Agroscope, SZG, FOEN Environmental technology promotion, Möri AG, VSGP, Grangeneuve, Inforama, Wyssa Gemüse

Sustainable Plant Protection in Vegetable Production with New Spot Spraying Plant Protection Robot

In vegetable row crops, spot spraying can save on insecticides and fungicides. Agroscope investigated the extent of this savings potential and compared the cost of spot spraying to broadcast treatments with a field sprayer.

Given the wide variety of crops and the strict quality standards, reducing the use of plant protection products (PPPs) in vegetable production is a major challenge for producers. Agroscope experts have therefore been testing a new plant protection robot (Prototype II) designed exclusively for spot spraying. With spot spraying, each individual crop is identified and treated in a targeted manner with fungicides or insecticides, which helps to save on PPP use. The specialisation on spot spraying makes the device lighter and allows a higher driving speed of 2 to 4 times faster than its predecessor (Prototype I), which simultaneously hoed weeds. As the Prototype II is focused on spot spraying, weeds must be controlled separately. This can be done by chemical or mechanical means.

Savings Potential Depends on Vegetable Bed Parameters

The savings potential in various crops was determined in test runs with the Prototype II. For lettuce at an early growth stage, for example, a savings potential of 87% for insecticides and fungicides was achieved. At this stage, the plants had an average diameter of 11cm. In general, savings potential decreases at later growth stages. For example, the savings potential was 58% for Chinese cabbage (Ø 21cm) and 78% for celeriac (Ø 24cm). For both of these crops, the device settings were adjusted to the target organisms: in celeriac, the interior of the plants where the aphids were located, were treated in a targeted manner, thus allowing a considerable amount of insecticide to be saved. In Chinese cabbage, the treatment spectrum was set wider, since the target organisms (flea beetles) were highly mobile. In addition to plant size, the savings potential depends on the plant density, the uniformity of the crop, the target organisms, and the device settings.

Savings Come with a Cost

Since many assumptions must be made for devices in the prototype stage, the economic calculations were difficult to make. Based on a partial cost calculation for the plant protection of 1 ha of field-grown butterhead lettuce, the extent to which these assumptions affected the results were tested. If the device can be utilised to a high capacity, the overall plant protection costs with spot spraying are still CHF 140/ha higher than with the standard field sprayer. However, this assumes a high degree of utilisation that is only feasible for large farms and contractors. If the Prototype II is utilised to the same capacity as field sprayers, additional costs of CHF 111 to CHF 138/ha per spot spray treatment are incurred during early treatments. For later treatments, however, additional costs of CHF 307 to CHF 334 per ha and treatment are incurred, since the plants are much larger and therefore fungicide and insecticide use cannot be reduced to the same extent.

Follow-Up Project Focusing on Environmental Aspects

The follow-up project “Sustainable Vegetable Production – Determining the Input of Plant Protection Products into the Environment with Spot Spraying” investigates the extent to which PPP inputs into the environment can be reduced with spot spraying. Running from 2023 to 2026, the project will focus on investigating how this new technology reduces the risk of drift and run-off.


  • With the new spot spraying robot, potential savings of 58 to 87% in fungicides and insecticides could be determined during treatments. As plants grow larger, savings potential decreases. Savings potential also depends on other factors such as plant density, target organism, and device settings.
  • Over the entire cultivation period, the amounts of fungicides and insecticides applied can be reduced by more than half. It should be noted that this device does not replace a field sprayer, which must be available when time sensitive plant protection measures are necessary due to weather conditions or other factors. The field sprayer is also used for later treatments, when almost no reduction in the amounts of fungicides and insecticides applied is possible.
  • With 2 to 4 times the travelling speed, the new prototype is more cost-efficient than the first. Under normal capacity utilisation, vegetable producers still incur additional costs when using this precision application technology.
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