Brown Spot Severity Research Articles

The interaction of fungicides and nitrogen dose under two crop establishment methods influences the severity of brown spot disease in rice

Brown spot (BS) disease poses a significant threat to rice cultivation globally, impacting millions of hectares annually. Research indicates that the severity of BS is closely linked to abiotic stresses and crop nutrition. A field experiment was conducted using transplanted (TP) and direct-seeded-rice (DSR) crop establishment methods to optimize the effective fungicide and nitrogen dose. The split-plot design was applied to study the effect of two factors (N-dose and fungicides) varying at different levels under two different crop establishment methods (TP and DSR) for two consecutive Kharif seasons (2021 and 2022). The BS severity was measured as the percent disease index (PDI), and the results of two seasons were pooled. The results indicated that all three factors significantly (p = 0.05) influenced the PDI and grain yield. The PDI under different fungicides was higher in DSR (30.20–88.90) than in TP rice (21.64–70.00). Similarly, increased N-dose altered the PDI negatively (p = 0.05) in both TP (32.16–46.12) and DSR (44.35–59.09) methods. The results indicated Tebuconazole 50% + Trifloxystrobin 25% WG (T7) at 125% recommended dose of nitrogen as the best combination, as it recorded the lowest PDI of 21.6 and 30.2 in the TP and DSR, respectively. Similarly, all three factors interacted significantly (p = 0.05) and affected the final grain yield. Overall, the BS is more severe in DSR, and a higher dose of N reduces the BS severity in both TP and DSR. Therefore, N fertilizer management, especially in the DSR, is essential, along with a fungicide, for effective management of the brown spot disease.

Efficiency of bacterial isolates on suppressing brown spot in rice plants

AbstractMany fungicides can control brown spot, caused by Bipolaris oryzae in rice (Oryza sativa L.), although searching for beneficial microorganisms for biocontrol will improve sustainable integrated pest management. The aim of this investigation was the selection of natural suppressors of the brown spot disease in rice. We performed biochemical (E1), molecular antagonism (E2) and severity suppression (E3) studies under laboratory and greenhouse conditions. The E1, E2 and E3 assays were performed with 21 isolates. The experimental design was completely randomized with three replicates. E1 characterized all 21 isolates for the production of extracellular enzymes, siderophores, biofilm, indole‐3‐acetic acid (IAA) and phosphate solubilization. E2 was conducted to test the in vitro antagonism between the 21 isolates and B. oryzae, and E3 was conducted under greenhouse conditions, where seeds of the rice cultivars BRS‐Primavera and Esmeralda were sown in plastic trays containing 3 kg of fertilized soil. After 45 days, rice leaves were sprayed and inoculated with a mixed suspension of bacterial cells (1 × 108 CFU) and B. oryzae. All of the 21 bacterial isolates produced lipase, N‐fixation, siderophore, IAA, biofilm and solubilized phosphorus. Bacillus cereus, Priestia megaterium, Stenotrophomonas nitritireducens, Serratia marcescens and Serratia nematodiphila reduced radial colony growth of B. oryzae and suppressed brown spot severity by up to 90%. This indicates the potential of these isolates for biocontrol of brown spot in rice as a component of rice disease management.

Climate and disease: tackling coffee brown-eye spot with advanced forecasting models.

Climate influences the interaction between pathogens and their hosts significantly. This is particularly evident in the coffee industry, where fungal diseases like Cercospora coffeicola, causing brown-eye spot, can reduce yields drastically. This study focuses on forecasting coffee brown-eye spot using various models that incorporate agrometeorological data, allowing for predictions at least 1 week prior to the occurrence of disease. Data were gathered from eight locations across São Paulo and Minas Gerais, encompassing the South and Cerrado regions of Minas Gerais state. In the initial phase, various machine learning (ML) models and topologies were calibrated to forecast brown-eye spot, identifying one with potential for advanced decision-making. The top-performing models were then employed in the next stage to forecast and spatially project the severity of brown-eye spot across 2681 key Brazilian coffee-producing municipalities. Meteorological data were sourced from NASA's Prediction of Worldwide Energy Resources platform, and the Penman-Monteith method was used to estimate reference evapotranspiration, leading to a Thornthwaite and Mather water-balance calculation. Six ML models - K-nearest neighbors (KNN), artificial neural network multilayer perceptron (MLP), support vector machine (SVM), random forests (RF), extreme gradient boosting (XGBoost), and gradient boosting regression (GradBOOSTING) - were employed, considering disease latency to time define input variables. These models utilized climatic elements such as average air temperature, relative humidity, leaf wetness duration, rainfall, evapotranspiration, water deficit, and surplus. The XGBoost model proved most effective in high-yielding conditions, demonstrating high precision and accuracy. Conversely, the SVM model excelled in low-yielding scenarios. The incidence of brown-eye spot varied noticeably between high- and low-yield conditions, with significant regional differences observed. The accuracy of predicting brown-eye spot severity in coffee plantations depended on the biennial production cycle. High-yielding trees showed superior results with the XGBoost model (R2 = 0.77, root mean squared error, RMSE = 10.53), whereas the SVM model performed better under low-yielding conditions (precision 0.76, RMSE = 12.82). The study's application of agrometeorological variables and ML models successfully predicted the incidence of brown-eye spot in coffee plantations with a 7 day lead time, illustrating that they were valuable tools for managing this significant agricultural challenge. © 2024 Society of Chemical Industry.

Rice resistance against Bipolaris oryzae infection is mediated by lower foliar potassium concentration

AbstractBrown spot, caused by Bipolaris oryzae, is a very important disease of rice. This study investigated the effect of potassium (K) on rice resistance to brown spot. The working hypothesis tested was that higher foliar K concentration could allow plants to respond more efficiently against fungal infection. Plants were grown in nutrient solution amended with three K rates (0.5, 1.0 and 2.5 mM) and noninoculated or inoculated with B. oryzae. The photosynthetic performance of plants, activities of defence and antioxidant enzymes and the concentrations of reactive oxygen species, phenolics and lignin were determined. Foliar K concentration was significantly higher by 38% and 91% for plants supplied with 1.0 and 2.5 mM K, respectively, compared to plants supplied with 0.5 mM K. Brown spot severity was significantly higher (≥20%) for plants supplied with 1.0 and 2.5 mM K than those supplied with 0.5 mM K (≤15%). Higher brown spot severity for plants supplied with 2.5 mM K resulted in changes in the photosynthetic apparatus, reduced chlorophyll a + b and carotenoids concentrations, and higher production of hydrogen peroxide and superoxide anion radical. In contrast, higher activities of defence and antioxidant enzymes and more production of phenolics for plants supplied with 0.5 mM K helped them to cope with B. oryzae infection more efficiently. In conclusion, rice resistance against brown spot was achieved by keeping a lower foliar K concentration linked to more active defence reactions, a robust antioxidative system and less damage to the photosynthetic apparatus.

English

Narrow brown leaf spot disease of rice caused by fungus Cercospora oryzae Miyake emerged as potential threat to rice crop in previous few years worldwide and can cause more than 40% yield loss. The disease symptoms were noted on various commercially important rice varieties in the rice growing districts of Punjab province of Pakistan. Hence, the studies were planned to assess the effects of Propiconazole fungicide application timings and different rice varieties on the severity of narrow brown leaf spot (NBLS) disease of rice to develop an accurate management strategy for the disease. The Propiconazole fungicide was tested at three various growth phases (early booting, late booting, and soft dough) of four rice varieties against the percent severity of the NBLS disease The experiments were designed under strip-plot (crisscross) design with four replications at research area of Plant Pathology Department, University of Agriculture Faisalabad. Analysis of variance has demonstrated that the main and interactive effects of fungicide applications and rice varieties were found significant. The main effects of years were found non-significant but their interactions with fungicide application timings and rice varieties were significant. Fungicide applications at soft dough and late booting phases of rice variety B-515 were found least effective to reduce the disease severity, respectively. Fungicide application at early booting of rice variety PK-1121 was found most effective by reducing the maximum percent diseases severity (47.25%) compared to control. It is concluded that, to minimize hazardous effects of chemicals on the environment by practicing multiple sprays at inappropriate growth phases of rice crop, fungicides must be applied during the early and late booting phases of rice varieties on mildly resistance, susceptible and highly susceptible rice varieties to reduce NBLS disease severity and to enhance the rice production and quality

Assessing narrow brown leaf spot severity and fungicide efficacy in rice using low altitude UAV imaging

The utilization of unmanned aerial vehicle (UAV)-based imaging systems offers precise detection of plant diseases and aids in decision-making regarding fungicide applications to optimize disease control. This study employed a twin-lens multispectral camera mounted on a low-altitude UAV to capture imagery data from rice field plots that were treated with different fungicides. The objectives of this study were to assess the severity of narrow brown leaf spot (NBLS) caused by Cercospora janseana and to evaluate the efficacy of fungicide control. Eighteen color features and vegetation indices were extracted from RGB images, while nine color features and vegetation indices were extracted from multispectral images. Through correlation analysis, four spectral features, namely Lab-a, ExGR, VDVI, and g, were found to exhibit high correlations with disease severity. Specifically, RGB imagery had greater correlation coefficients (exceeding 0.95) for both ExGR and Lab-a features compared to multispectral imagery. A multifeature inversion modeling approach was employed, using support vector regression with the top four spectral features to predict NBLS severity. The results indicated R2 values were above 0.93 for all support vector regressions. Furthermore, the efficacies of ten different fungicide treatments were evaluated, with UAV imaging consistently aligning with ground truth rating data in terms of efficacy ranking. These results demonstrate the potential of UAV imagery for use as a valuable tool for NBLS detection and assessing fungicide efficacy, offering significant benefits in the management of NBLS, which is a globally important disease in rice.

Dual effect of picolinic acid in the photosynthetic performance of rice plants infected by Bipolaris oryzae

AbstractBrown spot, caused by Bipolaris oryzae, is one of the most important diseases of rice. The non‐host toxin α‐picolinic acid (PA) has great potential to be used to enhance plant resistance against pathogen infection. The present study investigated the effect of spraying PA [0 (control), 1, 3, and 5 mg/mL] on the photosynthetic performance of rice plants (cultivar Metica‐1) infected or not with B. oryzae. Moreover, whether the PA treatment, especially at the highest concentration, could affect brown spot development was also evaluated. The chlorophyll a fluorescence parameters such as variable‐to‐maximum chlorophyll a fluorescence ratio (Fv/Fm), photochemical yield [Y(II)], yield for dissipation by down‐regulation [Y(NPQ)], the yield for non‐regulated dissipation [Y(NO)], and electron transport rate (ETR) as well as the concentration of photosynthetic pigments were determined. Based on the in vitro assay, PA inhibited mycelial growth of B. oryzae in a dose‐dependent manner and conidial germ tube length only decreased at 5 mg PA/mL. Conidia germination was not affected by the PA treatment. Necrotic lesions caused by PA were observed on leaves of non‐inoculated plants at 3 and 5 mg PA/mL. Symptoms of the brown spot were reduced on plants sprayed with 1 and 3 mg PA/mL compared to the control treatment. Brown spot lesions and those originating from PA toxicity overlapped for inoculated plants sprayed with 3 and 5 mg PA/mL. The photochemical performance of non‐inoculated plants was hampered by treatments with 3 and 5 mg PA/mL. Greater concentration of photosynthetic pigments and less impairment on the photosynthetic performance of inoculated plants sprayed with 1 mg PA/mL were noticed based on the values of Fv/Fm, Y(II), Y(NPQ), Y(NO), and ETR compared to inoculated plants non‐sprayed with PA. In conclusion, spraying rice plants with a low concentration of PA could decrease brown spot severity while preserving the photosynthetic capacity of the infected plants. The cellular damage generated by spraying the plants with the highest PA concentration did not favour the infection process of B. oryzae.

Effect of Sowing Times and Rice Varietal Resistance on the Severity of Narrow Brown Leaf Spot Disease in Relation to Environmental Conditions

The objective of this study was to investigate the effects of sowing times and genetic resistance of 10 commercially important rice varieties on the percent disease severity (PDS) of narrow brown leaf spot (NBLS) caused by Cercospora oryzae. Two sowing time treatments (mid-May and mid-June) each year were evaluated for this 2-year study. Rice varieties were drill seeded and arranged in randomized complete block designed plots with four replications for each variety. The effects of environmental factors (high and low temperature, relative humidity and precipitation) on the NBLS severity of the rice varieties at both sowing times were also evaluated. Disease data was analyzed using computer software GenStat 10th edition. Results: By changing cultivation timing of rice varieties, B-Chenab, KSK-434, PK-386, B-Kissan, and KSK-133 from mid-May to mid-June, their resistance levels were also changed from a higher to a lower. Weather conditions during the mid-June cultivation of 2019 induced a higher level of disease severity than did the mid-May weather conditions of 2018. The variation in temperatures affected the percent disease severity more as compared to relative humidity and precipitation. High temperature of 31-33˚C and low temperature of 18-21˚C were found to be most effective in enhancing the NBLS development. Minimum NBLS severity 4.75% and 8.25% was noted on variety B-515 in mid-May and mid-June sowings respectively. Thus, its rating changed from resistant to mildly susceptible by changing sowing timing. Rice variety PK-1121 depicted maximum NBLS severity 60.25 % in mid-May sowings, rated as very highly susceptible, while severity increased to 79.25% in mid-June sowings, and rated as completely susceptible. It is concluded that the severity of NBLS was affected by genetic resistance level of rice varieties, sowing times and weather conditions thus consideration of these factors is the key to the integrated management of the NBLS in rice.

Incidência da cercosporiose na fase vegetativa de cafeeiro cultivado em solo submetido a manejo sustentável

Abstract The objective of this work was to evaluate the influence of different soil coverings, fertilizer types, and soil conditioners on the incidence and severity of brown eye spot (Cercospora coffeicola) in coffee (Coffea arabica) during the vegetative stage. The experiment was carried out in a randomized complete block design, in a 3×2×5 factorial arrangement (soil coverings × fertilizer types × soil conditioners) in subdivided plots, with three replicates. Comparisons were made among: three soil covering (plastic film, Urochloa decumbens, and no covering) in the plots; two fertililizer types (conventional and controlled release) in the sub-plots; and four soil conditioners (coffee husk, agricultural gypsum, water retention polymer, and organic compound), as well as the control, in the sub-sub-plots. The area under the progress curve for disease incidence and severity showed the lowest mean without soil covering, whereas that for number of leaves was greater with the use of the controlled-release fertilizer. The plastic film provided a greater soil moisture and a lower soil resistance penetration. The chemical composition of the organic compound reduced coffee plants growth. Soil covering with plastic film or U. decumbens favors the high incidence of brown eye spot; however, it provides a greater soil moisture and, therefore, improves the growth of coffee plants in the vegetative stage.

Integrated management of brown spot disease of rice

Brown spot of rice incited by Drechslera oryzae (Breda de Haan) Subramanian and Jain is the most important disease of rice. Regular occurence of disease and heavy yield losses caused by this disease in Bihar prompted us to undertake the studies. Seven chemicals were used for seed treatment and seven other fungicides were used for foliar spray against brown spot of rice. Seed treated with Bavistin recorded minimum disease severity (4.10%) and maximum yield (2.36 t/ha). Out of seven fungicides tested Antracol 75 WP (1.5 g/l) and RIL-FA 200SC (2.5 ml/l) reduced the disease severity and increased the yield. Among the bio-pesticides Tricure (5 ml/l), Biotos (2.5 ml/l) and Achook (5 ml/l) were found significantly effective in checking the brown spot severity and increasing the yield.

Effect of Nitrogen fertilizer, weed control and seed rate on incidence and severity of narrow brown leaf spot in rice cultivation under the dry zone of Sri Lanka

Effect of Nitrogen fertilizer, weed control and seed rate on incidence and severity of narrow brown leaf spot in rice cultivation under the dry zone of Sri Lanka

Plant density and water management effect to leaf folder and narrow brown spot severity in irrigated rice

Rice Leaf Folder and Narrow Brown Spot cause yield losses of rice production. Environmental factors are suggested effects the severity of them. This research was aimed to determine the effect of plant density and water management to the severity of these pest and disease in the agro ecosystem of irrigated paddy field. Research was conducted using Inpari 44 variety in Godean Sleman Yogyakarta, April to July 2020. Experimental design was randomized block design with 4 treatments and 4 replications. Treatments were plant density (high = 50 kg ha-1 and low = 25 kg ha-1) and water management (alternate wetting and drying/AWD, and continues flooding). Results showed that highest attack intensity of leaf folder (25%) was occurred in 42nd days after planting in high plant density with AWD. Meanwhile, highest severity of narrow brown spot (58%) was found in 63rd days after planting in plant with low density and continues flooding. High leaf folder attack intensity was caused by high plant density, but not effected by water management. At the other side, high severity of narrow brown spot was affected by water management, but not effected by plant density.

Antifungal effect of glow discharge plasma and plasma activated water against brown spot disease of rice

The impact of atmospheric glow discharge plasma and plasma activated water on reducing rice seed-borne brown spot disease was investigated. It has been shown that the generation of reactive oxygen and nitrogen species by plasma containing electrons, positive or negative ions, and neutral species has antimicrobial activity. In this study, four plasmas were used for seed treatment viz., O2-air glow discharge plasma for 90 s, 120 s, air-plasma activated water for 9 and 12 min. Control (without treatment) and chemical treatment were used in order to compare the treatment effect. The plasma treatments used for this study showed a promising positive effect on seed germination and plant growth, and reduction of brown spot severity in the field. Among the plasmas, O2-air glow discharge plasma for 90s significantly increased seed germination (94.67%) compared to control (84.0%). Conidial suspension of Bipolaris oryzae treated with O2-air glow discharge plasma for 90 s and air-plasma activated water for 9 min successfully reduced the conidial germination ability of Bipolaris oryzae on Potato Dextrose Agar (PDA). The brown spot incidence and severity were significantly reduced in the plot which received seed treatment with O2-air glow discharge plasma for 90s and air-plasma activated water for 9 min. Interestingly, the same treatment remarkably enhances the plant growth parameters and yield of BRRI dhan28 compared to control treatment.

Pengaruh beberapa teknik pengendalian terhadap keragaman dan intensitas berbagai jenis penyakit yang muncul pada pertanaman pepaya di Pekon Way Nipah Kecamatan Pematang Sawa

The study was aimed to determine the diseases in papaya plantations and to evaluate the effect of various disease control techniques against the intensity of disease in papaya plants in Pekon Way Nipah, Pematang Sawa District, Lampung. This research was conducted in October 2018 to May 2019 in the Biotechnology Laboratory, Faculty of Agriculture, University of Lampung and in Pekon Way Nipah, Pematang Sawa, Tanggamus, Lampung. This study was randomized block designed (RBD) with eight treatments consisting of control (K), biological spray agent (AHSP), manure plus biological agents (PK + AH), soil biological treatment agent (AHSI), bactericide spray (BSP)), manure (PK), solarization (SL), and tillage (OT). The study showed that the diseases that occurred on papaya plantations were suspected as powdery mildew, brown spots 1, brown spots 2, curly cladosporium, leaf curly, root rot and stem base. The treatment of manure plus biological agents reduced the severity of brown spot 1, brown spot 2, powdery mildew, and cladospsorium curling while solarization treatment suppressed the occurrence of root rot and base stem disease.

Brown spot disease severity, yield and yield loss relationships in pigmented upland rice cultivars from East Nusa Tenggara, Indonesia

Abstract. Mau YS, Ndiwa ASS, Oematan SS. 2020. Brown spot disease severity, yield and yield loss relationships in pigmented upland rice cultivars from East Nusa Tenggara, Indonesia. Biodiversitas 21: 1625-1634. Brown spot is one of the most devastating diseases of rice, which could lead to total yield loss. The disease has a worldwide distribution, more specifically in areas where water supply is scarce, most specifically in the dry upland areas. Almost all stages of rice are affected by the disease, where leaves and grains are mostly affected. Considerable differences exist in susceptibility to brown spot among rice varieties, which may cause a large variation in yield loss caused by the disease. Therefore, the resistance level of rice varieties and their yield reduction has to be regularly evaluated and updated. There are only a few reports on the relationship between brown spot severity with yield and yield loss of upland rice, and is even lacking in pigmented upland rice. The objectives of the present study were to assess the brown spot severity and resistance level in pigmented upland rice cultivars from East Nusa Tenggara Province, Indonesia, and to elucidate their relationships with yield and yield reduction. Twenty four pigmented upland rice genotypes were evaluated in the field during May to October 2019, and their disease responses and yields were recorded. Disease severity was observed weekly and used to calculate Area Under the Disease Progress Curve (AUDPC) for comparison among the genotypes. The relationships between disease severity and AUDPC with yield and yield loss were also examined. The results showed significant variation in brown spot severity and AUDPC, ranging from, respectively, 11.11% to 40.70% and 398.42%-days to 1081.30%-days. Yields and yield losses of test genotypes also varied substantially. Yields under diseased-free and diseased plots ranged from, respectively, 2.34 t ha-1 to 6.13 t ha-1 and 1.68 t ha-1 to 3.74 t ha-1 while yield loss was between 10.46% and 56.15%. Six genotypes were moderately resistant, four genotypes were moderately susceptible and 14 genotypes were susceptible to brown spot. Neither disease severity nor AUDPC had a linear relationship with yield but both exhibited positive and linear relationships with yield loss.

Diagrammatic scale for quantifying severity of brown leaf spot on Carya illinoinensis.

Brown leaf spot disease, caused by the fungus Ragnhildiana diffusa, is responsible for losses in pecan orchards and quantification is essential in order to conduct epidemiological studies to establish levels of productivity losses, and assess control strategies. Therefore, the aim of this study was to develop and validate a diagrammatic scale for assessing the severity of brown leaf spot in pecan. 240 symptomatic leaflets were collected from adult trees in Anta Gorda, in the Brazilian state of Rio Grande do Sul, and used to assess the current percentage severity of the disease. The scale was based on the minimum and maximum observed severity of the disease, with six graduations defined according to the Weber-Fechner Visual Stimulus Law. The scale therefore consisted of eight levels (1.5, 4.6, 10.6, 17.3, 39.5, 65.1, 77.5, and 98%). The estimates of eight evaluators provided a basis for validating the scale. They made estimates of disease severity on 40 symptomatic digitalized pecan leaflets first, without using the scale and then referring to it. The scale provided greater precision, accuracy, and reproducibility of estimates and should result in more reliable epidemiological studies.

Diagrammatic scale for assessment of alternaria brown spot severity on tangerine leaves

Alternaria brown spot (ABS) is one of the main diseases of tangerine worldwide. It is necessary to use a practical and reliable method to quantify the disease severity of ABS and thus suggest management strategies. Thus, a diagrammatic scale (DS) constructed with color photographs was developed and validated to quantify the disease severity. Leaves were collected from crops and a nursery with different levels of ABS symptoms to determine the real severity digitally. The scale levels were determined according to the minimum and maximum severity values found and based on the frequency distribution of severity values. The DS validation was carried out by eleven assessors who estimated the severity of 50 leaves with different symptom levels. One assessment was performed without the DS and two using the DS at seven day intervals. The precision, accuracy, repeatability and reproducibility of the estimates were measured. The developed DS has nine score levels: 0 (0%), 1 (0.1–0.49%), 2 (0.5–1.0%), 3 (1.1–2.0%), 4 (2.1–4.0%), 5 (4.1–8%), 6 (8.1–18%), 7 (18.1–30%) and 8 (30.1–50%). The linear regression and Lin’s concordance correlation coefficient (LCCC) demonstrated an improved accuracy, precision repeatability and reproducibility of the estimates using the DS. The scale is appropriate, useful and reliable to visually estimate with the ABS severity in tangerine leaves.

リモートセンシングにおいて留意すべきイネごま葉枯病発病程度と正規化植生指数(NDVI)および分光特性との関係

リモートセンシングにおいて留意すべきイネごま葉枯病発病程度と正規化植生指数(NDVI)および分光特性との関係

Brown eye spot in coffee subjected to different drip irrigation and fertilization management

Brown eye spot is one of the main diseases of coffee trees. The aim of this study was to evaluate the severity of brown eye spot in coffee plantations subjected to different drip irrigation and fertilization management. The study was carried out in Lavras-MG, Brazil, in a plantation of the cultivar MGS Travessia. Disease assessments were performed monthly from March 2012 to June 2014. The experimental design was a randomized block design with 12 treatments. The irrigation treatments were the control without irrigation, irrigation all year, suspension of irrigation for 30 days in July, and for 70 days between July and September. Fertilization treatments were recommended rate of NK fertilizer, high rate of NK plus P and high rate of NK. severity of the disease integrated into area under the disease progress curve (AUDPC). There was a difference in AUDPC in the evaluated years, reflecting the biennial characteristic of the coffee crop. There was no significant interaction between irrigation and fertilization. However, when irrigation and fertilization treatments where analyzed separately, the suspension of irrigation for 70 days between July and September in 2012 favored brown eye spot and in the same year the high rates of NK increased productivity.

Combining quince (Cydonia oblonga) rootstock with soil-applied calcium chloride solution as a strategy to control brown spot (Stemphylium vesicarium) incidence in Abbé Fétel pear fruits

Brown spot (Stemphylium vesicarium) is a fungal disease widespread in European pear industry. The high number of fungicide applications required to control the disease can promote strains with fungicide resistance. The aim of the present study was to assess the effectiveness of soil- applied water solution of calcium chloride in combination with rootstock to control the incidence of brown spot in Abbe Fetel pear. Soil salinity, stem water and osmotic potential, along with fruit fraction of calcium and defence-mechanism related-enzymes such as peroxidase, polyphenol oxidase, phenyl-alanine ammonia-lyase, and β-1,3-glucanase were investigate in tree grafted on Fox 11 (Pyrus communis L.) and Sydo®, a quince (Cydonia oblonga) rootstock. Both grafting combinations were fertigated or not with calcium chloride. Sydo® showed a positive effect in reducing brown spot severity on Abbe Fetel. Compared to Fox 11, fruits from trees grafted on Sydo® showed higher calcium concentrations, fraction of calcium pectate, fruit firmness, polyphenol oxidase, phenyl- alanine ammonia-lyase and β-1,3-glucanase levels. Fruit calcium concentration was positively correlated with disease fruit tolerance. However, soil calcium applications were ineffective in promoting fruit calcium partitioning. Calcium chloride applications decreased leaf osmotic and stem water potential in trees grafted onto Sydo®, but this wasn’t found in those grafted on Fox 11. In conclusion, Sydo® rootstock promoted Ca acquisition, osmotic adjustment at leaf and fruit level, fruit synthesis of defence-related enzymes that all together reduced brown spot severity in Abbe Fetel pear.