scholarly journals Effect of Nitrogen Fertilization on the Density of the Corn Leafhopper and Its Impact on Both Disease Incidence and Natural Parasitism

2021 ◽  
Author(s):  
Eduardo Gabriel Virla ◽  
Erica B. Luft Albarracín ◽  
Cecilia Diaz ◽  
Guido A. Van Nieuwenhove ◽  
Franco D. Fernández ◽  
...  
Keyword(s):  
Nitrogen Fertilization ◽  
Plant Pathogens ◽  
Disease Incidence ◽  
Egg Parasitoids ◽  
Herbivorous Insect ◽  
Specialist Herbivore ◽  
Modern Agriculture ◽  
Randomized Design ◽  
Insect Populations ◽  
Corn Leafhopper

Abstract The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) is a specialist herbivore that attacks maize in the tropical and subtropical regions of the Americas. It is vector of three relevant plant pathogens being responsible for severe yield losses. Modern agriculture is dependent on the addition of fertilizers, especially nitrogen, which may influence the nutritional quality of the plants possibly with a subsequent increment of herbivorous insect populations. Through a field experiment, using a randomized design with four treatments with different levels of fertilization, we evaluated the effects of nitrogen fertilization in corn on the population levels of the vector D. maidis, on the incidence of the diseases transmitted by it, and on the levels of parasitism of the vectors’ eggs. The amount of nitrogen fertilizer used significantly influenced the density of the corn leafhopper and the parasitism by egg parasitoids, but not the incidence of the diseases transmitted by it. Two weeks after fertilization, the vector density was significantly higher in the highly fertilized treatment. The disease incidence was not directly linked with the level of fertilization, however, the symptoms of the diseases were much less evident in plants that received higher fertilization. Parasitism levels by egg parasitoids increased accordingly to the level of D. maidis populations.

Estimation of direct damage to maize seedlings by the corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae), under different watering regimes

2021 ◽  
pp. 1-7
Author(s):  
E. G. Virla ◽  
M. V. Coll Araoz ◽  
E. Luft Albarracin
Keyword(s):  
Plant Pathogens ◽  
Water Status ◽  
Plant Mortality ◽  
Present Contribution ◽  
Specialist Herbivore ◽  
Dalbulus Maidis ◽  
Direct Damage ◽  
Biomass Loss ◽  
Ad Libitum ◽  
Corn Leafhopper

Abstract The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), a specialist herbivore, is the cause of serious losses in maize yield for its capacity to transmit three important plant pathogens. They are also active phloem feeders, that insert stylets into the plant as they feed. Females place their eggs endophytically, totally inserted in the central midrib or the leaf blades, leaving conspicuous openings in the place where the ovipositor was inserted. In spite of the consequences that feeding and oviposition may have on the water status of the plant and the production of biomass, direct damage caused by the leafhopper has been only scarcely studied. In the present contribution, we measured biomass loss due to direct damage in maize plants under two watering regimes, with water supply ad libitum and with a watering restricted regime, emulating the most frequent field conditions. Moreover, we analyzed the effects of increasing densities of the vector on the biomass loss and plant mortality and the effects of females vs males. We observed that a density of 10 insects is sufficient to cause damage to 10-day-old seedlings, even in an ad libitum watering regime; however, in drought conditions, damage can be significantly greater, causing plant mortality. Also, females cause more damage than males, due to their oviposition habits.

Response of specialist and generalist predators to nonprogressive annual fluctuations in herbivorous insect populations

2021 ◽  
pp. 104810
Author(s):  
Toru Taniwaki ◽  
Kyohei Watanabe ◽  
Hirotaka Komine ◽  
Kahoko Tochigi ◽  
Masanobu Yamane ◽  
...  
Keyword(s):  
Generalist Predators ◽  
Herbivorous Insect ◽  
Insect Populations

scholarly journals DEVELOPMENT OF PIGEON PEA INOCULATED WITH RHIZOBIUM ISOLATED FROM COWPEA TRAP HOST PLANTS

2016 ◽  
Vol 29 (4) ◽  
pp. 789-795 ◽  
Author(s):  
SALOMÃO LIMA GUIMARÃES ◽  
LAURA CRISTINA REZENDE DAS NEVES ◽  
EDNA MARIA BONFIM-SILVA ◽  
DANIELA TIAGO DA SILVA CAMPOS
Keyword(s):  
Nitrogen Fertilization ◽  
Dry Weight ◽  
Pigeon Pea ◽  
Index Number ◽  
Randomized Design ◽  
Rhizobium Strains ◽  
Commercial Inoculant ◽  
Red Latosol ◽  
Inoculation Treatment ◽  
Bradyrhizobium Spp

ABSTRACT Pigeon pea is an important protein source grown in several tropical and sub-tropical countries, and is considered a multi-purpose plant that is resistant to the conditions of the Brazilian Cerrado. Among the possible uses for cowpea, its use as a green manure, increasing soil nitrogen content through the association with diazotrophic bacteria, generically known as rhizobia, is noteworthy. The present work aimed to evaluate the efficiency of Rhizobium strains isolated from cowpea plants in the development of pigeon peas cultured in Red Latosol. The experiment was conducted in a greenhouse, using a completely randomized design with seven treatments and four replications. Treatments consisted of inoculation with four Rhizobium strains (MT8, MT15, MT16, and MT23) and one commercial inoculant comprising Bradyrhizobium spp. strains BR 2801 and BR 2003. There were two controls, one absolute (without inoculation or nitrogen fertilization) and the other with nitrogen fertilization. Each experimental plot consisted of an 8-dm3 vase containing three plants. Analyzed variables included plant height, SPAD index, number and dry weight of nodules, and shoot and root dry masses. Pigeon peas responded significantly to inoculation treatment, since all the plants inoculated with Rhizobium strains isolated from cowpea strains showed results similar to plants in the nitrogen control and commercial inoculant treatments. This demonstrates a favorable plant-bacteria interaction, which can be utilized as an alternative nitrogen source for pigeon peas.

scholarly journals Production and quality of Tifton 85 pastures overseeded with black oat: effects of irrigation and nitrogen fertilization

2018 ◽  
Vol 39 (5) ◽  
pp. 2071
Author(s):  
João De Assis Farias Filho ◽  
Fabiana Luiza Matielo de Paula ◽  
Adalberto Luiz de Paula ◽  
Wagner Paris ◽  
Fabrício Ghinzelli ◽  
...  
Keyword(s):  
Nitrogen Fertilization ◽  
Dry Matter ◽  
Irrigation System ◽  
Neutral Detergent Fiber ◽  
Lower Percentage ◽  
Forage Production ◽  
Dry Matter Digestibility ◽  
Randomized Design ◽  
Dead Material

The objective of this work was to evaluate the effects of irrigation and nitrogen fertilization on the bromatological quality, forage production, and botanical and structural composition of Tifton 85 (Cynodon sp.) pastures overseeded with black oat (Avena strigosa). Four treatments were evaluated in a 2 × 2 factorial scheme (irrigated and non-irrigated × fertilized and non-fertilized), with three replicates, in a completely randomized design. In irrigated paddocks, the irrigation system was activated when the soil matric potential reached a value equal to, or higher than, 10 kPa and 135 kg N ha-1 was applied to fertilized paddocks, divided into four applications. The forage mass pre- and post-grazing, total forage production, and the botanical, structural, and bromatological composition of the pastures were evaluated. No interaction was observed between the irrigation and nitrogen fertilization factors for any of the variables and no significant differences were observed in forage mass between pre- and post-grazing or in Tifton leaf and stem percentages. Nitrogen fertilization had a significant effect on forage production, which was 2626.41 kg dry matter (DM) ha-1 higher in fertilized pastures than in unfertilized pastures. In addition, fertilization resulted in a lower percentage of dead material (6.66%), higher percentage of oat leaves (30.84%), higher leaf:stem ratio (1:45), higher crude protein content (24.13%), lower levels of neutral detergent fiber (NDF) (64.57%) and acid detergent fiber (ADF) (32.86%), and higher in vitro dry matter digestibility (73.01%) than in unfertilized pastures. The use of irrigation did not influence total forage production, however, it resulted in pastures with lower NDF (65.97%) and ADF (33.54%), and higher in vitro dry matter digestibility (73.48%) than unirrigated pastures. Nitrogen fertilization produced improvements in pasture structure, associated with higher dry matter yield and bromatological quality, while irrigation only produced pastures with lower fiber content and greater digestibility.

scholarly journals Nitrogen and silicon fertilization of upland rice

2003 ◽  
Vol 60 (4) ◽  
pp. 761-765 ◽  
Author(s):  
Munir Mauad ◽  
Carlos Alexandre Costa Crusciol ◽  
Hélio Grassi Filho ◽  
Juliano Corulli Corrêa
Keyword(s):  
Nitrogen Fertilization ◽  
Upland Rice ◽  
Essential Element ◽  
Rice Cultivar ◽  
Opening Angle ◽  
Mechanical Resistance ◽  
Randomized Design ◽  
Silicon Fertilization ◽  
Grain Productivity ◽  
Nitrogen Rates

Silicon is not considered an essential element for plant development and growth, but its absorption brings several benefits to some crops, especially rice, by increasing cellular wall thickness, providing mechanical resistance to the penetration of fungi, improving the opening angle of leaves and making them more erect, decreasing self-shading and increasing resistance to lodging, especially under high nitrogen rates. To evaluate the effects of nitrogen and silicon fertilization on vegetative and yield components, plant height, and yield of rice cultivar IAC 202, an experiment was carried out combining three nitrogen rates (5, 75 and 150 mg N kg-1 soil) applied as urea, and four silicon rates (0, 200, 400 and 600 mg SiO2 kg-1 soil) applied as calcium silicate. Trial was set up in a completely randomized design 3 ´ 4 factorial scheme, (N = 5). Nitrogen fertilization increased the number of stems and panicles per square meter and the total number of spikelets, reflecting on grain productivity. Excessive tillering caused by inadequate nitrogen fertilization reduced the percentage of fertile stalks, spikelet fertility and grain mass. Silicon fertilization reduced the number of blank spikelets per panicles and increased grain mass, but did not affect grain productivity.

scholarly journals Morphological and pathogenic characterization of Fusarium oxysporum in lulo (Solanum spp.)

2021 ◽  
Vol 38 (1) ◽  
pp. 20-37
Author(s):  
Yohana Patricia Anama ◽  
Ricardo Díaz ◽  
David Esteban Duarte-Alvarado ◽  
Tulio Cesar Lagos-Burbano
Keyword(s):  
Growth Rate ◽  
Fusarium Oxysporum ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Morphological Characterization ◽  
Sources Of Resistance ◽  
Randomized Design ◽  
Two Factors ◽  
Height Increase ◽  
Genotype G1

Fusarium oxysporum is one of the most limiting fungal pathogens of lulo crop. To determine its pathogenicity, this work morphologically and pathogenically characterized F. oxysporum isolates from different lulo-growing municipalities of the Department of Nariño. Twenty isolates were evaluated through a completely randomized design with two factors and three replicates per treatment, including a control. The first factor corresponded to 20 isolates of F. oxysporum and the second to 10 lulo genotypes. The morphological characterization involved determining growth rate (GR), color (CO), mycelial type (MT), medium coloration (Mc), shape (Sh), size (S), number (N) of macroconidial (Ma) and microconidial (Mi) septa, presence of chlamydospores (PC), and chlamydospore shape (CS). Moreover, the pathogenic characterization was based on the incubation period (IP), absolute growth rate (AGR), disease severity (DS), disease incidence (I), and vascular discoloration (VD). The morphological characterization demonstrated that all isolates corresponded to F. oxysporum. For IP, genotype G1 showed the lowest average at 18 days. For AGR, genotype G2 had the lowest height increase at 0.05 cm.day-1. For DS, genotype G1 reached the highest severity level (level 9) and a disease incidence of 100%. This study provides the first report of the special form of F. oxysporum f. sp. quitoense in Nariño. Solanum hirtum, Solanum sessiliflorum, and Solanum estramonifolium were resistant to the isolates evaluated, demonstrating that wild species should be considered as sources of resistance for breeding programs aiming to obtain resistant commercial genotypes.

scholarly journals Synergistic Antifungal Activity of Graphene Oxide and Fungicides against Fusarium Head Blight In Vitro and In Vivo

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2393
Author(s):  
Xiuping Wang ◽  
Fei Peng ◽  
Caihong Cheng ◽  
Lina Chen ◽  
Xuejuan Shi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Plant Pathogens ◽  
Antimicrobial Agents ◽  
Plant Protection ◽  
Disease Incidence ◽  
Agricultural Science ◽  
Plant Diseases ◽  
Synergistic Activity

Plant pathogens constantly develop resistance to antimicrobial agents, and this poses great challenges to plant protection. Therefore, there is a pressing need to search for new antimicrobials. The combined use of antimicrobial agents with different antifungal mechanisms has been recognized as a promising approach to manage plant diseases. Graphene oxide (GO) is a newly emerging and highly promising antimicrobial agent against various plant pathogens in agricultural science. In this study, the inhibitory activity of GO combined with fungicides (Mancozeb, Cyproconazol and Difenoconazole) against Fusarium graminearum was investigated in vivo and in vitro. The results revealed that the combination of GO and fungicides has significant synergistic inhibitory effects on the mycelial growth, mycelial biomass and spore germination of F. graminearum relative to single fungicides. The magnitude of synergy was found to depend on the ratio of GO and fungicide in the composite. In field tests, GO–fungicides could significantly reduce the disease incidence and disease severity, exhibiting a significantly improved control efficacy on F. graminearum. The strong synergistic activity of GO with existing fungicides demonstrates the great application potential of GO in pest management.

scholarly journals Preliminary Study on the Activity of Phycobiliproteins against Botrytis cinerea

Marine Drugs ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. 600
Author(s):  
Hillary Righini ◽  
Ornella Francioso ◽  
Michele Di Foggia ◽  
Antera Martel Quintana ◽  
Roberta Roberti
Keyword(s):  
Spore Germination ◽  
Plant Pathogens ◽  
Disease Incidence ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Gray Mold ◽  
Fungal Plant Pathogens ◽  
Ft Ir ◽  
Preliminary Study ◽  
Ft Raman

Phycobiliproteins (PBPs) are proteins of cyanobacteria and some algae such as rhodophytes. They have antimicrobial, antiviral, antitumor, antioxidative, and anti-inflammatory activity at the human level, but there is a lack of knowledge on their antifungal activity against plant pathogens. We studied the activity of PBPs extracted from Arthrospiraplatensis and Hydropuntiacornea against Botrytiscinerea, one of the most important worldwide plant-pathogenic fungi. PBPs were characterized by using FT-IR and FT-Raman in order to investigate their structures. Their spectra differed in the relative composition in the amide bands, which were particularly strong in A. platensis. PBP activity was tested on tomato fruits against gray mold disease, fungal growth, and spore germination at different concentrations (0.3, 0.6, 1.2, 2.4, and 4.8 mg/mL). Both PBPs reduced fruit gray mold disease. A linear dose–response relationship was observed for both PBPs against disease incidence and H. cornea against disease severity. Pathogen mycelial growth and spore germination were reduced significantly by both PBPs. In conclusion, PBPs have the potential for being also considered as natural compounds for the control of fungal plant pathogens in sustainable agriculture.

scholarly journals Effects of different post-harvest treatments on bio-chemical characters and diseases of litchi in storage

2020 ◽  
Vol 8 (1) ◽  
pp. 57
Author(s):  
Fakhar Uddin Talukder ◽  
Md. Sohanur Rahman ◽  
Md. Kamrul Hassan
Keyword(s):  
Low Temperature ◽  
Vitamin C ◽  
Ambient Temperature ◽  
Disease Incidence ◽  
Storage Period ◽  
Post Harvest ◽  
Randomized Design ◽  
Two Factors ◽  
Soluble Solid ◽  
Chemical Characters

Objective of the study was to evaluate the effects of different post-harvest treatments on bio-chemical characters and diseases of litchi (Litchi chinensis Sonn, var. Bombai). The experiment consisted of two factors. Factor A: Temperature viz. T1: Ambient temperature, T2: 4ºC temperature; Factor B: PP bags (Polypropylene bag) viz. P1: Control (unwrapped), P2: 50 micro meter (µm) PP bag, P3: 75µmm PP bag, P4: 100µm PP bag. The experiment was conducted in completely randomized design (CRD) with three replications. Significant variation was observed in total soluble solid, PH of fruit pulp, vitamin c content, percent disease incidence and disease severity during the storage period. TSS contents increased up to the 6th day of storage and there after declined. pH values were maximum (4.14) in the fruits kept in 100µ polypropylene bag at ambient temperature. Vitamin C continent decreased with the increase of storage period. Disease incidence and severity progress with the storage period. Among the treated and untreated fruits, 75µm pp bag at low temperature (4ºC) treatment exhibited better storage performance. More research should be conducted by using other litchi cultivar like Bedana, China-3 etc. Various technologies have been devised to minimize the post-harvest losses of litchi, one of such technologies is the use of PP bag & low temperature.  

scholarly journals Assessing Taro (Colocasia esculenta (L.) Schott) Leaf Blight Incidence, Severity, and Farmers’ Knowledge of the Disease in Fako Division of Cameroon

2020 ◽  
pp. 17-29
Author(s):  
Mandah Cicelia Takor ◽  
Ekwa Yawa Monono ◽  
Ojong Agbor Ntane ◽  
Jemimah Evenye Ngale ◽  
Lum A. Fontem
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Management Strategies ◽  
Leaf Blight ◽  
Cultural Methods ◽  
Randomized Design ◽  
High Prevalence ◽  
Severity Of The Disease ◽  
Blight Disease ◽  
Taro Leaf Blight

Taro leaf blight (TLB), a major disease of taro plant caused by Phytophthora colocasiae, a pseudo-fungus, that occurs in many taro producing areas, especially in the South West of Cameroon. A Survey was conducted to assess farmers’ knowledge, as well as to determine the incidence and the severity of the disease in taro fields. Structured questionnaires were administered in selected locations (Bokova, Ekona, Muea, Mile 16, Mutengene, and Likomba) of taro production. Two farms were selected with two quadrats of 64 m2 each were carved to assess disease incidence and severity on taro. The number of plants infected with taro leaf blight were counted and the area of the affected leaves measured was used to evaluate the disease incidence and disease severity. Data collected were subjected to ANOVA for complete randomized design and the means were compared using Tukey test at 0.05 probability levels. The results revealed that most of the farmers could identify the disease while practicing cultural methods in controlling the disease. The results also revealed significant differences (p = 0.001) in disease incidence and disease severity in all the localities, with Mile 16 showing the highest percentage mean of 96.53% and 85.59%, respectively. The severity scored showed high infection range of 3 – 3.95 in all locations except in Likomba (2.60).  It could be concluded from the results that there were high prevalence of taro leaf blight disease in Fako Division. Good management strategies are therefore required to control Taro leaf blight and improve taro production in the area.

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