I’m not going to sugar coat it. Farmers are dealing with drought conditions here in western Saskatchewan. And while there’s nothing you can do to make it rain, there are some things you can control.
To get your best possible crop under the circumstances, focus on three key areas: weed control, plant nutrition, and plant health.
When there is very little available soil moisture, you want your crop to be able to access whatever there is. That means eliminating the competition by controlling the weeds in your crop.
Be careful when assessing crop stage, because under dry conditions plants will look smaller than they would with adequate moisture. That means your crop could be more advanced than it seems from a distance, and some herbicides can cause damage when applied later in the crop’s development.
Cereal crops have roots that are close to the surface and will face more competition for water from other shallow rooted weeds (grassy species). Canola has a tap root, and it will face more competition from weeds that also have a tap root. Knowing this will help you choose the right herbicide for the job.
One of the defence mechanisms plants use in times of drought is to increase the thickness of the waxy layer on the outside of the leaves (the cuticle). Use higher water volumes when applying herbicide to help penetrate the cuticle of drought stressed weeds and improve herbicide efficacy.
The best way to maximize production in a drought year is with excellent nutrition. Plants have built-in defenses against drought, but without adequate nutrition these defenses can’t work properly. Plants can also use water more efficiently when they are well nourished.
Pay attention to chloride, the often-overlooked macronutrient that plays a large role in water use efficiency. Chloride helps regulate the opening and closing of stomata, which allow gas and water exchange from the plant’s leaves. Without adequate chloride, plants can’t shut their stomata and constantly lose water.
Chloride and potassium both play key roles in water use efficiency in plants, and many soils in Saskatchewan are deficient in one or both. Adding potash in next year’s blend, especially for cereals, can have a huge impact on your crop’s ability to cope with drought stress.
During a drought, crops have a more difficult time getting the nutrients they need from the soil. I recommend applying foliar nutrition as an action you can take today to get them through a particularly stressful time. Plants take nutrients up from the soil solution, without adequate moisture plants can't uptake nutrients. Foliar nutrition can be an excellent way to ensure sufficiency of nutrients that are immobile in the plant, like boron.
Many people think of micronutrients when talking about foliar nutrition, but supplying macro nutrients in times of stress is just as important. For example, plants need nitrogen to make chlorophyll and DNA so cells can divide. Plants need phosphorus for all energetic reactions in the plant and to maintain cell wall integrity. When a plant is unable to access these nutrients, it doesn’t stop photosynthesizing and growing. It uses nutrients from older tissue (when possible) to create new tissue. That’s why drought symptoms and N deficiency symptoms look so similar.
Just because it’s dry, it doesn’t mean you can cross disease off your list of concerns. Powdery mildew can thrive in dry conditions, and tan spot can still take hold with heavy dews in the crop canopy, even if there has been no rainfall. Drought-stressed plants are already in a weakened condition and are more susceptible to disease.
Cereals in particular are likely to see a benefit from fungicide application – especially fungicides that contain ingredients that enhance plant health – in a dry year. Fungal infections in the leaves make the plant far less able to regulate water loss, which compounds the effect of drought. Disease-affected plants also spend valuable resources fighting infection that could be used to help produce yield.
If you have questions about what actions you should take with a drought-stressed crop, contact your local Cargill agronomist.