Friday, 2 June 2017

Varieties, cattle and experimental design, it’s a busy demo field at SPot West

Knowledge Exchange Manager, Anne Stone has the latest from Heal Farms

A month after planting, emergence of most varieties is now nearly complete, though Royal has been rather slow to come through. There’s a slight metallic click across the field as irrigation pipes are fitted together, but more prominent is the sound of the resident cuckoos here at Heal Farms.

PCN and key processing varieties

The main demonstration at SPot West 2017 explores the tolerance of and resistance to Potato Cyst Nematode (PCN). 

Farm Manager, Matthew Wallace chose Maris Piper and Maris Peer varieties as part of this demonstration as they both have a commercial interest at Heal Farms. 

Resistance to
Resistance to G.rostochiensis
Maris Piper

Maris Peer

Not resistant
Data from breeder

Improving the PCN calculator
On the AHDB website a calculator can be found, to predict numbers of nematodes and guide planting and treatment decisions. This calculator could be more useful if the model in the background contained better information on:

·         variety tolerance and resistance,
·         effect of Brassicas in the rotation,
·         effect of action taken before the crop; nematicides, trap crops, biofumigation

Harper Adams University has a separate experiment at SPot West, which forms part of a SARIC (sustainable agriculture research and innovation club) project to improve help the PCN calculator.

Bill Watts, a Research Associate at Harper Adams University manages the field experiment.

Bill’s knowledge of biofumigation will be familiar to those who visited SPot West at James Daw’s ilast yearor you may recognise him as the star of AHDB’s biofumigation video. You can view the video by clicking here

This year Bill is helping to systematically assess PCN tolerance of the most widely grown varieties of potatoes.

Which statistics are best for PCN?
Trial design is not a topic   that would usually make our hearts beat faster in excited anticipation, however the SARIC trial will be set out in a neat way to tackle a problem PCN trials often face.

Nematode numbers vary across a field, sometimes with ‘hot spots’ which sees dramatic changes over a short distance.

The AHDB trial in the same field has four replicates of each treatment, randomly allocated within blocks, each next to each other in a row across the field: 1,2,3,4.

The SARIC trial will use ‘stratified blocks’. Each block will be of plots which are not necessarily next to each other, but which share similarity in numbers of PCN eggs. So the varieties will be tested fairly against each other.

Shocking egg numbers
When Bill counted egg numbers on his plots the results were a nasty shock, both to him and to Heal Farms. They ranged from 28 – 304 eggs per gram. The four blocks are linked to 

PCN density:

0 - 75eggs/g
75 -150 eggs/g
150 - 225 eggs/g
225 eggs/g

It will be a test of tolerance under really tough conditions.

PCN experiment has to fit in with calving
On April 22nd Bill Watts was busy. He had spent the night at home with a cow struggling to calve, came to mark out the trial, then rushed back home to help with calving again.
As you can see, all ended happily

On May 15th when quietly working in the field, sowing trap crop seeds, I looked up in surprise to see a group of  eight young cattle, which had broken into the field. I tried to encourage them away from my working area, which of course was more interesting to them than anywhere else. They followed me steadily for a while, then abruptly turned and rushed right through the trial!

Fortunately It didn’t do much harm.

On a more serious note, the Invasive Species Compendium by CABI reports that PCN cysts can pass unharmed through the guts of animals. Anecdotal evidence from this country suggests that places where cattle have dunged heavily after feeding on PCN infected potatoes become new hot spots of infection

Come and see for yourselves.
 Our first field walk is planned for next week, Tuesday 6 June: Where you will be see the latest from our PCN trials and hear first-hand knowledge from Dr Matt Back, who will be on hand to answer all of your question.

If you’re interested in the this event, you can register by clicking here

No comments :

Post a Comment