Johnson grass and other weeds in corn: how to save up to 70% on chemicals

Weed control plays a vital role in plant protection. Weeds represent a threat to cultivated plants, as they might shade them, drain nutrients and water from them and even hinder their ability to germinate.  Furthermore, weeds can cause health issues and may also impede the harvesting process. “About 100s of euros of yield loss per hectare caused by johnson grass” – a production challenge that the grower raised and invited Proofminder to help.

Proofminder’s trained AI model can identify numerous weed species, such as johnson grass (Sorghum halepense), creeping thistle (Cirsium arvense), and jimsonweed (Datura stramonium) for example. In this case study, we will be focusing on the johnson grass recognition AI model in hybrid corn. 

Corn is extremely sensitive to early weeding, as its ability to suppress weeds is still weak at that stage. Controlling johnson grass – one of the biggest threats to corn – is very important, as, if left uncontrolled, it can result in significant yield losses due to its ability to drain water and nutrients from the cultivated plants. Furthermore, johnson grass can be a host for the Maize chlorotic dwarf virus and Maize dwarf mosaic virus, and its allelopathic effect is also significant. 

This case study focused on a 26.8-hectare hybrid corn field plagued by a johnson grass infestation. During the application of the traditional field spraying technology, the entire field is sprayed with a specified dose, averaging 200-300 litres per hectare. However, this approach is less aligned with the latest precision farming trends. Spot spraying can be a much more environmentally friendly and cost-effective solution, since many weeds, such as creeping thistle, occur in localized patches. Targeted spraying of these weed-infested patches is more easily applied and efficient as using pesticides should be sufficient.  

  • A standard surveying drone (either the grower’s drone or Proofminder drone operator partner) conducts a comprehensive survey of the field, capturing high-resolution images.
Johnson weed in corn

Figure 1 – Johnson grass in corn, image from DJI drone

Johnson grass in corn

Figure 2 – Johnson grass in corn, field overview 

  • With the help of our trained AI model, the captured images are analysed and the weeds are distinguished, with high precision, from cultivated plants. This analysis also shows the extent of the infestation on the field.
Johnson grass and corn plants identified

Figure 3 – Proofminder AI Model for johnson grass recognition

AI model for Johnson grass recognition in corn

Figure 4 – Proofminder AI Model for johnson grass recognition, field overview

  • Based on the analysed data, a usage map is created, and presented in a standard geoinformatics format, such as a shapefile, which can then easily be downloaded to a machine sprayer or spraying drone.  
Weed map for hyper-precise spot spraying

Figure 5 – Proofminder weed map for hyper-precise spot spraying

Spot spraying using DJI Agras and Proofminder weed map

Figure 6 – Spot spraying with DJI Agras T30 using Proofminder weed map

  • Out of the total area of 26.8 hectares, only 7.3 hectares 74 precise spots) had to be sprayed with graminicides. Spot spraying was made possible with a drone in this case. As weather conditions during the day were windy, which is less than ideal, spraying took place at night. The spraying mission was a success as no spray drift occurred, and 112 EUR/ha worth of chemicals could be saved. 

Reach out to us to control weeds, save 40-70% on fertilisers, and stay ahead of the curve. 

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