Minimising the environmental impact of weed control in vegetables by weed detection and spot herbicide application

Novel image analysis-based weed detection and spot spraying systems were developed for volunteer potato control.

Results from the project demonstrated the potential for controlling volunteer potatoes in onion and carrot crops by the spot application of glyphosate at work rates and with total system costs that were competitive with any of the alternatives available at the time.

In field trials with a full-scale experimental system, typical levels of control of 90% in carrot and onion crops were achieved with a single application and with acceptable levels of crop contamination and damage.

The work in the project included: 

• Initial field studies to collect images of volunteer potatoes growing in both onion and carrot crops that could be used in the development of detection algorithms;
• The development of a weed detection algorithm that would identify the presence and positions of volunteer potato plants relative to the crop row in crops of onion and carrot;
• Field trials with both cropped and volunteer potatoes treated with variable doses and volumes of spray liquid containing a total herbicide and delivered through a pulsed nozzle system to determine a specification for a spot application system;
• A design study to identify possible methods of delivering a total herbicide spray to detected volunteer potatoes and similar weeds in such a way as to achieve high levels of control and minimise the risk of crop contamination and damage;
• The development of methods for quantifying the performance of the herbicide delivery system particularly relating to the targeting of the area to be treated and the risk of contamination of plants outside of this target area;
• The design and assembling of a single bed experimental rig that could be used in field trials to validate the approaches and systems developed and provide measures of overall system performance; undertaking field trials with the experimental rig as part of the development process and to obtain initial performance data;
• The design of a full‑scale field rig spanning three beds and using all of the systems developed within the project so as to test and evaluate the approaches at full scale in a final series of field trials.