Monilinia Laxa Research Articles

Hybridization breeding program for resistance to monilinia (Monilinia laxa) on apricot

Hybridization breeding program for resistance to monilinia (<i>Monilinia laxa</i>) on apricot

Evaluation of fungicides for the control of postharvest fruit rot pathogens of apple in Northern Greece

Postharvest fruit rots are of the most important diseases of fruit after picking. One of the main aims of this study was to investigate the pathogens causing apple fruit rots in Naoussa Imathia and Ptolemaida Kozanis. The results showed that the fungus Penicillium was responsible for about 78% and 84% in 2016 and 2017 respectively of the postharvest fruit rots of apples, while the fungus B. cinerea caused about 17% and 12% respectively. The fungi Monilinia laxa, Fusarium avenaceum, Fusarium proliferatum, Alternaria tenuissima, Truncatella angustata and Boeremia exigua were responsible for less than 5% of the total rotted fruit in both years. The sensitivity of 100 P. expansum isolates to the commercially available fludioxonil and the mixture fludioxonil + cyprodinil was also tested. None of the isolates was resistant to the fungicides tested. Finally, the efficacies of the above fungicides against P. expansum were examined. The results showed that both fludioxonil and the mixture fludioxonil + cyprodinil were appropriate to control P. expansum in apples. Both protected fruit for at least 30 days.

Is the Tolerance of Commercial Peach Cultivars to Brown Rot Caused by Monilinia laxa Modulated by its Antioxidant Content?

Brown rot, caused by Monilinia spp., provokes pre- and post-harvest damage in peach (Prunus persica (L.) Batsch), which causes an economic impact in the industry. With a view to breeding for increased tolerance to this disease, a screening test based upon artificial fruit inoculation was validated on several parental lines of a peach breeding program during the two-period harvest. In addition, cultivars with different total phenolic contents were included in the two-year study. All physicochemical fruit traits recorded at harvest showed differences among all cultivars. The antioxidant compound content determined using spectrophotometry (to measure ascorbic acid and antioxidant capacity) and UPLC-MS (to measure and identify phenolic compounds) also revealed important differences among all genotypes. The rate of brown rot lesion following fruit inoculation varied widely among cultivars, and it was possible to discriminate between highly and less susceptible cultivars. Cultivars with minimal development of damage were identified as germplasm with the desirable allele combination to increase brown rot tolerance in peach breeding programs. Finally, Pearson’s correlation coefficients (r) between pairs of variables were calculated, searching for any biochemical candidate conferring tolerance. The correlation of phytopathological traits with the antioxidant composition, concerning contents of ascorbic, neochlorogenic, and chlorogenic acids and total polyphenols in fruit, is discussed.

Efficacy assessment of pomegranate peel aqueous extract for brown rot (Monilinia spp.) disease control

Brown rot, caused by both fungal pathogens Monilinia laxa and M. fructigena, is considered as one of major pre-and postharvest pathogen of tree fruit. Therefore, this study aimed at evaluating the in vitro and in vivo ability of pomegranate peel aqueous extract (PGE) against both fungal pathogens causing brown rot. Results showed a significant antifungal activity on the in vitro mycelial growth of both fungi with inhibition rates ranging from 76.65 to 90%. In addition, obtained results highlighted a positive correlation between the concentration rates of PGE and the mycelial growth inhibition and the EC50 were 9.93 and 12.84 mg/ml for M. fructigena and M. laxa, respectively. Interestingly, spore germination of both pathogenic fungi was significantly reduced by PGE with EC50 of 7.7 and 8.58 mg/ml for M. fructigena and M. laxa. The germ tube elongation was significantly reduced by PGE. Furthermore, the in vivo trial on apple fruit showed promising results with disease severity of 21.03 and 42% respectively for M. laxa and M. fructigena at 50 mg/ml aqueous extract concentration. This concentration showed also the highest content of total phenolic (2737.44 mg GAE/L) and flavonoid (309 mg QE/L). It was concluded that the aqueous extract of pomegranate peels might be a sustainable alternative control strategy of brown rot. As a result, studies on mechanisms behind its effectiveness and practical use as formulated biofungicide product should be further considered in more details.

Different methods of evaluation of Monilinia laxa on apricot flowers and branches

Organic apricot production is currently not profitable. The main obstacle to sustainable profitability is the brown rot disease caused by the fungus Monilinia laxa. Differences exist in the apricot germplasm in the brown rot susceptibility. A good evaluation of Monilinia is essential for a precise diagnosis of the disease and for exhibiting differences between tolerant and susceptible cultivars and genotypes. For this purpose, different evaluation methods of disease susceptibility were developed and compared in a bi-parental population between ‘Bakour’ (tolerant to M. laxa) and ‘Bergeron’ (susceptible). The method consists in the observation of naturally infected trees on open field assessing the percentage of twigs showing symptoms of M. laxa infection. However, this method is weather dependent in relation with temperature, humidity and rain period during the flowering and needs to take into account the annual variation of Monilinia climatic contamination risk for each tree as a covariate. For this reason, new methods of evaluation of M. laxa were developed under the controlled conditions. In the first new method, a spore suspension was sprayed on flowers of each genotype, the second method consisted in putting exactly one drop of spores on the pistil, and finally for the third method a plug of mycelium was placed on the branch of each genotype, after removing the bark. Different levels of infection were observed within the bi-parental population for the three controlled phenotyping evaluations. No good correlation between the visual assessment in the field and the new controlled evaluation methods on branches or flowers was found. Surprisingly, symptoms in petals were not linked with the Monilinia infection according to our observations. However, a segregation was observed for the visual assessment and for the evaluation test on branches. Based onto the observed variability, a QTL approach can be applied for assessing the genetic components involved in M. laxa resistance.

Effects of developed thyme and oregano essential oil formulations on Monilinia laxa and Monilinia fructicola

Essential oils have been well-known for their antimicrobial properties for a very long time. Some of them have been effectively used in human medicine for decades. Our earlier investigation revealed a great potential of thyme and oregano essential oils as crop protectants against some postharvest fruit pathogens. The effects of formulated thyme and oregano essential oils on Monilinia laxa and Monilinia fructicola were studied in vitro and in vivo. In vitro antagonistic assays were performed on solidified PDA medium using a slightly modified agar overlay technique, while in vivo experiments were conducted on inoculated apple fruits. In vitro essays showed that the developed formulations (emulsifiable concentrates - EC) significantly inhibited the mycelial growth of Monilinia spp. Experiments in vivo, performed on inoculated apple fruits, revealed that the developed formulations provided a significant level of Monilinia spp. suppression. To our knowledge, another EC formulation of oregano essential oil intended for use in Monilinia spp. control has never been developed before. The presented results are initial findings and evaluation of the activity of the developed products should therefore proceed under field conditions to determine their efficacy and activity spectrum, and to estimate economic aspects of their use.

Susceptibility of Serbian plum cultivars to indigenous bacterial and Monilinia laxa isolates

The susceptibility of Serbian plum cultivars to pathogens originating from their phyllosphere was evaluated by inoculating detached young leaves and mature fruits. The virulence of indigenous isolates of the bacteria Pseudomonas syringae, Pseudomonas congelans, Erwinia persicina, Clavibacter michiganensis and Rhizobium nepotum was tested on detached leaves of four Serbian plum cultivars (Ranka, Pozegaca, Cacanska lepotica and Cacanska rodna). The Pseudomonas syringae isolates formed intense symptoms within 48 hours on all tested cultivars with severity index values in the range of 41 - 47%. The other isolates had significantly lower severity values or no symptoms were developed. This study demonstrates for the first time pathogenicity of Pseudomonas congelans on plum, with symptom intensity not significantly different from P. syringae after 96 h of incubation. Virulence of Monilinia laxa isolates was tested on mature fruit of the Cacanska rodna and Pozegaca cultivars and was detected in both of them. Higher susceptibility to M. laxa was recorded for the Pozegaca cultivar, with a fruit infection rate between 43 and 66%. In the case of the Rodna cultivar, no statistically significant difference in the fruit infection rate was detected between the four tested M. laxa isolates. These data indicate significant susceptibility of Serbian plum cultivars to indigenous P. syringae and M. laxa isolates.

Екологічно безпечні заходи регулювання чисельності шкідливих організмів у персикових (Persica vulgaris Mill.) насадженнях

According to the results of the researches in 2016-2018, the display terms and intensity of the major peach diseases development changes from year to year and depends mainly on the weather conditions that in the south of Ukraine are favorable for the mass spread and development of Taphrina deformans Tull., Clacterosporium carpophilum (Lev.) Aderh. and Monilia cinerea Bonord. The leaves affection by Taphrina damage appeared to be 35.0-56.3 %, the intensity of the disease development being 22.4-23.4 %; Clacterosporium – 16.5 and 5.4 %, Monilia – up to 15.0 %. When studying the species composition of the peach entomocomplex, 6 major pests were detected among insects as follows: Anarsia lineatella Zell., Archips rosana L., Grapholitha molesta Busck, Lithocolletis cerasicolella H.S, Sciaphobus squalidus Gyll. and Brachycaudus tragopogonis Kalt. Lepidoptera prevailes (67 %) among them. Other species of pests (17 %) belong to the rows Coleoptera and Homoptera. The complex application of the chemical (Bordeaux Isagro, 20 % Copper Sulphate, 5.0 kg/ha) and a mixture of the biological preparations (Trichodermin, 2.0 l/ha, Planriz, 1.0 l/ha, Pentofag, 5.0 l/ha, Gaupsin, 3.0-5.0 l/ha, Lepidocide, 10 l/ha) at the beginning of the bud swell, and before and after the peach flowering, proves to protect reliably the orchards against harmful organisms. The technical efficiency of the above mentioned preparations against the main diseases and dominant pests 63.0-89.0 and 50.0-94.0 % respectively.

Draft Genomic Resources for the Brown Rot Fungal Pathogen Monilinia laxa.

Monilinia laxa is the causal agent of brown rot on stone fruit, and it can cause heavy yield losses during field production and postharvest storage. This article reports the draft genome assembly of the M. laxa Mlax316 strain, obtained using a hybrid genome assembly with both Illumina short-reads and PacBio long-reads sequencing technologies. The complete draft genome consists of 49 scaffolds with total size of 42.81 Mb, and scaffold N50 of 2,449.4 kb. Annotation of the M. laxa assembly identified 11,163 genes and 12,424 proteins which were functionally annotated. This new genome draft improves current genomic resources available for M. laxa and represents a useful tool for further research into its interactions with host plants and into evolution in the Monilinia genus.

Future development of apricot blossom blight under climate change in Southern France

Climate change will have several consequences for agro-systems, one of which will concern changes to the development of pathogens. Because of the losses it causes, particularly in organic farming, Monilinia laxa is an important pathogen affecting apricot crops. This study focuses on the consequences of climate change regarding blossom and twig blight (Monilinia laxa) of apricot. To achieve this, a Climatic Index of cumulated Blight risk (CIB) was built, to obtain the weighted sum of blossom blight incidence throughout the blooming period. An epidemiological model to calculate the incidence of blossom blight during every potentially infectious episode and based on biological parameters, was calibrated using a trap pot experiment where trees were placed in orchards and subject to various meteorological conditions. The CIB derived from this model was evaluated on field data, and was shown to be a robust and useful tool to predict the effects of climate change on the development of apricot blight. Then, using the CIB with a phenological model to predict blooming periods in the future, we estimated the risks of apricot blight until 2100 on four contrasted apricot cultivars and in three geographical zones under climate change scenarios RCP 4.5 and 8.5. This study revealed different effects of climate change depending on the cultivar and altitude. Apricot trees would bloom earlier (up to a difference of 50 days between 1950 and 2100) under climate change. Under the combined effects of these shifts of blooming period and changing climatic conditions, late cultivars such as Bergarouge might see a reduction in the risk of blossom blight (down to 31%) because of warmer but dryer blooming periods. Other varieties (e.g.: Bergeron) could experience an increase in this risk by up to 27% with a shift of the blooming period towards rainier conditions at the highest altitudes. The results of this study could be used to anticipate future changes as well as be used at present as a decision-support tool for farmers.

Phyllosphere Fungal Communities of Plum and Antifungal Activity of Indigenous Phenazine-Producing Pseudomonas synxantha Against Monilinia laxa.

European plum (Prunus domestica L.) is a significant commercial crop in Serbia in terms of total fruit production, and is traditionally processed into slivovitz brandy. The brown rot disease caused by Monilinia laxa drastically reduces plum yield almost every year. Fungal communities associated with leaves and fruits of four local Serbian plum cultivars (Požegača, Ranka, Čačanska Lepotica and Čačanska Rodna) were investigated in two phenological stages during early (May) and late (July) fruit maturation. Alpha diversity indices showed that fungal communities were heterogeneous and Beta diversity indicated that autochthonous fungal communities depended upon seasonal changes and the cultivars themselves. The phylum Ascomycota was the most abundant in all samples, with relative abundance (RA) between 46% in the Požegača cultivar (May) and 89% in the Lepotica cultivar (July). The most abundant genus for all plum cultivars in May was Aureobasidium, with RA from 19.27 to 33.69%, followed by Cryptococcus, with 4.8 to 48.80%. In July, besides Cryptococcus, different genera (Metschnikowia, Fusarium, and Hanseniaspora) were dominant on particular cultivars. Among all cultivable fungi, molecular identification of eleven M. laxa isolates from four plum cultivars was performed simultaneously. Bacterial isolates from the plum phyllosphere were tested for their potential antifungal activity against indigenous M. laxa isolates. The most potent antagonist P4/16_1, which significantly reduced mycelial growth of M. laxa, was identified as Pseudomonas synxantha. Further characterization of P4/16_1 revealed the production of volatile organic compounds and phenazine-1-carboxylic acid (PCA). Crude benzene extract of PCA exhibited 57–63% mycelial growth inhibition of M. laxa. LC/MS analysis of the crude extract confirmed the presence of phenazine derivatives amongst other compounds. Scanning electron microscopy revealed morpho-physiological changes in the hyphae of M. laxa isolates caused by the cell culture and the P. synxantha P4/16_1 crude benzene extract. This is the first report of antagonistic activity of P. synxantha against M. laxa induced by diffusible and volatile antifungal compounds, and it appears to be a promising candidate for further investigation for potential use as a biocontrol agent against brown rot-causing fungi.

Rapid Detection of Monilinia fructicola and Monilinia laxa on Peach and Nectarine using Loop-Mediated Isothermal Amplification.

Monilinia laxa and M. fructicola are two causal agents of brown rot, one of the most important diseases in stone fruit. Two species cause blight on blossoms and twigs and brown rot on fruit in pre- and postharvest. Both species are distributed worldwide in North and South America, Australia, and Japan. In Europe, M. laxa is endemic, while M. fructicola was introduced in 2001 and it is now widespread in several countries. Currently, both species coexist in European stone fruit orchards. Monilinia spp. overwinter in cankers and mummified fruit. Mummy monitoring during winter permits growers to understand which species of Monilinia will be prevalent in an orchard during the following season, permitting planning of an appropriate crop protection. Traditionally, the identification has been carried out using morphological features and even with polymerase chain reaction (PCR)-based assays that requires time and well-equipped laboratories. In this study, two isothermal-based methods were designed to identify these pathogens in a faster way than using traditional methods. The loop-mediated amplification (LAMP) assays were validated on some isolates of Monilinia spp. coming from the mummy monitoring according to the international European and Mediterranean Plant Protection Organization standard (PM7/98), taking into account specificity, sensitivity, repeatability, and reproducibility. The sensitivity of both assays was checked by monitoring (at different time points) two nectarine varieties artificially inoculated and stored at two different temperatures. The reliability of both LAMP assays against the quantification of the inoculum was compared with previously published quantitative PCR assays. Both LAMP methods were able to detect a low number of cells. These LAMP methods could be a useful tool for monitoring brown rot causal agents in the field and during postharvest.

The resistance of apricot genotypes to the attack of certain pathogens in Romania

Among the pathogens which have an economic importance for the apricot tree culture, because of the fact that they are involved in the premature demise of this fruit-growing species are the following fungi: Monilinia laxa, Cytospora cincta and Stigmina carpophila. These pathogen agents cause severe diseases that affect not only the fruit production but the life of the trees itself, taking into account the climatic conditions of a specific year and especially the soil’s sensitivity. The aim of this research is to highlight the genotypes that are the most resistant to pathogens and their behaviour towards the pathogens attack in the soil-climatic conditions of Romania. With regard to the attack of the Monilinia laxa fungus, the majority of the studied cultivars proved to be tolerant (T). The ‘Orizont’, ‘Danubiu’, ‘Cristal’ and ‘Olimp’ cultivars displayed sensitivity (S) towards Monilinia laxa. In this pathogen’s case, we must mention the fact that the sensitivity of the cultivar is also influenced by the environmental conditions of each studied year. The cultivars that are very resistant, basically not attacked by Monilinia laxa and Cytospora cincta are ‘Traian’, ‘Tudor’, ‘Elmar’, ‘Ovidius’ and ‘Amiral’, whereas the most sensitive cultivars to the attack of Cytospora cincta and Stigmina carpophila are (2013-2015) ‘Augustin’, ‘Histria’, ‘Cristal’ and ‘Euxin’. Following research and study, the resistant cultivars have been cultivated in the nursery orchard and the most valuable genotypes are being cultivated in commercial orchards, occupying a good place in the structure of the apricot tree assortment from the south-eastern part of Romania.

Pectin methyl esterases and rhamnogalacturonan hydrolases: weapons for successful Monilinia laxa infection in stone fruit?

The secretion of cell wall‐degrading enzymes is one of the mechanisms used by necrotrophic fungi to colonize host tissues. However, information about virulence factors of Monilinia spp., the causal agents of brown rot in stone fruit, is scarce. Plant cell walls have three main components that are broken down by fungal enzymes: cellulose, hemicellulose and pectin. In order to identify Monilinia laxa candidate proteins involved in pectin hydrolysis, two in vitro approaches were conducted: (i) phenotypic and ecophysiological characterization of growth of the pathogen at different pHs, in glucose‐ and pectin‐containing solid media for 7 days' incubation; and (ii) expression analysis of genes encoding M. laxa pectin methyl esterases (MlPMEs) and rhamnogalacturonan hydrolases (MlRG‐HYDs) after incubation for 0.5, 2, 6, 24 and 48 h in glucose‐ and pectin‐containing liquid media. Phenotypic tests showed the role of carbon source on M. laxa growth rate and aggressiveness, and indicated that pectinases were greatly affected by pH. Gene expression analyses uncovered differences among members of each family of pectinases and between the two families, defining sets of genes expressed at earlier (0.5–6 h) and later (48 h) phases. Notably, the up‐ or down‐regulation of these target genes was carbon source‐dependent. Finally, an in vivo study confirmed the synergistic and complementary role that these genes play in the M. laxa–stone fruit pathosystem. Based on these results, it is hypothesized that MlPME2, MlRG‐HYD1 and MlRG‐HYD2 may be potential virulence factors of M. laxa in the process from infection to colonization.

Assessment of eleven South African peach cultivars for susceptibility to brown rot and blue mould

Species of Penicillium (blue mould) and Monilinia (brown rot) are major causes of postharvest loss of stone fruit. Breeding for resistance to these pathogens is a sustainable option that could reduce over reliance on postharvest chemical interventions to control the diseases. This study was aimed at selecting peach cultivars that are resistant to blue mould and brown rot pathogens through in vivo assays against the causative agents. Red and yellow skinned peach cultivars were artificially infected with Monilinia laxa and Penicillium expansum whilst the same cultivars were also assessed as naturally infected fruit. Fruit were stored at 0 °C for 14 and 21 days, and thereafter kept at 15 °C for 3 days to simulate market shelf condition. Physicochemical traits, such as fruit pH, antioxidant activity, total anthocyanins, and total phenols were measured at harvest, and after 14 days and 21 days of storage. The blue mould pathogen was more virulent than the brown rot pathogen in the fruit. The red cultivars showed less brown rot incidence (20%–35%) compared to the yellow cultivars (35%–65%). Artificial infections stimulated a higher biochemical activity in the fruit compared to natural infections. In general peach cultivars with high contents of antioxidant compounds had lower pathogen incidence. ‘Temptation’, (a red cultivar) showed highest resistance compared to the other peach cultivars used in this experiment and this was correlated to the high phenylalanine lyase activity, phenolic compounds, and concentrations of chlorogenic, caffeic acid and anthocyanin exhibited by the cultivar. Breeders can use these tests as indicative for blue and brown mould resistance.

Developing an integrated plan of harvest protection as a tool of improving food supply security in Kyrgyzstan

The article shows that apricot plants in the South of Kyrgyzstan are wide spread in the Batken Region. This region is favorable for growing apricots sold both in the domestic and in the foreign markets. It is here where they cultivate many varieties of apricots which are subsequently exported in dried form to CIS and non-CIS states. Heat-resistant and drought-resistant rare varieties of apricots are cultivated in the Batken Region, such as: Kandak, Mirsanjeli, Khurmai, Subkhoni, Babai, Akhrori, Arzami, Isfarak, Kursadyk, Ak Uriuk (Sovetskiy). 22 species of insect pests of apricot plants were found; they are conveniently classified into five orders. The dominant pests of apricot plants are as follows: apricot seed wasps (Eurytoma samsonovi Vass.), plum seed wasps (Eurytoma schreineri Schr.), apricot snout-beetle (Rhynchites auratus ferghanensis News.), gypsy moth (Lymantria dispar L.), casebearer (Coleophora hemerobiolla Fil.), European leaf roller (Archips rosana L.), acacia lecanium - (Parthenolecanium corni Bouche). The most common apricot diseases in the climate of the Batken Region of Kyrgyzstan are shot-hole disease (Clasterosporium carpophilum Aderh.), frostly pod rot (Monilia cinerea Bon.), bacterial blight (Gummi.), verticillium wilt (Verticillium dahliae Kleb.), twig die-back (Cytospora arphosperma Fr.).

Growth supression of plant pathogenic fungi using bryophite extracts

Chemicals are often used in attempts to control diseases caused by plant pathogenic fungi during food production. However, chemicals can have adverse effects not just on food, but they also remain active for a long time within ecosystems, and thus are not environmentally friendly. Therefore, development of bio-treatment and avoiding use of chemicals are urgently needed. With the aim of studying and developing new environmentally-friendly treatments, we tested extracts from selected bryophyte species (Porella platyphylla, Cinclidotus fontinaloides and Anomodon viticulosus) on five plant pathogenic fungi under controlled conditions. The fungi (Botryosphaeria dothidea, Phomopsis viticola, Calosphaeria sp., Colletotrichum acutatum and Monilinia laxa) were selected based on common diseases they cause on fruits and grapevine. They were isolated in cultures and treated with bryophyte extracts. Bryophyte extracts were shown to be effective in suppression of certain plant pathogenic fungi growth and to have a huge potential in development of novel biotechnological treatments and biofungicides. The best results were achieved in inhibition of B. dothidea, P. viticola and Calosphaeria sp.

A multiple volatile oil blend prolongs the shelf life of peach fruit and suppresses postharvest spoilage

Prolongation of the shelf life of delicate fruit such as peaches without the application of fungicides is a great challenge facing the horticulture sector. This study aimed to apply Thieves oil blend (six oils in one mixture) to protect peach fruit from spoilage during long-term cold storage. Alternaria alternata, Fusarium oxysporum, Geotrichum candidum and Monilinia laxa were isolated from naturally infected peach fruit showing symptoms of postharvest rot, and their pathogenicity was confirmed on the same fruit. Pathogens were identified by sequencing of their internal transcribed spacer (ITS). The results showed that Thieves oil blend at a concentration of 2.0 mL L−1 completely suppressed fungal growth in vitro. This concentration reduced the disease incidence to 12.0% and the disease severity index to 1.2 after 7 d at 27 °C in vivo. The oil blend prolonged the shelf life of peach fruit up to 30 d under cold storage conditions (4 °C). Electron microscopy confirmed the fungitoxicity of Thieves oil blend, which resulted in complete death of the fungal mycelia. Gas chromatography–mass spectroscopy (GC–MS) analysis of the oil blend showed the presence of 25 effective constituents that work synergistically to suppress the disease and its causal pathogens. The study recommends the application of Thieves oil blend for the first time as a safe multiple preparation to protect peaches and other fruit during transportation and cold storage to reduce losses during the marketing process.

CONTROL OF BROWEN ROT ON SOME STONE FRUITS DURING STORAGE USING SOME SALTS AND INDUCING RESISTANCE

Brown rot disease of Canino apricots and FlordaPrince peaches is a major serious decay disease during cold storage in Egypt and worldwide, Infection of stone fruits may occur during blooming until harvest harvest which cause decay during cold storage. The effect of fungicide safe alternatives, (Chemical salts and Inducing resistance). The effect of fungicide safe alternatives, i.e. sodium bicarbonate, calcium chloride, potassium sorbate, potassium silicate,boric acid and salicylic acid, on growth of Monilinia laxa M. fructigena and Monilinia sp. as major pathogens on apricots and peaches ,was investigated at different concentrations ranged from 1000 ppm to 5000 ppm amended in PDA in vitro. Sodium bicarbonate at 1000 ppm completely suppressed the growth of the three isolates of Monilinia spp., Calcium chloride at 1000 ppm to 5000 ppm, did not show any suppression of M. laxa or Monilinia sp., while it suppressed M. fructigena when used at ≥4000 ppm. Potassium silicate did not show considerable effectiveness against different tested isolates of Monilinia spp. IC50 values (chemical concentration that reduce fungal growth to 50%) of sodium bicarbonate, potassium sorbate and salicylic acid on M. fructigena were less than 1000 ppm. On M. laxa, only sodium bicarbonate showed IC50 less than 1000 ppm, while the IC50 values of potassium sorbate and boric acid were less than 2000 ppm. Regarding Monilinia sp. sodium bicarbonate and potassium sorbate IC50 values were less than 1000 ppm. Generally, sodium bicarbonate, potassium sorbate and salicylic acid showed IC50 values less than 1000 ppm, 2000 ppm, and 3000 ppm, respectively. These salts and inducers at 3000 ppm, were used as three preharvest sprays starting at growth stage no. 64 and then repeated twice at 10 days intervals in orchard located at Qualyubia and Ismailia, during seasons 2015 and 2016. These salts and acids were also adopted at 3000 ppm on naturally infected or artificially inoculated fruits after harvest at growth stage no. 81 during season 2016. Sodium bicarbonate, calcium chloride, potassium sorbate and boric acid were the most effective treatments to control brown rot disease on apricots and peaches during cold storage at 0oC and 90% RH for 15 days and 30 days, either these chemicals were sprayed preharvest or adopted after harvest. These treatments maintained fruit quality regarding firmness and acidity.

Genotypic structure of Monilinia populations in Western Australia two decades after incursion

In 1997, Monilinia fructicola and Monilinia laxa, fungi causing brown rot disease in stone fruit (Prunus species), were identified from Western Australia for the first time. Up until then, Monilinia were quarantine species, and importation of stone fruits to W.A. was prohibited. After Monilinia was identified in W.A., importation of stone fruit from sources outside W.A. was progressively permitted. Today, Monilinia is present in all stone fruit production regions in W.A. The aim of this study was to determine if the genotypes responsible for the first incursion subsequently spread, or if new genotypes have since become established. ISSR markers were used to identify the genotype of isolates collected during the initial incursion event in 1997, and compare them with isolates collected subsequently. Eight M. fructicola genotypes were identified, including a monotypic one on a fresh peach imported from the USA. M. fructicola isolates collected during the initial incursion in 1997 and an isolate from cherry collected in South Australia in the same year were all of the same genotype, suggesting fruit or germplasm from S.A. as the source of the W.A. incursion. However, this incursion genotype appears not have persisted, with different genotypes subsequently becoming widely or locally established. Four genotypes of M. laxa were identified. In contrast to M. fructicola, the 1997 incursion genotype of M. laxa has become widely established in W.A., infecting both stone fruits and pome fruits.