Malva neglecta and M. nicaeensis have petals that are twice as long as the calyx bracts whereas in M. parviflora and M pusilla they are barely longer than the calyx. However, the weed's abundance on Alberta cropland doubled between 1980 and 1985. The situation is similar in eastern Canada. On some farms it was a serious weed in orchards, strawberries, corn and other grains and forages. In forage it becomes a problem after the first cut is removed.
Crop loss is correlated with dry mass of mallow rather than the number of plants.
Besides yield losses, mallow remains green until late in the fall, which can cause harvesting problems. Chemical control of mallow with selective herbicides, unless applied at the seedling stage, is often unsatisfactory. Heavily infested land should be used for a competitive crop, such as cereals with flax and lentils avoided. It is important to plant so the crop emerges before round-leaved mallow. In Saskatchewan a wheat row spacing of a 23 and 30 cm row spacing produced higher losses than in Manitoba with a 15 cm spacing 6,9 .