Showing papers in "Journal of Plant Diseases and Protection in 2016"
TL;DR: The role of the amino acid exchange on resistance profile against the most relevant AHAS-inhibiting herbicides is highlighted and first indications were found that fitness of the Asp376Glu genotype is hampered.
Abstract: Recently, the acetohydroxyacid synthase (AHAS) amino acid substitution Asp376Glu was detected in a Lolium perenne population originating in France. This is the first documented occurrence of the Asp376Glu single-nucleotide polymorphism in a Lolium species. The effects on herbicide efficacy and plant fitness are presented. Separation of the original population into different genetic subgroups allowed the comparison of different L. perenne AHAS genotypes according to their susceptibility to AHAS-inhibiting herbicides. Root and shoot biomass accumulation as well as tiller production was analysed for resistant and sensitive populations. Genotype-specific AHAS activity and inhibition were studied in vitro, using recombinant Arabidopsis thaliana DNA. Plants expressing the AHAS Asp376Glu genotype were resistant against mesosulfuron + iodosulfuron, pyroxsulam and propoxycarbazone. To imazamox, reduced susceptibility for dosages below 140 g a.i. ha−1 was observed. In the absence of herbicide, no significant impact of the Asp376Glu genotype on shoot biomass and tiller accumulation could be observed, whereas root biomass of the Asp376Glu genotype was significantly reduced by 68 % compared to the AHAS genetic wild type. The AHAS enzyme study revealed reduced AHAS enzyme rate of 48 % for the Asp376Glu genotype compared to the AHAS genetic wild type. This study highlights the role of the amino acid exchange on resistance profile against the most relevant AHAS-inhibiting herbicides. First indications were found that fitness of the Asp376Glu genotype is hampered.
26 citations
TL;DR: Novel poly(dl-lactide-co-glycolide acid) copolymer-based biopolymeric nanoparticles and cellulose nanocrystals were evaluated as basic materials for their use as nanocarriers to develop innovative plant protection formulations.
Abstract: Nanotechnology can change the scenario of current tools minimizing the chemical inputs in plant protection. Here, novel poly(dl-lactide-co-glycolide acid) (PLGA) copolymer-based biopolymeric nanoparticles (NP) and cellulose nanocrystals (CNC) were evaluated as basic materials for their use as nanocarriers to develop innovative plant protection formulations. PLGA NP were synthesized and tested, and the effect of natural surfactants, such as starch and CNC, on the NP final properties was investigated. Moreover, CNC were evaluated as possible nanostructured formulation to be directly applied in plant protection treatment. The effect of both, PLGA NP and CNC, was investigated with respect to their influence on the survival of the causal agent of bacterial speck disease (Pseudomonas syringae pv. tomato, Pst), on plant development and damages (phytotoxicity effects), on tomato plant. The proposed nanocarriers are able to cover, with a uniform distribution, the tomato vegetal surfaces without any damage and to allow a regular development of the tomato-treated plants. Moreover, starch–PLGA NP formulations resulted unsuitable for Pst survival and multiplication along the time on the tomato plants surface. A great potentiality comes up of these nanocarriers on plants to carry out and to release antimicrobial active ingredients useful in innovative and sustainable plant protection strategies.
24 citations
TL;DR: A multifactor experiment investigating three different inoculation techniques using two pathogenic isolates of F. culmorum in Turkey and Fusarium pseudograminearum against known moderately resistant and susceptible wheat cultivars under controlled greenhouse conditions showed significant cultivar × inoculation method interactions, and the two species of FUSarium were considered to be virulent.
Abstract: Crown rot, caused by Fusarium culmorum and Fusarium pseudograminearum, is one of the most pervasive diseases of wheat throughout the world. Fusarium culmorum is the most prevalent causal agent in Turkey while F. pseudograminearum is the most predominant in the USA. Consistent and reliable screening methods are required to accelerate the identification and development of wheat cultivars for resistance to Fusarium crown rot in breeding programs. A multifactor experiment with seven replicates was established investigating three different inoculation techniques (seedling dip, stem base droplet and colonized grain) using two pathogenic isolates of F. culmorum in Turkey and Fusarium pseudograminearum in the USA, respectively, against known moderately resistant and susceptible wheat cultivars under controlled greenhouse conditions. Plants were harvested and evaluated for crown rot severity using a 0–10 rating scale. Results indicated that disease severity was greater in seedling dip, compared to colonized grain, and stem base inoculation (in decreasing order of severity), respectively. However, the colonized grain method produced an adequate level of severity and consistent cultivar ranking in both experiments. Results showed significant cultivar × inoculation method interactions, and the two species of Fusarium were considered to be virulent.
20 citations
TL;DR: Pathogenicity tests showed that all isolates of Phytophthora spp.
Abstract: Crown and leather rot of strawberry caused by Phytophthora spp. are major soil diseases of cultivated strawberry (Fragaria × ananassa) in Poland. In this study, in total 45 isolates of Phytophthora spp. from plants of cultivars Elsanta, Honeoye, Florence, Camarosa, Roxana, Onebor, Alba, Elegance, Albion, Senga Sengana and Malwina originating from crowns (20 isolates) and fruits (25 isolates) as well as 25 soil samples from the same fruiting strawberry plantations located in central, north-eastern, and south-eastern regions of Poland were identified. Among them, 44 isolates from plant organs and eight from soil samples were identified as Phytophthora cactorum and from one plant and one soil sample as P. citricola; of those remaining from the soil, one was identified as P. citrophthora and one as P. cryptogea. Identifications were based on morphological characteristics and DNA analyses. Species-specific polymerase chain reaction confirmed the presence of Phytophthora spp. in all positive examined plant and soil samples and confirmed that P. cactorum is predominantly responsible for crown and leather rot diseases of strawberry in monitored regions of Poland. Pathogenicity tests showed that all isolates of Phytophthora spp. originating from soil derived from strawberry plantations were pathogenic both to strawberry and to raspberry.
19 citations
TL;DR: Mass trapping with delta traps significantly reduced the percentage of infested leaves and fruits compared with insecticide-treated controls and factors affecting the trapping efficiency in the field are discussed.
Abstract: Tuta absoluta (Lepidoptera, Gelechiidae) has recently invaded and spread through the major tomato-growing regions in Europe, Africa, the Mediterranean Basin and the Middle East. The leaf-mining habit of this invasive pest makes chemical or biological control more difficult. As an alternative, mass trapping could be used to manage low initial densities of newly arriving populations by exploiting Allee effects. In 2012 and 2013, experiments were conducted with three types of traps using a density of 40 traps per ha in open-field tomato crops in Turkey. The treatments were comprised of: (1) delta traps baited with pheromone only; (2) water pan traps baited with pheromone only; (3) water pan traps with both pheromone and a light source; and (4) insecticide-treated control. The moths were first recorded in traps in mid-June. Moth catches showed a trimodal seasonal activity and continued until the end of harvest in late August. Delta traps caught significantly more moths than the other two trap types. Female moths were only captured in pheromone-baited water traps with a light source, representing 13.9 and 12.7 % of the total moth catch in these traps in 2012 and 2013, respectively. Mass trapping with delta traps significantly reduced the percentage of infested leaves and fruits compared with insecticide-treated controls. Factors affecting the trapping efficiency of each treatment in the field are discussed.
18 citations
TL;DR: Assessment of the metabolite-based defense response in Brussels sprout plants against the cabbage aphid was affected by the following LED-generated wavelengths of light, showing a significant reduction in B. brassicae performance in the UV-A treatment compared to the blue light treatment.
Abstract: Although short-wavelength light and especially UV radiation can induce resistance in plants against herbivorous insects, the optimal wavelengths, light intensities (photon flux rates), and illumination schedules for inducing resistance have not been previously determined. Light-emitting diode (LED) illumination enables researchers to subject insects and plants to narrow-banded light treatments. In this study, we assessed how the metabolite-based defense response in Brussels sprout plants (Brassica oleracea var. gemmifera) against the cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphididae), was affected by the following LED-generated wavelengths of light: 300 nm (UV-B), 365 nm (UV-A), 470 nm (blue light), and 660 nm (red light). Ambient greenhouse light supplemented with light from sodium vapor lamps served as the control treatment. The results showed a significant reduction in B. brassicae performance in the UV-A treatment compared to the blue light treatment; the reduction in the UV-A treatment was accompanied by a significant increase in glucosinolate concentrations. The UV-B treatment induced significant changes in plant flavonoid concentrations but did not affect B. brassicae performance.
18 citations
TL;DR: To select effective PC mutants as biocontrol agents against bacterial wilt disease in eggplant, control effect was investigated using five eggplant cultivars and 10 PC mutants, and two PC mutants showed highly suppressive effects and are anticipated to be practicable biocOntrol agents.
Abstract: Ralstonia solanacearum is a soil-borne pathogen that causes bacterial wilt and has a wide range of hosts in numerous plant species. This pathogen undergoes phenotypic conversion (PC) from a wild-type strain pathogenic form to a non-pathogenic form in broth culture, soil, plant, and water extract of the plant. Pre-inoculation of PC mutants to Solanum plants has been shown to have a protective effect against bacterial wilt disease. To select effective PC mutants as biocontrol agents against bacterial wilt disease in eggplant, control effect was investigated using five eggplant cultivars and 10 PC mutants. Control effects differed depending on PC mutants and eggplant cultivars. Two PC mutants (8224PC and 8103PC) showed highly suppressive effects in many eggplant cultivars and are anticipated to be practicable biocontrol agents. Furthermore, the antibacterial activities of PC mutants against the wild-type pathogen were tested to elucidate the relation between antibacterial activity of PC mutant and protective effect against bacterial wilt by PC mutant. Even the PC mutants that did not indicate antibacterial activity showed high suppression of bacterial wilt, suggesting that there are factors other than antibacterial activity involved in the suppression of bacterial wilt by PC mutant.
13 citations
TL;DR: Results showed that high- and low-DON production potential of F. culmorum isolates could be useful in other Fusarium sp.
Abstract: In vitro and in planta determination and quantification of deoxynivalenol (DON) are a crucial step in food safety. tri13 amplicons of 282 bp and tri3 partial region of 863 bp were obtained from 16 isolates with DON and 15-acetyldeoxynivalenol (15-AcDON) mycotoxin profiles. Similarly, 42 3-acetyldeoxynivalenol (3-AcDON) isolates yielded 282-bp band of tri13 and 583 bp of tri3 gene in multiplex polymerase chain reaction (PCR) assays. None of the isolates were characterized as NIV producers via PCR. All Fusarium isolates have been determined as high-level DON producers (more than 1 ppm) via tri5–tri6 intergenic regions polymorphisms. tri11 expression via reverse transcriptase PCR (RT-PCR) confirmed results obtained at genomic level. High-pressure liquid chromatographic (HPLC) analysis showed that DON and/or acetylated derivatives can be co-produced with NIV. Even if each assay characterized Turkish Fusarium species as high trichothecene producer via PCR assays, HPLC analysis yielded 0–2481 µg/kg level of trichothecene production including DON, 3-AcDON and NIV. In this study, chemotype determination was carried out via multiplex PCR and tri13, and tri3 genes were co-targeted in a single reaction tube. It is posited that this is the first report on low- and high-level DON production differentiation analysis in Fusarium graminearum isolates via tri5–tri6 intergenic region analysis worldwide. Results showed that high- and low-DON production potential of F. culmorum isolates’ from tri5 to tri6 nucleotide data could be useful in other Fusarium sp. characterization. This study covers the widest range of geographical regions in Turkey to be subjected to comprehensive class B-trichothecene analysis.
13 citations
TL;DR: Scanning electron microscopy study revealed previously unreported, pronounced effects of ODA on Fusarium oxysporum, Bipolaris sorokiniana, FUSarium proliferatum and Alternaria tenuissima, providing firm evidence of the toxicity of Oda to these pathogenic fungi.
Abstract: 9-Oxo-10,11-dehydroageraphorone (ODA) is a cadinene sesquiterpene isolated from Eupatorium adenophorum. The antimicrobial activity of ODA was tested in vitro against four fungal strains and four bacterial strains. The fungitoxicity of ODA was evaluated by percentage radial growth inhibition using the poisoned food technique. ODA inhibited Fusarium oxysporum more than the other tested strains, giving EC50 values of 0.325 mg ml−1 at 48 h and 0.365 mg ml−1 at 96 h. Tests also revealed that ODA inhibits the germination of Fusarium oxysporum spores, reducing germination by 97 % at 0.5 mg ml−1 concentration. The minimum inhibitory concentrations (MIC) of ODA against four tested strains of Ralstonia solanacearum ranged from 0.25 to 1 mg ml−1 using a micro-well dilution method. In addition, our scanning electron microscopy study revealed previously unreported, pronounced effects of ODA on Fusarium oxysporum, Bipolaris sorokiniana, Fusarium proliferatum and Alternaria tenuissima, including marked shrinkage in the mycelia of all tested strains, swelling at the ends of Bipolaris sorokiniana mycelia and inhibition of spore production in the strains of Bipolaris sorokiniana and Fusarium proliferatum, providing firm evidence of the toxicity of ODA to these pathogenic fungi.
12 citations
TL;DR: It can be seen that pre-harvest spray treatment of sweetcorn at the silk growth stage can reduce the level of A. flavus infection and aflatoxin contamination in grain.
Abstract: One of the most promising management tools to reduce mycotoxins in food and feed is the pre-harvest biological control of mycotoxigenic fungi using microbes. The goal of this investigation was to evaluate the potential of a stain of Trichoderma harzianum, T77, for control of Aspergillus flavus on sweetcorn. Under greenhouse and field conditions, T. harzianum was applied as a pre-harvest spray treatment to silks of sweetcorn plants at 1, 3, 6, 8, 10, 12 and 14 days post-midsilk. Toxigenic A. flavus was spray inoculated as a conidial suspension (103 spores ml−1) onto silks at 2, 4, 7, 9, 11 and 13 days post-midsilk. Percentage kernel infection, disease ratings, ELISA and HPLC analyses were used to quantify A. flavus infection and aflatoxin contamination. There was a significant reduction in toxigenic A. flavus infection and aflatoxin contamination after silk spray treatments with T77 at 10 and 12 days post-midsilk. In vitro dual culture bioassays and ultrastructural studies using environmental scanning electron microscopy revealed antibiosis and mycoparasitism are the probable modes of action. It thus can be seen that pre-harvest spray treatment of sweetcorn at the silk growth stage can reduce the level of A. flavus contamination of grain. An integrated approach consisting pre-harvest biological control using selected strains of T. harzianum in conjunction with other post-harvest management strategies could reduce A. flavus infection and aflatoxin contamination in grain.
11 citations
TL;DR: This is the first report of P. pv.
Abstract: In October 2015, a bacterial leaf blight was observed on Miscanthus × giganteus in Jinju, South Korea. Symptoms included chlorosis and necrotic lesions on the leaves. Bacteria belonging to the γ-proteobacteria genus Pseudomonas were isolated from the affected leaves. Physiological analysis, the Biolog system, MALDI-TOF MS, and molecular techniques identified the bacteria isolated as Pseudomonas syringae pv. syringae. Healthy M. × giganteus leaves inoculated with the strain MHGNU B101, isolated from leaf lesions, developed leaf blight. Bacteria re-isolated from the leaf lesions had identical cultural characteristics and rpoD gene sequence to the original strain. This is the first report of P. s. pv. syringae causing bacterial leaf blight on M. × giganteus.
TL;DR: Overall, the results indicate that the tested products showed higher efficacy when applied 40° h ai and when the pathogen was applied at the high inoculum rate, however, that was not always the case.
Abstract: The six products, Armicarb, Vitisan, lime sulphur, Caso, Calce Fiocco and Ulmasud were tested for their ability to control downy mildew (Plasmopara viticola) on grapevine (Vitis vinifera) in order to find effective alternatives to copper, a heavy metal that is commonly used as a fungicide in organic viticulture. Each product was applied to potted grapevines at i) 40°h (degree hours) and ii) 80°h after inoculation (ai) of the pathogen. These so-called stop-sprays were tested on plants that received two different P. viticola inoculum rates. The formulated potassium bicarbonate product Armicarb and lime sulphur reduced disease incidence and severity similar to or better than the copper hydroxide treatment. Armicarb and lime sulphur reduced disease incidence by up to 46 % and 22 %, respectively, and disease severity by up to 73 % and 77 %, respectively. However, observed effects were depending on both inoculum rates and time of application. Overall, the results indicate that the tested products showed higher efficacy when applied 40°h ai and when the pathogen was applied at the high inoculum rate, however, that was not always the case. The unformulated potassium bicarbonate product Vitisan and other products based on calcium chloride, calcium hydroxide and acid clay did not reliably affect disease incidence and severity. Possible roles of inoculum density, wetting agents, and sprinkler usage during the infection procedure are discussed.
TL;DR: With the exception of the treatments with stearic acid and palmitic acid, the treatments revealed statistically significant insecticidal effects against the cowpea beetle.
Abstract: In this study the biological impact of olive oil on Callosobruchus maculatus F. (Coleoptera: Bruchidae) and its development in stored grain was evaluated. The investigation was intended to validate the effectiveness of a traditional method of protecting vegetable crops as compared with the use of pesticides whose disadvantages are well known. Seed treatments were carried out by coating Vigna unguiculata (L.) with olive oil, and with each of the major fatty acids contained in olive oil (oleic, linoleic, stearic, and palmitic) and a mixture of these compounds. The biological parameters studied to evaluate the effects of these different treatments are longevity, fecundity, and amount of hatched eggs and emerged adults of the cowpea weevil. With the exception of the treatments with stearic acid and palmitic acid, the treatments revealed statistically significant insecticidal effects against the cowpea beetle. Moreover, it is shown that such insecticidal treatments do not negatively impact the germination ability of cowpea seeds.
TL;DR: A real-time PCR assay for the determination and quantification of A. rabiei infection in chickpea tissues and accurate monitoring of disease progression in plant materials inoculated with different inoculation methods is described.
Abstract: Ascochyta blight is a devastating disease of chickpea caused by Ascochyta rabiei. In this article, we described a real-time PCR assay for the determination and quantification of A. rabiei infection in chickpea tissues and accurate monitoring of disease progression in plant materials inoculated with different inoculation methods. The primer pairs HEF1/HEF2 were designed to anneal to conserved regions of translation elongation factor 1 alpha (EF) gene for specific amplification of 82-bp fragment of A. rabiei based on SYBR Green I technology. The detection limit of assay was determined as 0.1 pg DNA. PCR specificity was confirmed by testing against uninfected chickpea tissues and another fungal species associated with chickpea. The chickpea plants were inoculated by the methods of whole-plant and detached leaflet inoculation. Disease progression in resistant and susceptible cultivars was evaluated at certain time intervals after pathogen inoculation by real-time PCR. The results revealed a good correlation between visual assessments of disease reaction and pathogen quantification in infected chickpea tissues. The target DNA sequence was also amplified from the samples of DNA extracts from artificially infested seed. This technique could provide a useful approach for efficient selection of resistant breeding material in an early stage of infection as an alternative to the visual disease assessment and will be also used for the determination and quantification of A. rabiei infection.
TL;DR: Computed tomography was used to study the burrowing activity of larvae of Sitotroga cerealella Olivier, 1789 (Lepidoptera: Gelechiidae) in damaged maize grain, and the emerged holes and the larval cavities were found to be linked by larval passages, which have been prepared directly before the pupation.
Abstract: Computed tomography was used to study the burrowing activity of larvae of Sitotroga cerealella Olivier, 1789 (Lepidoptera: Gelechiidae) in damaged maize grain. The randomly selected cobs were shelled, and the damaged maize grains were measured. The volumes and locations of cavities formed by larvae were mapped by means of a new computer-based three-dimensional imaging method. The use of new technologies have greatly improved and facilitated the detailed investigation of injured grain. The results provided additional data for biological information to covertly developing S. Cerealella. Significant volume destructions were observed only in the highly perforated grains (P = 0.032). The embryos of the infested grain were destroyed independent of the number of larvae. The emerged holes and the larval cavities were found to be linked by larval passages, which have been prepared directly before the pupation.
TL;DR: 9-oxo-agerophorone is a potential candidate as a phytotherapeutic agent for soil-borne fungal diseases and shown moderate bactericidal activity against R. solanacearum strains, with an emphasis on the growth and morphogenesis of fungi at scanning electron microscopy level.
Abstract: 9-Oxo-agerophorone is a cadinene sesquiterpene, isolated from the leaves of Eupatorium adenophorum. This study evaluated the antimicrobial activity of 9-oxo-agerophorone against three strains of Ralstonia solanacearum and four pathogenic fungi, with an emphasis on the growth and morphogenesis of fungi at scanning electron microscopy level. The determination of minimal inhibitory concentrations demonstrated that 9-oxo-agerophorone exhibited moderate bactericidal activity against R. solanacearum strains. However, antifungal assays showed that 9-oxo-agerophorone has strong toxicity against Fusarium oxysporum, Bipolaris sorokiniana, Fusarium proliferatum, and Alternaria tenuissima with median lethal concentrations ranging from 0.476 to 0.357 mg ml−1 after 4 days incubation on potato dextrose agar medium. The main changes observed by scanning electron microscopy after 9-oxo-agerophorone treatment were fungal cell wall shrinkage, loss of conidia, formation of short branches in F. oxysporum and F. proliferatum, collapse, broken cell walls, and increased hyphae diameter in A. tenuissima. The tested treatments were also effective in inhibiting spore germination of Fusarium species. The results indicated that 9-oxo-agerophorone is a potential candidate as a phytotherapeutic agent for soil-borne fungal diseases.
TL;DR: Pathogenicity tests validated on nine different sugarcane cultivars showed strain cfCHA infected maximum seven cultivars, whereas Co671 cultivars infected by all the isolates of C. falcatum were unable to infect the Co94004 cultivars.
Abstract: Red rot of sugarcane caused by the fungus Colletotrichum falcatum Went is the most destructive and severe disease worldwide. The present study identifies the C. falcatum which causes sugarcane red rot in the south Gujarat province of India. A survey was carried out in different sugarcane cultivars region, and nine strains isolated were identified as C. falcatum by using the sequencing of ITS rRNA gene. Pathogenicity tests validated on nine different sugarcane cultivars showed strain cfCHA infected maximum seven cultivars (virulence frequency 77.9 %). Interestingly, none of the C. falcatum isolates were able to infect the Co94004 cultivars, whereas Co671 cultivars infected by all the isolates of C. falcatum. This result has important implications for sugarcane breeding programmes in which Co94004 can be recommended to the farmers of south Gujarat regions, India.
TL;DR: The aim of this study was to estimate the incidence of eyespot in Lithuania and to use real-time polymerase chain reaction to determine the structure of Oculimacula fungi in winter wheat crops, which has not been previously established.
Abstract: Eyespot, caused by Oculimacula acuformis and O. yallundae, is one of the most damaging diseases in areas, including Lithuania, where mild and damp autumn and winter conditions favour the development and spread of the pathogens. The aim of this study was to estimate the incidence of eyespot in Lithuania and to use real-time polymerase chain reaction to determine the structure of Oculimacula fungi in winter wheat crops, which has not been previously established. From 2008 to 2012, 122 winter wheat fields in three different agro-ecological zones of Lithuania were reviewed for incidences of eyespot. Eyespot was identified in 95.9 % of the tested fields. Eyespot incidence in winter wheat varied depending on the experimental year and location, and the disease was spread over almost all of the tested fields. Depending on the year, the incidence of eyespot in different agro-ecological zones varied from 26.7 to 60.8 %. Both O. acuformis and O. yallundae were found to coexist on winter wheat stems. The amounts of Oculimacula spp. DNA varied between experimental years and sites. The highest amounts of both O. acuformis and O. yallundae were found in mid-lowland zones. For all years, higher averaged amounts of O. acuformis DNA were found in Middle Lithuania; however, for 2 years out of 3, averaged amounts of O. yallundae DNA were higher in eyespot-diseased winter wheat stems from western zones.
TL;DR: Crop sequence was found the prime factor for risk posed by foot and root rot diseases, while the lack of fungicidal control mostly impacted the risk posedBy leaf and head pathogens.
Abstract: Three strict field experiments (2010–2013) were conducted at the Experimental Station of Cultivar Testing in Chrząstowo in Poland (53°11′N, 17°35′E). Diagnosis of fungal pathogens to determine the threats posed by complex of diseases to two wheats, cv. Cytra (bread type) and cv. Monsun (quality type), was carried out. Risk assessment in the context of integrated pest and disease management considering crop sequence, sowing date, and control by fungicide application was carried out. This method also investigates the grain yields of wheat to address the context of disease risk with grain production. The experimental factors were fixed: pre-crop for wheat (sugar beet—B, corn for grain—C, wheat—W), the sowing date: facultative in late autumn (F) and spring (S), fungicidal intensification: C1—untreated, C2—one treatment at T2 stage (BBCH 32–65) with fluoxastrobin and prothioconazole, C3—two treatments made at T1 (BBCH 30–32) with prothioconazole and spiroxamine and at T2 (BBCH 41–65) with fluoxastrobin and prothioconazole, C4—three treatments performed at stage T1 (BBCH 29–31) with prothioconazole and spiroxamine, T2 (BBCH 37–51) with fluoxastrobin and prothioconazole, and T3 (BBCH 65–69) with prothioconazole and tebuconazole. A total of 12 wheat diseases were diagnosed, four units for foot and root rot and eight related with leaf and head. The most healthy status reached the crops of cv. ‘Monsun’: BFC4–C3, BSC4–C3, WSC4–C3, WFC4–C3, CFC4–C2 CSC4–C3, and for root and stem base: BSC4–C1, BFC4–C1, CSC4–C1, CFC4–C1. The lowest risk possessed by root and root rot diseases for cv. Cytra had crops: BFC4–C1, BSC3, CFC4–C3, and due to leaf and ear diseases the crops: BFC2–C4, BSC2–C4, WFC2–C4, WSC2–C4, CFC2–C4, CSC2–C4. Crop sequence was found the prime factor for risk posed by foot and root rot diseases, while the lack of fungicidal control mostly impacted the risk posed by leaf and head pathogens. The highest increases in yield from controlled crops were attributed to facultative wheat followed after beet (49–66 %) or wheat (36–47 %). Wheat responded positively to C2 program with a rise in yield of 26 % for cv. “Monsun” and 21 % for cv. “Cytra.” The cost-effectiveness based on two indicators E and Q has been calculated for fungicide treatments on all 48 crops.
TL;DR: Nets with wider mesh size may be appropriate in landscapes with low colonisation pressure by cabbage whiteflies since 0.8 mm mesh size had the disadvantages to support the peach-potato aphid and hinder colonisation by spiders.
Abstract: Crop cover nets are used in vegetables to reduce damage by pests. Recently, nets with 0.8 mm mesh size were recommended to protect Brassica vegetables from whiteflies, but farmers doubted their efficacy. We compared the impact of different mesh sizes on the abundance of insect pests and their antagonists on Brussels sprout in a field study and considered also important resource habitats, i.e. oilseed rape, in the surroundings. Cabbage whitefly was the most abundant pest followed by peach-potato aphid, cabbage aphid and diamondback moth. Aphid parasitism reached 48 % while syrphid larvae and spiders were the most abundant predatory taxa. The cabbage whitefly was less abundant under 0.8 mm nets in June and August compared to 7 mm nets, while no effect was observed in October. In general cabbage aphid, diamondback moth, syrphids and aphid parasitism were not affected by nets, but peach-potato aphid density increased under 7 mm nets late in the season. In contrast, spiders were less abundant under 0.8 mm than under 7 mm nets. Moreover, only the cabbage whitefly was positively affected by oilseed rape growing. In summary, 0.8 mm nets may be beneficial to reduce colonisation by cabbage whiteflies, especially in early summer and in landscapes with high colonisation pressure. Nets with wider mesh size may be appropriate in landscapes with low colonisation pressure by cabbage whiteflies since 0.8 mm mesh size had the disadvantages to support the peach-potato aphid and hinder colonisation by spiders.
TL;DR: The toxicity of an aqueous extract of fresh leaves of brassica species was tested on G. rostochiensis encysted eggs and infective, second-stage juveniles (J2) in vitro and decreased potato cyst nematode reproduction rates to below one and populations of eggs and J2/g soil were reduced.
Abstract: Potato cyst nematodes (PCN), Globodera spp., are major pests of potato worldwide. In this study, the toxicity of an aqueous extract (1 g/ml) of fresh leaves of brassica species (savoy cabbage, cauliflower, broccoli, red cabbage, turnip, white mustard and edible radish) was tested on G. rostochiensis encysted eggs and infective, second-stage juveniles (J2) in vitro. Soil infested with cysts (Pi 20 eggs/g soil) was either fumigated with metham sodium and/or biofumigated with 2 % green manure of brassica and wheat under glasshouse conditions. More than 99 % of the J2 were paralysed after 24 h and <1 % of J2 hatched from encysted eggs during a 6-week exposure to brassica extracts. Nematode reproduction on the susceptible potato cv. Marfona was reduced by green manure amendments, the numbers of new cysts was reduced by between 60 % in radish- and 33 % in cauliflower-treated soil. The reproduction rate of G. rostochiensis was reduced to less than 1, and final populations of eggs and J2/g soil were reduced by between 73 % (white mustard) and 92 % (edible radish). Likewise, green manure of wheat and metham sodium fumigation decreased potato cyst nematode reproduction rates to below one, new cysts by 50 and 42 %, and final eggs/g soil by 81 and 88 %, respectively. In infested soil, total fresh weight of aerial parts and roots of potato was decreased by 64 %, while total weight of plants was increased between 21 and 74 % in brassica amended soil, and 56 and 76 % in wheat and metham sodium-treated soil, respectively.
TL;DR: The addition of adjuvants can improve the herbicidal effects of caraway and peppermint oil; however, further research into these effects is warranted.
Abstract: Essential oils have herbicidal effects, which can potentially be improved by the addition of adjuvants. The present study evaluated (1) the stability and other physicochemical properties of peppermint and caraway oils in oil-in-water emulsions and mixtures with commercially available adjuvants and (2) the phytotoxic effects of the foliar application of peppermint and caraway oil emulsions and mixtures to Chenopodium album L. (common lamb’s quarters) and Avena fatua L. (wild oat). An investigation was conducted with two multifunctional adjuvants, two nonionic surfactants, and two mixture constituents, i.e., organic acetic acid (vinegar) and citric acid, to assess the physicochemical properties of emulsions and mixtures with essential oils. In addition, two series of greenhouse pot experiments were set up to evaluate the herbicidal effects of these emulsions and mixtures against two common weed species. None of the emulsions or mixtures under study exhibited satisfactory stability. The emulsions of both essential oils had a significant herbicidal effect against C. album. None of the adjuvants significantly improved the efficacy. On the other hand, the herbicidal effect of emulsions against A. fatua depended on the ambient temperature in the greenhouse with treatments more effective at higher temperatures. The multifunctional adjuvants AS 500 and Atpolan Bio enhanced the herbicidal effect of caraway oil against A. fatua over 2 weeks. Peppermint oil alone induced considerable short-term herbicidal effects. Some adjuvants improved the efficacy of peppermint oil shortly after application, but due to regrowth no significant effects on biomass were obtained at harvest. In summary, the addition of adjuvants can improve the herbicidal effects of caraway and peppermint oil; however, further research into these effects is warranted.
TL;DR: A disease severity analysis presented as decay diameter of leaves and length of the stem rot suggested that the isolated pathogen not only caused extensive damage to the stem of melon, but also posed potential harm to the whole melon plant including seedlings and leaves.
Abstract: In recent years, melon culture in East China represented by Shanghai district has been severely affected by a stem rot disease. Symptoms were described as the presence of badly water-soaked soft rot associated with spilled brown juice in the later stages. Based on our disease diagnosis study, 30 bacteria were isolated from the stem tissues of affected plants and one bacterial pathogen, named EXXP-01, was highly virulent on melon stem dipped in bacterial suspension. This bacterium has caused significant damage in late autumn melon cultures, and a disease severity analysis presented as decay diameter of leaves and length of the stem rot suggested that the isolated pathogen not only caused extensive damage to the stem of melon, but also posed potential harm to the whole melon plant including seedlings and leaves. The strain EXXP-01 was also found to be most closely related to P. fluorescens based on physiological and morphological characterization, and also the sequencing analysis of 16S rDNA gene and 16S–23S rDNA internal transcribed spacer gene. Moreover, sequence analysis of another housekeeping gene, the RNA polymerase β-subunit gene (rpoB), indicated that P. fluorescens EXXP-01 could be classified as P. fluorescens bv. I. This confirmed that P. fluorescens is the causal agent of melon stem soft rot. Further bactericidal test in vitro suggested that the strain EXXP-01 has strong resistance to various germicides and should be worthy of attention.
TL;DR: To the knowledge, according to the result of this study, physiological races of this pathogen were identified as race 2.5 for the first time in Ortaca and Fethiye districts of Muğla province.
Abstract: Leaf mold caused by the fungus Passalora fulva has been a serious disease in greenhouse tomatoes in Turkey. This study was conducted to determine races of tomato leaf mold that caused by the P. fulva. Single-spore cultures of twenty-two isolates were obtained from infected samples that are collected from different greenhouses which product tomato in Fethiye and Ortaca. According to the morphological characters, all of the 22 isolates were identified as P. fulva. All isolates of P. fulva were highly pathogenic to the susceptible tomato cultivars (Moneymaker (MM)-Cf-0). These isolates were tested for determination of races of P. fulva on a set of tomato differentials (MM-Cf-0, MM-Cf-2, MM-Cf-4, MM-Cf-5, MM-Cf-9) with different Cf resistance genes. To our knowledge, according to the result of this study, physiological races of this pathogen were identified as race 2.5 for the first time in Ortaca and Fethiye districts of Mugla province.
TL;DR: The role of BABA as an effective resistance inducer against Pcc that might be considered in integrated diseases management programs was confirmed and was also confirmed to have direct antibacterial effect in vitro.
Abstract: Stem rot of tomato caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) results in economic yield loss worldwide. Previous studies have demonstrated the role of β-aminobutyric acid (BABA) in control of numerous plant diseases. To extend our understanding for the efficacy of BABA as an inducer agent against plant diseases, we evaluated the effect of BABA on disease severity of stem rot during infection of tomato by Pcc. BABA at concentration of 200 µM reduced the disease severity and offered protection against Pcc. On the other hand, BABA did not have direct antibacterial effect in vitro. Furthermore, we examined the effects of BABA on expression of pathogenesis-related gene 1 (PR-1), pathogenesis-related gene 2 (PR-2), phenylalanine ammonia-lyase (PAL) and catalase (CAT). Pretreatment with BABA led to more expression of PR-1 and PR-2 after Pcc infection when compared with their counterparts pretreated with water (control). PR-1 expression in BABA/Pcc treatment increased 2.83-, 4.31-, 2.46- and 1.88-fold at 24, 48, 72 and 96 h postpathogen inoculation (hpi), respectively, compared to water/Pcc treatment. Moreover, PR-2 expression in BABA/Pcc treatment increased 2.66-, 3.43-, 2.19- and 1.91-fold at 24, 48, 72 and 96 hpi, respectively, compared to water/Pcc treatment. On the other hand, PAL expression was transient during enhanced resistance by BABA. In comparison with water/Pcc treatment, PAL expression enhanced 2.42-fold at 24 hpi in BABA/Pcc treatment, whereas PAL expression was remained unchanged at 48, 72 and 96 hpi. CAT expression increased in early stages of the resistance induced by BABA. In BABA/Pcc treatment, CAT expression enhanced 4.6- and 3.1-fold at 24 and 48 hpi, respectively, compared to water/Pcc treatment. Our data confirmed the role of BABA as an effective resistance inducer against Pcc that might be considered in integrated diseases management programs.
TL;DR: The pathogenicity of B. xylophilus towards different German pine provenances was studied in the framework of Pest Risk Assessment and Management as well in Contingency Planning in Germany.
Abstract: The pine wood nematode, Bursaphelenchus xylophilus, can cause pine wilt disease on susceptible conifer species, mainly Pinus spp., outside its natural range. One of the management options for pine wilt disease in recent decades in affected countries such as Japan was the evaluation of potentially tolerant or resistant host species. In the framework of Pest Risk Assessment and Management as well in Contingency Planning in Germany, we studied the pathogenicity of B. xylophilus towards different German pine provenances. According to the German Legal Ordinance on Regions of Provenance, 2- to 3-year-old Pinus sylvestris saplings of eight provenances were artificially inoculated with B. xylophilus using a suspension of 4000 B. xylophilus in 300 µl of tap water per tree. No significant differences in tree death between the provenances were detected. All inoculated provenances reached a mortality of 100 %, but significant differences occurred in the time course of disease development.
TL;DR: Phoma herbarum was isolated and identified on the basis of morphological characters from the necrotic areas of leaf and Koch’s pathogenicity postulates were verified, marking the first report of P.Herbarum as a pathogen of leaf necrosis of C. revoluta in Pakistan.
Abstract: Necrosis on Cycas revoluta leaves was observed on trees growing in a local garden in Lahore, Punjab, Pakistan. Phoma herbarum was isolated and identified on the basis of morphological characters from the necrotic areas of leaf. Morphology-based identification was confirmed by sequencing of ITS region of rDNA. Koch’s pathogenicity postulates were verified. To our knowledge, this is the first report of P. herbarum as a pathogen of leaf necrosis of C. revoluta in Pakistan.
TL;DR: This is the first report of tomato fruit rot caused by N. mesopotamica in Iran and the world, and on the basis of morphological and cultural characteristics, the fungus was identified as Neopestalotiopsis mesopotAMica.
Abstract: Severe fruit rot symptoms were observed on tomato crop (Lycopersicon esculentum) located in Hamedan province of Iran, in spring 2014. Affected fruits showed gray to dark spot that expanded rapidly. A fungus was consistently isolated from infected fruits. On the basis of morphological and cultural characteristics, as well as the sequences of the internal transcribed spacer region, β-tubulin and tef1 taxonomic markers, the fungus was identified as Neopestalotiopsis mesopotamica. This is the first report of tomato fruit rot caused by N. mesopotamica in Iran and the world.
TL;DR: A study on the utilization of the interpolation method in supporting and facilitating of assessing the value of the MRLs which are now being in use, and in creating their consistent system in the future is initiated.
Abstract: Setting of maximum residue levels (MRLs; tolerances in the USA) in crops requires a big amount of data concerning residues from a number of supervised field trials for each pesticide/crop combination. This task is time-consuming, costly and fairly complicated. Therefore, we initiated a study on the utilization of the interpolation method in supporting and facilitating of assessing the value of the MRLs which are now being in use, and in creating their consistent system in the future. A mathematical formula for predicting the initial pesticide residue level in mature apples was developed by establishing the relationship between application rates and residue levels of the pesticide active ingredients in mature apples. This dependence was described by a linear equation R
0 = 1.2593 × D, with coefficient of determination r
2 = 0.984, where D is an application rate of a given substance. This relationship makes it possible to predict a residue level of other substances of fungicidal activity. Thus, residue levels (both predicted by the formula and obtained in the frame of Polish National Monitoring Program) of fungicides now used in apple orchards, in mature apples were typically lower than those of the statutory MRLs. Bearing in mind that the European Union policy is directed towards substantial reduction in pesticide use, the MRLs might be reconsidered in order to be set at lower values.
TL;DR: The strategic approach described in this paper demonstrates an efficient way of screening microorganisms for biocontrol activity and validates the notion that certain microorganisms can be antagonistic to a variety of plant pathogens.
Abstract: Pepper Phytophthora blight, caused by Phytophthora capsici is the most destructive soilborne pathogen, can lead to serious economic losses in pepper. Some strains Trichoderma isolates can act as potential biocontrol agents and are able to control many plant diseases in crops. The present study was carried out to screen valid Trichoderma isolates against P. capsici and to study potential modes of action of involved. In vitro, the most successful isolate, Trichoderma HNA12, was able to inhibit P. capsici development and significantly reduce sporulation, inhibition effect for 62.3 % compared to the control treatment. Trichoderma HNA12 was further evaluated under field condition and, over a 2-year period, was able to significantly suppress P. capsici on root and stem parts giving a similar level of disease control as the fungicide thiram, and Trichoderma HNA12 showed the lowest disease index and significantly increases the plant stem heights and the fresh and dry weights. The mechanisms of action of Trichoderma HNA12 were postulated to be a combination of competition for space, production of antifungal metabolites and possible mycoparasitism. Mycoparasitism appeared to contribute to the aggressive nature of Trichoderma HNA12 against P. capsici when observed under scanning electron microscope. Trichoderma HNA12 was identified as T. Harzianum by molecular identification technology. The strategic approach described in this paper demonstrates an efficient way of screening microorganisms for biocontrol activity and validates the notion that certain microorganisms can be antagonistic to a variety of plant pathogens.