If you believe prairie growing conditions will get warmer in future years, and possibly drier too, here’s what that could mean for the spread of kochia.
Kochia is more than tough – it’s almost unfair. It is comfortable growing in cool temperatures and soil, and can emerge weeks before spring-planted crops. Then again, kochia also thrives when hot summer temperatures cause crops like wheat to suffer.
Meanwhile, as summer temperatures creep higher year by year due shifting environmental conditions, it’s no surprise to learn that kochia likes that just fine as well.
Charles Geddes, Lethbridge-based Weed Scientist with Agriculture and Agri-Food Canada has conducted research that models what happens to kochia’s range as temperatures rise – bio climate modeling of kochia. He’s looked at scenarios where temperature rise 1C, 2C and 3C, as predicted by climate change modelling.
“As temperature increase, you see the kochia range in the northern Prairies extending farther north,” says Geddes. “At an increase of +2C, conditions are quite suitable for kochia even up into the Peace River region – and even more so at +3C.”
“As we start seeing higher and higher temperatures,” says Geddes, “we see the northern range for kochia moving farther and farther north.”
He notes that kochia plants need approximately 2,300 to 2,400 cumulative Growing Degree Days to produce viable seeds. For a long time, only the southern Prairies could provide this consistently, which is what kept the weed largely confined to this region.
In his research, Geddes has modelled as far out as the year 2070 what the range of kochia may look like based on its biology and ecology. Warmer growing temperatures mean that kochia’s seed viability/reproduction, which is limited to above 2300 - 2,400 cumulative growing degree days, will allow it to spread into the northern latitudes of the prairies and up into Peace River region of Alberta. If these agriculture production regions continue to become warmer and have high enough cumulative growing degree days, the environment will be more suitable for kochia growth and development.
However, north isn’t the only direction for kochia expansion. Geddes took the current range of kochia (the southern Prairies, more or less) and modelled what happens if precipitation declines by 20% in the coming years. “As we see drier and drier conditions, we also see the kochia range expanding further into Eastern Canada,” he says.
In his research on kochia, Geddes has studied the weed’s biology and ecology, the factors behind its geographic spread and the possible impact of climate change. There’s a silver lining, too. Geddes has confirmed through his research that a viable kochia defense strategy is there for the taking.