Automated tomato leaf disease classification using transfer learning-based deep convolution neural network

Journal of Plant Diseases and Protection - Early and accurate detection of plant diseases is necessary to maximize crop yield. The artificial intelligence based deep learning method plays a vital...     

基于卷积神经网络的农作物叶片病害诊断

农作物病害诊断对于及时发现并采取防控措施具有重要意义.本研究针对苹果、玉米、番茄、葡萄等典型农作物的常见叶片病害问题,使用了两种目前使用最广泛的卷积神经网络——VGG 16及Resnet50,对典型农作物叶片病害进行识别.使用AI Challenger比赛的农作物叶片病害数据集图像,并对这些图像进行预处理,构建了47 ...     

Weather-based prediction of anthracnose severity using artificial neural network models

Data were collected and analysed from seven field sites in Australia, Brazil and Colombia on weather conditions and the severity of anthracnose disease of the tropical pasture legume Stylosanthes scabra caused by Colletotrichum gloeosporioides . Disease severity and weather data were analysed using artificial neural network (ANN) models developed using data from some or all field sites in Australia and/or South America to predict severity at other sites. Three series of models were developed using different weather summaries. Of these, ANN models with weather for the day of disease assessment and the previous 24 h period had the highest prediction success, and models trained on data from all sites within one continent correctly predicted disease severity in the other continent on more than 75% of days; the overall prediction error was 21·9% for the Australian and 22·1% for the South American model. Of the six cross-continent ANN models trained on pooled data for five sites from two continents to predict severity for the remaining sixth site, the model developed without data from Planaltina in Brazil was the most accurate, with >85% prediction success, and the model without Carimagua in Colombia was the least accurate, with only 54% success. In common with multiple regression models, moisture-related variables such as rain, leaf surface wetness and variables that influence moisture availability such as radiation and wind on the day of disease severity assessment or the day before assessment were the most important weather variables in all ANN models. A set of weights from the ANN models was used to calculate the overall risk of anthracnose for the various sites. Sites with high and low anthracnose risk are present in both continents, and weather conditions at centres of diversity in Brazil and Colombia do not appear to be more conducive than conditions in Australia to serious anthracnose development.     

Multiple Alternaria species groups are associated with leaf blotch and fruit spot diseases of apple in Australia

Leaf blotch and fruit spot of apple caused by Alternaria species occur in apple orchards in Australia. However, there is no information on the identity of the pathogens and whether one or more Alternaria species cause both diseases in Australia. Using DNA sequencing and morphological and cultural characteristics of 51 isolates obtained from apple leaves and fruit with symptoms in Australia, Alternaria species groups associated with leaf blotch and fruit spot of apples were identified. Sequences of Alternaria allergen a1 and endopolygalacturonase gene regions revealed that multiple Alternaria species groups are associated with both diseases. Phylogenetic analysis of concatenated sequences of the two genes resulted in four clades representing A. arborescens and A. arborescens‐like isolates in clade 1, A. tenuissima/A. mali isolates in clade 2, A. alternata/A. tenuissima intermediate isolates in clade 3 and A. longipes and A. longipes‐like isolates in clade 4. The clades formed using sequence information were supported by colony characteristics and sporulation patterns. The source of the isolates in each clade included both the leaf blotch variant and the fruit spot variant of the disease. Alternaria arborescens‐like isolates were the most prevalent (47%) and occurred in all six states of Australia, while A. alternata/A. tenuissima intermediate isolates (14%) and A. tenuissima/A. mali isolates (6%) occurred mostly in Queensland and New South Wales, respectively. Implications of multiple Alternaria species groups on apples in Australia are discussed.     

Regression and artificial neural network modeling for the prediction of gray leaf spot of maize

ABSTRACT Regression and artificial neural network (ANN) modeling approaches were combined to develop models to predict the severity of gray leaf spot of maize, caused by Cercospora zeae-maydis. In all, 329 cases consisting of environmental, cultural, and location-specific variables were collected for field plots in Iowa between 1998 and 2002. Disease severity on the ear leaf at the dough to dent plant growth stage was used as the response variable. Correlation and regression analyses were performed to select potentially useful predictor variables. Predictors from the best 9 of 80 regression models were used to develop ANN models. A random sample of 60% of the cases was used to train the networks, and 20% each for testing and validation. Model performance was evaluated based on coefficient of determination (R(2)) and mean square error (MSE) for the validation data set. The best models had R(2) ranging from 0.70 to 0.75 and MSE ranging from 174.7 to 202.8. The most useful predictor variables were hours of daily temperatures between 22 and 30 degrees C (85.50 to 230.50 h) and hours of nightly relative humidity >/=90% (122 to 330 h) for the period between growth stages V4 and V12, mean nightly temperature (65.26 to 76.56 degrees C) for the period between growth stages V12 and R2, longitude (90.08 to 95.14 degrees W), maize residue on the soil surface (0 to 100%), planting date (in day of the year; 112 to 182), and gray leaf spot resistance rating (2 to 7; based on a 1-to-9 scale, where 1 = most susceptible to 9 = most resistant).     

Comparison of sampling procedures for two rice diseases: leaf blast and tungro

The precision and accuracy of eight random and systemic sampling methods, along with various sample sizes, were compared by means of a sampling simulation program with actual field data for two rice diseases, leaf blast and tungro. Three severity levels of leaf blast and two incidence levels of tungro were used. Precision depended primarily on disease intensity, followed by the sample size and the sampling method. Relative accuracy did not prove to discriminate sampling methods adequately, but simulated absolute accuracy is able to identify biases of systematic sampling paths. The results emphasize the necessity of pilot sampling at various stages of epidemics. The usefulness of simulated sample sizes and sampling methods based on real data is also demonstrated. With this approach a more practical combination of sample size and method may be found for different levels of disease intensity using precision and absolute accuracy as criteria.     

Volatile metabolite profiling to detect and discriminate stem-end rot and anthracnose diseases of mango fruits

The volatile metabolites from the headspace gas of containerised mango ( Mangifera indica ) cv. Tommy Atkins fruits, surface wounded and inoculated with the two fungal anamorphic pathogens Colletotrichum gloeosporioides and Lasiodiplodia theobromae , or non-inoculated (controls), were profiled using a portable gas chromatograph/mass spectrometer to discriminate diseases of mango. Thirty-four compounds were detected relatively consistently among replicates. Several of these were disease/inoculation-discriminatory and were classified into three groups: (i) compounds unique to only one treatment; (ii) compounds common to two or more treatments, but not to all; and (iii) compounds common to all treatments, but varying in their abundance. Two compounds, 1-pentanol and ethyl boronate, were detected in L. theobromae- inoculated mangoes alone, while thujol was observed only in C. gloeosporioides- inoculated mangoes. Discriminant analysis models based on the abundance of significant mass ions and consistent compounds correctly classified diseases/inoculations in up to 100% of cases. The disease-discriminatory compounds and discriminant analysis models developed here have the potential to be used in the early detection of postharvest diseases of mango fruits after validation under commercial conditions.     

Correction to: Droplet-vitrification cryotherapy and thermotherapy as efficient tools for the eradication of apple chlorotic leaf spot virus and apple stem grooving virus from virus-infected quince in vitro cultures

European Journal of Plant Pathology -     

BP神经网络和时间序列模型在包头市空气质量预测中的应用

运用BP神经网络法和时间序列法,对包头市的二氧化硫、二氧化氮和可吸入颗粒物的年份浓度值和月份浓度值进行预测。预测结果为:包头市2010年的二氧化硫的年浓度值为0.0578mg/m3,二氧化氮的年浓度值为0.0402mg/m3,可吸入颗粒物的年浓度值为0.1024mg/m3。2011年3月的二氧化硫的浓度值为0.0592mg/m3,二氧化氮的值为0.0372mg/m3,可吸入颗粒物的月浓度均值是0.1210mg/m3,由预测结果可以发现污染物浓度降低,空气质量呈好转趋势。     

Comparison of the reaction of tomato lines to infection by tomato yellow leaf curl begomovirus in Lebanon

Tomato yellow leaf curl begomovirus (TYLCV), transmitted by the whitefly Bemisia tabaci , is epidemic in Africa, the Middle East and South-East Asia. It is also reported in some European countries and the American continent. In Lebanon, it is the major limiting factor for summer and autumn production of tomato. Comparison of the nucleotide sequence in the intergenic region with other reported leaf curl viruses showed the Lebanese TYLCV isolate to be closely related to Egyptian, Israeli and Jamaican isolates (94–96% identity). However, it is not closely related to isolates from Sardinia, Spain and Thailand, or to tomato leaf curl isolates from India, Taiwan and Australia. In field and greenhouse screening tests conducted for 5 years on 67 tomato lines, several were identified as promising. TY-Carla, PSR and RS lines were among the most promising with determinate growth, while S&G 143 and the DR lines were the most promising with semi-determinate and indeterminate growth, respectively. Virus concentrations in most, but not all, tolerant tomato lines were significantly lower than in the susceptible lines. None of the lines tested was immune to the virus. A survey of TYLCV alternative hosts on at least 58 plant species, using nucleic acid hybridization, showed that Amaranthus sp., Malva sp., Sonchus oleraceus , Plantago sp., Solanum melongena , Phaseolus vulgaris and Mercurialis annua may play an important role in the epidemiology of TYLCV in Lebanon. Mercurialis annua is a newly reported host for TYLCV.     

Susceptibility of European pear cultivars to Pseudomonas syringae pv. syringae using immature fruit and detached leaf assays

The susceptibility of thirty-three pear cultivars and two pear rootstocks to four virulent strains of Pseudomonas syringae pv. syringae was evaluated by inoculating detached immature fruits and young leaves. The four strains were similarly virulent and did not show cultivar specificity although they were isolated from different pear cultivars and exhibited different biochemical profiles. The most frequently planted pear cultivars, Conference, Abate Fetel, General Leclerc, Williams, D. Comice, El Dorado, Alexandrine, B. Anjou, Passe Crassane and the rootstock OHxF 333 were susceptible to P. syringae pv. syringae. Maximal severity values were obtained on 'Preguystar' leaves (about 90%). The rootstock Winter Nelis was less susceptible. Results with immature fruit and detached leaf assays agreed with field observations on cultivar susceptibility to bacterial blast. However, the detached leaf test gave a more accurate prediction and has the advantages that symptoms develop quickly (48 h), and leaves are available for a longer period of time than fruits. This method is proposed as a rapid and reproducible screening system of cultivar susceptibility to bacterial blast of pear.     

A new experimental approach to the chemical control of Striga using simplified models in vitro

Two species of the parasitic genus Striga, S. hermonthica (Del.) Benth. and S. gesnerioides Willd., cause severe damage to graminaceous and leguminous crops, respectively, in tropical and semi tropical areas. Striga seed germination requires the presence of germination stimulants exuded by the roots of host plants. After attachment to the host root, the young parasite exhibits a subterranean stage of development during which it already induces considerable damage in the crop. Then, the parasite emerges from the soil, develops chlorophyllous shoots and, after flowering, produces a large number of minute seeds. Many field experiments performed in the USA to control another species (S. asiatica) have shown that application of chlorthaldimethyl, di camba or dinitroanilines prevented Striga emergence. Nevertheless the phenological stages of the parasite which are sensitive to the herbicides, as well as the mode of action of these products, are still unknown. Our experiments, performed in vitro, clearly show that chlorthal-dimethyl, dicamba or pendimethalin inhibit germination of S. hermonthica and S. gesnerioides seeds in the presence of natural germination stimulants. Moreover dicamba, clopyralid and linuron are able to induce the germination of S. gesnerioides seeds in the absence of stimulants (suicidal germination). Even if the mode of action of these herbicides in inhibition or induction of Striga seed germination has yet to be studied, such products can be useful to control Striga before attachment, thus preventing the crop from suffering the early damaging effect of the parasite. Moreover bromoxynil, ioxynil, bentazone and pyridate are potent inhibitors of photosynthesis in S. hermonthica, while they do not affect the hosts (maize and sorghum). Linuron also inhibits photosynthesis in the parasite, but it may affect these crops according to the rate applied. All these inhibitors of photosystem II could be used to control S. hermonthica after emergence, thus preventing seed production. Nouvelle approche expérimentale pour la recherche de méthodes de lutte chimique contre les Striga: utilisation de modelès simplifiés in vitro Les Striga sont des Scrophulariacées hémi-parasites de racine. Deux espèces, S. hermonth-ica (Del.) Benth. et S. gesnerioides Willd. provoquent des pertes de rendement très importantes respectivement dans les céréales et les légumineuses, notamment dans la zone inter tropicale de l'Afrique. La germination des graines de Striga nécessite la présence de stimulants de germination exsudés par les racines de l'hôte. Après fixation sur les racines de son hôte, le jeune parasite présente une phase de vie souterraine hétérotrophe au cours de laquelle il inflige déjà de sévères dommages à la culture. Après émergence le parasite développe un ap-pareil aérien chlorophyllien fleurit et fructifie, produisant des milliers de graines minuscules. De nombreux essais, réalisés en plein champ aux USA pour lutter contre une autre espèce (S. asiatica) ont montré que l'application de chlorthal-diméthyle, de dicamba ou de diverses dinitroanilines inhibe partiellement l'émergence du parasite. Le stade phénologique du parasite sur lequel ces produits agissent, de même que leur mode d'action sont inconnus. Nos expériences, réalisées in vitro, montrent chlorthal-diméthyle, le dicamba et la pendiméthaline inhibent la germination des graines de S. hermonthica et S. gesnerioides en présence des stimulants de germination. En outre, le dicamba, le clopyralid, et surtout le linuron, sont capables d'induire la germination des graines de S. gesnerioides en l'absence des stimulants (germination suicide). Tous ces produits, dont le mode d'action dans l'inhibition ou l'induction de la germination reste èétudier, ouvrent des perspectives prometteuses pour la lutte préventive—la plus efficace—contre les Striga. En outre le bromoxynil, l'ioxynil, la bentazone et le pyridate, sélectifs du Maïs et du Sorgho, sont d'excellents inhibiteurs de la photosynthèse de S. hermonthica. Le linuron inhibe également la photosynthèse du parasite, mais il est moins sélectif des céréales. Ces herbicides inhibiteurs du photosystème II pourraient être utilisés dans le cadre d'un programme de lutte pour détruire S. hermonthica après émergence, empêchant ainsi la production des graines.     

Note: Comparison of three laboratory methods to evaluate the pathogenicity and virulence of tenPseudomonas syringae pv.syringae strains on apple, pear, cherry and peach trees

The pathogenicity and virulence of ten GreekPseudomonas syringae pv.syringae strains from different hosts (citrus, pear, apple, peach and cherry) were evaluated using three different laboratory methods, which produced results in good agreement. All ten strains were virulent on apple, pear, cherry and peach trees. The extent of tissue colonized varied considerably among strains and cultivars. On excised shoots and twigs of apple and pear, strains BPI 176, BPI 203, PI 2 and PI 14 were the most virulent and strains BPI 689, BPI 992, BPI 4, BPI 20, PI 18 and PI 19 were the least virulent. On excised shoots and twigs of peach and cherry, strains BPI 176, BPI 203, PI 2, PI 14, PI 18 and PI 19 were the most virulent and strains BPI 4 and BPI 20 were the least virulent. Moderate virulence was evinced by strains BPI 689 and BPI 992. These pathogenicity assays are proposed as rapid and reproducible screening systems to evaluate the susceptibility of apple, pear, cherry and peach cultivars to this bacterial pathogen.     

Comparison of leaf proteomes of potato (<Emphasis Type="BoldItalic">Solanum tuberosum</Emphasis> L.) genotypes with ER- and HR-mediated resistance to PVY infection

The Ny-1 and Ry-fsto genes of potato (Solanum tuberosum L.) confer hypersensitive response (HR) and extreme resistance (ER), respectively, to Potato virus Y (PVY). ER-type resistance was also observed in potato plants with both alleles (Ny-1 and Ry-fsto). Using two-dimensional electrophoresis (2-DE), quantitative differences between PVY-infected and non-infected control plants were found for 35, 32 and 15 protein spots identified in leaves of potato cultivar Rywal (possessing Ny-1), and potato tetraploid clones PW 363 (with Ry-fsto) and PB 08–137 (with Ny-1 + Ry-fsto), respectively. We recognized 29, 12 and 21 PVY-induced protein spots involved in qualitative changes in Rywal, PW 363 and PB 08–137 plants, respectively, which were processed and analysed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. A database search indicated that these 62 proteins belong to various functional categories. Their expression was genotype-specific. In the case of cultivar Rywal with HR-mediated resistance, proteins involved in photosynthesis and primary metabolism were the most abundant. For PW 363 and PB 08–137, both with ER–mediated resistance, stress-responsive proteins were the most numerous. Only two proteins – glutamate–glyoxylate aminotransferase 2 (GGAT2) and monodehydroascorbate reductase 5 (MDHAR5) – were identified in all three genotypes. These two proteins are components of the reactive oxygen species (ROS) defence mechanism against pathogens in plants. The present study showed that the differences in PVY-induced proteins in the leaves of Ny-1, Ry-fsto and Ny-1 + R-fsto genotypes do not correspond to the type of gene conferring the resistance or to the observed phenotype.     

A comparative assessment of potential components of partial disease resistance to <Emphasis Type="Italic">Fusarium</Emphasis> head blight using a detached leaf assay of wheat,barley and oats

The relative resistance of 15 winter barley, three winter wheat and three winter oat cultivars on the UK recommended list 2003 and two spring wheat cultivars on the Irish 2003 recommended list were evaluated using Microdochium nivale in detached leaf assays to further understand components of partial disease resistance (PDR) and Fusarium head blight (FHB) resistance across cereal species. Barley cultivars showed incubation periods comparable to, and latent periods longer than the most FHB resistant Irish and UK wheat cultivars evaluated. In addition, lesions on barley differed from those on wheat as they were not visibly chlorotic when placed over a light box until sporulation occurred, in contrast to wheat cultivars where chlorosis of the infected area occurred when lesions first developed. The pattern of delayed chlorosis of the infected leaf tissue and longer latent periods indicate that resistances are expressed in barley after the incubation period is observed, and that these temporarily arrest the development of mycelium and sporulation. Incubation periods were longer for oats compared to barley or wheat cultivars. However, oat cultivars differed from both wheat and barley in that mycelial growth was observed before obvious tissue damage was detected under macroscopic examination, indicating tolerance of infection rather than inhibition of pathogen development, and morphology of sporodochia differed, appearing less well developed and being much less abundant. Longer latent periods have previously been related to greater FHB resistance in wheat. The present results suggest the longer latent periods of barley and oat cultivars, than wheat, are likely to play a role in overall FHB resistance if under the same genetic control as PDR components expressed in the head. However the limited range of incubation and latent periods observed within barley and oat cultivars evaluated was in contrast with wheat where incubation and latent periods were shorter and more variable among genotypes. The significance of the various combinations of PDR components detected in the detached leaf assay as components of FHB resistance in each crop requires further investigation, particularly with regard to the apparent tolerance of infection in oats and necrosis in barley, after the incubation period is observed, associated with retardation of mycelial growth and sporulation.