German woodland owner uses water cannon to battle bark beetle

AS a result of the dry summer of 2018, 40 cubic metres of beetle wood built up in Alex Gerke’s forest near Wipperfürth. When another summer drought threatened in 2019, the woodland owner resorted to unconventional methods: he watered part of his woodland using a 6,000-litre slurry tanker, with amazing results: the bark beetle remained active in 2019 – but only where the water didn’t reach due to the limited spraying range of the slurry tanker.

And in 2019, just one tree became infested by the bark beetle. But a slurry tanker can spray a distance of only 10 metres or so, and it is also totally unsuited to travelling along racks.

After further thought, Alex and his father mounted a 1,000-litre IBC container on a three-point-linkage pallet fork, acquired a PTO pump and a part-circle sprinkler and put the whole lot together. With this combination on the tractor, Alex’s father was now able to water the places that the jet from the slurry tanker could not reach. But even this solution did not satisfy the two woodland owners.

A water tank on a forwarding trailer helps prevent thirsty trees. The jet reaches 20 metres.

BY THE INDUSTRY, FOR THE INDUSTRY

This gave rise to the idea of mounting a water tank on a timber trailer. Using a standard petrol-driven water pump, Alex was now able to spray the water a distance of 20 metres – twice as far as with the slurry tanker.

Since this woodland owner is also the leader of a volunteer fire brigade unit, it was only natural for him to design his system in such a way that it could also be deployed for forest fires. The decision to build a device of this kind was finally made when fire broke out in neighbouring Gummersbach, destroying 50 ha of forest.

The spray pattern can be altered by means of an adjustment screw.

Alex acquired a second-hand, 4,000-litre water tank and welded suitable brackets for the bunks. In the rear bunks he built a support for the crane. This is also used to hold the nozzle in position. The baseplate on which the 65 hp petrol-driven water pump is mounted is held in position by a single M10 screw, and the tank is held in place by just two straps, which are quite adequate. Mounting and disassembly can therefore be done in under five minutes.

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All connections on the tank and on the pump are designed to fit Storz couplings and are therefore ‘fire brigade compatible’. The jet has a nozzle diameter of 19 mm. The pump delivers 300 litres per minute with a spraying range of 20 m. The spray pattern can be altered by means of an adjustment screw. And all for less than 1,000 euros for the entire outfit.

Alex Gerke and his father Josef are passionate forest owners and cherish their woodland.

100,000 LITRES TO FIGHT THE GREAT THIRST

Alex Gerke does not water his entire woodland – just the spruce and the new plantings. His oaks have to learn to withstand dry spells.

Driving about 200 metres in the lowest gear – with a spraying distance of 20 m – empties the 4,000-litre tank. The water moistens the soil to a depth of about five cm. However, it must also be noted the trees absorb evaporating water through their leaves and needles.

The water comes from the Gerkes’ own pond, which is situated near the forest. Water flows into this, and it also has a spring, so the fact that water is taken during the dry season is hardly noticeable.

The motor and pump are mounted on a platform at the rear of the trailer.

When there is no rainfall, Alex and his father water the forest very frequently, and they used about 100,000 litres of water last year. And their success proves the woodland owners are onto something. Particularly on higher areas of their 5.5 ha, the water treatment can be shown to have caused the beetles to leave the stand in peace, or possibly the watering has had a stabilising effect on the trees, enabling them to fend off the beetles with increased resin flow. Of course, both forest owners continue to keep a close eye on their trees, and if there is the slightest infestation of beetles, they will resort to the saw.

HE’S DOING SOMETHING!

This method has not been scientifically researched and Alex does not know whether it is economically viable; he hasn’t worked out the figures and doesn’t want to. But at least he isn’t standing by helplessly, watching his forest die. He is doing something about the disaster. The forester responsible for his woodlands, with whom Alex has a very good relationship, laughed when he first saw the watering operation. Today, even this initially very sceptical man says that the Gerkes’ method seems to have been successful.

This was only an interim solution – an IBC container with a capacity of 1,000 litres.

Alex and his father have both the machines and the time to care for their woodlands. 46-year-old Alex is a trained industrial engineer and works for a medium-sized mechanical engineering company.

The Gerkes primarily produce firewood from their woodlands and use it to heat their houses. They have an impressive list of machinery: three winches, four tractors from 16 to 98 hp, a Källefall FB90 forwarding trailer, an all-terrain forklift, a flail mulcher and a three-point-link chipper.

NOTE: The original German-language version of this article, written by Dieter Biernath, appeared in FORSTMASCHINEN-PROFI. We are grateful for their permission to print an English translation in this issue. All photographs provided by Alex Gerke (email: alexgerke@freenet.de).

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