Varietal mixing is an agricultural practice that consists of sowing a heterogeneous mixture of varieties of the same species in the same plot. The many advantages of this practice have been demonstrated on cereal crops such as wheat, barley and sorghum. One of the aims of varietal mixtures is to find an alternative to plant protection products for limiting the appearance of diseases and the damage they cause.

One way of curbing the spread of disease is to mix and diversify varietal resistances by relying on compensation effects. Compensation consists in reducing a variety’s susceptibility to a disease by intercropping it with other varieties that are resistant to the same disease. Varietal mixtures help limit economic losses by stabilizing the yield of the crop in place. Furthermore, stresses of non-biological origin (such as water stress) are less frequent, thanks to complementary water and nutrient uptake capacities.

At the technical level, it is not easy to implement varietal mixtures. A number of precautions need to be taken before selecting varieties for mixing. For example, the earliness and height of the varieties in the mix must be fairly close, so that they reach maturity at the same time, limiting competition effects and simplifying harvesting. Millers may also prefer pure wheat varieties, intercropping them themselves to optimize bread-making. Varietal mixtures are interesting alternatives to plant protection products. In a context of climate change, varietal mixtures, which are more resilient and more easily adaptable, present interesting prospects that require futher exploration.