While the nation’s farmers face the impending ban on diquat, German manufacturer Grimme has relaunched its high-output KS600 haulm topper, as UK potato growers search for new methods of pre-harvest crop canopy desiccation.
Simon Henley reports.
The herbicide diquat dibromide needs no introduction. Diquat is a broad-spectrum contact herbicide which has been an essential element in popular desiccants including Reglone.
Since the ban on sulphuric acid in 2009, diquat has become arguably the most effective and reliable method for ‘burning-off’ potato canopies prior to harvesting. But not any longer.
Last year, the European Commission made the decision not to renew an approval for the use of diquat within the European Union.
It was concluded all products containing the chemical needed to be withdrawn by May 4, 2019, with a suggested use-up period ending on February 4, 2020.
In the scheme of things, the diquat ban comes as no surprise. Furthermore, while it may be conceived by some growers as a major inconvenience, the news of its loss has actually forced the UK potato industry to think outside the box and develop new methods of desiccation.
Trials conducted by AHDB, under what it calls the Strategic Potato (SPot) Farm Programme, have determined specific blends of desiccants, such as Spotlight Plus and Gozai, can offer about 60 per cent of the desiccation power of diquat when combined with a pre-spray flail treatment.
The key to the success of using a desiccant such as Spotlight Plus, is to ensure the crop foliage is at its most vulnerable prior to the application of the herbicide.
To achieve this, the crop must first be topped using a flail when the foliage is green, about three weeks prior to harvesting. The removal of potato haulm requires a purpose-built flail topper, and one of the most well-developed on the UK market today is the Grimme KS600.
The KS600 was originally designed for Grimme by the founder of Sumo, Shaun Wealleans. Developed for large potato growers and contractors, it initially made its debut in 2000 and quickly became a popular choice for growers throughout the eastern counties.
Grimme UK East Yorkshire area sales manager, John Taylor says: “The original preproduction model and the first production KS600 we sold, are still on the same farm. “At one point these machines were topping 9,000 acres per season between them, and they are still going strong today.”
In recent years, Grimme has taken a step back from selling haulm toppers. Yet with the impending loss of diquat, the company has relaunched the high-output KS600, as farmers seek alternative methods for desiccating their crops.
“The heavy-duty design of the KS600 makes it the ideal machine for pre-desiccation green haulm topping applications,” adds Mr Taylor.
“The idea is the topper should be set up to leave 150mm- 200mm of stalk, so when the crop is lifted the haulm roller on the potato harvester can get purchase on the remaining crop stem.”
The KS600 system is a six-row/three-bed design, which features a single front-linkage mounted topper and two rear toppers which are attached to a subframe mounted on the tractor’s rear linkage.
During transport, the rear toppers are hydraulically folded upright like a set of mowers. “The front topper is designed so it is wider than the rear units,” says Mr Taylor.
“The front unit flails the middle two rows passing under the tractor. However it also takes about 50 per cent of the rows on either side, so the uncut stalks on the outside ridges don’t get pulled down by the tractor wheels.
Stalks flattened by the wheels can’t be sucked up and presented to the rear toppers, which ultimately means they will remain uncut.”
The Grimme KS600 flail rotors are made from heat-treated, seamless steel tubes, which are pressure cooled as the flail mounts are welded on, to prevent distortion.
Balanced to rotate at 1,300rpm, the rotors are fitted with different sizes and lengths of flails which are contoured to match the shape of the rows in each bed.
The flails fitted are suited to the farmer’s requirements, taking into account the number of rows in a bed and the size of each row.
Working on a 72-inch bed, there are commonly six flails required to clear the top of each row, however this may vary according to the type of planter being used.
In keeping with the layout of the flails, each Grimme KS600 is equipped with a contoured shearbar which is matched to the length and shape of the flails fitted to each specific machine. As the haulm is chopped, it passes over the rotor onto two deflectors.
The purpose of these is to guide the crop residue so it falls between the rows. Were it allowed to remain on top of the rows, the effectiveness of the desiccant, which is typically applied within seven to 10 days, would be compromised.
The cutting height, is controlled by either manually-adjusted depth wheels, using crank handles, or with an optional hydraulic adjustment system.
Topper bodies are suspended so the cutting height is constantly maintained while the topper follows the contours of the ground.
On the rear toppers, the suspension is provided by a parallel linkage arrangement on the subframe, which uses coil springs to provide the necessary compression. As each row is topped, it is sealed using a floating press wheel.
The press wheels, which are mounted behind the machine, are equipped with a flotation tyre which has a zero inflation pressure.
The tyre is used to gently close any cracks in the top of the row, which might expose tubers to sunlight and ultimately turn them green.
“Once the crop has been topped cleanly, the chopped stalks are fully exposed,” says Mr Taylor. “This enables the Spotlight Plus to be fully absorbed by the plant, to produce the maximum desiccating effect possible.
“The days of using a topper to remove desiccated haulm in front of the harvester are in the past.
The versatility of the Grimme KS600 means we can provide potato growers with a viable alternative for haulm desiccation, using a well-proven machine which can be adapted to suit virtually any type of growing conditions.”
The Grimme KS600 is a heavy-duty, six-row, three-bed haulm topper, capable of topping up to 100-acres/day.