As fusarium head blight marches west, agronomists and farmers are finding more sophisticated ways to manage the disease.
Cory Willness, agrologist and president of CropPro Consulting, says evening out crops is part of their fusarium management strategy. CropPro Consulting is based in Naicam, northeast of Humboldt, Saskatchewan.
“We find traditionally that the tops of the hills are the most advanced areas and quite often the depressions are the least advanced, or they’re somewhat behind,” says Willness.
Often that maturity gap is part of the reason crops are greener in depressions. “It’s not just that they have more moisture during the year, but they tend to start slower.”
Having the entire crop at the same stage, with minimal tillers, makes it easier for farmers to apply fungicide at the right stage. While they vary fertilizer rates, the whole field gets the recommended fungicide rate, Willness adds.
Soil, water and topography maps
CropPro Consulting pulls in a range of information to create field maps. Willness says they collect electrical conductivity and RTK elevation data. RTK elevation data helps reveal how water flows and where it accumulates.
The result is a map that incorporates water flow and salinity. Salinity will be the same shape on the map as it is in the field, says Willness.
“We find water is the number one driver of variability. So in wet years, wherever water is collecting, wherever it’s flowing, those areas are affected by excess moisture,” says Willness.
Programs also include soil-applied prescriptions, Willness says. Mobile nutrients such as nitrate, sulphate and chloride typically move where water moves, he adds. Organic matter will build in areas that accumulate water. The tops of hills will be low in organic matter, have thin topsoil, and fewer nutrients.
If farmers apply a flat rate of fertilizer to variable fields, the depressions can end up with too much nitrogen, Willness says. That can delay maturity, promote lodging, and create other issues that make it harder to control disease in those areas.
Plant stand variability is also a factor, says Willness. Areas where water accumulates, along with the extreme tops of hills, tend to have sparser plant stands. One goal is to create optimal plant stands through the whole field by bumping seeding rates in those sparse areas.
How much of a difference does it make to have an even, optimal plant stand when fusarium headblight arises? Willness says the differences are small, but small differences can add up to big differences in grade.
“The difference between malt barley and not malt barley could be 0.25 per cent.”
Most of CropPro Consulting’s clients are in northeastern Saskatchewan, and during bad fusarium years, people do see better grades, he adds.
Willness says they’ve been perfecting this program on clients’ farms since 2013.
“Since then I would say we’ve had a lot of success with it. And every field is different, every farm is different. You’re always tweaking things.”
Fusarium prevention tips
With no genetic silver bullet for fusarium in the near future, Ron Knox, plant biotechnology research scientist with Agriculture and Agri-Food Canada at Swift Current, had a list of fusarium management tips:
- Use disease-free seed.
- Follow a rotation that includes crops that are non-hosts to fusarium.
- Manage crop residues. The fusarium pathogen can colonize debris from other crops. Well-chopped straw will help speed up the decay process.
- During harvest, “adjust the combine to try and blow out the lighter kernels,” Knox said. Post-harvest cleaning can also be an option.
- Use fungicides, although they won’t provide complete control. Timing is challenging, as there’s a very small window for effectiveness. While fusarium risk maps are available online, they are “not a substitute for farmers knowing their fields and what the moisture situation is.”
- When applying fungicides, use a forward-angled nozzle, a medium-sized droplet, 10 gallons per acre and a slower speed.
- Stagger planting of durum fields, so you won’t have every crop exposed to moist conditions at the optimal time for disease development.
- If you irrigate, don’t do it at a time when crops are susceptible.
- Adjust row spacing to alter the microclimate.
- Use the most resistant varieties available.