Orange: Canola petals can turn orange in response to stress, usually heat stress. There is nothing that can be done about heat damage.
White or pale flowers can have many possible causes:
—Pale yellow petals are a possible sign of sulphur deficiency, but if the deficiency is bad enough to affect petals, leaves will also be cupping and have purple around the edges. A late application of sulphur can help.
—Healthy white petals that form pods on plants scattered uniformly throughout the field may be from genetic off-type in the seedlot. In the past there have been a couple of varieties registered with white petals.
—Clubroot that cuts off nutrient flow can cause flowers to be pale.
could be pale.
—Heat at flower can cause yellow flowers to bleach just before they drop. In this case, pods could still be forming, although may be stunted by heat, or the flower/young pod may be aborted.
—Pale petals have been observed in research plots with late application of herbicides.