Thatch Management

Andy Walker, SISIS Field Support Manager answers some frequently asked questions on thatch management
Andy Walker, SISIS Field Support Manager answers some frequently asked questions on thatch management

It’s fair to say that when you talk about thatch, many people say that you need to go deeper and deeper into the soil to remove it. Andy Walker, Field Support Manager for SISIS says that the most frequent question he is asked is how deep does the machine go? In his opinion, that is not the correct way to control thatch and here are some commonly asked questions he’s asked to answer.

What is the difference between scarifying and verticutting? And do I need to do them both?

These turf maintenance operations vary in their objective, the depth to which they are performed and the machinery used to carry them out. Whether you need to do any or all of them will depend on the species of grass in your turf and the condition of the sward.

Deep scarification is a deeper action, usually done twice yearly which penetrates the surface – deep into the thatch layer to remove fibres, debris, thatch and moss. It can be of benefit where a layer of fibrous material has built up and is beginning to cause problems with water infiltration or during renovation work prior to top-dressing. Thatch build-up is particularly noticeable where there is a prevalence of annual meadow grass, in fine turf and where the grass is mown regularly and cut low.

There is a wide range of pedestrian-operated and tractor-mounted equipment available to combat this. During scarification, lateral grass growth can also be controlled. SISIS has become renowned for specialising in the production of equipment for scarification.

Verticutting or light scarifying uses a machine fitted with blades that reach vertically into the turf canopy and are set to a depth where they can achieve their objective of cutting through laterally growing and creeping grasses. The blades may also dislodge a small amount of thatch but should not penetrate into the soil or turf root zone.

SISIS has four main machines which are suitable for use on golf courses. The SISIS Rotorake Mk 5 is a heavy duty, self-propelled scarifier and de-thatcher, the Rotorake TM1000 is a tractor mounted heavy duty scarifier, de-thatcher and linear aerator, the Veemo MK 2 is a triple mounted hydraulically driven tractor mounted heavy duty scarifier and de-thatcher and lastly the Rotorake 602 which is a heavy duty powered scarifier, de-thatcher and linear aerator which is also available with an optional seeder. It’s worth noting that all SISIS pedestrian scarifiers and the TM1000 collect the debris as part of the operation.

Thatch can be kept at bay with good maintenance regimes that invariably require mechanical methods, one such method is scarification. Why should you scarify in different directions?

If you want to remove thatch; it’s important that you do it in more than one direction rather than just going deeper each time. You will find that you get a much better result by doing a fairway in two directions at 10mm than in one direction at 20mm.

What determines the type of machine to be used on tees and greens?

This very much depends on depth of cut that the greenkeeper or course manager wants to achieve and whether they want a pedestrian machine or a tractor mounted machine and budget. For tees and greens, if you are just wanting to go shallow (up to 10mm), then I would suggest using a pedestrian machine like our Rotorake MK 5 with its interchangeable reels. If you want to keep a pedestrian machine, but go deeper, I’d suggest the 602. If you are not particularly concerned with taking a tractor on to your tees and greens then the TM1000 is an option changing the reel accordingly by changing the blades.

What determines the type of machine to be used on larger areas?

The type of machine that you want to use on larger areas is something that is quick. For instance, you wouldn’t really use our TM1000 on a fairway, it wouldn’t be feasible – it’s not really a fairway machine because of its width. Most people would use our hydraulic Veemo machine. Generally, this machine would be used with the 2mm tungsten tipped blades set at 40mm centres, but there is also an option if you want to use it as a verti-cutter to change to a 1mm blade at 12 or 18mm centres, to trim any lateral grasses and also trailing grasses.

Why would someone choose a floating head machine over a fixed head machine?

You would choose a floating head over a fixed head machine as it can follow the contours of the ground closely without ever scalping it. The biggest benefit of our Veemo machine is that it follows any undulations of the ground on a fairway without any danger of damaging the turf. Fixed head units just dig in to the ground and take the top of the hump off. The Veemo doesn’t do that because it’s got fully floating heads independent from the main frame  which move in all degrees of motion – up, down, back, forwards and from side to side and the contours of the ground are always followed by the two rollers.

Any disruption of the playing surface will affect playability of the surface, how do the SISIS machines reduce this?

The Rotorake MK 5, 602 and TM1000 all contra-rotate. The patented contra-rotation principle was developed after research at the Sports Turf Research Institute and incorporates a reel of blades rotating at high speed in the opposite direction to that of the conventional cylinder mower. The blades therefore cut upwards, continuously taking fibre away from the surface rather than pushing it into the surface. This also ensures that the machine is held to the ground and a consistent working depth is always maintained. This has a number of benefits for a greenkeeper – it leaves a much cleaner slit when you use it because it doesn’t take the thatch through the soil structure, but the biggest reason for the clean surface is the speed of the reel.

What is the difference between the light scarifying reel, scarifying/thatch removal reel and the Verticutter/thatch control reel?

The Scarifying reel on the MK5 is 1.6mm tungsten tipped blade set at 20mm centres. The scarifying reel on the 602 is 2mm tungsten tipped blade set at 24 mm centres and the TM1000 has a 2mm blade set at 30mm centres so basically, it’s the thickness of the blade and the spacing’s between the blades on the scarifying side. As for the verti-cut reel; on the MK5 it’s a 1mm tri-tipped blade set at 12mm centres, the 602 is a 2-tipped blade at 1mm set again at 12mm centres and the TM1000 is a 1mm blade again set at 12mm centres, although you can change the spacing’s between the blades in increments of 6mm. You would never go to 6mm, but could go to 12mm, 18mm, 24mm etc.

When would you use the above reels?

You would use the scarifying reels, pre-season, maybe to do a little more than verticutting. You can also use these reels because of the thickness of the blades for over-seeding. By completing several passes in different directions and then broadcasting seed onto the surface. You could then give the surface a light top dressing before brushing it in to give the seed something to key into. The light scarifying reels or the verticut reels would be used throughout the playing season when the grass is growing to cut laterally growing grass.

For further information or a no obligation demonstration, please contact SISIS on 01332 824 777 or visit

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Dennis Mowers