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Slug populations have increased significantly after a wet summer, says Dick Neale, of agronomy company Hutchinsons. Continued moist conditions this autumn have been in... 5 steps to tackle serious autumn slug threat

Slug populations have increased significantly after a wet summer, says Dick Neale, of agronomy company Hutchinsons. Continued moist conditions this autumn have been in stark contrast to the past two years which were both much drier and lower risk.

“Continuous growth, breeding and egg laying, along with rapid volunteer growth and catch and cover crops have all combined to generate a significant population in almost all situations, not just after winter oilseed rape.”

Such high numbers make control more challenging. They require extra vigilance from growers and agronomists – especially during the crucial early stages of establishment when just a few minutes feeding on an individual seed or seedling can destroy the plant

Post-emergence the above ground leaves can tolerate far more grazing and still survive. “Ultimately, we will never control slugs,”says Mr Neale. “The objective is to reduce the feeding population sufficiently to allow the newly sown crop to establish successfully.”

With this in mind, Mr Neale highlights five steps to help manage the risks from high slug populations this autumn.

1. Consolidate seedbeds

Ensuring seedbeds are firm and well consolidated is the first step in reducing slug activity. This makes it harder for them to move around and reduces the number of safe resting places compared with cloddy soils. Doing so also improves seed-to-soil contact, which will help crops establish faster and grow past the most susceptible stage for slug damage.

2. Monitor crops

With high slug numbers in many fields, it is vital to check newly-sown crops frequently – possibly daily – to look for signs of damage, assess slug activity, and decide on pelleting requirements. Leave it too long between inspections and there may be no crop left to protect.

Ferric phosphate pellets work differently to metaldehyde, as slugs feed and crawl off into the soil to die, so are not visible on the soil surface.

This can make it harder to assess the effectiveness of pelleting strategies, other than through a reduction in crop damage, or the fact that all applied pellets have been eaten.

3. Ensure there are enough baiting points

Slugs are generally random feeders. With higher populations, it is imperative there are sufficient baiting points per square metre. This  increases the chances of slugs finding a pellet before the crop. In wet years like this, there acan be hundreds of slugs in a single square metre. This means one application of 40-50 or even 90 pellets may not be enough.

4. Repeat applications

Equally, where pellets are being consumed very quickly, repeat applications may be necessary in order to maintain sufficient baiting points throughout the crop’s most vulnerable stage. Label restrictions vary, but many products cannot be reapplied within one week, so if a repeat application is needed before that, then products will have to be alternated.

5. Choose pellets wisely

Pellet choice is not really an overriding issue when it comes to controlling high numbers, although in continuously wet conditions and frequent rainfall, pasta based pellets are more resilient than dry or steam processed pellets.

Recommended doses and the number of baiting points that dose will deliver do vary though, so consider options carefully. Some products also have limits on the number of applications that can be used, so always check the label carefully and consult your agronomist.