Brassica trials highlight soil health and pest management – Agronomist & Arable Farmer

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Hutchsinsons Trials demonstrate way forward for the brassica sector

Hosted by kind permission of F Daubney & Son (R Daubney)at Bayholme Farm, Old Leake, Boston in conjunction with the Allium & Brassica Centre, the trials day looked at near-market insecticide and fungicide products, early nutrition and plant health and cover cropping with a view to improving soil health in an intensive vegetable production system.

HLH brassica open day

Our trials focussed on kale and brussels sprouts but the knowledge gained can then be transferred to all brassica crops, explained Peter Waldock, Hutchinsons technical support for vegetables.

“We also wanted to offer growers and agronomists the chance to recognise how and where measures can be taken in intensive vegetable production to improve soil health so we included trials on various cover cropping mixes, ”

“As well as a visual assessment of the soil structure under the different planting mixes and tillage systems, we were able to assess variations in soil microfauna using the FungiAlert sensors.”

Effective aphid management

aphids on kale

“Many of the new products coming on the market are predominantly protectant rather than having a knock-down effect so applications have to be better timed to optimise efficacy,” said Peter.

“With the loss of Cruiser (Thiomethoxam) for aphid control, growers are likely to become more reliant on foliar sprays, so plots were established to look at products both on their own and in combinations.”

These plots were treated with Tracer (spinosad) for cabbage root fly control but has no effect on aphids or white fly, he explained.

“All the treatments showed positive results for aphid control, although when using Movento (spirotetramat) to get the best results it should be applied ahead of aphid populations building to give the best control.”

“Included within the trials was the forthcoming Isoclast aphicide (Closer 240SC) which should be approved ahead of next summer’s aphid pressure.”

“It demonstrated good control when compared to other aphidices in the trials and as it has minimal impact on beneficials it should fit well within IPM programs.”

aphids on brussels

However the dry summer of 2018 was not conducive to leaf disease pressure, making it difficult to pull out differences between products, he added.

“Brussels sprouts are susceptible to light leaf spot and ring-rot, while kale is more likely to be affected by powdery mildew.

“With an early application of Signum (Boscalid/pyraclostrobin) on at around four weeks after planting it is possible to extend the benefits of its protectant properties for longer than the recognised 10 to 14 days,” he pointed out.

He warned growers not to be careful not to breach label restrictions when using Amistar Top and Amistar highlighting the resrictions regarding the grams active of azoxystrobin (500 gai/ha) per hectare per year with Amistar and a restriction on the Amistar Top label for difenoconazole (250 gai/ha)

“We hope that these trials will give both agronomists and growers a better understanding of  product efficacy when applied in combination and also how to use disease forecasting to better target application with systems such as Brassica Alert and FungiAlert.”

Healthy Soils

The cover crop trials looked at how cover crops can improve soil structure, reduce surface capping, improve water filtration, reduce soil erosion, control weeds and improve soil biological balance in an intensive vegetable system.

Choosing the right  varieties to grow an effective cover crop is crucial, said Dick Neale, Hutchinsons technical manager.

“You want enough biomass and root matter to make a difference to soil health, but its important to recognise that the needs of vegetable farmers are different from arable growers.”

“Vegetable growers are looking for a manageable amount of top growth with finer roots which don’t interfere with more complex planting and harvesting precedures”.

Cover cropping

  • Drilling Date: 3rd August 2018
  • Mixes:
    • Vetch + Berseem Clover
    • Vetch + Berseem Clover + Linseed + Fodder Radish
    • Vetch + Berseem Clover + Linseed + Fodder Radish + Phacealia
  • Linseed radish and phacelia established well, but not the Vetch and berseem clover as the soil had run together impacting their emergence.
  • A mix of rye, linseed and berseem clover could work well as it will fix N and be relatively easy to strip-till and plant vegetables directly into it.

Harvesting cover crops

A crimper roller with helical blades to roll, break and bruise cover crops ahead of the drill developed by Cousins of Emneth was being demonstrated.

Cousins crimper roller

A front mounting means that rolling and drilling can be done in a single pass.

When rolled down in the direction of planting, the cover crop  can form a dense weed suppressing mat on the soil surface while allowing successful crop establishment, explained managing director Laura Cousins.

“The blades are spiral so this helps prevent vibrations and keeps the machine moving smoothly. They are also blunt to prevent cutting through the cover crop,” she said.