SUGAR beet crops have emerged well this season and now weeds are also germinating rapidly after recent rainfall.

According to United Phosphorus national technical manager Pam Chambers, volunteer oilseed rape and field pansies are emerging in high numbers and other weeds also putting in an appearance include black bindweed, pale persicaria and redshank.

She says: “Generally field pansy is not considered a problem but when it emerges in large numbers at the same time or shortly after the beet it can compete and reduce yields.

“At the UPL Suffolk site last year numbers in untreated plots exceeded 50 plants/sq.m by the end of the trial.

“When at the cotyledon stage field pansies are relatively easy to control with phenmedipham, desmedipham and metamitron being particularly effective.”

The addition of ethofumesate is also useful for field pansy control particularly if the first true leaves are starting to appear. Later germinating field pansies are seldom competitive and tend to be suppressed sufficiently by herbicides used to control other weeds, adds Ms Chambers.

Control of volunteer oilseed rape is relatively easy, with triflusulfuron and traditional actives such as phenmedipham and lenacil are also quite capable of controlling rape volunteers, says Ms Chambers.

“The addition of desmedipham and adjuvant oils are also beneficial when the weeds are beyond the cotyledon stage. “Compared to many annual broad-leaved weeds volunteer oilseed rape is relatively easy to control and it is safe to wait until the first true leaves or beyond are emerging before spraying. In delaying the control of volunteer rape a reduction in the number of herbicides required during the season may be possible as the last few seasons has seen volunteer rape continuing to germinate well into June. Delaying the start of post-emergence sprays also removes the risk of causing any crop damage.”

Source - http://www.farmersguardian.com/