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Continued Attack On Paterson’s Curse

Control Paterson’s Curse now to reduce infestations and halt the spread of seed.

By Department of Primary Industries - 27th August 2003 - Back to News

The Department of Primary Industries (DPI), in conjunction with the Department of Sustainability and Environment, is again targeting Paterson’s Curse. After another dry season, reports are indicating a heavy germination of seed this year.

Plants are varying from only a few centimetres in diameter to flowering, which indicates very early germination in some cases. This is largely due to spasmodic rainfall and a lack of competitive pastures. Like all weeds, strong competitive pastures curtail their establishment.

It is normal to have several germinations of seedlings during a season and this year looks particularly bad.

Gippsland may also see an increase in the number of infestations through the introduction of contaminated produce. Landholders who have brought hay or grain onto their properties should be on the lookout for the tell-tale sign of the plant, the easily identifiable rosette.

Paterson’s Curse is a declared noxious weed and landholders are legally responsible for its control on their properties.

A long-term control program needs to be put into place with a concentrated effort to contain the spread of the plant this year. Landholders must destroy plants before they set seed to prevent new infestations. Paterson’s Curse infestations require a minimum of two treatments due to the staggered germination of the plant.

DPI Catchment Management Officers will soon be inspecting properties with known infestations of Paterson’s Curse. The Good Neighbour Program will also be targeting Paterson’s Curse on areas of Crown Land in Gippsland.

Further information can be obtained by contacting a Catchment Management Officer at your local DPI office.

BLOAT

Bloat is a seasonal problem in cattle. The condition is usually precipitated by the rapid consumption of lush legume pasture species, especially clover and lucerne.
Bloat is caused by an increase in the gas pressure within the rumen (paunch) as these feeds are fermented. The gas cannot be belched up normally and death results from the pressure causing heart and lung failure. The gas is often trapped in the form of stable foam. Traditional methods of bloat prevention rely on chemicals which break up the foam and release the gas.

ANIMAL MANAGEMENT - Bloat is often triggered by cattle gorging themselves with legume rich pasture. Hungry cattle should not be allowed access to these areas. Feed out grass hay a few hours before the cattle are moved into a new paddock.

PASTURE MANAGEMENT - Fast growing, clover dominant pastures should be avoided. Mature pastures with less than 30% clover content pose little risk of bloat. Increasing the fibre intake of cattle will reduce bloating. Feeding grass hay daily can help to reduce the intake of 'bloaty' pasture.

ANTI-BLOAT MEDICATION

• Sustained release anti-bloat capsules - Each capsule is approximately 150 mm in length and is administered as a large plastic pellet down the throat and into the rumen. They provide a continuous supply of ingredient for 80 - 100 days and must be given one week prior to the cattle being introduced onto 'bloaty' pasture.
• Bloat blocks - Bloat blocks or licks place minimal demands on management and so are popular with farmers. Several types are on the market and many contain Teric 12A23B which is an effective detergent. Cattle can be encouraged to use the blocks by placing them close to stock camps and watering points.
• Water trough treatments - Medication of the cattle through their water supply is another alternative. Frequent addition of the concentrate is required to maintain protection.
• Hay treatments - Anti foaming agents may be added to the hay. The addition of tallow, a tallow and bloat oil proprietary mix, or a 1:1 mixture of Teric and molasses to the hay will provide about 12 hours of protection for those animals consuming the correct dose.
• Roller licker drums - This method uses a drum partially submerged in a bath of medicated molasses. Cattle lick the molasses off the drum as it revolves in the bath. As with the bloat block, success with the roller licker drum depends on the cattle being educated to use them. Once accepted, Teric should be added to the mixture to give a daily dose of 40 mls per animal.
  
  

STEP ON THE GAS WITH NITROGEN

By Ivor Awty, DPI Ellinbank

It is widely recognised that the lack of soil nitrogen (N) is a major limiting factor in growing pastures in dairy systems. Nitrogen applied to pasture can be likened to a car’s accelerator, where P, K and S applied to pasture can be likened to car fuel. Once the fuel is in the right balance and the engine is at its peak, then apply the accelerator to regulate the performance. No wonder N is often referred to as a feed supplement and not classed as a fertiliser!

Here are some general facts regarding N use:

• Urea is the cheapest form of N (46 kg N per 100kg of Urea);
• The optimal N rate is between 30-60 kg N/ha per application;
• Pasture responses to fertiliser N will not be as effective if phosphorus (P), potassium (K) or sulphur (S) are limiting, but high soil P, K or S levels are not required to gain maximum growth from applied N;
• The best growth response will be when you have actively growing grass with more than 20% moisture;
• There will be very little loss of nitrogen through volatilisation from urea if it is put on moist soil (above 20% moisture) in the colder wetter months, but can be as high as 25% in summer. Volatilisation losses of urea N occurs mainly between 24 and 48 hours after application;
• Expect some soil acidification with N use.

To avoid the risk of nitrate poisoning, it is important to avoid grazing between four and 18 days after N application. There is a time lag of four to six days from when N is applied to when it becomes available to plants. Some plants found in pasture such as volunteer brassicas, capeweed and small-flowered mallow or marshmallow, accumulate nitrates, and increase the risk of nitrate poisoning of cattle, particularly seven to 14 days after N fertiliser has been applied.

If N were applied seven days after grazing, a minimum rotation of 25 days would be required to allow the 18-day safety margin. Those farmers that have a quicker grazing rotation of say 18 to 20 days may well be better off applying lower N rates at around 30kg N/ha in each application.

Olsen P levels of around 18-22 mg/kg is ideal to optimise growth with or without N. Phosphorus for Dairy Farms research at DPI Ellinbank showed that there is no economic advantage in having higher P levels.

Colwell K levels of between 150-250 mg/kg are also adequate, while below 150 mg/kg, pasture performance may be limited. Beware of soil K levels above 400 mg/kg as there is a danger of grass tetany. This does not mean that cows will die, but it does mean that there is an increased risk of grass tetany.

Sulphur levels of around 8-12 mg/kg (using the KCl₄₀ soil test) are regarded as adequate. Below 6 mg/kg, and you may expect that pasture performance will be limited, while above 12 mg/kg and there is no economic gain. The use of low S fertilisers such as DAP may be more profitable when S levels are adequate. Soil pH levels between 5.4 and 7.0 generally suit all species of grasses and legumes that the dairy industry uses.

Potassium and Sulphur fertilisers are water-soluble and therefore, can be lost through leaching and surface runoff across pasture soils. Phosphorus is a little different in that it is generally very reactive with the soil and therefore, is not prone to leaching unless the soil is very sandy. However, P loss through surface runoff is important and it makes good sense to not apply P fertiliser prior to storm events or irrigation.

Soil testing is the only tool available to get a handle on these basic soil nutrient levels. By applying these principles to your fertiliser planning, farmers can profit by growing more pasture at a cost much less than bought in forage or grain.

Source: http://gippsland.com/

Published by: news@gippsland.com