Crown rot is a formidable challenge in European strawberry production, threatening yield, fruit quality, and plant survival. This complex disease, caused by a suite of fungal and oomycete pathogens, manifests through similar above-ground symptoms such as wilting, chlorosis, stunted growth, yet requires specific diagnostics and tailored management. As climate change, monoculture, and international plant trade intensify disease emergence, European growers and researchers are compelled to adopt a pathogen-specific and evidence-based approach.
Pathogen Overview and Management Options
The table below highlights major crown rot pathogens currently impacting European strawberry cultivation, summarizing their distribution and key management recommendations:
| Pathogen | Occurrence | Management Recommendations |
| Neopestalotiopsis spp. (e.g., N. rosae) | Emerging in Italy, Spain, Germany | Use of certified, disease-free transplants; sanitation protocols; preventive fungicide treatments (notably fludioxonil-based dips); crop rotation and organic debris removal; experimental biocontrol adjuncts. |
| Phytophthora cactorum | Widespread | Preplant soil fumigation or solarization; good drainage and raised beds; resistant cultivars (e.g., Fronteras, Portola); fosetyl-Al and mefenoxam treatments; water management. |
| Pestalotiopsis clavispora | Netherlands, Spain | Frequently misdiagnosed as P. cactorum; effective fungicide rotation, stress mitigation, and strict hygiene are essential. |
| Fusarium oxysporum f. sp. fragariae | Spain and broader EU | Emphasis on sanitation; cultivar resistance screening underway; few effective chemical options; biocontrol under research. |
| Phytophthora fragariae | Widespread across the EU | Disease-free planting material, fungicide applications (metalaxyl or fosetyl-Al), resistant cultivars, raised beds, and trials on plant growth-promoting rhizobacteria (PGPR). |
Breeding for Resistance: European Trials
In Huelva- Spain, Europe’s largest strawberry-producing region, targeted breeding programs are evaluating resistance to P. cactorum. For instance, breeding line A14205P is undergoing multi-season inoculation under controlled environments were weekly assessments track symptom development, with goals of identifying germplasm with durable resistance. However, progress remains limited outside Phytophthora fragariae, for which some race-specific resistance genes have been identified in studies.
Biocontrol Advances and Field Trials
Recent biocontrol efforts in Germany and the Czech Republic focus on rhizosphere microbial agents. Promising candidates include:
- Raoultella terrigena
- Bacillus amyloliquefaciens
- Pseudomonas fluorescens
These agents, when applied via root drench or substrate integration, can achieve suppression rates of 40–60% in field conditions. However, their efficacy varies with environmental conditions, underlining the need for stratified multi-location trials.
Research Gaps and Future Directions
While current control strategies show partial success, one may look forward to resolving the following gaps:
- Pathogen Diagnostics: Emerging pathogens such as Neopestalotiopsis spp. are often misidentified, hence molecular assays, including multilocus sequencing (ITS, TEF1-α, β-tubulin), are required for precise diagnostics.
- Resistance Breeding: While some cultivars resist P. fragariae, no commercial varieties are resistant to Neopestalotiopsis or Fusarium pathotypes. That being a concern, breeding for broad-spectrum resistance is a long-term need now.
- Fungicide Registration & Evaluation: Fungicides such as cyprodinil + fludioxonil, prochloraz blends, and newer biosolutions lack full registration or efficacy data under EU frameworks. To make that better, rigorous field trials and toxicological assessments are essential.
- Biologicals Integration: Expanded screening of Trichoderma spp., PGPR, and microbial consortia across variable European climates is crucial to verify consistency in biocontrol effectiveness. ‘Permutations and combinations’ could be the go-to approach going forward.
References
- Pestalotiopsis.pdf
- Biological Control of Root Rot of Strawberry by Bacillus amyloliquefaciens Strains CMS5 and CMR12 – PMC
- (PDF) Biological Control of Strawberry Crown Rot Disease (Pestalotiopsis sp.) using Trichoderma harzianum and Endophytic Bacteria
- Resistance of strawberry genotypes to leather rot and crown rot caused by Phytophthora cactorum | European Journal of Plant Pathology
- Compendium of Strawberry Diseases, Second Edition | Diseases and Pests Compendium Series
- First Report of Phytophthora cactorum on Strawberry Plants in Spain | Plant Disease
Photo, Frank Louws, Botrytis Crown Rot of Strawberry, NC state extension publications, 2014.
