BCN-resistant cover crops are an under-utilised tool in sugar beet rotations – Arable Farming – Darryl Shailes
We've recently been clearing the overgrown areas in the garden which are left to grow wild each year ...
Our task in October was to cut it all back, remove and compost the excess vegetation to maintain the low nutrient status of the wild areas.
We do this to encourage mixed species, such as meadowsweet and ragged robin, and reduce the nettles, thistles, etc. that would otherwise take over.
This is all on the advice of my daughter who works for the Suffolk Wildlife Trust, although her time is now taken up looking after our first granddaughter.
This year’s area was bigger than normal as we got caught by all the rain and exuberant growth in summer and didn’t have time or suitable kit to sort the much longer than normal grass. Luckily hiring an Oleo Apache makes short work of it. Other ride on brush-cutters are also available of course.
The secret to excellent growth, as if we didn’t know, is good soil conditions, nutrition, then rain and sunshine with some agronomy input of course. Pretty obvious, but it’s amazing how often we don’t get all that come together.
This season some potato fields that were planted early into wet soil which then got heavy rain after planting suffered badly from poor rooting, but also free-living nematode damage on some of the light soils I work with, and yields were a long way down. Conversely, where fields were planted later into better growing conditions, the yields were much stronger, even those crops planted in June were better than some in early March with the excellent growing conditions we had in summer.
PCN
I wonder if next season patience will be the winner, or will the desire to get going even when we know we shouldn’t take over once again.
The excellent growing conditions has meant that the PCN catch crops I’ve been looking at recently have also been excellent.
PCN is still a huge challenge for growers, but crops of DeCyst Prickly (Solanum sisymbriifolium) and DeCyst Broadleaf (Solanum scabrum) can play a big part in a farm’s PCN management. These catch crops both being from the same plant genus as potatoes (Solanum tuberosum) cause the cysts that are dormant in the ground to hatch out into the juvenile stage, but they cannot then reform cysts. PCN declines of up to 85% have been recorded, but the crops need to be strong with good root systems to enable this to happen.
The trials I visited in Shropshire, run by the DeCyst trials consortium and Crop Health and Protection (CHAP), looked at all aspects of growing a successful crop and the host farm has had such good results over the years in combination with resistant varieties that its PCN problem is largely under control.
Beet cyst nematode is an often-undiagnosed issue on many farms and this year has seen a lot of infection and subsequent yield loss. Testing soils in a heavy sugar beet rotation is a way forward but done much less often than testing for PCN. Richard Austin Associates is one lab that can quickly identify BCN from soil samples. Oilseed rape can also increase BCN, and it wasn’t long ago that beet and rape weren’t grown in the same rotation because of this.
While we don’t have any truly resistant varieties the tolerant varieties have to have a PfPi (final population divided by initial population) of less than 2 to make the list. This means that they will reduce the build-up over non-tolerant varieties which can have PfPi of 5 or more, as well as maintaining yield in the presence of BCN.
With the increasing use of cover crops in sugar beet rotations I’m surprised that we don’t see more use of BCN resistant crops such as certain species of oil radish which reduce BCN numbers in the same way as the DeCyst crops. A tool underused at present I suggest.
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