Article taken from the Fruit Grower, written by Robert Harris
The canker model is the latest addition to Growers Choice Interactive (CGI), Agrovista’s web-based forecasting tool that tracks development of pests and diseases to ensure maximum, cost-effective control. “Like the existing scab and codling moth models in GCI, the new canker model interprets live data collected from our network of weather stations,” says Agrovista fruit agronomist Alex Radu.
Based on this data, the model calculates potential infection events, the time of occurrence and their magnitude. That allows growers to monitor disease progress in their orchards and to target fungicides more accurately, says Alex. “Canker infections have been getting worse, due to the combination of susceptible varieties being grown and a run of dull wet summers and warm wet winters. The model will help maximise yields and fruit quality and can soon repay the initial cost many times over.” The canker model uses all the available information on production, dispersal and germination of canker spores, which infect trees though fresh wounds.
While pruning cuts, bud-burst, petal-fall and fruit-drop are all risk periods, the biggest danger comes at leaf-fall in the autumn. Relative humidity and leaf wetness tend to be higher in the autumn, aiding infection, while low temperatures slow tree growth, leaving leaf drop wounds open for much longer than at other timings. In addition, there is no incidental control from scab fungicides at this timing, says Alex. “Accurate data for leaf wetness, rain, relative humidity and temperature are essential to produce accurate model output. This is provided by high-quality Plantsystems weather stations that GCI growers lease.”
Information is forwarded every 15 minutes to a central server. The software model, based on RIMpro pest and disease prediction software, integrates this data with canker’s lifecycle information. The resulting graph shows spore germination, relative numbers of spores on wounds and a resulting infection value.
As canker infection can only occur through fresh tree wounds, the display also includes a graph showing the amount of fresh and healing wounds caused by leaf drop, based on orchard information supplied by the grower as well as weather station information. “The model estimates the pace of the leaf-drop process and the number of fresh wounds it causes. This can be backed up by a visit to the orchard if required. If there are few fresh wounds then treatment may well not be required, regardless of infection value. But if there are significant numbers and the trend is rising and coincides with a high infection value, treatment should be considered.”
The final point to consider is: How much residual fungicide from previous treatments remains in the orchard? Growers who subscribe to GCI Premium can input their spray programme. The model then calculates the amount of fungicide, based on UV levels, rainfall, relative humidity and temperature. “In addition to supplying real-time information, GCI also includes a 10-day weather forecast which indicates the likelihood of disease outbreaks over that period,” says Alex. “This allows growers to apply preventative sprays with confidence two to three days ahead, which can be a big advantage if prolonged heavy rain or wet ground would otherwise prevent a timely spray being applied.”
The overall result is a model that ensures that growers only spray for canker and when they need to, rather than applying three or more prophylactic treatments in the autumn. “This is good for their pockets and the environment, and will help growers meet tightening supermarket protocols,” says Alex.
The canker model is the latest addition to Growers Choice Interactive (CGI), Agrovista’s web-based forecasting tool that tracks development of pests and diseases to ensure maximum, cost-effective control. “Like the existing scab and codling moth models in GCI, the new canker model interprets live data collected from our network of weather stations,” says Agrovista fruit agronomist Alex Radu.
Based on this data, the model calculates potential infection events, the time of occurrence and their magnitude. That allows growers to monitor disease progress in their orchards and to target fungicides more accurately, says Alex. “Canker infections have been getting worse, due to the combination of susceptible varieties being grown and a run of dull wet summers and warm wet winters. The model will help maximise yields and fruit quality and can soon repay the initial cost many times over.” The canker model uses all the available information on production, dispersal and germination of canker spores, which infect trees though fresh wounds.
While pruning cuts, bud-burst, petal-fall and fruit-drop are all risk periods, the biggest danger comes at leaf-fall in the autumn. Relative humidity and leaf wetness tend to be higher in the autumn, aiding infection, while low temperatures slow tree growth, leaving leaf drop wounds open for much longer than at other timings. In addition, there is no incidental control from scab fungicides at this timing, says Alex. “Accurate data for leaf wetness, rain, relative humidity and temperature are essential to produce accurate model output. This is provided by high-quality Plantsystems weather stations that GCI growers lease.”
Information is forwarded every 15 minutes to a central server. The software model, based on RIMpro pest and disease prediction software, integrates this data with canker’s lifecycle information. The resulting graph shows spore germination, relative numbers of spores on wounds and a resulting infection value.
As canker infection can only occur through fresh tree wounds, the display also includes a graph showing the amount of fresh and healing wounds caused by leaf drop, based on orchard information supplied by the grower as well as weather station information. “The model estimates the pace of the leaf-drop process and the number of fresh wounds it causes. This can be backed up by a visit to the orchard if required. If there are few fresh wounds then treatment may well not be required, regardless of infection value. But if there are significant numbers and the trend is rising and coincides with a high infection value, treatment should be considered.”
The final point to consider is: How much residual fungicide from previous treatments remains in the orchard? Growers who subscribe to GCI Premium can input their spray programme. The model then calculates the amount of fungicide, based on UV levels, rainfall, relative humidity and temperature. “In addition to supplying real-time information, GCI also includes a 10-day weather forecast which indicates the likelihood of disease outbreaks over that period,” says Alex. “This allows growers to apply preventative sprays with confidence two to three days ahead, which can be a big advantage if prolonged heavy rain or wet ground would otherwise prevent a timely spray being applied.”
The overall result is a model that ensures that growers only spray for canker and when they need to, rather than applying three or more prophylactic treatments in the autumn. “This is good for their pockets and the environment, and will help growers meet tightening supermarket protocols,” says Alex.