Unwanted potato control starts before sugar beet is drilled

UK - April 23, 2004

For sugar beet growers facing a volunteer potato problem one Shropshire agronomist has adopted a dual approach program.

Wrekin Farmers Ltd’s Iain Briggs recommends starting volunteer potato control in the potato crop with Fazor^~. He then follows up with Dow Shield^† in the sugar beet crop.

A sugar beet specialist, Mr Briggs expects anywhere with potatoes and sugar beet in the rotation to have a volunteer potato problem. It can be intensified by a very wet autumn when lifting potatoes as a higher numbers of tubers than usual will be left in the ground.

“British Sugar trial work has shown that 1.0l/ha of Dow Shield is required to maximise volunteer potato control in the sugar beet crop,” says Mr Briggs. “I usually spread this over three applications of 0.33l/ha, although some growers just split into two applications of 0.5l/ha.”

The detrimental impact of volunteer potatoes on sugar beet crop yield is reason enough to adopt the program. But Mr Briggs points out that volunteer potato control should also be part of the hygiene regime to suppress pests and diseases.

“Volunteer potatoes will produce daughter tubers, increasing the volunteer potato problem. Firstly, over the course of a rotation these daughter tubers encourage potato cyst nematode populations. Secondly, volunteer potatoes in following crops, whether cereals or sugar beet will get blighted — encouraging the disease in neighbouring potato crops.”

The Dow Shield spray program begins when there are sufficient volunteer potatoes to justify a first application in conjunction with broad-leaved weed control. The volunteers should be 2 – 4 inches in size. Follow-up sprays are usually 7 – 10 days later. These also pick up late germinating volunteers.

Mr Briggs warns growers to use the full 1.0l/ha, even if the crop canopy closes over before the final spray.

“Growers can make the mistake of missing the final spray as they believe that the problem has disappeared if they can't see the volunteers after crop canopy closure. This is a false economy and can lead to problems later in the rotation.”

As part of his dual approach Mr Briggs encourages growers not to put the costs of the volunteer potato program onto the sugar beet crop.

“The costs of the herbicide program should be spread over the whole rotation, or included in the costs of the potato crop,” said Mr Briggs.

^† Trademark of The Dow Chemical Company