Rapeseed fields are beginning to bolt, meaning they’re beginning to develop reproductive structures. It won’t be long now before these fields are covered in beautiful yellow flowers and buzzing with pollinators.
Warm temperatures in the spring trigger rapeseed to move out of the rosette stage, where it has been all winter, and into the reproductive stage. Once the flowers are pollinated, they will begin developing the seed pods which contain the seeds that will be harvested.
The photo below shows a very small pod. The flower was pollinated and the petals have fallen off. This little guy has a ways to go before it is harvestable.
Below is a stem left behind by a flower that was aborted for some reason (left side of stem). Maybe the flower didn’t get pollinated in time. You can see the entire flower was abscised and left nothing behind, unlike the photo above.
Pretty soon this field will be one large mass of yellow flowers.
Now that rapeseed is moving into the reproductive stage, it is susceptible to cold damage. If we have a good hard freeze (20 degrees or below), we could be in trouble. A 25 degree freeze could cause flower abortions that would cost us some yield. Hopefully we won’t see those temperatures again this year. This is also the stage where we see the most problems with Sclerotinia (white mold). The fungus gets established in dead material (fallen flower petals) and then can attack healthy plants in contact with the dead material. It then causes lesions on the stem that can kill the plants by girdling them. TCI has recommended applying Proline when white mold is observed in fields. For images on Sclerotinia structures, refer back to this post. For more info on rapeseed production, check out this UGA production guide.