PLACO:

As the local Piper aircraft distributor PLACO took over the spraying of the tsetse flies under contract. But it was no easy affair to acquire this lucrative contract. The civilian operators came on to the scene due to the efforts of Peter van der Woude who contacted Dr. Rennie du Toit, a professor at Onderstepoort Laboratories. This was after he learned that the SAAF experienced problems with spare parts for the Avro Ansons as they were being phased out due to old age. In fairness the contract was put to tender with COMAIR, AFRICAN AIR SPRAYERS and PLACO as the main contenders.  All the contenders had to produce the required equipment in house to be ready for evaluation trials at Wonderboom Airport, being the closest airfield to Onderstepoort. Everyone thought that AFRICAN AIR SPRAYERS under the leadership of Harry Back who had been in the crop spraying business for years would be the company to watch out for. In the concept of smoke producing an atomized mixture of diesoline and an insecticide everyone was a novice and one had to experiment in order to achieve any significant results. At that time, PLACO imported a Piper crop spraying aircraft for the SA market. The smoke mist to be produced had to be heavier than air in order to drop below the foliage to reach the tsetse flies where they normally rested.

An old Piper Cruiser (PA12) formed the basis of the test bed for the in-house developed smoke producing equipment. Instrumental in the designs of the smoke equipment was C.H. (“Obie”) Oberholzer one of the aircraft engineers at PLACO and also a commercial pilot. The right hand wing fuel tank of the Piper PA12 was used as the supply of the liquid to be atomized by the exhaust system. The left tank supplied the fuel for the engine. Liquid was sprayed through a custom designed orifice welded into the exhaust stack. The size of the orifice and the positioning in the exhaust was a very important part of the spraying system. During the early days, the exhaust stack needed constant replacing due to cracking. PLACO then realised they lacked field experience and subsequently embarked on a 50 hour flight test program. During this time Obie Oberholzer discovered the answer to prevent the exhaust cracks by pre-heating the spraying mixture before it entered the exhaust system. This was achieved with a coiled mixture supply piping around the exhaust pipe and subsequently no more cracked exhausts were experienced. Naturally, the exhaust muffler was no longer needed, as noise was not a problem in the bush; however a carburettor heater had to be improvised and incorporated in order to meet the airworthiness requirement. Prior to the evaluation date two Anson pilots from the SAAF, Captain Magnesan and Lieutenant Fields accompanied pilots from the various contenders on some of the test flights.  Both experienced pilots in aerial spraying, they offered all the contenders the same assistance and advice. The contestant companies performed all the evaluation flights on 29 June 1951 at Wonderboom Airport for an evaluation team of Onderstepoort. A very important test was the measurement of the actual droplet as delivered via aerial spraying onto a large canvas. PLACO was announced the winners with their perfect droplet size – the only contender to achieve the correct droplet size. On the enquiry on how PLACO managed to do this, Obie Oberholzer stated one has to listen to the client’s requirement and supply him with exactly that. BUT as the modifications were carried out on a commercial aircraft the Department of Civil Aviation had to approve any such alterations. For the final approval the two internal passenger seats were removed and replaced with an internal tank for the insecticide. Both fuel tanks were required as the spraying session was to last around three and half hours. It was not easy due to the centre of gravity, but DCA finally approved the design and the selection and training of pilots could start in earnest. PLACO’s operating base was Mazimba in Zululand, near Richardsbay. The company provided very pleasant living quarters for the pilots and engineers that had to service the aircraft. The best aircraft maintenance engineers were hired for the job and they received thorough training in the newly designed equipment. PLACO also provided them with the best equipment and adequate spare parts should they be required. The service was excellent and the piloting very professional. There was never a serious mishap, all but for one of the SAAF helicopters A2 on 11 September 1952, detached to PLACO and flown by Bill Fortuin, a PLACO employee. Hitting the tops of tall trees was to be expected, but nothing resulted in an accident, except for A2, but the pilot survived. Very seldom was PLACO head office required to go down and assist with maintenance. When an aircraft engine was due for major repairs or an overhaul, it was flown to Wonderboom and thoroughly checked. Upon completion of the elimination of the tsetse flies in Zululand, PLACO's Salisbury branch announced that they also obtained a contract to spray the tsetse flies at Kario, north of Salisbury. This contract lasted a further year and a half.

In the end the battle was won against the tsetse fly and the relevant sleeping and “nagana” diseases totally eradicated. This was also in part due to the Natal and Swaziland area enjoying a wide separation from the more common “nagana” disease areas of middle Africa.