Can you imagine a world where a farmer automatically receives a warning each time a potential problem is detected in his fields? Or where the potential threat this may pose is automatically calculated making decision-making simple? And, when action is needed, can you imagine the farmer being able to spray just a tiny amount of pesticide directly at the problem, secure in the knowledge the pest has been dealt with?
This kind of scenario is not as far-fetched as you may think and one group of ENDURE researchers is working hard to explore and maximise the benefits innovative technologies can bring to agriculture.
The work is based on the knowledge that if we can detect diseases, pests and weeds much earlier than is possible at present, it makes it much easier to limit the amount of chemicals that subsequently need to be used. Furthermore, early detection makes it possible to use more environmentally friendly measures such as biological controls or other techniques to control the problem.
The group (Research Activity 2.2) is seeking to identify the best innovative diagnostic tools and examining how best these may be combined and integrated with precision spraying techniques to reduce pesticide use to the absolute minimum needed for crop protection.
The team has so far produced three reviews. The first described techniques for detecting plant pathogens in air, soil, starting material and in the fields, with the team examining both molecular and serological diagnostic tools.
The group notes that major innovations in molecular methods have been made over the past 20 years or so. This means that DNA and RNA (similar to DNA but with some different structural details) amplification methods (see below for more details) can make accurate diagnoses, making it easier to detect, characterise and identify pathogens (germs), genes and disease-suppressing micro-organisms or antagonists (microbes that combat plant pathogens).
This approach is being matched by efforts in the spheres of engineering and information technology. Here a review has focused on the existing technologies and research prototypes for precision spraying (see below for more details).
The rationale behind precision spraying is simple: if you have just a few weeds in a field, for example, what is the point of spraying the whole field with herbicide? Targeting only the weeds and eliminating them with the minimum herbicide necessary is easier on both the farmer’s pocket and the environment.
Information has been gathered on precision spraying in field crops, orchards and vineyards, for example, through ENDURE partners in Denmark, the Netherlands and Spain.
A third review has now been completed and describes how diagnostic tools can facilitate the use of precision spraying techniques and from this an innovative cropping system will be designed based on four key stages:
Prevention: Guaranteeing the cropping system begins with disease-free starting material and soil.
Monitoring: Detecting pathogens and pests in the air and field.
Interpretation: Transferring detection data into spraying maps with required dosages.
Application: Deciding which spraying technique should be used given the specific demands for the application.
The result, says team leader Carolien Zijlstra, from Wageningen University and Research Centre in the Netherlands, will be a model that envisages how crop protection can be performed in the future, employing innovative technologies to ensure hardly any pesticides need to be used at all.
“My own field of expertise is molecular diagnostics,” she said. “When ENDURE offered the possibility of studying the combination of diagnostic tools with precision spraying tools, I became very enthusiastic. It has broadened my view of innovative possibilities to minimise the application of pesticides. Moreover, I believe these two completely different disciplines strengthen each other in reaching this goal.”
About DNA and PCR
Anyone who enjoys TV detective programmes will probably have at least some notion of what DNA is and how it can be used (in TV crime detection at least!). DNA stands for deoxyribonucleic acid and it can be found in all-known living organisms and some viruses.
DNA is sometimes described as a set of blueprints, since it contains the instructions for the construction of other components of cells, including proteins and RNA molecules. DNA naturally occurs in a double-stranded form with nucleotides (molecules) on each strand complementary to each other, forming what look like rungs on a twisted ladder.
DNA-based detection methods have been identified by ENDURE’s research group as holding great potential for the identification, detection and quantification of pathogens and pests. Not only are the tests very sensitive but recent advances in real-time PCR (polymerase chain reaction, see below) have made it possible to quantify the amount of pathogen and pest DNA in a sample.
PCR is a method of producing lots of DNA from a tiny sample. It uses a heat tolerant enzyme (DNA polymerase) to make copies of DNA in a test tube. The essential ingredients are the sample you wish to copy DNA from, primers (short stretches of DNA that will bind to your original DNA and to which the polymerase can bind), DNA nucleotides (molecules), polymerase and a thermocycler, a machine which raises and lowers the temperature of the tubes.
Heating the sample separates the strands of DNA, cooling it then allows the primers to bind, a higher temperature allows polymerase to make a full copy of the DNA and cooling again then allows the strands to reseal. This procedure can be repeated to produce as much DNA as you like.
About precision agriculture
The group has defined precision agriculture as a system that seeks to optimise agricultural production. In particular, it opens up the possibilities of treating smaller areas in the field by applying pesticides only to where they are needed. Commercial systems currently available are developing from whole boom application to just boom sections and even down to individual nozzles. Researchers believe that in the future it will become possible to apply pesticides to 10cm squares or even individual plants.
Systems for precision agriculture use information technology and integrated sensors for detecting the spray target so the application can take place at the right time and with the right dose. At the heart of this is the use of a Global Position System (GPS), the same principle as used by the GPS systems found in cars and trucks.
Different crops have different demands, of course, when it comes to precision agriculture. For cereal crops, for example, the ability to detect weeds in the crop could be crucial, while for orchards, the challenge may more likely be to achieve an even distribution of pesticides to the leaves while avoiding spray drift.