Article taken from Agronomist & Arable Farmer, November 2017.
Disease, particularly blight, can explode in the humid microclimate often found in potatoes, and other stresses caused by underlying pest, disease or soil health problems can cause significant damage to the current crop in the field and/ or in store. Some also pose a significant threat to future crops if left untreated.
Sprayer operators have a front row seat when it comes to spotting and logging such areas. However, given the time pressures they are under, as well as the concentration the job requires, even the best can miss the telltale signs.
Agronomists also have large expanses of ground to cover and cannot inspect every part of each field. Walking a 10-l5 ha field to fully assess crop health would take one to two hours - it is difficult to crisscross the rows, while an eye level of less than 2m limits vision in a dense potato canopy.
Blight is one obvious opportunist, but other diseases such as Rhizoctonia, which causes stem canker and black scurf, and blackleg also need a keen eye.
Detailed maps
Over the past few seasons, Agrovista colleagues Andy Steven, who specialises in potato agronomy, and Lewis McKerrow, the company's head of precision services, have been flying drones over a large area of potatoes, producing detailed aerial maps across a range of sites and varieties, both for research and to support their conventional agronomy services.
""Drone technology is constantly moving forward," says Mr McKerrow. ""New drones are equipped with the latest camera technology and innovative ways of processing data. These are rightly considered serious agronomic tools, capable of undertaking increasingly complex tasks.""
Camera resolution is now so advanced that agronomists can zoom in from whole field maps to individual plants, helping them identify potential problems earlier than from the ground.
""We've picked up stunted areas of growth, an early indicator of Rhizoctonia, and other signs of stress, such as PCN effects, and those caused by soil and drainage problems," says Mr Steven.
A single flight can reveal stress levels as low as 0.5% of the field area, he adds. This can pinpoint stress from a disease like blackleg, which has to be hand rogued. This reduces roguing costs and the risk of bacterial spread caused by roguers walking through large areas of standing crop to find infected plants.
Plant counts
Drone maps can also be used to assess plant counts, helping to target corrective action if they vary from the ideal. ""A 10% inaccuracy is not unusual, but can have an impact," comments Mr Steven. ""If plants in seed crops are too far apart, they may need to be desiccated earlier than planned to maintain the correct tuber size.
""Plant a ware crop too close and the tubers may never reach the correct size, too thin and they may hit specification quicker than you think.""
Such information, coupled with the ability to more accurately predict yield, can improve supply chain and customer relations management and can also help minimise wastage in fields, says Mr Steven.
Plant counts are also valuable for seed inspectors as plant density affects permitted disease levels.
Drone developments
Mr McKerrow predicts a rapid uptake of drones among UK growers. ""You can now buy a very versatile hobby drone like the DJ! Mavic Pro for around £l,100," he adds. ""Twelve months ago the same technology would have been closer to £3,000.""
While these tools are not a replacement for good agronomy, they are becoming a valuable addition to it, he says. ""Within five years I believe all young farmers will be mapping their own crops. They will still need an agronomist to work with them to interpret and act on the findings, but our role as agronomists will change.""
Improvements in battery life will extend the range of flights, camera quality will continue to improve and processing power will deliver maps faster and in greater detail.
The ability of drones to measure establishment, biomass and presence of weeds and diseases will increase. Drone maps, coupled with soil and yield maps, are already being used to construct variable rate seed and nutrient maps, and targeted spraying and irrigation are not far behind.
To make full use of those capabilities, application kit will need to be developed so they can deliver targeted applications of inputs and water, says Mr McKerrow.
""We can spot spray specific problems in vegetable crops, but not yet in broadacre crops like potatoes and cereals," he adds. ""We aren't a long way off though, and when it comes, it will be invaluable for potato growers.""