The strawberry (Fragaria × ananassa Duch.) is a high-value crop with an annual cultivated area of ~500 ha in Taiwan. Over 90% of strawberry cultivation is in Miaoli County. Unfortunately, various diseases significantly decrease strawberry production. The leaf and fruit disease became an epidemic in 1986. From 2010 to 2016, anthracnose crown rot caused the loss of 30-40% of seedlings and ~20% of plants after transplanting. The automation of agriculture and image recognition techniques are indispensable for detecting strawberry diseases. We developed an image recognition technique for the detection of strawberry diseases using a convolutional neural network (CNN) model. CNN is a powerful deep learning approach that has been used to enhance image recognition. In the proposed technique, two different datasets containing the original and feature images are used for detecting the following strawberry diseases-leaf blight, gray mold, and powdery mildew. Specifically, leaf blight may affect the crown, leaf, and fruit and show different symptoms. By using the ResNet50 model with a training period of 20 epochs for 1306 feature images, the proposed CNN model achieves a classification accuracy rate of 100% for leaf blight cases affecting the crown, leaf, and fruit; 98% for gray mold cases, and 98% for powdery mildew cases. In 20 epochs, the accuracy rate of 99.60% obtained from the feature image dataset was higher than that of 1.53% obtained from the original one. This proposed model provides a simple, reliable, and cost-effective technique for detecting strawberry diseases.

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Detection of Strawberry Diseases Using a Convolutional Neural Network.

Role of Neopestalotiopsis rosae in causing root rot of strawberry in Beijing, China

Blueberries (Vaccinium corymbosum) have been increasingly cultivated in Portugal. Although blueberry is known to be susceptible to twig blight and dieback caused by pestalotioid fungi, there is still scarce information regarding this issue. To bridge this gap, a survey on blueberry plantations in Portugal was carried out to assess the diversity of pestalotioid fungi associated with symptomatic blueberry plants. A collection of 51 fungal isolates was characterized by multilocus sequence analyses of the rDNA internal transcribed spacer region (ITS), translation elongation factor 1-alpha (tef1-α) and β-tubulin (tub2). The phylogenetic analyses revealed the presence of Pestalotiopsis australis, P. biciliata, P. chamaeropis, Neopestalotiopsis rosae and three novel species described as Neopestalotiopsis scalabiensis, N. vaccinii and N. vacciniicola. The new species were fully characterized based on their morphology and temperature growth requirements. The pathogenicity trials carried out on cultivar “Duke” revealed that all isolates tested were pathogenic to blueberry plants, with N. rosae being the most aggressive species. This study provides the first report of P. chamaeropis, P. biciliata and P. australis associated with blueberry dieback and twig blight symptoms in Portugal and worldwide. Additionally, N. rosae is also newly reported from Portugal. This survey disclosed the occurrence of several pestalotioid species, which may represent a threat to Portuguese blueberry plantations.

Diversity and pathogenicity of pestalotioid fungi associated with blueberry plants in Portugal, with description of three novel species of Neopestalotiopsis

Avocado (Persea americana) represents an important emerging tropical crop in Italy, especially in the southern regions. In this study, young plants of avocado showing symptoms of stem and wood lesion, and dieback, were investigated. Isolations from symptomatic tissues consistently yielded colonies of Neopestalotiopsis-like species. The characterization of representative isolates was based on the observation of morphological characters, the effect of temperature on mycelial growth rate, and on the sequencing of three different gene regions, specifically ITS, TEF1, and TUB2. Phylogenetic analyses were conducted based on maximum parsimony and maximum likelihood approaches. The results showed the presence of two species, viz. Neopestalotiopsis rosae and N. siciliana, the latter of which is here described as a new species. Pathogenicity tests were conducted using the mycelial plug technique on young potted avocado trees for both Neopestalotiopsis species. The results showed that both species were pathogenic to avocado. This study represents the first report of these two species affecting avocado and results in the description of a new species within the genus Neopestalotiopsis. Based on phylogeny, Pestalotiopsis coffeae-arabicae is combined in Neopestalotiopsis.

https://www.mdpi.com/2309-608X/8/6/562/pdf?version=1653533171

Neopestalotiopsis siciliana sp. nov. and N. rosae Causing Stem Lesion and Dieback on Avocado Plants in Italy


 Rosa (Rosaceae) is an important ornamental and medicinal plant genus worldwide, with several species being cultivated in China. Members of Sporocadaceae (pestalotioid fungi) are globally distributed and include endophytes, saprobes but also plant pathogens, infecting a broad range of host plants on which they can cause important plant diseases. Although several Sporocadaceae species were recorded to inhabit Rosa spp., the taxa occurring on Rosa remain largely unresolved. In this study, a total of 295 diseased samples were collected from branches, fruits, leaves and spines of eight Rosa species (R. chinensis, R. helenae, R. laevigata, R. multiflora, R. omeiensis, R. rugosa, R. spinosissima and R. xanthina) in Gansu, Henan, Hunan, Qinghai, Shaanxi Provinces and the Ningxia Autonomous Region of China. Subsequently 126 strains were obtained and identified based on comparisons of DNA sequence data. Based on these results 15 species residing in six genera of Sporocadaceae were delineated, including four known species (Pestalotiopsis chamaeropis, Pes. rhodomyrtus, Sporocadus sorbi and Spo. trimorphus) and 11 new species described here as Monochaetia rosarum, Neopestalotiopsis concentrica, N. subepidermalis, Pestalotiopsis tumida, Seimatosporium centrale, Seim. gracile, Seim. nonappendiculatum, Seim. parvum, Seiridium rosae, Sporocadus brevis, and Spo. spiniger. This study also represents the first report of Pes. chamaeropis, Pes. rhodomyrtus and Spo. sorbi on Rosa. The overall data revealed that Pestalotiopsis was the most prevalent genus, followed by Seimatosporium, while Pes. chamaeropis and Pes. rhodomyrtus were the two most prevalent species. Analysis of Sporocadaceae abundance on Rosa species and plant organs revealed that spines of R. chinensis had the highest species diversity.


Diversity of Sporocadaceae (pestalotioid fungi) from Rosa in China

In the 2017 strawberry season, several transplant losses reaching 50% were observed in Zamora, Michoacan Valley, Mexico, due to a new fungal disease associated with root rot, crown rot, and leaf spot. In this year the disease appeared consistently and increased in the following seasons, becoming a concern among strawberry growers. Thus, the aim of this research was to determine the etiology of the disease and to determine the in vitro effect of fungicides on mycelial growth of the pathogen. Fungal isolates were obtained from symptomatic strawberry plants of the cultivars 'Albion' and 'Festival' and were processed to obtain monoconidial isolates. Detailed morphological analysis was conducted. Concatenated phylogenetic reconstruction was conducted by amplifying and sequencing the translation elongation factor 1 α, β-tubulin partial gene, and the internal transcribed spacer region of rDNA. Pathogenicity tests involving inoculation of leaves and crowns reproduced the same symptoms as those observed in the field, fulfilling Koch's postulates. Morphology and phylogenetic reconstruction indicated that the causal agent of the described symptoms was Neopestalotiopsis rosae, marking the first report anywhere in the world of this species infecting strawberry. N. rosae was sensitive to cyprodinil + fludioxonil, captan, iprodione, difenoconazole, and prochloraz.

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Uriel Acosta-González

Papers

An Emerging Strawberry Fungal Disease Associated with Root Rot, Crown Rot and Leaf Spot Caused by Neopestalotiopsis rosae in Mexico.