The CleanFruit project aims to design and promote a crop protection strategy to produce zero-residue (ZeR) fruit.
Find out more about the project in our Introductory video:
Grower Survey
Part of our project is to better understand growers’ interest and attitudes towards pest management methods that leave zero pesticide residues on fruit. Would you be willing to complete a short questionnaire (10-15 minutes) on your experiences and attitudes towards pest management? This would help us with our research.
You can find the online questionnaire at the following link: Survey: Fruit Grower Attitudes Towards Zero Residue Pest Management Approaches
CleanFruit Project
Development of CleanFruit strategy protocols
The CleanFruit research team includes partners from Italy, Spain, Netherlands and the UK.
The group includes researchers from the University of Torino, Italy, and the University of Reading, UK, providing scientific support and expertise in plant pathology, entomology, crop protection, pollination and consumer and farmer acceptance. Koppert develops and supplies sustainable strategies and products for crop protection that will be used in strawberry and apple production.
Also involved are growers of apple and strawberry crops, and the processors of the fruit. Grupo AN is trialling the CleanFruit approaches in its own orchards. There are also farmers in Italy taking part in 2020, who will be joined by those from the UK and the Netherlands in 2021. Companies Döhler and Givaudan process fruit and produce strawberry- and apple-based juices, flavours and aromas, free from pesticide residues, and they will conduct tests to evaluate the quality of the fruit from this research.
The CleanFruit approach is to bring the knowledge of these diverse groups together to work on a set of protocols which are flexible, sustainable and environmentally friendly. They will provide an effective crop protection strategy to monitor pests and diseases, putting effective natural controls in place, and provide good pollination services to produce quality fruit with zero residues (ZeR).
Pilot field testing
Pilot farms have been identified in Italy, Spain, UK and the Netherlands. Trials were due to begin at locations within each country in 2020, but due to Covid-19 travel restrictions, the trials have been limited. Field tests started in Italy and Spain during 2020 on both strawberries and apples, and in 2021 these will be repeated in Italy as well as trialled in the UK and the Netherlands.
Strawberry field trials have taken place in polytunnels in Italy for 2020. Plant pathogens and arthropods have been monitored at regular intervals throughout the fruit growing seasons, identifying diseases such as botrytis fruit rot, and any pest outbreaks including spider mite and aphids. Within the CleanFruit strategy test plots the growers were provided with appropriate biological control products. Control polytunnels were also in place, where fruit was grown using conventional methods, including synthetic chemical sprays. Meteorological data and phenological development stages of the crop were assessed when products were applied.
Strawberry polytunnel
Apple trials have also been taking place throughout the year in Italy and Spain, and will be repeated in Italy, UK and the Netherlands in 2021. Similar measures to those in strawberries have been taken to reduce effects of apple pests and diseases within those orchards, with direct comparisons to be made between the CleanFruit strategy trial plots and conventional orchards. On apple, the CleanFruit strategy is also compared with an organic approach.
Fruit processing and quality
When the strawberries are harvested, yield (e.g. mass and size) is compared between the conventional and Cleanfruit strategy study plots. Fruit quality from both treatments in the strawberry trials is tested, including acidity levels, sugar content, fruit firmness, and post-harvest rot, plus storage quality and processing effects. Strawberries harvested in Italy in 2020 were sent to Givaudan for analysis, and Strawberry puree will be generated for sensory, analytical quality and pesticide residue analysis to compare results between the two different treatments.
Acidity testing
Apple harvest occurs later in the year, but similar tests will be done on the different treatments to compare quality and yield.
Sustainability performance and farmer take up
Sustainable means for pest and crop disease protection should have a reduced impact on humans, beneficial organisms and ecosystems, with zero pesticide residues in the fruit.
Economic sustainability and acceptability will be quantified using online surveys for growers and consumers, and telephone interviews with growers participating in the field trials. A shortened survey will be sent to a wider group of growers, including those participating in virtual open days, to assess the attitudes in the wider community. These surveys will help to evaluate the acceptability of the CleanFruit strategy to growers and consumers.
Project impact
Therefore, CleanFruit should provide:
- A sustainable way to grow fruit without relying on pesticides
- Fruit production with a reduced environmental impact
- Fruit free from pesticides for the consumer
Project Status & Results - Strawberry Trials
Strawberry field trials have taken place in polytunnels on 2 farms in Italy for 2020. Plant pathogens and arthropods were monitored at regular intervals throughout the fruit growing season, identifying diseases and pest outbreaks. Within the CleanFruit strategy test plots the growers were provided with advice and appropriate biological control products from Koppert. Control polytunnels were also in place, where fruit was grown using conventional methods.
The two farms were 8 km apart, growing the same variety (‘Premy’) of strawberry. There were some differences in their growing conditions:
- Plants 25 cm apart in a 50 m-long tunnel for one, 30 cm apart in a 80 m long tunnel for the other;
- Differences in effectiveness of plant residue removal in the spring;
- Fertigation differences, with one applying only irrigation, and the other including some fertiliser with the irrigation;
- Differences in attitude towards the residues as they had different market channels – wholesaler vs direct sale
Assessments on strawberries in both control and CleanFruit plots found issues with Botrytis cinerea, Cladosporium spp., Fusarium avenaceum, and Alternaria spp.
Alternaria spp. on strawberry leaves
Fusarium avenaceum on Strawberry
Throughout the treatment, the pathogens were assessed 2-3 times in both conventional and CleanFruit plots, and in most cases, no significant differences were found – i.e. the CleanFruit biological treatments were just as effective as the conventional chemical treatments. Some differences were found on one farm, with more Botrytis cinerea and powdery mildew present in the CleanFruit plots.
Assessment of strawberry plants for pests and pathogens
Botrytis cinerea on strawberry fruits
Post-harvest quality of the fruits showed no significant differences in either farm between the two treatments, with weight, fruit firmness, sugar, acidity and colour. One farm showed a difference in storage quality of the fruit, with the CleanFruit strawberries having a higher incidence of fruit rot and grey mould than those from the conventional plot.
The overall conclusion is that the zero-residue strategy has no impact on the quality of the strawberries. The high incidence of grey mould may be limited by applying good agronomic practices to limit its spread. The spread of powdery mildew can be limited by sulphur or sodium bicarbonate treatments and by increasing the distance between plants. Aphids have been controlled thanks to beneficial insects applied during the season. Regarding spider mite, a careful monitoring of the population is recommended throughout the season and acaricide treatments should be avoided approaching harvest time.
Acidity testing for strawberries
Strawberry purees and powders were also tested and showed that the strategy, CleanFruit or conventional, had no impact on the sensory quality of strawberries. Strawberries obtained from both farms are a little different to each other, with higher sugars, acidity, taste intensity and sweetness in one farm, potentially reflecting a slightly higher degree of ripeness. This difference disappears after spray drying.
Strawberries were tested for chemical residues. None of the samples strictly meets the target of zero residue.
- We are almost there with the CleanFruit plot sample from one farm.
- Both CleanFruit samples look better than the conventional ones
- We have a problem of Fosetyl Aluminium almost everywhere
- We observed various individual pesticide traces, especially in conventional samples in both farms, that may be representative of applied pesticides.
These differences and issues will be investigated further in 2021, with alternative treatments identified.
Project Status & Results - Apple Trials
Apple field trials have taken place on farms in Italy and Spain for 2020. In Italy, 2 varieties of apple were targeted: ‘Gala’ and ‘Jeromine’, both being grown on the same farm. In Spain the variety was ‘Gala'. As with strawberries, plant pathogens and arthropods were monitored at regular intervals throughout the fruit growing seasons, identifying diseases and pest outbreaks. Within the CleanFruit strategy test plots, the growers were provided with advice and appropriate biological control products from Koppert.
Gala apples
Jeromine apples
The control plots in Italy differed from each other: for ‘Gala’ this was an organic treatment, and for ‘Jeromine’ this was a conventional plot, using mainly a variety of chemical applications alongside some pheromone attractants and soil bacteria treatments.
The organic control treatment was very similar to the CleanFruit treatment. The main differences were use of a green slurry and the soil bacterium Bacillus thuringiensis, which were used in the organic but not in the zero-residue treatments, and for the CleanFruit zero residue treatment the nematode Steinernema feltiae was included.
The main issues for apples were incidences of fireblight (Erwinia amylovora), apple scab caused by the fungus Venturia inaequalis, and presence of several species of aphid, including Rosy apple aphid (Dysaphis plantaginea), apple aphid (Aphis pomi), and woolly apple aphid (Eriosoma lanigerum).
Fireblight
Aphis pomi
In addition, spotting on leaves caused by Alternaria spp. fungi were found, plus fruit rots caused by Monilia spp. infection, and occurrences of codling moth (Cydia pomonella).
Alternaria leaf spot
Monilia fruit rot
Throughout the season, the pathogens and pests were assessed 2-3 times in both organic/conventional and the CleanFruit zero-residue plots, and in most cases no significant differences were found, the CleanFruit biological treatments being equally as effective as the conventional chemical or organic treatments. Some differences were found on one farm, with fewer incidences of Alternaria leaf spotting on ‘Gala’ apples within the CleanFruit treatment than in the conventional organic treatment plots. In general, during the trial, there was a low incidence of the key apple pathogens (Venturia inaequalis, powdery mildew) on the zero-residue plots. Codling moth was well managed with sexual confusion and granulosis virus. Furthermore, Eriosoma lanigerum was naturally parasitized by Aphelinus mali.
Post-harvest quality of the ‘Gala’ fruits showed no significant differences between the two treatments regarding weight, size, shape, sugar levels and acidity. There was a significant difference between the two treatments about firmness, with the CleanFruit apples being firmer than the organic fruits. There were no significant differences between the treatments for the ‘Jeromine’ apples.
Apples were also tested for chemical residues. For ‘Gala’ apples, all conformed to the required tests for residue levels, both in the organic and the CleanFruit treatments. The analysis of the residues on 'Jeromine’ apples, showed the presence of captan residues as the only active ingredient found. Next year new pesticides will have to be adopted to replace it. Possible prospects for next year will be the use of half the dose for some plant protection products; the adoption of chemical control until full bloom and of biological control from mid to late season with copper, sulphur, sodium bicarbonate and neem based products.
Any differences and issues will be investigated further in 2021, with alternative treatments identified where needed.
Having seen few differences between the treatments, and therefore the results for the ‘Gala’ apples, in 2021 comparisons will be made with a conventional crop protection strategy.
