NIAB webinar highlights new soft fruit research
13th March 2025
NIAB’s Scott Raffle picks out some of the key research findings presented at the recent soft fruit technical webinar.
The annual NIAB soft fruit technical webinar at the end of November saw 15 speakers brief the industry on the latest results from research projects led by NIAB and partner organisations.
N and water use
Mark Else outlined how with Innovate UK funding, NIAB has adapted a mathematical model which predicts the plant’s nitrogen demand for each growth stage. Inputs are then adjusted to account for the effects of environmental variables such as temperature on nitrogen demand and partitioning.
The model gave rise to a 76% reduction in nitrogen use compared to a commercial nitrogen feeding regime (figure 1) and a 37% reduction in water use, without affecting marketable yields or berry quality.
Katia Zacharaki explained that similar models are being developed by NIAB at East Malling for Junebearer and everbearer strawberries whilst a three-year Defra-funded project is producing high-health, pest-and disease-free tray plants with a greater and more consistent cropping potential.
Grown in Vertical Future’s prototype strawberry propagation facility at East Malling using LED lighting, the project will compare tray plants grown in this more consistent environment with those raised under commercial best practice.
WET Centre update
Trevor Wignall reviewed the work at NIAB’s WET Centre since its inception in 2017. The focus was precision on-demand irrigation using the latest technologies, and subsequent adoption by the industry has reduced the average water use for an everbearer strawberry variety from 82m3/tonne of fruit produced in 2013 to 60m3/tonne in 2023.
The approaches deployed at NIAB’s WET Centre achieved an average of 43m3/tonne and at best reduced it to 28m3/tonne. When combined with rainwater harvesting and re-use, precision irrigation resulted in 90% self-sufficiency in water, even in very dry seasons.
A PhD study by Ece Moustafa on the legacy effects of coir drying in raspberry demonstrated that the use of smaller pots (4.7-litre) can lead to a detrimental reduction in berry yield and quality compared to larger pots (7.5-litre) following a mild rootzone water deficit.
Recycled coir
Louisa Robinson-Boyer has been carrying out Growing Kent & Medway (GK&M) funded research on raspberry propagation and growth at East Malling.
To date, the trends suggest that coir treated with arbuscular mycorrhizal fungi (AMF) increases berry size in both virgin and recycled coir, that recycled coir from strawberry crops is likely to be suitable for raspberry crops, and that the addition of AMF to recycled coir in long-cane raspberry crops can help to sustain yields at the level expected from virgin coir.
Matevz Papp-Rupar has been working with Overland Ltd to assess their recycled coir products (figure 2) through Innovate UK and GK&M funded research. He has demonstrated that strawberry produces comparable yields in virgin and recycled coir and that recycled coir retains more water than virgin, necessitating different management.
In addition, recycling appears to inactivate different phytophthora strains (crown/root rot) and weed seeds whilst having no adverse effects on the establishment of biocontrol organisms. NIAB and Overland also calculated that recycled coir emitted around 40% less CO2 than virgin coir shipped from Sri Lanka.
Large raspberry aphid
Francis Wamonje outlined progress on a GK&M funded project to develop optimal biological control solutions for the large raspberry aphid (figure 3) under protection. This project has revealed that the predominant naturally occurring aphid parasitoid species vary as the season progresses, so the use of introduced parasitoid mixes under protection will need to reflect this.
Work done to attempt to spray green lacewing (Chrysoperla carnea) eggs onto raspberry leaves as a cheap method of introduction showed that the eggs need to adhere to the leaves to be effective. A sticking agent was identified that works well. Deploying brown lacewings (Micromus angulatus) early in the season under protection offered some control, but its efficacy is likely to increase as temperatures rise.
SWD progress
Rachel Turner (Russell IPM) outlined some recent Innovate UK-funded research using the SWD attractant ProBandz. Previous research with the product had shown that applying a narrow band spray of Probandz with Tracer or Exirel at 4% of the recommended rate to strawberry, raspberry and cherry crops, provided the same level of SWD control as an overall crop spray of Tracer or Exirel at full rate. This latest project has demonstrated the same effect using the product Hallmark at 8% rate on strawberry.
Michelle Fountain introduced a GK&M funded project that aims to investigate the use of naturally occurring UK parasitoids to control SWD.
Fruit inoculated with fruit flies is being deposited in tent-like structures which prevents flies from escaping but allow parasitoids to emerge into surrounding areas, potentially reducing reservoirs of SWD in hedgerows and woodlands.
