New thermal weed control machine for vineyard use
LPG specialist D.J. Batchen Pty. Ltd. recently announced the availability of a new thermal weed control machine for use in under vine applications. The trailer-mounted machine, called the StingerV1300C, is designed for tractor towing. It incorporates patented steam quenched combustion technology that offers possibly the cleanest and most effective means of thermal weed control.
To eliminate the risk of fuel residue on the fruit the generators are fired by clean burning LP-Gas.
Both sides of the vine row are treated simultaneously. Heat from the burners is retained under a Kevlar canopy to assist thermal transfer and reduce any wind effect.
The canopy skirt is held by a framework of spring steel rods, to allow flexibility and reduce vine damage if contact is made. The canopy is easily removed for transport and attached in the vineyard, and the trailer has mounting facilities for on board storage.
Width adjustment is hydraulic and made from an extension control panel in the cab.
Sensors on the extremity of the unit control the hydraulic cylinders that move the canopies on either side away from obstacles, and return them to the original width setting when clear.
Vine row width settings are hydraulically adjusted and are infinitely variable from 2.4 - 3.6 metres.
Hydraulic adjustment control is also made from the extension control panel in the tractor cab.
The machine can be made with automatically retractable canopies to assist maneuvering in and out of vine rows. The canopies return to set width when the machine is again in line. Alternatively, it can be made with a shorter wheel base that will fit most headlands.
The generators and canopies are supported by castor wheels which can be adjusted from horizontal to work on mound angles of 30 degrees.
Application bandwidth is immediately under and 500mm out from the vine.
Application speed varies with weed height, type and stage of growth (mainly moisture content) as well as ambient conditions, but is generally 3 to 4kmh.
With the canopies removed the generators can be rotated and raised for use in de-suckering (this feature is being monitored to determine the effectiveness of the application).
Steam generator burners can be manually turned down to half fire while manoeuvering. To minimise vine and irrigation equipment damage the generator burners will automatically go to half fire if the machine is stationary for more than 5 seconds and revert to full fire when motion is detected again.
An operating temperature advisory light tells when the generators have reached operational temperature on start up.
The trailer is designed for on road use and can be easily towed by a 4WD vehicle.
To ensure optimum performance of the steam generators in low ambient temperatures, the gas tank incorporates a fuel pump operated by a pressure switch to maintain full gas pressure to the burners.
The generators can be fuelled with either propane gas or blends of propane and butane (including readily available auto-gas blends). The gas tank is fitted with an automatic fill-limiting device that allows for filling at any service station or auto-gas outlet.
To minimise fire danger and equipment damage each generator outlet has a high temperature sensor. A buzzer warning sounds if the generator outlets are running above design temperature and the system shuts down after 15 seconds if the problem is not rectified (generally the problem is caused by the P.T.O. running below the required 540 rpm and starving the generators of water)
The gas system will shut down or not start if it detects low water level in the storage tank, low gas level in fuel tank, low water pressure, freezing of water in supply lines, high temperature at any generator outlet, roll over, or if the machine is stationary for more than 2 minutes.
Although the operating temperature is designed to prevent combustion of dry mulch material, a permit will be required to use a thermal weeder during fire ban season.
Effects on weeds
The effect of thermal energy on weeds will vary with size and type of weed, ambient temperature, machine travel/application speed and possibly soil moisture content.
Thermal weeding provides only a knockdown effect on larger, mature weeds and weeds that grow from underground parts. It can kill small weeds, with the actual size of weeds completely controlled varying depending on the length of time the weed is exposed (or travel speed of the tractor).
Immediately after treatment weeds do not appear dead. At first only a minor colour change and limpness of the plant is apparent. Over the next few hours, the plant will wilt and the tops will die. This effect is caused by rupturing cell walls, under the influence of high heat, for a short time. While this does mean that re-treatment is necessary, depending on time of year, growth cycles of the weed and seasonal conditions, it has the advantage of preserving the organic matter, and allows the machine to be used longer into the growing season.
A demonstration of the Stinger V1300C at Langhorne Creek recently revealed that it produces more usable heat from less gas than other thermal weeders , because of the steam generation and delivery system, and the canopy effect. It also produced less stray heat than other machines.
D.J. Batchen will make the machines to order for the 2003 season. Batchen are happy with the steam quenched combustion generator system, but will continue to develop the canopy system with anyone who purchases the first model. A reduced price is available for the first ten machines to encourage collaborative development of the system.
Batchen envisage that the machine will be particularly attractive to organic growers, growers who wish to reduce herbicide residues in their produce or soil, and vineyards close to herbicide sensitive targets, such as homes, schools and public facilities.
Stinger V1300C Specifications
Retracted width 2.1mts
Extended width (max) 3.6mts
Total length (max) 4.3mts
Length (axle-pivot). 2.1mts
Weight (including water and gas) 1400kgs (approx.)
Turn angle (max.) 88 degrees
2 x Steam Quenched Combustion Generators
LPG consumption (approx) (26 Litres/hr each) - Total 52 litres/hr
Water consumption (approx)
LPGas capacity 175 litres (useable)
Water tank capacity 400lts