Top Crop Manager

Features Agronomy Cereals
Growers can zoom in on their own farm

November 30, 1999  By Carolyn King

Crop stage, insect pest stage and disease risk: these and many other crop management considerations are closely tied to the weather. Recent upgrades to two of WeatherFarm’s online crop management tools allow farmers to customize these weather-based tools for their own situation.

WeatherFarm’s Prairie-wide network of more than 750 on-farm weather stations is operated by the Canadian Wheat Board (CWB) and a US weather forecasting company called WeatherBug, with support from industry partners. The data from those stations feed into WeatherFarm’s free online weather centre ( ).  Along with modelling and mapping tools, the centre provides local weather information updated every five seconds, weather forecasts, historical weather data and other information like market prices.

The recent customization upgrades apply to the Growing Degree Day (GDD) tool and the Fusarium head blight (FHB) model. “The concept is to take the “one map for all Western Canada”-approach and have it so that you can set up the tools for the area you farm,” says Guy Ash, CWB weather network manager.


Growing degree days (GDD) is a cumulative measure of the temperatures above zero degrees C for a specified time period. GDD is linked to things like crop, weed and insect development. For instance, accumulated GDD from a grower’s seeding date is a good indicator of crop stage.

CWB agronomist Mike Grenier notes, “The big change for the Growing Degree Day tool is the ability to customize it based on your own farm location and your seeding dates. Up until now the model was running off a calendar date of, say, May 1. So, if a farmer seeded a week earlier or a week later or even three weeks later, the GDD information wasn’t as applicable.” With the upgrade, the model is able to calculate the accumulated growing degree days from the farmer’s actual seeding date.

The tool generates a map showing the accumulated GDD, based on the seeding date a grower selects for a 60- by 60-kilometre area, based on the weather station selected as an individual’s home station. Weather stations are shown on the map as dots.

Growers can click on each dot to get a table of the station’s weather data, and generate graphs of that data. It is also possible to zoom out to see accumulated GDD for all of Western Canada. As well, growers can click on “view interpretation commentary” to find out how GDD relates to wheat growth stage.

Grenier says, “Growers can use this tool in time management operations, like herbicide applications and fungicide applications that are targeted to a specific crop stage. They could also use it in fertility management if they were planning a post-seeding or top-dressing fertilizer application.”

He adds, “And farmers can do this for as many individual fields as they want. If they have two fields that differ quite a bit in seeding date, they can look at the GDD for each date. Or if the fields differ quite a bit in geographic distance, they can look at the data from two different weather stations.”

WeatherFarm’s FHB model evaluates the weather-related risk of this disease occurring in wheat; the model uses relative humidity as the main weather factor affecting risk. The actual disease risk in a grower’s fields will also depend on whether the FHB pathogen is present in the area and whether the wheat crop is flowering, which is the susceptible stage.

With the upgrade, the model can now be customized for a grower’s individual location, the choice of spring or winter wheat, a variety’s FHB susceptibility and an assessment date. The model generates a colour-coded map showing the FHB risk for a variety in a 60- by 60-kilometre local area.

No replacement for getting into a field
Ash emphasizes that using the FHB model, or any of the other WeatherFarm models, is not a replacement for field scouting. “The model won’t tell you the amount of inoculum or disease present. The model is a check on what’s happening in the region and locally in terms of the environmental conditions. In areas where there are economic thresholds or there is disease pressure for a particular problem, the environmental model holds.”

However the tools can help with timing of crop scouting. Grenier gives an example: “If you have many acres to cover, the growing degree day tool will let you zero in on how and where things are changing in the field. If there is a particularly time-sensitive management practice, you could use this model to help make sure you’re hitting the right field at the right time. Of course, you still need to go out there and crop scout to see how close your field is to what the model is showing.”

Continual improvement of its online tools is a vital aspect of WeatherFarm. “That’s part of our research here and why we go to the experts in the scientific community for input on the models we offer on WeatherFarm. They are constantly coming out with new model versions based on new research,” notes Ash.

In addition, WeatherFarm staff conduct research to field test the tools and make sure they are fine-tuned to local conditions, and to improve delivery of these tools to users. “We are continuing to grow WeatherFarm. We are continuing to look for new tools and features to add. We have some releases, fixes and fine-tuning happening over the winter, and then in the spring we are planning a major release with new models. And we want to continue to add in more of the very localized tools that farmers can use for a whole host of agronomic problems,” says Ash.

Grenier adds, “I encourage growers to look at WeatherFarm this winter and play around with it. They’ll get more value out of it as they understand what the different tools can achieve and how to customize them to get the most benefit.”

Predicting, and understanding, winter cereal survival
One of the tools on WeatherFarm that growers can experiment with is the Winter Cereal Survival model. It not only allows growers to forecast the likelihood of winterkill for their winter cereals, but also to explore a wide range of what-if scenarios to better understand how changes in management practices influence winter survival.

The addition of this model to WeatherFarm came about through a partnership of the Canadian Wheat Board (CWB), Ducks Unlimited Canada, the University of Saskatchewan’s Dr. Brian Fowler, and Western Ag Innovations. “Dr. Brian Fowler is the key knowledge source and fellow who has worked on the winter wheat survival model from its inception,” explains Ken Greer of Western Ag Innovations, an agricultural consulting company focusing on technology to empower growers to make wise decisions.

In 2003, Fowler and Greer worked together to develop a web-based version of Fowler’s original model. That web-based version is a good fit with WeatherFarm.

The CWB’s Guy Ash says, “We provide the data flow through our WeatherFarm network of stations that can help enhance and provide more local data.” The model relies on soil temperature at the crown depth to determine the probability of winterkill. So far, WeatherFarm is feeding soil temperature data from about 15 locations into the model. The project team is also working on various ways to enhance and improve the model.

To use the model, a grower can select a station source for the soil temperature data and a crop variety from a wide range of winter cereal varieties. Growers can also click on “management impact calculator” and specify practices, such as seeding depth and date, fertilizer application rates and other parameters. The model generates a graph with a black line showing the soil temperatures at the selected station and a red line showing the minimum temperature that the crop can withstand before 50 percent of the plants are killed, based on the selected variety and management practices.

Greer explains, “The downward spikes of very cold soil temperatures are just like a boxer taking a punch; every punch that you take means you can take one less punch. If a winter cereal gets hit with a lot of cold temperature spikes over and over again, that will cause the plants to lose hardiness and sooner or later that will cause winterkill.”

If the crop does not take many hits, the picture behind the graph will show a healthy crop. If it takes quite a few hits, the picture will show a field with patchy growth.

Perhaps the most valuable aspect of the tool is the ability to investigate what-if scenarios; how the survivability would change with a different variety or a modification of a particular management practice. “It’s a tool to understand winter cereal survival, what if, how sensitive and when, what variety is best, as opposed to just answering whether the crop is alive or dead. That’s an easy question, yes or no, alive or dead. Answering questions like ‘What could I have done differently?’ That’s the key with decision support tools that empower or transfer knowledge,” says Greer.

He adds, “Really it’s a risk management tool. I want to know how the survival would change if something else changed and I want to find out which factors are the most sensitive factors controlling the outcome because those are the ones I have to watch the most. That sensitivity analysis is what farmers are doing more to reduce their risk.”


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