PFDINN: Comparison between Three Back-propagation Algorithms for Pear Fruit Disease Identification

The diseases presence in various species of fruits are the crucial parameter of economic composition and degradation of the cultivation industry around the world. The proposed pear fruit disease identification neural network (PFDINN) frame-work to identify three types of pear diseases was presented in this work. The major phases of the presented frame-work were as the following: (1) the infected area in the pear fruit was detected by using the algorithm of K-means clustering. (2) hybrid statistical features were computed over the segmented pear image and combined to form one descriptor. (3) Feed forward neural network (FFNN), which depends on three learning algorithms of back propagation (BP) training, namely Scaled conjugate gradient (SCG-BP), Resilient (R-BP) and Bayesian regularization (BR-BP), was used in the identification process. Pear fruit was taken as the experiment case during this work with three classifications of diseases, namely fire blight, pear scab, and sooty blotch, as compared to healthy pears. PFDINN framework was trained and tested using 2D pear fruit images collected from the Fruit Crops Diseases Database (FCDD). The presented framework achieved 94.6%, 97.3%, and 96.3% efficiency for SCG-BP, R-BP, and BR-BP, respectively. An accuracy value of 100% was achieved when the R-BP learning algorithm was trained for identification.

Precipitation Impacts Dissemination of Three Sooty Blotch and Flyspeck Taxa on Apple Fruit

The spatial dissemination of three prevalent taxa of sooty blotch and flyspeck (SBFS) fungi under several levels of precipitation was compared during 2015 and 2016 in an Iowa apple orchard. Overhead irrigation was used to supplement ambient precipitation in order to insure SBFS spore dissemination and colony development. There were five irrigation levels, involving 1-min-long periods of irrigation that were imposed either once or twice per hour at intervals of 3, 6, or 12 h, as well as a nonirrigated control. Preselected apple fruit were inoculated with one of the three SBFS taxa to serve as sources of inoculum. Dissemination from these inoculated apple fruit was assessed at harvest by counting SBFS colonies on water-sprayed and nontreated fruit. As a further control, additional fruit were enclosed in fruit bags throughout the fruit development period. In both 2015 and 2016, the number of colonies of the SBFS fungus Peltaster gemmifer per apple increased sharply as the duration of irrigation increased, whereas the number of colonies of Microcyclosporella mali increased to a lesser extent and Stomiopeltis sp. RS1 showed no increase. In 2015, the linear relationship between the duration of irrigation-imposed precipitation levels and the number of colonies on the water-sprayed apple fruit was similar for P. gemmifer (slope = 0.09), Stomiopeltis sp. RS1 (slope = 0.07), and Microcyclosporella mali (slope = 0.13); whereas, in 2016, the slope was higher for P. gemmifer (0.28) than for Stomiopeltis sp. RS1 (−0.09) or M. mali (0.06). The results indicated that dissemination of P. gemmifer increased sharply in response to increased irrigation-imposed precipitation, and that dissemination patterns differed considerably among the three SBFS taxa. The apparent advantage of P. gemmifer in precipitation-triggered dissemination may stem from its ability to produce spores rapidly by budding. To our knowledge, this is the first article to assess splash dispersal by SBFS fungi in the field and the first to document taxon-specific patterns of dissemination in this pathogen complex.

Cyphellophora sp. Isolated from a Corneal Ulcer in the Human Eye

Cyphellophora is a black yeast-like fungus with most of the strains being isolated from soil and plants. It tends to cause sooty blotch and flyspeck disease in plants. In humans, it is known to cause superficial skin and nail infections. This report highlights the case of a patient who initially presented with a small corneal abrasion which rapidly progressed into a corneal ulcer after the patient did not respond to the initial conventional treatment. The laboratory results from the corneal scraping found it to be Cyphellophora sp.

Stealth Pathogens: The Sooty Blotch and Flyspeck Fungal Complex

Sooty blotch and flyspeck (SBFS) fungi produce superficial, dark-colored colonies on fruits, stems, and leaves of many plant genera. These blemishes are economically damaging on fruit, primarily apple and pear, because they reduce the sale price of fresh fruit. Fungicide spray programs can control SBFS but are costly and impair human and environmental health; thus, less chemically intensive management strategies are needed. Although the scientific study of SBFS fungi began nearly 200 years ago, recent DNA-driven studies revealed an unexpectedly diverse complex: more than 100 species in 30 genera of Ascomycota and Basidiomycota. Analysis of evolutionary phylogenetics and phylogenomics indicates that the evolution of SBFS fungi from plant-penetrating ancestors to noninvasive ectophytic parasites was accompanied by a massive contraction of pathogenicity-related genes, including plant cell wall–degrading enzymes and effectors, and an expansion of cuticle-degradation genes. This article reviews progress in understanding SBFS taxonomy and ecology and improving disease management. We also highlight recent breakthroughs in reconstructing the evolutionary origins of these unusual plant pathogens and delineating adaptations to their ectophytic niche.

Impact of Exclusion Netting Row Covers on ‘Honeycrisp’ Apple Trees Grown under Northeastern North American Conditions: Effects on Photosynthesis and Fruit Quality

Exclusion nets have been used successfully to protect fruit from insect pests of apples under various conditions, but the effect of each particular netting system on the plant itself has rarely been investigated. In this study, a complete exclusion system—in which the soil is also excluded—was used to grow ‘Honeycrisp’ apples for six years in southern Quebec, Canada. Abiotic conditions, as well as plant photosynthesis and fruit quality characteristics (colour, firmness, size, sugar content, number of seeds, ripeness and skin integrity) and yield were estimated yearly and compared in netted (either with or without a rainproof top) and unnetted row units. Although annual variations were high and results showed little or no difference between netted and unnetted rows for all measured variables, with the following exceptions; colour (increased red surface on fruits from unnetted rows some years), size (fruits from unnetted rows were smaller) and maturity (fruits from unnetted rows matured slightly faster). Fruits produced under nets had fewer microcracks at the surface than fruits produced without nets. Reduced cracking possibly helped decrease sooty blotch and flyspeck incidence and severity. Impacts for pest control and prospects for pesticide-free production are discussed.

Postharvest quality implications of preharvest treatments applied to enhance Ambrosia™ apple red blush colour at harvest

Two approaches for enhancing red blush in Ambrosia™ apple were evaluated: (i) reflective row covers or (ii) application of foliar phosphorus-rich sprays, both applied several weeks before anticipated harvest. Two experiments were conducted, the first to evaluate a white reflective row cover versus foliar phosphorus spray, and the second to evaluate two types of reflective row cover, one made of a woven white polyethylene sheet and the other a solid silvered Mylar®. The comparative effects of these preharvest treatments on at-harvest fruit quality and quality after storage were assessed in both experiments. It was determined that foliar phosphorus sprays or one of the two types of reflective row covers resulted in similar enhancement of red blush colour, with no negative effects on at-harvest quality. However, in the first experiment it was found that after 8 mo of controlled-atmosphere storage (1 kPa O2 + 1 kPa CO2 at 0.5 °C), apples from the phosphorus foliar spray treatment developed greasiness and sooty blotch compared with those from the reflective row cover or control treatments. In the second experiment, after 5 mo of air storage at 0.5 °C, the apples from the silvered Mylar® reflective row cover treatment developed severe soft scald and soggy breakdown compared with the control and white reflective row cover treatments, which developed lower or very slight incidence of soft scald, respectively, and no soggy breakdown. These results indicate that when preharvest treatments are applied to apples, post-storage quality effects should be evaluated.