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Important reminders from the Slingsby cultivation and nematicide demonstration trials

25 November 2013

Summer 2013 saw AHDB Potatoes sponsor field trials in Slingsby, when Matt Smallwood of SAC Consulting and John Sarup of Spud Agronomy worked together with Yorkshire grower, Andrew Wilson to produce replicated field trials on Andrew’s farm on the Castle Howard estate. 

 
These trials examined a range of primary and secondary cultivation methods, nematicide application methods and use of in-furrow fungicides. 
 
As planting is not so many months away now, we caught up with Spud Agronomy’s John Sarup to see how the report was progressing. 
 
When we spoke to John, he was busy looking at fields for next years’ potato crops, and he reminded us of why we need to examine cultivations, saying, “Potatoes, out of all the arable crops, are comparatively poor-rooting. So getting cultivations right so root systems can establish properly is vital. 
 
“Growers around the country plant potatoes on a wide variety of soil types, often within the same field, so timing of cultivations is crucial if compaction is to be avoided, not always easy bearing in mind that the number of growers is reducing but the planted area remains relatively static. Therefore with commercial pressures and weather windows, planning your cultivation work and having the ability to be flexible is ever-more vital. 
 
John continues “Growers need to understand the consequences of each cultivation they carry out. For example, if bed-tilling is carried out in the wrong conditions, just speeding up the de-stoner can be counter-productive as it can create more of a soil pan that would otherwise be the case.”
 
The trials showed the effects of different primary and secondary cultivation methods on the canopy, and therefore on eventual yield. There was such interest from grower groups, we video’d the talks and the visible difference in canopy development is plain to see in the Slingsby trials site footage. However we will be publishing the full results of the trials in early December. 
 
With our industry spending in the region of £14m per annum on nematicides, and with only 80% effectiveness of PCN control being achieved at best, correct application of nematicide products are crucial. If incorporation is less than precise, growers could be looking at a drop of up to 50% return on investment (time and costs) on their PCN control, ultimately achieving only around 30% of potential PCN control, with the inevitable consequences this will have on yield. 
 
As an example   using the PCN online model with a Maris Piper crop and a planned yield of 50t/ha, a reduction from 80% to 30% control could reduce the yield from 47t/ha to 41t/ha, with the final PCN population after harvest more than doubling. Reduced efficacy can be caused by a number of factors, including soil moisture causing ineffective mixing and too long an interval between incorporation and planting. 
 
AHDB Potatoes’s Technical Executive, Gary Collins comments, “Possibly the most significant factor is incorporating nematicide to a depth below the optimum of 15-20cm to around 30-35cm. This causes huge dilution which has the effect of reducing PCN control, regardless of species. It is a challenge to incorporate up to 100kg of granules into 3,000 tonnes of soil effectively.”
 
The Slingsby site is populated with PCN so was particularly useful for demonstrating the effects of different nematicide application techniques and depths, and the canopy differences can clearly be seen in the video footage. 
 
1Final results to be submitted by SAC Consulting.
2Maris Piper grown in a sandy loam soil with a G. pallida egg count of 5 eggs/gram, with the incorporation of a granular nematicide at 80% and 30% control.
 
So what is the solution to PCN control? John advises “As well as applying nematicides to the correct depth – between 15-20cm   – and with the correct machinery, growers must understand that PCN populations vary considerably and just because a soil sample comes up with a ‘None Found’, it doesn’t mean that PCN is not present in their soils. Therefore using the correct soil sampling technique is important; the more soil samples you take, the better chance you have of finding PCN in your soil and being able to treat it accurately.”
 
John reminded us that “Knowing which species of PCN is in your soil is also fundamental to its management. Rostochiensis is easier to control as the eggs hatch earlier so the nematicides will have retained their efficacy. However, Pallida has an extended hatching period, so there is the risk that the nematicide product has started to degrade and as a result is less effective, particularly if applied too deep. So understanding your PCN population and species really helps when choosing which product to use, when to apply it and varietal choice.”
 
The importance of effective soil sampling and testing to preserve land available for potato growing has led AHDB Potatoes to launch the industry-supported Soil Pest Management Initiative (SPMI), which will address challenges related to the sustainable control of nematodes and other soil pests including standardisation of soil sampling and laboratory testing and to stimulate cross-industry collaboration, the outcomes of which will help growers implement the best possible soil testing regime for their fields.
 
You can see the video talks from the Slingsby trials online where Matt Smallwood, John Sarup and host farmer Andrew Wilson go into detail on the approach, content and outcomes of the trials.
 
AHDB Potatoes’s Gary Collins will be at BP2013 to discuss PCN modelling amongst other topics, and AHDB Potatoes’s online PCN Calculator
 
Further details on these and other current projects to help growers can be obtained and discussed at BP2013, 27-28 November, Harrogate, Yorkshire. www.bp2013.co.uk
 
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