There are four key aspects that affect the canopy size of fodder beet: sowing date, plant population, the rate of canopy expansion and its duration.

Sowing the crop too early, for example, in the middle of September, does not necessarily increase yield and may result in the need for an extra post-emergence herbicide and the chance of bolters occurring if the plants are under any stress from cold weather or early herbicide damage.

In contrast, sowing later in November does not allow the canopy to reach row closure before the longest day around 22 December, resulting in the canopy intercepting less solar radiation to direct to growing bulbs.

Plant population is important because if the crop drops below seven plants per m², the final yield reduces dramatically. It also allows weeds to grow where there should be fodder beet plants.

Seedbed preparation is vital to ensure an even plant population and increase the efficacy of residual herbicides. The ideal sowing rate is between 90,000 to 100,000 plants which allows for some seeds to not emerge, or fail, due to seedling diseases like Rhizoctonia or Pythium.

The rate of canopy expansion is dictated by the early application of nitrogen (N) and weed control. The importance of good weed control in fodder beet should not be underestimated. Beet crops are sensitive to weed competition in the early stages of development. Weeds that emerge within eight weeks of crop emergence, and grow above the crop and shade it, cause large yield reductions.

Control the most competitive weeds, such as wireweed, cornbind, fathen and volunteer potatoes, early in the programme. Consider grass weeds too, and take them out separately to broadleaf weeds. Uncontrolled grass weeds like couch can become a problem in subsequent pastures following winter crops.

Remember to always use a spraying oil with your grass herbicide. The best approach is to kill the weeds slowly whilst allowing the beet plants to flourish. Early N increases the rate of canopy expansion and also helps with weed suppression. Depending on your soil N status and the previous crop, it is rarely necessary to apply over 100 to 120 kg of N per ha.

Canopy duration through late summer and early autumn is achieved by controlling the major foliar diseases of beet like Cercospora and beet rust. Maintaining green leaf area allows the plant to focus on growing the bulbs. There are a couple of fungicide options; discuss these with your local PGG Wrightson Technical Field Representative.

Late summer is also a good time to test the plant leaves for nutrient status which can then be corrected with a foliar trace element spray, if required.

To formulate a fodder beet management programme, contact your local PGG Wrightson Technical Field Representative.