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Wet weather heightens slug risk in potatoes

Following the recent extreme rainfall across parts of the UK, potato growers are being warned of the potential increase in slug numbers which could now occur if soil temperatures rise sharply.

 

According to Norfolk-based grower and independent potato specialist, Andrew Alexander, there is a real need for vigilance and preparation for the possibility of entering a season totally unlike the last two.

 

“Already this year planting has been very stressful,” notes Andrew. “We are only two thirds of the way through planting at a time when we should be finished.”

 

He also warns of the slug risk. “Over the last two seasons slug pressure has not been horrendous by any means, with slug pelleting applications around the 50% level,” he notes.

 

“Slugs were dormant, retreating as far as one metre deep into the soil during last summer’s hot weather,” notes Andrew referring to sightings in pits dug last year.

 

“But we now may be entering into a totally different, high-pressure season – purely driven by the weather,” he believes.

 

“Conditions are ideal. The very wet field situations mean that if temperatures now rise we may see a mass of slugs appearing in potato crops.

 

Andrew is keen that growers are mindful of the stewardship advice relating to metaldehyde should conditions worsen.

 

“It is important that we protect metaldehyde for the future in order to continue producing the products our customers want and deliver upon high quality, profitable, high yielding crops.

 

 “We must act responsibly and be conscious of what we are using,” he urges.

 

“Particularly on heavy land with ditches and under drained soils – this situation demands particularly careful management, especially if we are faced with increasing slug pressure and the need to treat.”

 

Andrew is urging against adopting a pelleting programme as a matter of course, advocating the use of a risk management approach and test baiting to inform decisions. “It is important to ensure we are not treating and using metaldehyde quantities unnecessarily, both from a stewardship point of view but also from a financial point of view, avoiding unnecessary spend. 

 

“The decision to treat should be based on a an assessment of a number of factors – the variety can be a significant factor influencing the risk, so too is the soil type, the pre-existence of slugs, the previous crop and also whether crop residues have been incorporated.”

 

Working within the Metaldehyde Stewardship Group guidelines, Andrew reminds growers that the maximum application rate is 700g metaldehyde/ha/calendar year, and is also a statutory requirement.

 

The maximum individual application rate is 210g metaldehyde per hectare, which on the recommendation of a BASIS qualified advisor this can be reduced to 160g/ha or less for metaldehyde based slug pellets.

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