Rapeseed Starting to Bolt

We’ve had a solid week now of slightly above average temperatures and its feeling like an early spring.  The pine pollen is really falling and turning everything yellow and the rapeseed fields will also be turning yellow shortly.

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Its hard to tell in the photo above, but the plants have begun to stretch upwards and a few early bloomers have already bolted and put on some flowers.  You can see a few in the photo below.

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We’ve had very light disease pressure so far this year, but keep an eye out for Sclerotinia white mold now as the plants begin to bloom and drop flower petals.  If the weather continues to stay warm, we shouldn’t expect to see much Sclerotinia infection in the fields, but a fungicide application may still be needed to protect against Alternaria.  Most fungicide labels recommend timing applications at 20-30% bloom and possibly another later on.

Another thing to scout for is the cabbage seedpod weevil.  They are already showing up on the few plants that have bolted.  The female weevils will punch a hole in the developing pods and lay an egg inside which will hatch and feed on the seeds as they grow.  Here are a couple photos of adult seedpod weevils.

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If needed, insecticides are most effective when applied at 75% bloom.  The threshold  is 2 or more weevils per plant during 50-75% bloom.  About the only things effective on seedpod weevils are pyrethroids, but remember there are lots of pollinators in a rapeseed field at 75% bloom and pyrethroids kill pollinators.  Make your applications either early in the morning or late in the evening when pollinator activity is at its lowest.  You can look at the insecticides labeled here on page 128 of the UGA Pest Management Guide.

For more information on rapeseed and canola production, take a look at the UGA Canola Production page.

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