Reduction of plant protection agents: experiences with band sprayers and SpotSpraying
Theo Leeb reports on his experiences with BandSpraying and SpotSpraying over the last two years. Are these methods worthwhile? What impact do they have on quality and yield?
The reduction of plant protection agents remains a constant issue: “We are following this discussion about the reduction of plant protection agents and fertilisers and feel a certain degree of uncertainty because of the lack of agreement in the European Parliament in 2023 regarding the Green Deal and the Farm to Fork Strategy,” Theo Leeb says. “But regardless of any developments, our objective is to apply plant protection agents as efficiently and precisely as possible – for both economic and environmental reasons. This is why we are constantly researching and working on systems and strategies to achieve this.” Currently, the focus for saving plant protection agents is on two methods: BandSpraying in row crops and SpotSpraying in row and field crops.
Experience with band sprayers
“Our boom control system allows for BandSpraying with a field sprayer, a method which is widely used on farms,” Theo Leeb reports. However, the system has not proven to be feasible in all conditions in practice. Problems occur mainly on slopes or on small and irregularly shaped fields: “As soon as the terrain becomes hilly or undulating and the tramlines are no longer straight, it becomes difficult to hit the rows reliably across the entire working width.’
To counteract this, a band sprayer with a working width of 18 m was built in 2024 specifically for sugar beet in southern Germany. Then, in 2025, came a 24 m machine divided into three 8 m segments. This allows for working in a multi-sectional way as the segments are controlled independently of each other over the rows within a seed drill width.
“We also implemented a closed system from seeding to BandSpraying,” Theo Leeb says. While sowing, the seed track on the seed unit is precisely recorded by means of a GPS receiver. The segments of the band sprayer are matched to the width of the seed drill (e.g. 8 m). Each of the three 8 m segments of the band sprayer is equipped with its own GPS receiver which accesses this data and controls the segment precisely over the row. “The system has proven itself in practice and is a robust solution. When sowing, the last centimetre of accuracy is no longer an issue during the bout tracking as the segments of the band sprayer, which are matched to the seed width, are controlled individually.”
In addition, there is a high degree of flexibility with regard to row widths: row widths of 25, 50 or 75 cm are easy to implement. However, the widely used spacing of 45 cm and 22.5 cm for sugar beet are also feasible.
The use of GPS control allows for applying herbicide between the rows before emergence. “Due to the reduced herbicide stress during emergence, we noticed that the beets developed faster, and the rows closed sooner. This meant that the first hoeing pass was no longer required.” This is particularly advantageous on slopes as the low vegetation cover during the first hoeing pass, which would otherwise be necessary, increases the risk of erosion in the event of heavy rainfall. Hoeing at a later date when the beets are larger reduces the risk of erosion.
"Application between the rows proved to be very positive in 2025. Even on sites with problematic black grass or ryegrass pressure, we will pursue the idea of inter-row application more intensively, even with a row spacing of 25 cm. Another crop where band application could be interesting from an economic point of view is rapeseed with a row spacing of 50 cm. We are discussing the use of systemic insecticides as a band application on rapeseed rows with the farmers. Another application in rapeseed could be the treatment of old rapeseed between the rows with the band application system."
“All in all, the band sprayers are robust and easy-to-use machines,” Theo Leeb sums it up. The band sprayer is currently a proof of concept: “We can't say yet whether something like this will go into series production as we need more information, but it's definitely possible.”
SpotSpraying in the offline method
In 2025, the focus of SpotSpraying was on offline methods. This involves flying a camera drone over the population and then evaluating the images obtained by means of AI algorithms. The application map generated from this is transferred to the terminal and the field is treated. “Over the past two years, we carried out several tests in this sector together with SAM Dimension and the chemical industry,” Theo Leeb states.
The offline method (image captured by a drone and application by plant protection technology) allows for generating much more accurate data: “This is because the drone looks vertically at the population which means that the shadowing effect is less than with a camera directly on the boom.” Another major advantage is that the computing power of various stationary high-performance servers can be used to process the resulting amount of image data. With the online method, the camera has to take a picture, and the system has to decide what to do within a few hundredths of a second.
Due to the factors of time and computing power ad libitum, more complex AI models can be used in offline processes to reliably identify weed species and grasses. “These weed/grass maps provide farmers with more information to help them decide whether it makes sense to spot now or at a later date – or whether they should only treat specific areas, such as thistle patches,” Theo Leeb explains. In his opinion, the ability to post-process the image data is a major advantage of the drone system. This data can be optimised in terms of exposure and contrast – to finally achieve the optimum detection rate.
The results of the tests show that the savings in agents roughly amortise the costs of the method. “This naturally raises the question of whether it justifies the effort – especially as the detection system also operates with a certain degree of error tolerance and SpotSpraying generally requires more frequent driving which in turn entails risks,” Theo Leeb says.
A far more interesting finding with regard to SpotSpraying became apparent when looking at the quality of the harvest: "Although we did not notice any significant yield surplus between the fields treated across the entire surface and those treated with SpotSpraying, the sugar beet showed clear differences in sugar yield per hectare. It was significantly higher in the spot-sprayed variant than in the variant treated across the entire surface. We are talking about up to 300 € per hectare of surplus yield output due to the higher sugar yield. This is a sum that makes the method very interesting from an economic point of view."
The article “It's not just about saving money” in the magazine DLG Mitteilungen 2/25 also presented results that confirm these quality advantages. Finally, herbicide applications cause stress in our crops which affects their development. Crops that have not been sprayed with the herbicide due to the spotting method are not slowed down which ultimately has a positive effect on quality and yield. “We now have to continue to observe this and test it in other crops to see if we notice similar effects,” Theo Leeb looks ahead.
Conclusion
“Agriculture has to be economical – and this includes methods for the optimal use of plant protection agents. This is where BandSpraying and SpotSpraying come in,” Theo Leeb points out. Both systems show that targeted plant protection does not only save resources but can also have a positive impact on plant development and yield. In the long term, the objective is to combine technology and practice in such a way that agriculture remains efficient and sustainable.