Potato day draws crowds and interest – The Vegetable Farmer
At this year's Hutchinsons Potato Day held at Worth Farms, interactive discussions were held around field trials and practical research to help growers address some of the industry's most important...
Talks covered research on wireworm, PCN, and RLN, and delegates heard about this year’s field trials set up to assess post-emergence herbicide crop safety, the potential of new foliar bio-nutrition products, and cover crop species aimed at reducing soil pest populations.
With regards to the use of cover crops in potatoes, Hutchinsons root crop technical manager Darryl Shailes revealed that the company is trialling buckwheat, a high glucosinolate mustard and a lower glucosinolate standard mustard, and a multi-variety cover crop for soil health to assess their impact on wireworm populations.
Reducing PCN levels is also a priority, and this year trials are refining understanding of how to get the best results from growing DeCyst-Prickly (Solanum sisymbriifolium) and DeCyst Broadleaf (Solanum scabrum) as cover crops.
Initial populations have been recorded and will be compared. against those after these crops have been destroyed; up to 80 percent reductions may be possible, visitors heard. Darryl said: “These cover crops, which can be grown anywhere in the rotation, also contribute up to 12t/ha of green manure, and may be suitable for integrating into your SFI.”
Crop safety from post- emergence herbicides
Michael Rodger of Richard Austin Agriculture updated delegates on the herbicide crop safety trials being held on 26 varieties, including some new, coded varieties provided by the breeders. While last year’s trials were focused on metribuzin, hotter herbicide mixes have been used this year, he said.
Michael said: “Sometimes when you apply a post-emergence herbicide to a commercial crop, you do not really see a difference, but when you compare treated and untreated plots, you can really see the yellowing.
“Some of the treatments last year, when applied at ideal timings did not show any crop effects. However, this year, crops are water-stressed, and five days after treatment, we have observed that some of the varieties have been much more affected than last year, while others look good.”
This implies that crop damage can be seasonal, as the condition of the crop and timing of application are crucial. “We will be taking these plots through to harvest to assess any yield or quality differences,” said Michael.
Foliar nutrition trials aimed at helping growers reduce inputs
Rob Jewers, crop nutrition specialist at Hutchinsons, introduced the foliar bionutrition trial, which is aimed at providing information on whether growers can safely reduce fertiliser inputs without taking a hit on yield.
Rob said: “The products that we are trialling, which include Vixeran, R-Leaf and Utrisha N, have already been used successfully on cereal crops for the past four years.”
Utrisha N (also marketed as Blue N) and Vixeran are both biological and are applied to the leaf. The bacteria colonise it and then reproduce and extract N from the atmosphere, conferring it into the plant, he explained, adding that Vixeran is also claimed to have root activity, so can be applied in- furrow.
“Our first work with Utrisha N was done during dry springs, when granular fertiliser was lying on the ground for several weeks, and not being uptaken by the plants. Foliar nutrition is one of the range of products we are looking at to assess whether we can get N more effectively into the leaf.”
He went on to explain that the other product, R-Leaf, is a photo-catalyst, which claims to be able to extract nitrous oxide from the atmosphere, which would have a significant impact on carbon footprint.
“As well as the field work, we have done some proof of concept, under glass with plants inserted in media with no N grown them on and taking cuttings. In all of them there was an increase in N in the leaf compared with the control. “There has been a lot of work done on cereals with these products, but so far, very little on potatoes. Further replicated trials of these products are underway to explore whether they impact on yield, and what the effects are when the base-line fertiliser is reduced.”
Integrated PCN management strategies
Simon Faulkner of SDF Agriculture updated delegates on the PCN varietal resistance trials assessing a mix of older and newer varieties.
The background PCN level for the field was 20 eggs/gram, and on creating the plots, the plots were then re-sampled to identify eggs/g per plot, which ranged from 0.5-20 eggs/g of soil. These details will enable an accurate before and after count (pf/pi) to be calculated for each variety after harvest.
The trial is monitoring 26 varieties put forward by a number of breeders, with varieties for processing, packing, chipping and crisping, with Lanorma, Cara, Markies and Maris Piper as control varieties. Plots have been divided into two, with one side being treated with a nematicide the other without, and three replicates used to achieve some statistical data.
Some varieties appear to be displaying resistance as well as a degree of tolerance, but Simon emphasised that the resistance score will not be seen until after harvest when pf have been achieved to give pf/pi ratio. Until then the observations can only reflect tolerance to PCN.
He reminded delegates that tolerance means that a particular variety can still maintain growth even when under considerable pressure from PCN; so better canopies are an indication of potential tolerance. “When a variety is resistant, it means that the nematodes multiplication is reduced or prevented, reducing viable numbers of cysts forming.”
Regenerative potato practices
Following the core principles of agroecological farming will help create healthy soils which in turn will produce healthy crops, Hutchinsons head of agroecology services Ed Brown told delegates.
Minimising soil disturbance, keeping soil covered, maintaining living roots in the soil throughout the year, maximising diversity, and where possible, integrating livestock into the rotation are the basic activities, but he stressed that there is flexibility within the system. “These principles can also be applied to vegetable and potato crops grown in intensive rotations, but the terminology is ‘minimise’ or ‘maximise.’ It does not mean eliminate. Implementing these practices in your context on your own farm, as best as you can, will deliver clear benefits.”
Other work is exploring companion cropping potatoes with legumes such as peas and beans. “This brings in diversity into the crop and attracts beneficials such as pollinators and reduces disease pressure.
“Cover crops will help you tick a lot of these boxes, and the positives far outweigh the very few negatives, but nevertheless, it is one small element in the context of a larger system of the soil food web.
“If you think that slugs may become an issue, you can manage that with appropriate choices of the species in your cover crops; trials are exploring the use of French Marigolds around the headlands for slug control.”
Ian Robertson head of soil services for HLH drew attention as to possible reasons for why nematodes may be proliferating, such as too short rotations and lack of predators for those nematodes in the soil food web.
The soil food web is a grouping of soil flora and fauna according to what they eat, into five trophic levels. It is a complex system which includes photosynthesisers, decomposers, pathogens, grazers and various. levels of predators which consume prey and then excrete waste, creating nutrient cycling.
Ian said: “We need to ensure that the soil food web is balanced, so individual species never get a chance to take hold.”
Root lesion nematode populations reduced by certain cover crops
Soil populations of root lesion nematode (RLN) Pratylenchus spp. can be reduced when French marigold (Tagetes patula) and oilseed radish are grown as cover crops, Vongai Chekanai of Harper Adams told visitors. Pratylenchus can enter the roots and then leave again, leaving a wound through which other soil-borne pathogens can enter, for example potato early dying disease pathogen.
As part of her PhD studies, trials compared the nematode- suppressiveness of different cover crop species including French marigold, Indian mustard, oilseed radish, forage chicory, alfalfa, phacelia, and Japanese oats, using disturbed and undisturbed fallows as a control.
Vongai said: “There were no changes in the plots left fallow, and the results from our trials indicated that oilseed radish and French marigolds were poor hosts and suppressed RLN population numbers.” However, Caliente Mustard, which is popular as a biofumigant to suppress potato cyst nematodes (PCN), increased Pratylenchus spp. numbers.
Japanese oats and Phacelia were observed to be in the maintenance host category, she said. “The implication is that choice of cover crop species needs to be tailored to any particular pests proliferating where you plan to grow potatoes.” The final outcomes of all the trials will be revealed at the Hutchinsons Results Meeting.
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