17 May 2002

Management is the key for success in controlling weeds

By John Burns

SUCCESSFUL weed control on farms producing a wide range of organic vegetables is more about skilled management than sophisticated weeding equipment, says Guy Watson after 18 years experience at his familys Riverford Farm, Totnes, south Devon.

"The cost of weed control is not vitally important for many of our higher value crops, but doing a good job is," he said at a recent Soil Association mechanical weeding event at nearby Landscove.

"Some of the more sophisticated tools take a lot of setting up correctly and that is not much help when we have many different crops, several soil types and rather steep slopes. So we have gone back to less complicated tools."

The main equipment used at Riverford is a brush hoe and a traditional scuffle or inter-row hoe. "Tine weeders have not worked particularly well here, so much depends on soil conditions and crop stage. But we have the brush hoe in almost continuous use from now until September.

"It is fairly brutal on the top inch of soil, but it is very versatile and kills almost 100% of the weeds, even when it rains afterwards. It is pretty basic kit and does need a good operator. Fatigue is an element – it can be very stressful on the operator."

Scuffles too are used all summer, mainly mid-mounted on tool-carrier tractors, and usually fitted with a sweep behind the blades to push soil into the rows. "A good operator is also the key to success with scufflers. 80% weed kill is not good enough. It has to be 90% minimum," insists Mr Watson.

Although he claims to be obsessed about stale seed-beds for good weed control he also admits pressure on space and time often precludes them.

Heavy rain just before the SA event prevented working demonstrations and visitors had to be content with viewing stationary equipment at the Hayllor familys Gullaford Farm, Landscove.

Host Stewart Hayllor is a member of South Devon Organic Producers co-op, which was set up with UK and EU funds by Riverford, which buys the produce and was initially a member.

The co-op owns a collection of equipment, which members hire. Mr Hayllor finds a tined weeder useful in recently planted brassicas and leeks, though agrees well set scuffles will do as good a job. The tines are also useful in cereals, he finds.

As at Riverford, the brush hoe is used a lot, especially on carrots. The flame weeder is also used on carrots just pre-emergence, but almost always some hand weeding is needed and the co-op average cost is £2500/ha, a figure Mr Watson considers too high.

Most flamers are too heavy for wet soil conditions, but Riverford has a very lightweight unit. "A good flame weeding can be worth £500/acre on carrots," says Mr Hayllor.

Like Mr Watson, he is keen on stale seed-beds, though he accepts they are most relevant to later-season crops.

Both were interested in the automatic guidance systems Eco-Dan and Robo Crop, but neither felt they were appropriate for their conditions at present. The extra cost was not justified in their situation, said Mr Hayllor, and Mr Watson felt work rate was less important for his crops than for those with large areas of lower value crops such as sugar beet.

But both thought the Kress finger weeders looked promising and would be asking for a demonstration. Mr Watson would also like to try the Danish Egedal rotary tine weeder developed for tree nurseries. It proved promising for brassicas and is due to be tested on other crops this year by importer Tony Deptford. &#42

South Devon organic veg grower Guy Watson (below) is interested in trying the Kress finger wheel weeder from the Netherlands (bottom right) and the Egedal rotary tined weeder (right). But management skill is more important than the sophistication of the weeder, he says.

A terrifying sight… The 6m propane-fuelled Green Dragon flame weeder was just one of a host of flame weeders on show at Gullaford Farm, south Devon. Background crop is organic lettuce under fleece.