Tower sprayer gives better protection against diseases and less drift
A 95 to 99 per cent spray drift reduction and a better protection of avenue trees against diseases can be achieved at the same time. This is the result of the tower sprayer, a novel spraying technique developed by Applied Plant Research (PPO) together with a number of partners.
Avenue tree growers are normally using an axial sprayer to protect their crops against pests and diseases. The axial sprayer, however, has two major drawbacks. With this sprayer growers will find it difficult to meet government demands: a 90 per cent spray drift reduction in comparison with 1998. Another problem is that the maximum spraying height of the axial sprayer is about four metres. This means that a pest or disease can freely develop in high trees above this level.
Developing a new sprayer
Researchers of PPO and Plant Research International have together with Damcon and a number of growers developed a new sprayer. This tower sprayer is 5.60 metres high, has 34 nozzles at both sides and thus reaches to the top of most trees.
The sprayer is also fitted with sensors. These detect whether green material is present. The nozzle closes as soon as room between the trees is detected.
Up to the top of the tree
Measuring results show that the leaves of the tree up to a height of 6 metres are reached. No more than 5 to 6 per cent of the leaves are not sprayed. From the first metre an axial sprayer reaches all leaves in the crown but not a single leaf is sprayed above 3 metres.
The price, however, is a major drawback of the tower sprayer. At the moment there only is a prototype; this costs about 20 000 Euro. This is much more than the price of the axial sprayer which costs 4000 to 6000 Euro. Damcon has, however, together with a grower, developed a mini-tower sprayer which costs about half of the large tower sprayer. This mini-tower sprayer reaches a height of about 5 metres and has no sensors.