Weed beet control opportunity in autumn crops

Make the most of the opportunity to control higher populations of emerging weed beet this autumn, the British Beet Research Organisation is saying.

More weed beet are emerging than normal, it says in its latest advisory bulletin. In cereals this provides an excellent opportunity to reduce the number of weed beet in the rotation using a combination of effective herbicides and winter weather, the bulletin suggests.

Products containing mesosulfuron + iodosulfuron, such as Atlantis, should give 95-100% control in the autumn, while other sulfonylurea herbicides, such as metsulfuron-methyl (Ally SX) provide control in the spring. Fluroxypyr (Starane 2) is also effective.

However, control of weed beet in oilseed rape is much more tricky, with cyanazine no longer approved. Products containing metazachlor (as in Butisan S) give some control during the two to four-true-leaf stage of weed beet, while it would be expected that bifenox (Fox) and picloram (Galera) have some effect, although they have not been tested by BBRO.

But good cover by the oilseed rape crop together with winter frosts should reduce weed beet numbers, especially if suppressed by herbicides, BBRO says.

A single weed beet plant can shed 1,500 seeds when growing in a normal competitive beet crop and even more in a non-competitive situation, such as being left uncontrolled in onions.

“It can take only two rotations for the seed from a single weed beet plant, shed in a beet crop, to result in more than 4m weed beet seeds in the soil if progeny are not controlled,” BBRO warns.

In non-beet crops, the presence of weed beet will also act as a bridge for problems such as beet cyst nematodes and rhizomania, making it important to take every opportunity to control weed beet through the rotation.

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