Prepare for the spring slug threat

The impending arrival of warmer weather is likely to bring a renewal of the slug activity that caused so much concern last autumn, growers are being warned.

The Met Office is forecasting a return to warmer weather from April with average temperatures set to rise steadily to almost 15oC by mid-summer.

With many soils still wet to a reasonable depth the arrival of warmer temperatures is likely to result in yet another year of ideal breeding conditions for slugs.

“The winter may have killed a few, but slugs are resilient creatures and with the numbers we had last autumn there is certain to be sufficient carryover to represent a threat this spring,” warns ProCam director of technical services, Dr Tony John.

The warning is all the more timely given the backward state of many crops which will still be highly vulnerable to attack, he says.

“In a normal year we would expect crops to be big enough to sustain some damage, but that isn’t the case this year. Many crops have failed to tiller as growers would like while the large area of spring sown crops means more young plants will be at risk.”

Dr John is advising growers to develop a strategy that combines a quality pellet with the beginning of any activity.

“Once average temperatures reach 4-5oC slug activity will be widespread, but crop growth is still likely to be slow so growers should be monitoring for signs and apply pellets as soon as conditions allow.

“Metaldehyde remains the most effective means of control, but for good results to be achieved it is important to use a quality pellet such as TDS or, at the very least, another a wet process pellet. Slugs are discerning creatures and with plants likely to be soft and lush it is imperative to use a quality pellet,” says Dr John.

With the spring workload on many farms intense he is encouraging growers to opt for a pellet with good environmental characteristics to save on repeat applications.

“Wet process pellets typically use better ingredients than dry process while the manufacturing process means they are more robust so would be a better option this spring. The slug also needs to ingest sufficient bait to cause death so growers should choose a minimum pellet size of 2.5mm otherwise it may not have the durability, persistence or ballistic scores necessary to achieve good control.”

For those who regard baiting points as an important consideration he advises caution. “It is the active substance applied per hectare that is the determining factor. While the pellet needs to be easily located just 30 (+/- 10%) evenly distributed pellets per square metre of a decent pellet is sufficient to ensure effective control while also adhering to the application guidelines of the Metaldehyde Stewardship Group.”

Autumn control
While spring crops will be the immediate concern of growers Dr John is urging growers to plan ahead for the autumn if crops are to be protected.

“Favourable weather, a high population carryover and good ground conditions all indicate that slugs are likely to be another serious threat this autumn.

“Even if we get a drier May than last year which means breeding will be less intense, numbers are sufficient to suggest that crops will face a tough time. Growers should be monitoring population numbers in the run up to harvest and then again in stubbles prior to cultivations if they are to avoid being caught out,” he says.