Typically, radishes planted in a cover crop blend late July send down deep tap roots before the first killing frost. Not so this year.

Due to extreme heat in August across much of South Dakota, the daikon oilseed radish reacted by bolting.

"The plant went into self preservation mode and thought it needed to reproduce. They shot out flowers instead of putting more energy into its tap root. It's a defense mechanism many plants exhibit when they are stressed," says Justin Fruechte, forage specialist for Millborn Seeds, Brookings, S.D. "In the past, we haven't had any issues with bolting. This summer we discovered which varieties are heat tolerant and which are not."

Although the radishes have bolted, Fruechte says there's a chance the seed won't mature in time produce volunteer plants next spring.

"It takes about 30 to 45 days of mild dry weather for the seed in the pod to become a viable seed. A killing frost should hit before the seed matures," Fruechte says.

Without a deep tap root, the cover crop won't be as effective in repairing soil compaction, however, if the cover crop was planted for grazing purposes the bolted radishes should serve their purpose.

"There are no harmful side effects of grazing bolted radishes," Fruechte says. Bolted plants will only lose some palatability and nutrient value.

Based on how different varieties handled heat stress this summer, Fruechte recommends the graza radish. It a later-maturing certified variety and did not bolt this summer.

For more information, contact Justin Fruechte at 888-498-7333 or [email protected].

Source: Milborn Seeds