cropping on a limited scale potentially profitable in the woo/belt.

This article is intended to bring the various options for crop production to the …

Biological Control Of Doublegee : Israeli Weevil Could Help Fight Doublegee, John Scott, Paul Yeoh

Journal of the Department of Agriculture, Western Australia, Series 4

Since its deliberate introduction from South Africa as a salad vegetable in 1830 the doublegee has spread to become a major weed throughout much of Australia.

It is one of the most serious weeds of crops and pastures in Western Australia, smothering other more useful plants while young, and troubling both humans and animals with its sharp spiny seeds when mature.

Using biological control techniques, scientists are now attacking it and related docks in three ways - with an aphid, a weevil and a fungus.

Within a few years it is hoped that while still present, the doublegee will be …

Biological Control Of Doublegee : Doublegee Decline And The Dock Aphid, John Scott, Francoise Berlandier, Kristy Hollis

Journal of the Department of Agriculture, Western Australia, Series 4

Since 1990 farmers in the Western Australian wheatbelt have been reporting doublegee plants that appear to be diseased, stunted and producing poorly formed fruit (the spiny casing around the single doublegee seed). Often no obvious cause of this decline in plant health is apparent. Experiments carried out in 1990 showed that an aphid, which feeds hidden in the growing tips of doublegee stems and in young distorted leaves, is the most likely cause. This North American aphid, the dock aphid (Brachycaudus rumexicolens), arrived in WA in 1987. It appears to only feed on docks, doublegees and related plants and is …

Biological Control Of Doublegee : Fungi May Be Another Weapon, Roger Shivas, John Scott

Journal of the Department of Agriculture, Western Australia, Series 4

A fungus has been assessed both in Australia and South Africa since 1989 for its potential to control doublegee.

Under optimal environmental conditions it causes a severe stem blight which ultimately kills the plant. It also infects seeds, and caused up to 30 per cent mortality at a field site near Badgingarra.

Hopes to develop the fungus as a mycoherbicide (fungal killer of plants) have had to be dropped because it produces a potent toxin but it is still contributing to control in the field.

Clearwing Moths Are Key To Dock Control, Kingsley Fisher

Journal of the Department of Agriculture, Western Australia, Series 4

Two clearwing moths imported from Morocco and France could be the key to controlling dock (Rumex pulcher) - one of the worst weeds of high rainfall pastures in southern Australia

New Leaf Rust Helps To Control Blackberry, Jonathon Dodd, Sandy Lloyd

Journal of the Department of Agriculture, Western Australia, Series 4

The release of spores of the blackbeny leaf rust in spring 1991 marked the second attempt in Western Australia at controlling weedy blackberries with a biological agent. The strain of rust now being used is expected to be more effective than the one released in the 1980s.

This article describes the techniques used for rearing and releasing the fungus and illustrates the effects of the rust on blackbeny.

Paddock Sampling For Management Of Annual Ryegrass Toxicity, Ian Riley

Journal of the Department of Agriculture, Western Australia, Series 4

Annual ryegrass (Lolium rigidumJ seedheads containing corynetoxins, a group of bacterially produced antibiotics, are poisonous to livestock. Animals that eat affected ryegrass develop annual ryegrass toxicity (ARGT), suffer convulsive staggers and die within a few days of eating a lethal dose. ARGT is characterised by high death rates, especially where pastures are not known to be affected and where stock-owners are not expecting the problem. Fortunately, there are commercial tests that determine the levels of ARGT organisms in the paddock and the risk of getting the disease. These tests will help farmers plan their cropping and pasture programs for the …

Managing Brome Grass In The Wheat:Lupin Rotation, Aik Hock Cheam, Gurget Gil, Christine Zaicou

Journal of the Department of Agriculture, Western Australia, Series 4

Some farmers and scientists are questioning the sustainability of the cereal:lupin rotation in the Western Australian wheatbelt.

Being a 'tight' rotation, its continuation is constantly under threat by disease, especially lupin root rots caused by Pleiochaeta (the brown spot organism) and Rhizoctonia fungi. To control disease, some farmers have lengthened the rotation to three years, such as wheat:wheat:lupins or wheat:barley:lupins. The longer cereal phase also helps to stabilise soil against wind erosion. However, such rotations can lead to a rapid buildup of brome grass during the two consecutive years of cereals. The implications of these rotations on the severity of …

Using Goats To Control Weeds, John Peirce

Journal of the Department of Agriculture, Western Australia, Series 4

Feral goats are common in the woodland and tall shrubland areas of arid Australia. They survive and reproduce despite regular shooting, capture and droughts. These goats are considered vermin in Western Australia because of their competition with sheep for forage and their reputation as destroyers of vegetation. Research elsewhere, however, has indicated that it is only the uncontrolled grazing by large numbers of goats that causes degradation, in the same way that uncontrolled grazing by sheep can cause erosion. To some people, however, feral goats are a valuable source of income. They have the potential for meat sales, and they …

Monitoring Western Australia's Rangelands, Ron Hacker, David Beurle, George Gardiner

Journal of the Department of Agriculture, Western Australia, Series 4

Rangelands, native pastures used for grazing domestic livestock, occupy about 100 million hectares or 40 per cent of Western Australia, extending from the tropical grasslands of the Kimberley to the arid shrub steppe of the Nullarbor Plain.

The rangelands are characterized by highly variable seasonal conditions. Carrying capacity can fluctuate dramatically from year to year. Grazing management requires a tactical approach from one season to the next because of the great variation in the capacity of the land to support stock.

Rangeland monitoring provides pastoralists with objective information on these changes to assist their management decision making. The Western Australian …

Biological Control Of Doublegee, Dane Panetta

Journal of the Department of Agriculture, Western Australia, Series 4

Doublegee (Emex australis) is one of the worst agricultural weeds in Western Australia. To date, however, biological control of this weed has proved elusive. Multiple releases of two weevils which attack doublegee have not led to insect establishment. For one of these species, further research has shown that doublegee control would probably not be achieved in the wheatbelt even if insect establishment were enhanced by growing its host during the summer months. A joint Western Australian Department of Agriculture/ CSIRO project is investigating the virulence and host specificity of an undescribed South African species o/Phomopsis fungus. Should this pathogen prove …

Biological Control Of Paterson's Curse, John Dodd, Bill Woods

Journal of the Department of Agriculture, Western Australia, Series 4

The long- delayed biological control programme for the weed Paterson's curse (Echium plantagineum) has begun with the release of the leaf mining moth (Dialectica scalariella)' an insect slightly bigger than a mosquito. Yhe caterpillar stage of the moth feeds inside the leaves, producing tunnels and chambers which damage the leaf.

The leaf mining moth has already become established in suitable areas. Although the familiar purple haze of Paterson's curse will continue to be seen for years to come, we expect that the leaf mining moth - and other agents yet to be released - will make it a more manageable …

Control Take-All And Gain Other Benefits Of Eliminating Grass From Ley Pastures By Chemical Manipulation, W J. Macleod, Gordon Macnish

Journal of the Department of Agriculture, Western Australia, Series 4

Take-all is the most serious root disease of wheat and barley in Western Australia.

The fungus which causes take-all (Gaeumannomyces graminis var tritici) is wide spread throughout the wheatbelt but is most common in the high and medium rainfall regions (400mm to 750mm average annual rainfall, see map).

Elsewhere in the wheatbelt the presence of take-all affected cereal plants and the loss of crop yield may go unnoticed unless the roots of cereal plants are examined in detail.

The Potential For Skeleton Weed, John Dodd, F. D. Panetta

Journal of the Department of Agriculture, Western Australia, Series 4

Since its introduction into Australia during the 900s skeleton weed has become one of the most economically significant weeds. Its presence in cereal crops in south-eastern Australia has caused suvere yield reductions and harvesting problems.

Skeleton weed was first found on a Western Australian farm in 963. Since then it has been the subject of an intensive eradication campaign organised by the Agricultural Protection Board and funded by an annual levy on wheat growers. Such campaigns, which rely mainly on volunteer searchers, do not exist in eastern Australia because the weed is so widespread it would be impossible to eradicate. …

Using The Zadoks Growth Scale, M W. Perry, D. G. Bowran, G. Brown

Journal of the Department of Agriculture, Western Australia, Series 4

The Zadoks growth scale, which is already used overseas as an aid to better crop management, is gradually being adopted in crop production in Western Australia.

By using the scale grain growers are able to identify the various stages of crop development, particularily those growth stages that are closely related to practices such as crop spraying where treatment too early or too late may be ineffective or damaging.

Control Strategies For Annual Ryegrass Toxicity, W J. Burdass

Journal of the Department of Agriculture, Western Australia, Series 4

In 982-83, annual ryegrass tocicity (ARGT) was estimated to have cost Western Australian sheep farmers between $7 and $8 million in total economic losses.

The disease can severely disrupt farming operations. Sheep must be checked daily and if affected moved to a 'safe' paddock. The availability of paddock feed is reduced, as is stock carrying capacity. Worry about the possibility of dramatic stock losses, and uncertainty about what decisions to make, are all stressful.

Stock losses from ARGT can be minimised by the use of selective herbicides to control ryegrass in pastures and crops. This breaks the disease cycle - …

Tolerance Of Cereal Crops To Herbicides, D G. Bowran

Journal of the Department of Agriculture, Western Australia, Series 4

Herbicides have come to play an important role in the control of weeds in Western Australian cereal crops, with some estimates showing that sufficient herbicide was applied to treat every hectare of cereal grown in 1984.

While the use of herbicides reduces competition from weeds, they may have a hidden cost. As chemicals which affect plants, herbicides may also affect plants, herbicides may also affect and damage the crop which they are protecting. The crop may possibly fail, and some or all of the economic benefits obtained from the chemical control of weeds may not be realised.

Biological Control Of Parkinsonia, W M. Woods

Journal of the Department of Agriculture, Western Australia, Series 4

One of the most troublesome weeds in northern Australia'a lastoral country is Parkinsonia aculeata, commonly called Parkinsonia, Jerusalem Thorn, Palo Verde or Retama. In 983 Western Australia, ueensland and the Northern Territory started a joint biological control programme against this perst by sending the author overseas to search for its natural predators in southern USA, Mexico and Central America. A few insects show promise and one, a bruchid beetle Mimosetes ulkei, is being tested under Quarantine in Queensland.

Barley Breeding Update, P A. Portmann

Journal of the Department of Agriculture, Western Australia, Series 4

Barley production in Western Australia has increased over the past few years, peaking at 1.42 million tonnes in 1984. The European Economic Community, however, has flooded world markets for barley and over half of ourbarley was sold for feed to Saudi Arabia last year. Current prices therefore have declined as has the total area sown to barley in this State.

Despite this, the potential to increase barley yields is most promising. The Department of Agriculture has cross-bred lines in advanced stages of field testing which could increase yield by 10 per cent across the agricultural areas.

In the longer term, …

Beating The Blackberry, J H. Moore, E. B. Hoskins

Journal of the Department of Agriculture, Western Australia, Series 4

The blackberry is an aggressive, strongly-growing plant that has spread throughout parts of the south-west of Western Australia.

Although most blackberry infestations on agricultural land have been dramatically reduced since compulsory control measures were introduced 30 years ago, about 3,600 hectares are still infested today.

Recent research has shown that three new herbicides are highly effective against blackberry, and much safer to use than the older ones.

Effective biological control of blackberry may also be possible.

Skeleton Weed : How Serious A Threat In Western Australia?, F D. Panetta, J. Dodd

Journal of the Department of Agriculture, Western Australia, Series 4

Skeleton weed is probably the most serious weed ever to threaten the Australian wheat industry. It interferes with wheat cropping at two stages: through competition with the growing crop, particularly for nitrogen and water during the crop's development: and later through the production of a tall, wiry flowering stem which tangles in harvesting machinery and can make harvesting difficult, if not impossible.

The weed is a major problem in eastern Australia although a combination of cultural, chemical and biological control programmes is helping to reduce its impact.

In Western Australia, skeleton weed is being contained mainly by eradication efforts. Weed …

A 'Natural Herbicide' Against Calotrope?, A H. Cheam

Journal of the Department of Agriculture, Western Australia, Series 4

Buffel grass produces a chemical compound which is toxic to the growth of calotrope seedlings, a declared weed in Western Austrsalia north of the 26th parallel. This new discovery id highly significant in view of the increasing emphasis now placed on weed management as opposed to weed control and the desire to use fewer pesticides.

Research On Declared Plants And Other Weeds, G. A. Pearce

Journal of the Department of Agriculture, Western Australia, Series 4

Knowledge about weeds is necessary to assess their significance, devise control measures and to select those which are to be declared for the purposes of the Agricultural and Related Resources Protection Act.

Once a plant has been declared in Western Australia, all landowners must control and prevent its spread to new areas and work towards eradicating known infestations. The Act also declares plants which are prohibited from entering the State.

It is becoming more and more important to provide specific reasons for the declaration of a weed and its placement in a certain category. Such decisions require appropriate action to …

Doublegee Control In Pasture : What Is It Worth, D J. Gilbey, R. J. Lightfoot

Journal of the Department of Agriculture, Western Australia, Series 4

A recent study showed that the cost of spraying to control a heavy doublegee infestation can be recovered in the first year of the spraying.

Lupin Yields Are Not What They Should Be : Viewpoint, M Ferguson, S. Trevenen

Journal of the Department of Agriculture, Western Australia, Series 4

Mike Ferguson has been in charge of the Three Springs office of the Department of Agriculture since 1977.

Based on trials he has done and others he has seen, he believes farmers can greatly increase their yield of lupins.

The Place For Annual Brome Grass, G W. Anderson

Journal of the Department of Agriculture, Western Australia, Series 4

Grasses in the anual pastures of southern Australia are particularly important early in the growing season.

The main grass sown, has been annual rygrass, but concerns are emerging with 'annual ryegrass toxicity' and and 'in crop' competition.

This work looks at the role of annual brome grass in pastures.