Monilia Laxa Research Articles

In vitro antifungal examination of ethanol plant extracts from Berberis vulgaris and Tamarix tetrandra towards Monilia laxa and Phytophthora capsici

Tests in in vitro conditions with ethanol extracts from the radix of Berberis vulgaris and the flower twig of Tamarix tetrandra prepared by the method of maceration were performed with two economically important plant pathogens such as Monilia laxa and Phytophthora capsici. The received results show that the extracts from the radix of the common barberry (Berberis vulgaris) are able to fully block the growth of mycelium of Monilia laxa at 0.5 % (m/v) concentration during the entire period of testing (14 days). However, the effectiveness of the tested plant extracts towards Phytophthora capsici was significantly lower and Tamarix tetrandra expressed better action.

RESEARCHES ON MONITORING AND EARLY WARNING OF BROWN ROT MONILIA LAXA ATTACK ON SOME VARIETIES OF CHERRY AND PLUM

Brown rot caused by Monilia laxa (Aderh. & Ruhland, Honey) is one of the most damaging fungal disease for stone fruit species, in all European countries and in Romania as well. A great deal effort is done to study its biology and ecology, for disease monitoring and containment. This paper presents the result obtained at RIFG Pitesti Romania during 2018-2020 in monitoring and early warning of the disease attack, using two different weather stations and forecast modules made in Europe and USA. A correlation was found (R2=0.0146, r=0.1208, n=585), which proves that the microclimate was favorable for stone fruits brown rot infections, for varieties evaluation and classification and to supply data to develop new early warning tools as well. The results obtained with the two forecast systems makes possible the early warning on the attack risk of brown rot, both cherry and plum orchards. In the same period 26 cherry and 22 plum varieties were studied regarding their behavior to the pathogen natural infections. Among the Romanian varieties the ones with the lowest damages degree were: 'George', 'Clasic', 'Daria', 'Negre de Bistriţa', 'Roşii de Bistriţa', 'Rubin', 'Severin' and 'Uriaşe de Bistriţa' (DD%=0.13-0.14) on cherry and 'Pescaruş' 'Record', 'Gras ameliorat', 'Romanţa', 'Roman, 'Ialomiţa' and 'Dâmboviţa' (DD%=0.03-0.14) on plum. Under long term study, the most sensitives to brown rot attack were 'Lapins' cherry variety (DD%=3.93) as well as 'Stanley' Centenar and 'd’Agen' plum varieties (DD%=4.68-4.72), which can be used as 'indicators', in order to triggers the phytoprotection programs.

PRELIMINARY RESULTS ON BEHAVIOR OF APRICOT, PEACH AND PLUM TO MONILINIA SPP. IN EXPERIMENTAL FIELD OF USAMV BUCHAREST

" The stone fruits occupy an important place in the human diet due to their complex chemical composition such as sugars, free organic acids, pectic substances and vitamins. The main damage of economic importance to the stone fruit species is caused by the monilia disease caused by the fungus Monilia laxa (Aderhold et Ruhland). The disease can affect several host tissues these include blossom blight, shoot blight, fruit blight and brown fruit rot. The purpose of this research was to evaluate the attack produced by the pathogen on peach, apricot and plum from the first decade of May until the second decade of August in Experimental Field of Horticulture Faculty, USAMV Bucharest in 2019. Results showed that plums had the highest attack rate (14%) and the lowest was in apricots (0.8%). It should be noted that monilia disease is a major threat for stone fruit trees because of its aggressive manifestation on the fruit, especially in plums and peaches."

Essential oil of Calamintha nepeta (L.) Savi subsp. nepeta is a potential control agent for some postharvest fruit diseases

The antifungal activity of essential oil from Calamintha nepeta (L.) Savi subspecies nepeta was investigated against some destructive fungal pathogens of postharvest fruit. A preliminary in vitro assay was used to assess the inhibitory effect using vapour contact and direct contact of the essential oil against Botrytis cinerea, Penicillium digitatum, Monilia laxa and Penicillium italicum. Both methods demonstrated that the essential oil was effective against all the fungal species tested in a dose-dependent manner, although the antifungal activity was more potent with the vapour contact test. Additional in vivo tests confirmed the efficacy of the vapour phase of the essential oil against P. digitatum and M. laxa on clementine and plum fruit, respectively. Total control of both brown rot and green mould was achieved on artificially inoculated fruit at doses of 133.3 μL L. Furthermore, excellent control efficacy, similar to that obtained with conventional fungicides, was achieved at a dose of 66.6 μL L. Chemical analysis of the essential oil by gas chromatography-mass spectrometry showed that pulegone (44.7%), menthone (16.4%), piperitenone (13.3%) and piperitone (6.01%) were the major constituents. These results suggest that the essential oil of C. nepeta subsp. nepeta has the potential to be used by vapour diffusion as an alternative biocontrol agent to conventional fungicides for postharvest management. However, it is important to do further research to validate these results under conditions that mimic commercial facilities and to optimise the application of essential oil vapours.

Field susceptibility of almond cultivars to the four most common aerial fungal diseases in southern Spain

From 2004 to 2012, the incidence and severity of the four most common almond aerial diseases were evaluated in ten experimental fields in the main almond-growing areas of Andalusia, southern Spain. The studied experimental fields were representative of the different geographic locations, agronomic characteristics and farming systems in Andalusia. A total of 14 early-flowering and 26 late-flowering cultivars (cvs.) currently grown in the new almond plantings of Andalusia and the Mediterranean basin were evaluated. The incidences of red leaf blotch (RLB), shot hole (SH), blossom blight (BB), and leaf curl (LC), which were caused by Polystigma amygdalinum, Thyrostroma carpophilum, Monilia laxa and Taphrina deformans, respectively, were monitored in each field and year. RLB was the most prevalent disease, although its severity varied markedly among fields and years. BB caused the higher outbreaks, but this was only the case when rainfall coincided with flowering, and fungicide treatments were not applied. The early-flowering cvs. were more affected than the late-flowering cvs. by BB, although most of the early-flowering cvs. were less susceptible than the reference cv. Marcona to BB. However, ‘Marcona’ was less susceptible than most of the early-flowering cvs. to RLB. Among the late-flowering cvs., the reference cv. Guara was susceptible to the four monitored diseases. The responses of the cvs. to the diseases varied markedly among fields and years, with significant differences among cvs. for all diseases. This work represents the first study to evaluate a broad range of almond cvs. infected with the main almond foliar diseases in natural field conditions, making an important contribution to the understanding of varietal susceptibility of almonds to four significant foliar diseases. Moreover, this study highlights the need to consider cultivar resistance in the development and selection of plant material for new almond plantings and in integrated pest management.

Identificación del agente causal de la pudrición parda en frutos de duraznero (Prunus pérsica, L. Batsch) en Boyacá

La enfermedad fungosa más limitante del duraznero (Prunus pérsica, L. Batsch) en Colombia es la pudrición parda, Monilia spp., que afecta flores, brotes y frutos, causando pérdidas hasta del 80%. El objetivo de la investigación fue identificar el patógeno asociado a pudrición parda en cuatro variedades: Dorado, Rubidoux, Diamante y Rey negro en el departamento de Boyacá. El estudio inicio con la colecta de frutos enfermos en Jenesano, Paipa, Tuta, Sotaquirá y Nuevo Colón. En laboratorio se realizó la obtención, aislamiento y purificación de los hongos presentes. Se realizó también caracterización morfológica de las colonias y conidias sobre cultivos monospóricos y caracterización molecular mediante amplificación por PCR del ADN ribosomal empleando iniciadores ITS4 e ITS5. Se obtuvieron 32 aislamientos del género Monilia y se identificaron tres especies presentes en la zona muestreada: Monilia fructícola, Monilia fructígena y Monilia laxa, en 62,5%, 25% y 12,5%, respectivamente. En la amplificación de la región ribosomal se observaron diferencias entre las dos primeras especies, en el tamaño de las bases amplificadas, siendo M. fructicola de 550 pb y M. fructigena de 545pb. Este trabajo contribuye a la caracterización de las especies de Monilia que afectan al duraznero en varias regiones del departamento de Boyacá.

DISSIPATION RATE AND RESIDUES OF ACETAMIPRID AND IPRODIONE IN SWEET CHERRY FRUITS

A neonicotinoid insecticide acetamiprid and dicarboximide fungicide iprodione,are used in sweet cherry for control of the major pest (Rhagoletis cerasi L.) andpathogen (Monilia laxa). For the purpose of the safe consumption of agriculturalproducts after pesticide application, studies on their dissipation kinetics areessential to work out their half-lives (DT50) and pre-harvest intervals (PHI).However, there is a lack of information on the persistence of acetamiprid andiprodione in sweet cherry fruits in different climatic conditions of production.Therefore, the objectives of this study were to investigate the dissipation andresidues of acetamiprid and iprodione in sweet cherry fruits, as well as to evaluatethe validity of prescribed PHI for these pesticides. Field experiments wereconducted in a sweet cherry orchard, near Novi Sad, where acetamiprid andiprodione were applied at a recommended concentration. At various time intervals,from treatment to harvest, having in mind PHI (14 days for acetamiprid and 7 daysfor iprodione) representative samples of sweet cherry fruits were collected.Extraction of pesticides was carried out by QuEChERS method, followed byHPLC-DAD analysis. The method was validated in accordance with theSANCO/12571/2013 document and was used the determination of pesticides inreal sweet cherry samples. During the study period, the concentration ofacetamiprid and iprodione decreased from 0.52 mg/kg to 0.11 mg/kg and from 0.29mg/kg to 0.07 mg/kg, respectively. The dissipation of acetamiprid and iprodioneresidues over the time fitted to the equation Ct=0.52-0.22t and Ct=0.29-0.20t, with DT50of 3.15 and 3.47 days, respectively. Finally, the content of acetamiprid andiprodione in sweet cherry samples, at the end of PHI, were below the maximumallowed level specified by the Serbian (1.5 mg/kg and 3 mg/kg) and EU MRLs (1.5mg/kg and 10 mg/kg).

Yeasts isolated from figs (Ficus carica L.) as biocontrol agents of postharvest fruit diseases

Fresh fruit is highly perishable during postharvest life, mainly due to fungal growth. Thus, fungal control is an important goal for the fruit industry. In this work, a selection of antagonistic yeasts isolated from fig and breba crops were screened in vitro. The isolated yeasts were challenged with three moulds isolated from decayed figs and breba crops, identified as Penicillium expansum M639 and Cladosporium cladosporioides M310 and M624, and pathogenic moulds Botrytis cinerea CECT20518 and Monilia laxa CA1 from culture collections. Two yeast isolates, Hanseniaspora opuntiae L479 and Metschnikowia pulcherrima L672, were selected for their ability to inhibit the growth of aforementioned moulds. These yeasts reduced the radial growth of moulds on PDA by between 45.23% and 66.09%. Antagonistic activity was associated with the interaction of live yeast cells with moulds. M. pulcherrima L672 apparently parasitised C. cladosporioides isolates. In addition, challenges were assayed using wounded apples and nectarines, with significant reductions in percent infection and lesion size for all moulds tested. To our knowledge, this is the first report identifying H. opuntiae as an antagonist against different pathogenic moulds.

Antioxidant and antimicrobial activity of natural phenolic extract from defatted soybean flour by‐product for stone fruit postharvest application

Fresh fruit is highly perishable during storage and transport, so there has been growing interest in finding safe and natural antimicrobial compounds as a control tool. Phenolic compounds are secondary metabolites naturally present in vegetable material and have been associated with antimicrobial and antioxidant properties. Therefore, the aim of this study was to investigate the antioxidant capacity and potential antimicrobial effect of phenolic extract obtained from defatted soybean flour against selected pathogenic bacteria and microorganisms responsible of fruit decay. Analysis of phenolic composition by HPLC-MS showed the presence of a wide range of compounds, with isoflavones and phenolic acids the main polyphenols identified. Furthermore, the phenolic extract had important antioxidant activity by two different assays. Related to antimicrobial activity, in vitro experiments demonstrated that phenolic extract displayed a high activity against the main foodborne pathogens, while a moderate inhibition was found against five spoilage yeasts and Monilia laxa and a scarce effect for Penicillium glabrum, Cladosporium uredinicola and Botrytis cinerea. Interestingly these compounds considerably inhibited the mycelial growth of Monilia laxa, in both in vitro and in vivo experiments. The results of the present study revealed that defatted soybean flour is an important source of phenolic compounds with remarkable antimicrobial and antioxidant activity, suggesting the possibility of using them as natural additives in postharvest treatments to extend the shelf life of fruit.

Gum in apricot (Prunus armeniaca L.) shoots induced by methyl jasmonate

It has been well known that some fungal pathogens (<i>Monilia laxa, M. fructigena, Cytospora cincta</i>), larvae of <i>Grapholita molesta</i> and plant hormone - ethylene, induce gummosis in apricot shoots. Methyl jasmonate (JA-Me) was also found to induce gummosis in apricot shoots as well as biotic and abiotic factors mentioned above. In order to know the mode of action of JA-Me on gum induction and/or formation, chemical composition of polysaccharides (after hydrolysis) in gums of apricot shoots induced by JA-Me compared with those by ethephon and their mixture, and naturally occurring ones was studied, resulted in the succesful identification of monosaccharides, and the similarity of a composition consisting of xylose, arabinose and galactose at molar ratio 1:10:14, respectively. These results suggest that beside different inducers of gum in apricot the mechanism of polysaccharides biosynthesis of gums is the same or similar. The physiological role for JA-Me on gum induction and/or formation in apricot shoots, and other species are also discussed.

Characterization of M. laxa and M. fructigena isolates from Hungary with MP-PCR

Monilinia laxa (Monilia laxa), Monilinia fructicola (Monilia fructicola) and Monilinia fructigena (Monilia fructigena) are the causal agents of brown rot on pome and stone fruits in Hungary. Forty-five isolates collected from different hosts, different years in several orchards were used for characterization of the M. laxa and M. fructigena population in Hungary. The isolates were identified on species level based on morphological and molecular biological methods; out of these 24 were M. laxa, 20 were M. fructigena and 1 was M. fructicola. Populations of the three Monilinia species were studied with microsatellite primers and the degree of genetic diversity within the species was measured. The population structure analysis revealed that genetic diversity within M. laxa subpopulations was H<sub>S</sub>= 0.1599, while within M. fructigena subpopulations was H<sub>S</sub>= 0.2551. The total genetic diversity was H<sub>T</sub>= 0.3846, while genetic diversity between M. laxa and M. fructigena subpopulations was D<sub>ST</sub>= 0.1771. No clustering relationship was observed among isolates by the different years or hosts.

Different responses of sensitive and resistant apricot genotypes to artificial Monilia laxa (Aderh. & Ruhl.) infection

Blossom blight caused byMonilia laxa(Ehr.) is the most important fungal disease in Hungarian apricot orchards. The cultivars traditionally grown in the country are susceptible toMonilia laxa(Ehr.) to various extents. In this study the shoots of one tree each of the varieties Zard and Korai Zamatos and 48 hybrids from their cross were artificially infectedin vivowithMonilia laxa(Ehr.). The results indicated that when artificial infections are made to evaluate pathogen resistance, this should be carried out on one-year-old shoots, since this is the natural infection point ofMonilia. It also appears that, due to the great variability in the size of destroyed tissues, the microscopic analysis of the infections could provide a more reliable evaluation of progeny resistance than comparing the sizes of destroyed shoot areas.

Growth of mycelia of phytopathogenic fungi after application of abscisic acid in in vitro conditions

The effect of abscisic acid (ABA) on growth of mycelia of the phytopathogenic fungi Schizophyllum commune, Monilia laxa and Monilia fructigena in in vitro conditions was studied. All concentrations ofABA (from 10–5 to 10–9M) stimulated mycelial growth of these fungi in Lilly-Barnet medium, when cultured for either 10 or 15 days. The results suggest thatABA secretion may be a factor of pathogenicity.

Immunodetection of Botrytis-specific Invertase in Infected Grapes

Invertase (β-fructofuranosidase, EC 3.2.1.26) activity was shown to be stimulated in grape berries after infection with Botrytis cinerea. By using organism-specific extraction methods, evidence was found proving that both partners contribute to the increase in activity. Qualitative analysis of the extracts by SDS-PAGE showed a new invertase species in the botrytised material, with a molecular weight similar to that of Botrytis invertase (BIT). A method allowing the preparative isolation of homogeneous invertase from liquid cultures of B. cinerea in only three steps (ethanol precipitation, DEAE anion exchange and hydroxyapatite chromatography) with 50% recovery was developed. BIT appeared to be strongly glycosylated; interestingly, the amount of glycan seemed to vary and had a remarkable influence on the chromatographic behaviour of the enzyme. After chemical deglycosylation with TFMS, the BIT peptide was used for the production of polyclonal antibodies in chickens (anti-BIT-IgY). The antibodies recognised glycosylated as well as deglycosylated BIT, a partial denaturation of the protein being necessary for reaction. This indicates that the deglycosylation procedure had been successful and that the antibodies were in fact directed to the peptide moiety. However, after a short incubation at 70°C, native BIT was detectable by anti-BIT-IgY, while still active. Western blotting with extracts of diseased berries confirmed the fungal origin of the new invertase form. The anti-BIT-IgY proved highly specific, although some cross-reaction with a protein in Monilia laxa extracts occurred. The importance of careful immunogen preparation in the production of specific antibodies, and the potential of BIT as a target molecule for the immunological detection of B. cinerea are discussed.

`Antoñeta' and `Marta' Almonds

Vigor and growth habit. Trees of both ‘Antoneta’ and ‘Marta’ are very vigorous, similar to ‘Ferragnes’. The original trees, although originally grown close together with the other seedlings, had developed trunk diameters measuring 20 and 25 cm, respectively, after 13 years. ‘Marta’ is very erect with vigorous branches that are easily adapted to the Italian vase, with three or four primary branches. It produces very few lateral branches during the first years, leading to the development of thick, erect, primary scaffolds. The later development of lateral branches gives it a more balanced, not excessively dense appearance. ‘Antoneta’ is more open, with more lateral branches on the scaffolds during the first stages of growth, even on nonpinched primary branches. Concerning growth habit and branching, ‘Nonpareil’ is intermediate between ‘Antoneta’ and ‘Marta’. Productivity. The harsh conditions (cold with frequent frost) under which the evaluation was carried out made assessment of long-term productivity difficult. During years without frost, the yield was greater than that of commercial cultivars and other selections from the breeding program grown in the same orchard. In spite of the drought in 1999, the yield for ‘Antoneta’ and for ‘Marta’ was very high. Disease resistance. The climatic conditions of the area are favorable for brown rot (Monilia laxa Aderh.) and polystigma (Polystigma occhraceum Wahl.) Both cultivars had a greater resistance to brown rot than did ‘Ferragnes’. Resistance to polystigma was similar to that of other cultivars. Fusicoccum (Fusicoccum amygdali Del.) and rust (Tranzschelia pruni-spinosa Pers.) infections were rare for selections.

Contribution to the study of cytokinin production by phytopathogenic fungi

The excretion of cytokinins into the cultivating medium, which are produced by the phytopathogenic fungiMonilia sp. andCytospora sp. has been investigated. All the isolates of the fungi used in the experiments (Monilia fructicola, Monilia fructigena, isolate 2 and 4,Monilia laxa isolate 3 andCytospora sp. isolate CPL and C1) have been found to produce cytokinins. The production is increased during the formation of the fructification organs. Among the isolates investigatedMonilia fructigena isolate 4 andCytospora sp. isolate CPL showed the highest production of cytokinins. After chromatographic separation, cytokinin activity was found at RF 0.7–0.8 values by the biological test as well as by identification according to UV spectra. Application of purified cytokinins produced by the fungi evoked the formation of “green islands” on isolated barley leaves underin vitro conditions.