The control of apple scab (Venturia inaequalis) with some recently developed fungicides

1964 ◽  
Vol 4 (12) ◽  
pp. 55
Author(s):  
J Kuiper ◽  
BS Janes
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Black Spot ◽  
Field Trials ◽  
The Other ◽  
Single Trial

In field trials, dodine (n-dodecylguanidine acetate) controlled apple scab or black spot, Venturia inaequalis (Cke.) Wint., more effectively than several other fungicides at commonly used concentrations. The other fungicides in decreasing order of effectiveness were :-glyodin (2-heptadecyl-2-imidazoline acetate), thiram (tetramethylthiuram disulphide) and tecoram (bis-(dimethyldithiocarbamoyl)-ethylenebisdithiocarbamate). In a single trial, glyodin was superior to 2-heptadecyl-2-imidazoline. No phytotoxicity was observed in the trials.

scholarly journals Treatment of overwintering apple leaves to reduce primary inoculum of apple black spot

2003 ◽  
Vol 56 ◽  
pp. 95-99
Author(s):  
K. Tshomo ◽  
I.J. Horner ◽  
M. Walter ◽  
A. Stewart ◽  
M.V. Jaspers
Keyword(s):  
Venturia Inaequalis ◽  
Black Spot ◽  
Field Trials ◽  
Water Control ◽  
Primary Inoculum ◽  
Apple Leaves ◽  
Fungal Isolates ◽  
Glass Slides ◽  
Ascospore Production ◽  
Nutrient Amendments

Field trials were conducted in Hawkes Bay and Lincoln into methods of treating overwintering apple leaves to reduce ascospore production by the apple black spot pathogen Venturia inaequalis The leaf treatments comprised three levels of nutrient amendments (including a water control) and five levels of saprophytic fungal isolates (including a nofungus control) in a factorial design Leaves were left to overwinter on the orchard floor and in spring the V inaequalis ascospores released were trapped on glass slides and counted Ascospore numbers were reduced (Plt;005) by the leaf amendment urea which alone caused 73 reduction but not by the BioStarttrade; product The effect of fungal isolates was not significant (P012) although when combined with the water treatment the isolates Chaetomium Phoma and Epicoccum spp and Trametes versicolor reduced numbers of ascospores by 33 27 15 and 28 respectively compared to the nofungus control When combined with urea the Chaetomium isolate reduced ascospore numbers by 92 and 82 compared to the nil fungus/water control treatments in Hawkes Bay and Lincoln respectively indicating that this treatment has potential for reducing primary inoculum of apple black spot

scholarly journals Field comparison of sterol-biosynthesis-inhibiting fungicides used alone and in combination with protectant fungicides for apple scab control

2005 ◽  
Vol 71 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. Warner
Keyword(s):  
Disease Control ◽  
Broad Spectrum ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Field Trials ◽  
Sterol Biosynthesis ◽  
Scab Control

Several sterol-biosynthesis-inhibiting (SBI) fungicides were tested alone and in combination with a broad-spectrum protectant material in field trials for control of Venturia inaequalis. When used in a 10-day spray schedule, SBI fungicides, whether used alone or in a mixture, provided improved scab control as compared to the protectant material used alone. With bitertanol, diniconazole, and penconazole, the mixture also provided better scab control than when the SBI fungicide was used alone. However, with flusilazole and myclobutanil, no improvement in disease control occurred with the mixture as compared to the SBI fungicide alone. Fruit russeting was observed after a post-bloom application of hexaconazole and growth-regulating effects on the foliage were observed following cyproconazole and hexaconazole use. The use of SBI fungicides in mixtures to avoid or delay the development of fungus resistance is discussed.

scholarly journals A new apple scab risk model that integrates ascospore release infection risk and susceptible leaf area

2004 ◽  
Vol 57 ◽  
pp. 20-24 ◽  
Author(s):  
R.M Beresford ◽  
W.R. Henshall ◽  
J.W. Palmer
Keyword(s):  
Leaf Area ◽  
Risk Model ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Black Spot ◽  
Infection Risk ◽  
Weather Data ◽  
Scab Control ◽  
Ascospore Release ◽  
Maturation Rate

A new model has been developed for assessing daytoday variation in risk of infection of apples by Venturia inaequalis the scab or black spot pathogen The model comprises three components ascospore availability wetnessbased infection risk based on Mills periods and susceptible leaf area The ascospore and wetnessbased infection risk components were adapted from previous models whereas the susceptible leaf area component is new When the model used weather data from Hawkes Bay and Nelson in spring 2003 the predicted risk incidence was determined mostly by wetnessbased infection risk but the magnitude of risk periods was greatly influenced by predicted ascospore release The susceptible leaf area component predicted a hitherto unidentified increase in infection risk after the peak in ascospore maturation rate had occurred The model is intended to assist in fungicide selection and timing for scab control in New Zealand apples but needs to be field tested before implementation

scholarly journals Effect of Leaf Wetness Duration, Temperature, and Conidial Inoculum Dose on Apple Scab Infections

Plant Disease ◽  
1999 ◽  
Vol 83 (6) ◽  
pp. 531-534 ◽  
Author(s):  
J. R. Hartman ◽  
L. Parisi ◽  
P. Bautrais
Keyword(s):  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Apple Scab ◽  
The Other ◽  
Leaf Wetness ◽  
Leaf Wetness Duration ◽  
Inoculum Dose ◽  
Golden Delicious ◽  
Wetness Period ◽  
Series Of Experiments

Apple seedlings (2 months old, ‘Idared’ × ‘Golden Delicious’) were inoculated with conidia of Venturia inaequalis in order to study the effects of inoculum dose and leaf wetness duration on development of apple scab symptoms. For each experiment, the C3 curve (indicating heavy infection levels) was used as the basis for relating infection to temperature and leaf wetness duration. In one series of experiments, seedlings were treated with inoculum doses of 1.5, 5.4, 15.6, 32.2, 81.2, and 250 × 103 conidia/ml and leaves were kept wet during C3 infection periods at temperatures of 6, 11, 16, and 22°C. At all four temperatures, disease incidence (scab lesions/plant) increased with increasing inoculum doses up to about 81.2 × 103 conidia/ml. Disease incidence was lower at 22°C than at the other temperatures. In a second series of experiments, seedlings inoculated with 10 × 103 conidia/ml were kept moist for infection periods ranging from 0.6 to 2.0 times the C3 leaf wetness duration curve at 6, 11, 16, and 22°C. Disease incidence increased with increasing duration of leaf wetness and generally leveled off between 150 and 200% of the C3 curve. At this inoculum dose (10 × 103 conidia/ml), doubling the leaf wetness duration indicated by the C3 curve resulted in high disease incidence, similar to levels obtained with a higher inoculum (250 × 103 conidia/ml) and shorter wetness period (1.0 C3).

scholarly journals Avoiding apple bud damage from autumnapplied urea for black spot (Venturia inaequalis) control

2000 ◽  
Vol 53 ◽  
pp. 382-386
Author(s):  
P.N. Wood ◽  
R.M Beresford
Keyword(s):  
Venturia Inaequalis ◽  
Black Spot ◽  
Field Trials ◽  
One Year

Three field trials in Hawkes Bay and Pukekohe which involved the apple cvs Braeburn Royal Gala Fuji and Granny Smith showed that urea applied to trees in autumn for black spot (Venturia inaequalis) control at concentrations >5 was associated with death of apple buds the following spring Urea containing 09 biuret caused significantly more bud death than urea with 035 biuret but the toxicity of biuret appeared to be unimportant compared to the toxicity of the urea itself when urea was applied at concentrations >5 There was no cumulative bud damage between seasons when urea was applied at 5 in four successive autumns Multiple applications of urea in a single autumn caused bud death and it appeared that the total amount of urea applied in one year should not exceed 100 kg/ha (equivalent to one application of 5 urea)

scholarly journals Toward an Integrated Use of Biological Control by Cladosporium cladosporioides H39 in Apple Scab (Venturia inaequalis) Management

Plant Disease ◽  
2015 ◽  
Vol 99 (4) ◽  
pp. 535-543 ◽  
Author(s):  
Jürgen Köhl ◽  
Christian Scheer ◽  
Imre J. Holb ◽  
Sylwester Masny ◽  
Wilma Molhoek
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Field Trials ◽  
Cladosporium Cladosporioides ◽  
Yield And Quality ◽  
Scab Control ◽  
Apple Production ◽  
First Time ◽  
Important Disease

Apple scab, caused by Venturia inaequalis, is the most important disease in apple production, reducing yield and quality of fruit. Control of apple scab in commercial orchards currently depends on multiple applications of fungicides. The potential of the antagonistic isolate Cladosporium cladosporioides H39, originating from a sporulating colony of V. inaequalis, to control apple scab development was tested in eight trials during 2 years in orchards in Eperjeske (Hungary), Dabrowice (Poland), and Bavendorf (Germany) planted with different cultivars. Treatments were conducted as calendar sprays or after infection periods. Additional trials in an orchard in Randwijk (The Netherlands) focused on the effect of timing of antagonist application before or after infection periods. The overall results of the field trials consistently showed—for the first time—that stand-alone applications of the antagonist C. cladosporioides H39 can reduce apple scab in leaves and fruit. This was demonstrated in an organic growing system as well as in conventional orchards by spray schedules applied during the primary or the summer season. In both systems, the same control levels could be reached as with common fungicide schedules. Efficacies reached 42 to 98% on leaf scab incidence and 41 to 94% on fruit scab. The antagonist was also effective if applied one or even several days (equivalent to approximately 300 to 2,000 degree h) after infection events in several field trials and a trial conducted in Randwijk with single-spray applications at different intervals before or after infection events. Better understanding of the biology of the antagonist will help to further exploit its use in apple scab control.

scholarly journals The Effect of Different Forms of Sulphur on Incidence of Apple Scab on Apple Tree (Malus x domestica Borkh) Gloster CV.

2019 ◽  
Vol 26 (1) ◽  
pp. 199-208
Author(s):  
Hana Bělíková ◽  
Martin Mészáros ◽  
Ladislav Varga ◽  
Július Árvay ◽  
Barbara Wiśniowska-Kielian ◽  
...  
Keyword(s):  
Foliar Application ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Orchard ◽  
The Other ◽  
North East ◽  
Infection Pressure ◽  
Scab Control ◽  
High Infection ◽  
The Individual

Abstract From 2014 to 2015 the influence of foliar application of sulphur on apple trees (Gloster cv.)was investigated in the apple orchard at the Research and Breeding Institute of Pomology in Holovousy (North-East Bohemia, Czech Republic). The experiment was based on foliar applications of fertilizers containing different forms of sulphur: elemental S0, sulphate SO42− and thiosulphate S2O32− (in combination with other macro- and microelements) and fungicides with or without sulphur: Kumulus (S0 + F) and the conventional fungicide programme (F), in the respective treatments. Apple scab incidence on leaves and fruits was investigated in each experimental year according to the relevant methodology of the OEPP/EPPO standard PP1/5(3) Venturia inaequalis. Data on the incidence of apple scab correlate with the process of pathogen life cycle and risk of infection on the given dates. The incidence of apple scab was the lowest in 2014 in treatment S0 + F (10.8 % on leaves, 2.8 % on fruits) and F (15.8 % on leaves, 6 % on fruits) where conventional fungicides were used. When compared with the other treatments these treatments were the most effective even if the incidence of scab in the individual treatments in 2015 increased by 28 to 60 % due to high infection pressure. The results confirmed the efficiency of the conventional fungicide programme (S0 + F and F) against apple scab incidence on fruits. What is more, the results were slightly better in the treatment, where the conventional fungicide programme was combined with fertilizer containing elemental S (S0 + F) in comparison with fungicides applied alone (F). The effect of the other forms of sulphur (SO4 and S2O3) on apple scab control has not been confirmed. According to the results, the application of the conventional fungicide programme (S0 + F and F) is more effective against scab incidence than the inorganic forms of sulphur alone.

scholarly journals Suppression of Venturia inaequalis (apple scab) ascospore production using autumnapplied fungicides

2008 ◽  
Vol 61 ◽  
pp. 54-58
Author(s):  
P.N. Wood ◽  
R.M. Beresford ◽  
T.J. Taylor
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Black Spot ◽  
Field Application ◽  
Copper Hydroxide ◽  
Apple Leaves ◽  
Application Rates ◽  
Resistant Strains ◽  
Ascospore Production

In autumn 2006 apple leaves with visible scab (black spot) symptoms were collected at the time of leaf fall and dipped in fungicides at concentrations equivalent to field application rates The leaves were overwintered on gravel and ascospore production measured on three dates during the following spring using suction spore traps Of ten fungicides tested myclobutanil trifloxystrobin captan dodine tolyfluanid and cyprodinil either reduced or delayed ascospore production by Venturia inaequalis during the following spring compared with a waterdipped control Metiram dithianon urea and copper hydroxide had a minimal effect on ascospore production Leaves from a separate orchard trial produced significantly fewer ascospores after myclobutanil treatment than after captan treatment Captan and tolyfluanid are recommended for autumn application to control scab because they significantly reduced or delayed ascospore production and have a low risk of selecting resistant strains of V inaequalis Although also effective myclobutanil trifloxystrobin dodine and cyprodinil should not be used for autumn application because of the risk of fungicide resistance

scholarly journals Delayed Development of Resistance to QoI Fungicide in Venturia inaequalis in Israeli Apple Orchards and Improved Apple Scab Management Using Fungicide Mixtures

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 396
Author(s):  
Lior Gur ◽  
Keren Levy ◽  
Amotz Farber ◽  
Omer Frenkel ◽  
Moshe Reuveni
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Resistance Management ◽  
Field Trials ◽  
Qoi Fungicides ◽  
Development Of Resistance ◽  
Strategic Approach ◽  
Fungicide Mixtures ◽  
Mutation Region

Quinone outside inhibitors (QoI) fungicides group were introduced for commercial use against apple scab (Venturia inaequalis) in Israel in 1997. Unlike other regions in the world, in which resistance of V. inaequalis to QoI fungicides was observed within 3–5 years of use, in Israel it only occurred after 14 years of use. Field trials conducted between 2007 and 2017 showed a significant reduction in susceptibility to QoIs in northern Israel only since 2011. The delay in the development of resistance is related to limited fungicidal sprays resulting from unfavorable conditions for the pathogen. Of the 28 isolates collected from infected leaves or fruits of commercial orchards in northern Israel, 27 were resistant to the QoI fungicide Kresoxim-methyl. Amplification of the CYTB gene and sequencing of the G143A mutation region confirmed the resistance of all 27 isolates to QoIs. Resistance is demonstrated in the orchard, in vitro and molecular-based study, which forced the growers to avoid using QoIs against apple scab. We show that foliar applications of tank mixtures of systemic fungicides plus captan or prepacked fungicidal mixtures improved efficacy and can be used as a strategic approach in fungicide resistance management, including in orchards in which resistance to QoIs has been detected.

scholarly journals The Influence of Calcium Sprays to Reduce Fungicide Inputs Against Apple Scab [Venturia inaequalis (Cooke) G. Wint.]

2009 ◽  
Vol 35 (5) ◽  
pp. 263-270
Author(s):  
Glynn Percival ◽  
Ian Haynes
Keyword(s):  
Management Practices ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Calcium Content ◽  
Field Trials ◽  
Growth Stages ◽  
Urban Landscapes ◽  
Separate Study ◽  
Scab Control ◽  
The University

A goal of pathogen management in the arboriculture industry should be to eliminate or reduce the amount of active ingredients of synthetic fungicides used within a growing season. The aim of this research paper was to evaluate a nonfungicidal pathogen management system by investigating the hypothesis that replacing an apple scab fungicide spray program with calcium reduces fruit and leaf scab severity. In addition, a separate study investigated if a relationship existed between calcium concentrations within foliar tissue of resistant, intermediate, and sensitive apple species and varieties toward scab infection. A number of commercially available calcium products were applied to apple cv. Crown Gold trees at four distinct growth stages (bud break, 90% petal fall, early fruitlet, two weeks after early fruitlet). A comparative evaluation of the synthetic fungicide penconazole commercially used for scab control was also conducted. The experiment was performed in 2006 and repeated in 2007 at the University of Reading Experimental Field Site (UK). Application of calcium sprays significantly reduced the leaf and fruit scab severity of apple cv. Crown Gold however; in a separate study no relationship existed between foliar calcium content and susceptibility to apple scab attack between resistant, intermediate, and sensitive Malus species. Greatest protection in both field trials was provided by the synthetic fungicide penconazole. Within the calcium products evaluated, greatest protection in both field trials was provided by calcium chloride and calcium hydroxide. The integration of calcium foliar sprays into existing scab management practices offers a useful addition to reduce scab severity on ornamental apples that has applicability against other foliar diseases frequently encountered within urban landscapes.

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