Winter damage to perennial forage crops in eastern Canada: Causes, mitigation, and prediction

Abstract

R. 2006. Winter damage to perennial forage crops in eastern Canada: Causes, mitigation, and prediction. Can. J. Plant Sci. 86: 33-47. Harsh winter climate results in frequent losses of stands and yield reduction in many forage-growing areas of Canada and other parts of the world. Climatic conditions and crop management both affect the winter survival of perennial forage crops. In this review, we present the main causes of winter damage in eastern Canada and we discuss crop management practices that help mitigate the risks of losses. Predictive tools available to assess the risks of winter damage both spatially and temporally are also presented. Our understanding of the causes of winter damage and of the plant adaptation mechanisms to winter stresses, particularly the role of N and C organic reserves, has improved. Forage species commonly grown in eastern Canada differ in their tolerance to subfreezing temperatures and to anoxia caused by the presence of ice on fields. Some improvement in winter hardiness of forage legume species has been achieved through breeding in eastern Canada but new technologies based on laboratory freezing tests and the identification of molecular markers may facilitate the future development of winter-hardy cultivars. Crop management practices required for good winter survival are now better defined, particularly those involving cutting management and the interval between harvests. Simulation models and climatic indices derived from our current knowledge of the causes of winter damage provide general indications on the risk of winter damage but their degree of precision and accuracy is still not satisfactory. Further improvements in winter survival require a more thorough understanding of the different causes of winter damage and, primarily, of their complex interactions with genetic, climatic, and management factors.

Predicted Yield and Nutritive Value of an Alfalfa–Timothy Mixture under Climate Change and Elevated Atmospheric Carbon Dioxide

“…Winter survival can be compromised by unsuitable conditions for winter hardening during the fall, inadequate snow cover during the winter, and/or ice encasement of plants and anoxia damage caused by the formation of an ice layer at the soil surface (Bélanger et al, , 2006Castonguay et al, 2006). Unlike timothy, which is a winter-hardy species (Rapacz et al, 2014), alfalfa is sensitive to harsh winter conditions (Bélanger et al, 2006;Castonguay et al, 2006). Furthermore, it has been demonstrated that elevated atmospheric [CO 2 ], as predicted in future scenarios, reduces alfalfa freezing tolerance (Bertrand et al, 2007a).…”

Yield, persistence, and nutritive value of autumn harvested tall fescue

“…Under the conditions of the mid-north of eastern Canada, forage crops are managed in such a way as to minimize risks of winter damage (Bélanger et al 2006). A rest period that can vary in length is usually recommended before the autumn harvest to ensure good winter survival, especially for legume species (MacLeod et al 1972;Bélanger et al 1992;Dhont et al 2004).…”

Variability of herbage production in mixed leys as related to ley age and environmental factors: a farm survey

“…Thus, instead of being caused by factors detrimental solely to red clover the negative correlation between humus content and herbage production was obviously related to factors adverse both to clovers and grasses. Extensive uptake of N during late summer and autumn has negative effects on hardening and viability of overwintering crops (Bélanger et al 2006). Frost heaving may have affected both clovers and grasses.…”

“…The harvest regime is critical with respect to the maintenance of a productive sward with a reasonably high proportion of clover. Intervals between cuts as well as between the last cut and the first killing frost have to be long enough to allow for sufficient accumulation of the energy and nutrient reserves necessary for persistence and regrowth (Bélanger et al 2006).…”