If left untreated, slugs can cost the potato industry £53 million each year.
With predictions of a high pressure slug season ahead, and the potential damage these pests can do to a crop both physically and financially, Robert Boothman, commercial director of Boothmans Agriculture, explains how to keep one step ahead of the pest.
“The milder, wet winter and lack of ground frosts we’ve seen this year will have allowed for a longer slug breeding season, resulting in larger populations.
“We’ve already noted an increased level of damage from slugs feeding over the winter, especially on oilseed rape canopies, and pest alerts have warned of high levels of juvenile slugs this year.
“Juvenile slugs are known to cause a greater degree of damage to crops on a weight by weight basis in comparison to larger, more mature slugs. And therefore, we need to be proactive with control as we head into the planting season,” says Mr Boothman.
He explains, that when it comes to managing slugs and implementing an effective control strategy, there is no substitute for a good knowledge of soil type, field history and awareness of the risk presented by previous crops.
“Potatoes are undoubtedly a capital intensive, high value crop, and therefore identifying potential risks at an early stage will help ensure the impact from slug damage is minimised,” he says.
“Varietal resistance to slug damage should not be underestimated. Avoiding planting the most susceptible varieties, such as Maris Piper, on heavier clay and sandy clay loams will minimise exposure to the pest.”
Mr Boothman also explains how an awareness of fields that have previously had high slug pressures may also help determine an effective control strategy. “Having this knowledge, as well as considering the crop rotation will mean growers can get the most out of pellet applications, ensuring timings and pellet choice are suited to the system.”
Application and timing
The demise of methiocarb has meant growers have had to seek alternative actives for slug control. With this, many have resulted to using a multi-dimensional approach.
“Growers have had to adapt to the loss of methiocarb, but at the same time they are aware of the restrictions on the use of metaldehyde, and the potential risk to water from the active. Therefore, many are using a combination of the remaining actives, metaldehyde and ferric phosphate, as well as various cultural strategies to manage slug pressures,” says Mr Boothman.
He explains that traditionally timings for slug pellet applications have been heavily weighted towards 50% of canopy closure, closely followed by 75% of canopy closure and tuber bulking. “However, progressive growers are experimenting with slug pellet injection at the point of planting, using equipment such as the Stocks Rotor Meter.
“This technique positions pellets underground, in a zone where slugs are active, facilitating control, up to two months before surface applications become effective. Slug pellet longevity is also maximised with the soil coverage protecting the bait from direct contact from rainfall,” he says.
“By building a complete picture of the slug risk factors on-farm, and devising a multi-dimensional control strategy that looks at pellet choice, application technique and timings, growers can ensure an effective control strategy is in place against the number one pest,” says Mr Boothman.
With restrictions on metaldehyde and the risk that, if not managed correctly this could be another active lost from the market, Certis’ key account manager, Morley Benson, explains the benefits of a ferric phosphate based slug pellet as part of a programmed approach.
“The advancements in slug pellet chemistry means that growers have a choice, and a degree of flexibility to suit modern farming systems and machinery.
“Ferric phosphate pellets hold a very strong environmental profile with no buffer zone restrictions or harvest intervals, and have no impact on non-target organisms.
“All products are pasta based, and Sluxx HP is a wet processed formulation which, in wet conditions particularly, result in pellets that are more cohesive and tend to maintain their integrity for a longer length of time, which is key for irrigated potato crops.”
The advancements of Certis’ ferric phosphate based slug pellet Sluxx to Sluxx HP, also mean that these pellets are a more vibrant, blue colour providing greater visibility in the field. The addition of a mould inhibitor to the formulation, also means that the persistency of the pellet has been further enhanced.
Mr Benson says, “There is room for both metaldehyde and ferric phosphate in the market place, as our portfolio demonstrates. And, if used effectively in an integrated programme, both actives can continue to offer a good level of slug control.
“We need to be mindful that growers need to gain experience with alternative active ingredients, understand key differences and have confidence with using these,” he adds.