The brown rot fungi of fruit crops (Monilinia spp.): II. Important features of their epidemiology (Review paper)

Plant disease epidemiology provides the key to both a better understanding of the nature of a disease and the most effective approach to disease control. Brown rot fungi (Monilinia spp.) cause mainly fruit rot, blossom blight and stem canker which results in considerable yield losses both in the field and in the storage place. In order to provide a better disease control strategy, all aspects of brown rot fungi epidemiology are discribed and discussed in the second part of this review. The general disease cycle of Monilinia fructigena„M. laxa, M. fructicola and Monilia polystroma is described. After such environmental and biological factors are presented which influence the development of hyphae, mycelium, conidia, stroma and apothecial formation. Factors affecting the ability of brown rot fungi to survive are also demonstrated. Then spatio-temporal dynamics of brown rot fungi are discussed. In the last two parts, the epidemiology of brown rot fungi was related to disease warning models and some aspects of disease management.

The brown rot fungi of fruit crops (Monilinia spp.): III. Important features of disease management (Review paper)

In the third part of this review, important features of disease management are summarised for brown rot fungi of fruit crops (Monilinia fructigena, Monilinia laxa, Monilinia fructicola and Monilia polystroma). Several methods of brown rot disease management practices were collected and interpreted in five main chapters. In these chapters, details are given about the legislative control measures, the cultural, physical, biological and chemical control methods. Chemical control is divided into two parts: pre-harvest and post-harvest chemical control. In addition, host resistance and fungicide resistance statuses are also included in this part of the review. Finally, future aspects of brown rot disease control are discussed.

Determination of chlorophyll content in case of peach leaf curl disease (Taphrina deformans) with spectral analysis

One of the most important conditions of high quality fruit production is the early detection of hytopathologycal infections. The most dangerous disease of peach (Prunus persica) is the Taphrina deformans, which causes serious damages mainly in the years where the weather condition is cool and wet. In this study, healthy and naturally diseased leaves by peach leaf curl were investigated in the laboratory of University of Debrecen, CAAES, Institute of Water and Environmental Management. Both of hyperspectral measurement and the values of spectrophotometer shown the chlorophyll content of diseased leaves were lower than the healthy samples. Based on the experiments the water status of investigated leaves established the infected leaves contained more water in their tissues.

The increasing importance of grapevine trunk diseases

Grapevine trunk diseases (GTDs) are destroying the woody parts of the plants, resulting decline or dieback of the grapevine. More detailed research of the GTD began in 1950s, when Hewitt et al. (1957) observed that specific symptoms cannot be detected on the diseased trunks every year. Latest results have also proved that abiotic factors affect the appearance and the severity of the disease. Moreover several pathogenic fungi may play role as causative agents (Bertsch et al., 2013). Eutypa, Botryosphaeria, Phomopsis dieback, esca disease complex, and Petri disease are considered the major GTDs, where a variety of pathogens attack the woody perennial organs of the vine and ultimately lead to the death of the plant (Lehoczky, 1974; Larignon & Dubos, 1997; Rolshausen et al. 2010; Kotze et al., 2011; Bertsch et al., 2013; Fontaine et al., 2015).
The GTD incidence has been reported to be increased during the last decades (Úrbez-Torres et al., 2014). The esca incidence has reached 60% to 80% in some old vineyards in southern Italy (Pollastro et al., 2000; Surico et al., 2000; Calzarano & Di Marco, 2007). The disease incidence of the esca was reported to be increased from 1.83% to almost 13%, between 2003 and 2007 in Hungary (Dula, 2011). There was detected a five times increase in the GTD disease incidence in the Tokaj Wine Region, Hungary between 2014 and 2016 (Bihari et al,

Disease threshold for cherry leaf spot incidence on commercial sweet cherry cultivars

The aim of this study was to demonstrate the 10% threshold level for cherry leaf spot incidence on 23 commercial sweet cherry cultivars in two training systems. Twenty three cherry cultivars were evaluated in the two training systems with a spacing of 4 x 1 m and with a spacing of 2 x 5 m. Results showed that leaves of many cultivars were heavily infected, e.g. cultivars (cvs) ’Biggareau Burlat’, ’Sunburst’, while others showed low disease incidence e.g. cvs ’Celeste’ and ’Blaze Star’. According to the 10 % threshold level, cv ’Celeste’ proved to be the most resistant cultivar to leaf infection, while cv ’Münchebergi korai’ exceeded extremely the 10% threshold level. Leaf spot incidence was affected by training system on most cultivars. Thirteen cultivars had less than 10% infection in the 4 x 1 m spacing (i.e. they did not reach the 10% disease threshold level). At the same time, only 3 cultivars showed less than 10% infection in the 5 x 2 m spacing.

Disease warning models for brown rot fungi of fruit crops

In this review, disease warning models for brown rot fungi, including Monilinia fructigena, M. laxa and M. fructicola, were summarized. Few studies have been made to relate epidemiology and disease warning in brown rot infection caused by M. fructicola and M. laxa in order to predict infections or develop decision support models for fungicide applications during the growing season. More recently a disease warning model and a decision support system were also performed for M. fructigena for organic apple orchards. This review gives an overview on some details of the above disease warning models and decision support system.

Analyses of temporal dynamics of brown rot development on fruit in organic apple production

In a two-year study, yield loss and temporal dynamics of brown rot development caused by Monilinia fructigena (Aderh. & Ruhl.) Honey were quantified and analysed in two organic apple orchards (Debrecen—Pallag and Debrecen—Józsa). The first infected fruits were observed at the beginning of August in both years and both locations, except for one occasion when the first infected fruit was found at the end of July. Temporal disease development was continuous up to harvest time in both years and locations. In the two years, pre-harvest yield loss on the trees amounted between 8.9% and 9.3% at Debrecen-Pallag and between 9.7% and 10.8% at Debrecen—Jozsa by fruit harvest. Incidence of infected fruits on the orchard floor ranged from 32.4% to 43.2% and from 53.3% to 61.9%, at Debrecen—Pallag and Debrecen—Józsa, respectively, by fruit harvest. Analyses of temporal disease progress showed that the best-fitted mathematical function was the power function in both orchards and years. Both parameters of the power function clearly demonstrated that incidence of brown rot on fruit increased faster on the orchard floor than on the tree. Moreover, the disease increase was faster at Debrecen—Józsa in most cases than at Debrecen—Pallag. Our results indicated that the strategy of disease management, the ripeness of the fruit and the presence of a wounding agent played an important role in the yield loss and in the temporal development of fruit disease incidence caused by M. fructigena in organic apple orchards. Biological and practical implications of the results are discussed.

Some aspects of disease management of cherry leaf spot (Blumeriella jaapii) with special reference to pesticide use

In this review, some aspects of disease management of cherry leaf spot (Blumeriella jaapii) are summarised with special reference to pesticide use. In the first part of the review, we show the non-chemical control approach (e. g. removal of fallen leaves, planting resistant cultivar) against leaf spot. In the second part of the review, the effect of pesticides including fertilizers (urea) and fungicides on cherry leaf spot are discussed. Special attention are given to the fungicides of copper, dodine, captafol, captan, benomil, chlorothalonil, sterol demethylation inhibitors (e.g. fenarimol, fenbuconazole, myclobutanil, tebuconazole), and strobilurins about their effectiveness against cherry leaf spot. In the final part of the review, possibilities of cherry leaf spot control are discussed in integrated and organic cherry orchards.

Mechanical and physical control in apple orchards as preventative fungal disease management

In this minreview, mechanical and physical control against apple fungal diseases among non-chemical control approaches were summarized. This overview listed five groups of mechanical and physical control methods:  pruning, removal of inoculum sources, shredding of leaf litter, burying of inoculum sources and flaming of leaf litter. These methods were shown to reduce succesfully infection potential of inoculum sources in orchards and these non-chemical control measures are one of the most essential approaches for preventative fungal disease management. However, most of these methods are not widely spread in the apple-growing practice due to relatively low control efficacy, medium to high labour costs and/or time limits during the season.

Apple powdery mildew caused by Podosphaera leucotricha: some aspects of disease management

Apple powdery mildew (Podoshphaera leucorticha) occurs wherever apples are grown. One of the most important fungal disease of apple which causing severe econimic loss on susceptible apple cultivars. This review focuses on the control of apple powdery mildew. The first part of the study provides details of novel aspects of non-chemical control approaches, including agronomic measures, mechanical and biological control options as well as essential features of apple cultivar resistance. After this, developments in chemical control options are described sperately for integrated and organic apple orchards.

Brown rot blossom blight of pome and stone fruits: symptom, disease cycle, host resistance, and biological control

In this paper, important features of symptoms, biology and biological disease management are summarised for brown rot blossom blight fungi of pome and stone fruit crops (Monilinia laxa, Monilinia fructicola and Monilinia mali). Firstly, European brown rot caused by Monilinia laxa is discussed highlighting the blossom epidemiology features, then host susceptibility of the most important stone fruit species including several Hungarian and international cultivars. At the end of this chapter, recent biological control possibilities against Monilinia laxa are also included. Secondly, American brown rot caused by Monilinia fructicola is discussed. Symptoms, biological features of blossom blight and host susceptibility of flowers to Monilinia fructicola are demonstrated. Finally, the symptoms and the biology of the least frequent species, Monilinia mali are shown.

Effect of dry and wet years on primary inoculum source, incubation period and conidial production of Venturia inaequalis

The present study focuses on the characteristics of epidemics caused by the selected model-pathogen, Venturia inaequalis in relation to weather elements, with special respect to the increasing or decreasing effects of the specific weather elements. First, those weather elements are discussed which have a role in the development of scab epidemics. Subsequently, by accepting the thesis that climate change includes also weather extremes, an extremely hot and dry year (2003) and a colder year of higher than average precipitation (2004) were chosen as models. The presented examples verified that the variability of weather elements had had an undoubtable effect on the development of epidemics. The variability of weather elements manifests in the unusual behaviour of the pathogen, resulting in no or extreme disease epidemics. The extremities are well demonstrated by the fact, that in a year of drought an efficient protection can be achieved by considerably less applications than average, while in the next rainy year, the susceptible cultivar cannot be protected effectively even with such a high number of applications as is usual under humid Western-European climate conditions. It can also be noted, that the pathogen has a very good adaptability under unfavourable weather conditions. Consequently, more efficient management strategies should be developed for protection against the effects of extremities. However, it should be emphasized that it is very difficult to adapt to the variability and extremities of weather in the practice, because no long-term, accurate and reliable information is available about the variability of these elements.

Role of organosilicone surfactant in apple scab control under scab conducive weather conditions

Fungicides of integrated fruit production (dithianon, captan, and diclofluanid) and an organosilicone surfactant were compared in spray schedules from green tip until summer in order to control apple scab caused by Venturia inaequalis and to evaluate their phytotoxicity on fruit. Sixteen sprays of 1.8 kg ha-1captan, 0.41 ha-1 dithianon, and 1.8 kg ha-1 diclolfluanid significantly (P=0.05) reduced the incidence of leaf or fruit scab compared to unsprayed products. All fungicides applied with organosilicone at 0.1% resulted in lower incidence of scab on young and older leaves as well as on harvested fruit, but these were not statistically always better than fungicides applied alone. In case of diclofluanid, the fungicide applied with organosilicone at 0.1% resulted in significantly lower (P = 0.001) incidence of scab on young and older leaves. Diclofluanid applied with organosilicone at 0.1% gave the best scab control on leaf and fruit. Treatments applied with fungicides alone had no significant effect on plant phytotoxicity compared to untreated control. All fungicides applied with organosilicone at 0.1% increased (P = 0.05) fruit damage compared to untreated control or fungicide applied alone, though these were not always significantly different. In case of percentage of fruit russet, treatment of dithianon 0.4 1/ha + 0.1% organosilicone significantly increased fruit russet, while fruit russet index significantly increased in the treatment of diclofluanid 1.8 kg/ha + 0.1% organosilicone compared to untreated control. In sum, application of surfactants can help to increase efficacy of scab fungicides; and consequently, to reduce the risk of fungus infection under high scab disease pressure. This fact may also be helpful in fungicide resistance management and reduced-spray programs with accurate scab warning systems.

Biological performance of grape varieties in Eastern Hungary

Eurasian and interspecific grape varieties and candidates were inspected for biological productivity in the variety collection of the University of Debrecen at the Horticultural Experimental Station in Pallag. In this paper, data are reported on yields (kg/stock), cane production (kg/ stock) and use-up index of wood yield of each cultivar in the experimental years 2011-2012. From the range of Eurasian (Vitis vinifera L.) white wine-grape qualified cultivars and candidates ’Ezerfürtû’, ’Generosa’, ’Jubileum 75’, ’Müller Thurgau’, ’Zöld veltelíni’,’B-11’, ’CSFT-92’, ’Pintes’, from the range of Eurasian (Vitis vinifera L.) red wine-grape qualified cultivars and candidates ’Kármin’, ’Pinot noir’, ’Alicante Bouschet’ and ’Rubintos’ were highlighted. Promising data of interspecific ’Aletta’, ’Csillám’, ’Kunleány’, ’Orpheus’, ’Refrén’, ’Taurus’, ’Viktória gyöngye’, ’Alföld 100’, ’Reform’, ’RF38/32’, ’Toldi’ white, and ’Dunagyöngye’ ’Pannon frankos’ red wine-grape cultivars and candidates were emphasized. Published data refer only to the biological performance of the cultivars. The thorough evaluation of varieties needs respect to data on resistance to fungal disease and climatic extremities, and other characteristics concerning production technology and oenological parameters.

Field trials with non-bactericide products to control fire blight in apple orchards

Recently, novel strategies and chemical agents for prophylactic protection against the bacterial (Erwinia amylovora) disease fire blight are being sought. Resistance-inducing compounds, such as prohexadione-Ca represent promising alternatives. Prohexadione-Ca is the active ingredient of the bioregulator Regalis, currently being introduced in several European countries and overseas. Another product used in this study was Biomit Plussz, a leaf fertiliser providing harmonic supply of nutrient elements, the complete supply is assumed to improve the tolerance against diseases.

Treatments' effects of both of these products were compared to the effectiveness of treatments with antibiotics repeated twice, three or four times a season.

In the years of 2001 and 2002, the effectiveness of both Regalis and Biomit Plussz in reduction of incidence of shoot blight was similar, or proved to be superior to the check treatments consisting of repeated sprayings of antibiotics. Last year (2003) treatments of streptomycin resulted — although within the same magnitude — in a somewhat better control of shoot blight than sprayings with the other compounds.

As regards severity of blossom blight, inconsistent results were recorded concerning both Regalis and Biomit Plussz.

In general, prohexadione-Ca is less efficient for controlling flower infection by E. amylovora as compared to shoot infections, since successful prophylactic treatments are difficult to carry out early in the season. The highest effectiveness in fire blight management can, therefore, be achieved by using prohexadione-Ca (as preventive protection) in combination with streptomycin or other suitable antibiotics (as curative protection).

Some aspects of reduced disease management against Blumeriella jaapii in sour cherry production

The aim of this study was to evaluate the effectiveness of reduced spray programmes against cherry leaf spot in integrated and organic sour cherry orchards. Altogether four spray programmes were performed i) standard integrated: sprays followed by forecasting systems during the season, ii) reduced integrated: sprays followed by forecasting systems but only 75% of the spray numbers used during the season-long spray programme, iii) standard oragnic: sprays applied every 7–14 days during the season and iv) reduced organic: 60 % of the spray numbers used during the season-long spray programme. Our study showed that cherry leaf spot did not increase above 3.1, 7.4, and 8.9% in 2008, 2009, and 2010, respectively, in the integrated orchards. However, leaf spot incidence was above 20% in all years in the organic field. Reduced spray programme did not increase significantly cherry leaf spot incidence in the integrated field in either years. However, leaf spot incidence increased significanly (above 20%) in the reduced spray programme for the organic orchard.

Some aspects of reduced disease management against Monilinia spp. in sour cherry production

The aim of this study was first to test the in vitro effeicacy of some fungicides against brown rot of sour cherry, and secondly to evaulate the effectiveness of reduced spray programmes against brown rot in integrated and organic sour cherry orchards. In vitro efficacy of 7 fungicides (Champion 50 WP, Kocide 2000, Nordox 75 WG, Olajos rézkén, Kumulus S, Rézkén, Rézoxiklorid) and another 6 fungicides (Score 25 EC, Efuzin 500 SC, Systane, Folicur Solo, Zato Plusz, Rovral) approved in organic and integrated production systems, respectively, were tested against brown rot of sour cherry. Altogether four spray programmes were performed i) standard integrated: sprays followed by forecasting systems during the season, ii) reduced integrated: sprays followed by forecasting systems but only 75% of the spray numbers used during the season-long spray programme, iii) standard oragnic: sprays applied every 7–14 days during the season and iv) reduced organic: 60% of the spray numbers used during the season-long spray programme. In vitro results showed that fungicides (with active ingredients of copper and sulphur) applied in organic production showed relatively high percent growth capacity of Monilinia fungus. Rézkén showed the highest and Kumilus S the lowest efficacy against brown rot. Fungicides applied in integrated production showed relatively low percent growth capacity of Monilinia fungus. Score 25 EC showed the highest and Rovral the lowest efficacy against brown rot. Field study showed that reduced spray programmes did not increase significantly brown rot incidence in the integrated field. However, brown rot incidence increased significanly (above 30%) in the reduced spray programme for the organic orchard.

Effects of DMI and strobilurin fungicide combinations on scab and powdery mildew incidence in apple production: a preliminary study

The aim of our study was to evaulate the effectiveness of four DMI and strobilurion fungicide combinations in a season-long disease management programme against apple scab and powdery mildew in two integrated apple orchards on cultivar Jonagold. The four spray programmes were: i) standard, ii) DMI dominant iii) strobilurin dominant, and iv) DMI and strobilurin dominant. Apple scab incidence as generally high in both orchards in the standard fungicide treatment plots ranged between 21.8 and 26.4%. Leaf scab incidence was higher in all treatments compared to fruit incidence. Scab incidence was generally higher at Mándok compared to Ófehértó. In both locations the lowest scab incidence was assessed in DMI dominant treatment ranged between 5 to 10.7%, which was not signifi cantly different from the DMI and strobilurin dominant treatment. Powdery mildew incidence was generally low in both orchards in all fungicide treatments ranged between 0.002 and 0.5%. Although there were no signifi cant differences among treatments, the lowest powdery mildew incidence was assessed in the DMI and strobilurin dominant treatment in Mándok and in the strobilurin dominant treatment in Ófehértó.