Implementing deep‐learning techniques for accurate fruit disease identification

Implementing deep-learning techniques for accurate fruit disease identification

To overcome the problem of manual identification of fruit disease here in this work we are proposing a deep-learning model to analyse fruit images to detect diseases the fruit is suffering from.


Abstract

To overcome the problems of manual identification of fruit disease, this work proposes a deep-learning model to analyse fruit images to detect diseases in the fruit. We are proposing here a convolutional neural network (CNN)-based model for fruit disease classification. By including many layers, the proposed CNN model extracts numerous features from the fruit, deals with the large data set and finally evaluates it. With the MobileNetv2 model, the disease prediction accuracy for papaya, guava and citrus was 99.4%, 98.8% and 95.8% and the recall values were 99.4%, 98.8% and 93.8%, respectively. With VGG16, the disease prediction accuracy for papaya, guava and citrus was 97.7%, 99.6% and 94.2% and the recall values were 96.5%, 99.6% and 89.2%, respectively. Finally, with DenseNet121, the disease prediction accuracy for papaya, guava and citrus was 99.4%, 97.6% and 99.2%, and the recall values were 98.8%, 97.6% and 99.2%, respectively.

Diversity of Colletotrichum species causing anthracnose on three oak species (Quercus acutissima, Q. mongolica and Q. variabilis) in China

Diversity of Colletotrichum species causing anthracnose on three oak species (Quercus acutissima, Q. mongolica and Q. variabilis) in China

The pathogenic species diversity of Colletotrichum on Quercus species from seven locations was assessed by morphological and phylogenetic analyses of ITS, gapdh, chs-1, act and tub2 sequences; nine species were identified.


Abstract

Anthracnose of oak (Quercus) caused by Colletotrichum spp. is one of the most common diseases in oak forests. To investigate the species diversity of Colletotrichum associated with oak anthracnose, symptomatic leaf samples of three oak species (Q. acutissima, Q. mongolica and Q. variabilis) were collected from Anhui, Hainan, Henan, Shaanxi and Shandong Provinces, Inner Mongolia Autonomous Region, and Beijing City in China from 2019 to 2022. A total of 219 Colletotrichum isolates were obtained and identified by morphological and phylogenetic analyses of the rDNA internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (gapdh), chitin synthase 1 (chs-1), actin (act) and β-tubulin (tub2) sequences. Nine species were identified: C. fioriniae (two isolates, 0.9%), C. camellia-japonicae (two isolates, 0.9%), C. karstii (three isolates, 1.4%), C. quercicola (two isolates, 0.9%), C. aenigma (three isolates, 1.4%), C. endophyticum (two isolates, 0.9%), C. fructicola (68 isolates, 31.1%), C. gloeosporioides sensu stricto (74 isolates, 33.8%) and C. siamense (63 isolates, 28.8%). Pathogenicity was confirmed using Koch's postulates, which showed that five species (C. camellia-japonicae, C. endophyticum, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. acutissima anthracnose, four species (C. karstii, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. mongolica anthracnose and six species (C. fioriniae, C. quercicola, C. aenigma, C. fructicola, C. gloeosporioides s. s. and C. siamense) caused Q. variabilis anthracnose. This study demonstrates the pathogenic species diversity of Colletotrichum on Q. acutissima, Q. mongolica and Q. variabilis.

Greater rate of nitrogen fertilizer application increases root rot caused by Phytophthora cinnamomi and P. plurivora in container‐grown rhododendron

Greater rate of nitrogen fertilizer application increases root rot caused by Phytophthora cinnamomi and P. plurivora in container-grown rhododendron

Application of nitrogen accelerated Phytophthora root rot disease symptoms in rhododendron plants inoculated with Phytophthora cinnamomi and P. plurivora.


Abstract

Phytophthora root rot, caused by many Phytophthora species, decreases the health of rhododendrons produced in nurseries. Optimizing nitrogen (N) fertilizer is often used to improve nursery stock quality, but there is little information on how N fertilizers influence root rot caused by these pathogens. To understand the impact of N fertilizer and pathogen species on root rot development, rhododendrons were grown with no (0 g N/pot), low (1.04 g N/pot) or high (3.12 g N/pot) rates of N and inoculated with either P. cinnamomi or P. plurivora. Noninoculated plants at low and high N rates had greater biomass, leaf greenness and enhanced N, potassium, magnesium, phosphorus, sulphur and manganese uptake compared to plants grown with no N. When either Phytophthora species was present, N application increased aboveground disease symptoms (wilting, chlorosis, reduced stomatal conductance and biomass), but had no effect on root rot severity belowground. In addition, P. cinnamomi restricted uptake of several nutrients while P. plurivora had less influence on nutrient uptake. Nurseries frequently apply high amounts of N to promote fast growth. However, our results show that this can exacerbate root rot when P. cinnamomi or P. plurivora is present. Although decreasing N can reduce the number of overtly symptomatic plants, this may conversely increase the risk for selling apparently asymptomatic plants with low levels of infection. Additional studies are needed to determine how N fertilization influences Phytophthora root rot for a broader range of rhododendron cultivars and nursery crop species.

Genetic variants associated with leaf spot disease resistance in oil palm (Elaeis guineensis): A genome‐wide association study

Genetic variants associated with leaf spot disease resistance in oil palm (Elaeis guineensis): A genome-wide association study

Genome-wide association study using a diverse genetic background of the oil palm population reveals associated genes contributing to leaf spot disease resistance.


Abstract

Leaf spot is considered as a common disease of oil palm, caused primarily by Curvularia spp. fungi. This disease mainly affects the early stages of oil palm and if not adequately controlled can cause plant death. Among the methods available to control the disease, breeding resistant varieties is the most economically effective and promising strategy. A genome-wide association study for leaf spot resistance was conducted on 210 individual tenera palms from seven different (origin) crosses. These palms were subsequently infected with Curvularia spp. pathogenic inoculum in a nursery trial located in an endemic area. The area under the disease progress curve was used as a phenotypic measure. In addition, a genotyping-by-sequencing (GBS) approach was used to obtain the genotyping data of each individual. We found two loci, at chromosome 2 and chromosome 13, that were significantly associated with leaf spot disease resistance. Six genetic variants at the two loci (five variants at chromosome 2 and one variant at chromosome 13) surpassed the threshold for genome-wide significance (p < 106). These loci are linked with three widely known disease-related genes, namely, resistance gene analogue 3 (RGA3), resistance gene analogue 4 (RGA4) and receptor-like protein 9a (RLP9a). The loci identified here can be used for marker-assisted selection when developing leaf spot disease-resistant oil palm varieties.

Genetic characterization and prevalence of Pseudomonas syringae strains from sweet cherry orchards in New Zealand

Genetic characterization and prevalence of Pseudomonas syringae strains from sweet cherry orchards in New Zealand

The study identified prevalent Pseudomonas syringae strains in New Zealand cherry orchards, with P. syringae pv. syringae as the predominant pathovar in Central Otago, providing valuable insights for future epidemiology research.


Abstract

Bacterial canker of cherry, caused by Pseudomonas syringae pathovars, is a major constraint to cherry growing in New Zealand. The prevalence of strains from cherry orchards in Central Otago, the main growing area for cherries in New Zealand, was studied, to better understand the epidemiology of the disease. Pseudomonas spp. isolates were collected from symptomatic and asymptomatic cherry tissue from 23 commercial cherry orchards in 2015. Isolates were classified into strains belonging to three different taxonomic groups by determining their phylogeny using the gltA gene sequence for all the strains and multilocus sequence analysis (MLSA) of four housekeeping genes for 35 strains. Pathogenicity of all Central Otago strains was tested on immature cherry fruit to support the phylogenetic classification. The two main taxonomic groups were P. syringae pv. syringae (Pss) and P. syringae pv. morsprunorum race 1 (Psm1), in Phylogroup 2 (PG2) and Phylogroup 3 (PG3), respectively. The third group comprised nonpathogenic strains classified as Pseudomonas spp. Strains of Psm1 formed a monophyletic group, representing an almost clonal population. There was more variation detected within strains of Pss, although they were restricted to group PG2d. Nonpathogenic Pseudomonas spp. and pathogenic Pss and Psm1 strains coexisted in the same orchard. It was concluded that Pss is the predominant pathovar in Central Otago. This is the first detailed study of the P. syringae species complex in cherry orchards in New Zealand and provides the basis for future epidemiology studies.