Bolters in Fodder Beet

It is important that farmers inspect all fodder beet crops from mid-January and through to grazing or harvesting, and remove plants that are bolting (producing flower stems). 

Bolters can occur in most fodder beet paddocks. There are two types, genetic bolters and annual bolters (see photos 3,4 &5 below), with annual bolters being the more serious. Remnant bulbs will also produce stems where farmers attempt second crops in paddocks.

The perils of not removing annual bolters were highlighted in a crop planted in the North Island in 2014 (see photo 2).  This paddock had fodder beet in the previous season, when a few bolting plants were noticed but not removed.  They have obviously dropped thousands of seeds into the soil and these have germinated in thick patches in the current crop.  As they cannot be sprayed out, these volunteers will severely reduce the yield of fodder beet, and mechanical lifting made more difficult.  Unfortunately this farmer may not be able to grow fodder beet in this paddock for 10 years or more, a big loss if they don’t have many paddocks suited to growing beet.

Photo 2:  A patch of annual weed beets in a second-year crop.

Annual weed beets will appear from January onwards.  Farmers should promptly remove them while the seed heads are still green and soft.  They should be pulled and tipped upside down to prevent roots re-establishing.  If they delay this task, the weed seed will ripen and require plants to be carefully lifted and carried out of the paddock and destroyed.  In other words, if done promptly the time involved is not great, but if delayed, the time taken to clean up the paddock skyrockets. 

This is another compelling reason why farmers should not grow fodder beet in the same paddock, and instead adhere to a minimum of four years between crops.  This then allows the weed beet plants to be controlled with herbicides commonly used in pasture and other crops.  Pasture paddocks previously used as a run-off for beet paddocks with bolters are also likely to contain weed beet seed that will establish in future crops.

Photo 3:  Seed heads of genetic and annual type bolters.

Photo 4:  Roots of annual bolters form a parsnip-shaped root, are usually white but can also be red.

Photo 5:  Genetic bolters (left) have bulbs of similar colour and shape to the variety, some annual bolters (right) have a red colour.