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 Autumnapplied urea and other compounds to suppress Venturia inaequalis ascospore production

2000 ◽  
Vol 53 ◽  
pp. 387-392
Author(s):  
R.M Beresford ◽  
I.J. Horner ◽  
P.N. Wood
Keyword(s):  
Venturia Inaequalis ◽  
Black Spot ◽  
Leaf Fall ◽  
Single Application ◽  
Apple Trees ◽  
Spot Disease ◽  
Apple Leaves ◽  
Cupric Hydroxide ◽  
Fallen Leaves ◽  
Ascospore Production

The effect of urea applied to apple leaves in autumn on production of ascospores of Venturia inaequalis (black spot) was quantified in four studies Autumn urea at concentrations from 020 reduced ascospore production in spring in proportion to the log of the urea concentration A single application of 5 urea sprayed onto fallen leaves gave an 88 decrease in ascospore production Urea applied to apple trees before leaf fall significantly reduced black spot disease on leaves the following spring in cv Fuji but not in cv Royal Gala Ascospore production was reduced by the fungicide cupric hydroxide but was not affected by a low concentration of fish fertilizer Three methods of ascospore assessment were used to detect differences in ascospore production

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

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 Role of urea in the reduction of apple primary infections by Venturia inaequalis (Cooke) Aderh

2013 ◽  
Vol 55 (1) ◽  
pp. 225-231
Author(s):  
Beata Meszka ◽  
Anna Bielenin
Keyword(s):  
Chemical Control ◽  
Primary Infection ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Leaf Fall ◽  
Urea Treatment ◽  
Apple Leaves ◽  
Leaf Infection ◽  
Ascospore Production

The effect of pre-leaf fall of 5% urea treatment on primary infection of apple by <i>Venturia inaequalis</i>, the cause of scab, was investigated in commercial apple orchards of McIntosh cv. in different regions of Poland, at Miłobądz, Sinołęka and Dąbrowice. Additionally, the development of pseudothecia and maturation of ascospores were evaluated in the spring on apple leaves of two cultivars (McIntosh and Gloster) treated with 5% solution of urea. Microscopic observations of leaves showed that urea treatment significantly reduced the number of pseudothecia (by ca. 90%) and ascospore production. Low number of ascospores after urea treatment has strongly affected primary infection of apple by the fungus in all tested orchards. Reduction of leaf infection on control trees was usually more than 30%. Also efficacy of chemical control of apple scab was significantly higher on plots treated with urea.

scholarly journals In vitro evaluation of fungal isolates and nutrient amendments for enhancing apple leaf decay

2003 ◽  
Vol 56 ◽  
pp. 90-94
Author(s):  
K. Tshomo ◽  
M. Walter ◽  
A. Stewart ◽  
M.V. Jaspers
Keyword(s):  
Leaf Litter ◽  
Trametes Versicolor ◽  
Black Spot ◽  
Fruit Trees ◽  
Fruiting Bodies ◽  
Fruit Crops ◽  
Leaf Discs ◽  
Fungal Isolates ◽  
Nutrient Amendments

Primary spread of apple black spot is by ascospores produced from overwintering apple leaf litter To find effective degraders of litter an in vitro trial screened 59 fungal isolates for the ability to colonise sterilised senesced apple leaf discs The isolates of Aureobasidium Alternaria Chaetomium Coniothyrium Epicoccum Fusarium Phoma Trichoderma and Ulocladium spp had originated from the phylloplane or leaf litter of fruit crops The whiterot basidiomycete isolates were from fruiting bodies on native beech poplar and fruit trees The 18 isolates that colonised leaf discs most rapidly were further tested with five nutrient leaf amendments for their biodegradation activity on leaf discs After incubation at 10C for 9 weeks the most effective isolates of Trametes versicolor Phoma Epicoccum and Chaetomium spp caused 54 39 37 and 23 weight reduction respectively while the leaf amendments urea and the mixture of Mycorrcintrade; and Digestertrade; caused 29 and 20 reduction respectively These treatments were selected for evaluation in a field trial

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 Calcium chloride against black spot on apples

2010 ◽  
Vol 63 ◽  
pp. 279-279
Author(s):  
K.S.H. Boyd-Wilson ◽  
R.C. Butler ◽  
M. Walter
Keyword(s):  
Calcium Chloride ◽  
Venturia Inaequalis ◽  
Disease Incidence ◽  
Black Spot ◽  
Growing Season ◽  
High Rate ◽  
Water Control ◽  
Veterinary Medicines ◽  
Foliar Damage ◽  
Apple Production

Calcium chloride which is classified as generally recognised as safe (GRAS) under the Agricultural Compounds and Veterinary Medicines Regulations 2001 has potential for use in an organic apple production system against black spot (Venturia inaequalis) The effectiveness of calcium chloride on control of black spot was evaluated in a field trial over the 2007/2008 growing season Calcium chloride was applied 10 times over the season at the commerciallyrecommended rate of 033 kg product/100 litres or at 2 kg/100 litres (the latter treatment was halved after two applications due to foliar damage) At harvest fruit treated with the high rate of calcium chloride had a lower disease incidence of 41 than the water control which had 97 incidence (P

scholarly journals Relationships between autumn black spot leaf litter and Venturia inaequalis ascospore production in apple orchards

2002 ◽  
Vol 55 ◽  
pp. 121-124
Author(s):  
I.J. Horner ◽  
M.B. Horner
Keyword(s):  
Leaf Litter ◽  
Management Strategy ◽  
Production Management ◽  
Management Practices ◽  
Venturia Inaequalis ◽  
Management Strategies ◽  
Black Spot ◽  
Disease Management Strategy ◽  
Spring Leaf ◽  
Ascospore Production

Ascospore production from pseudothecia in apple leaf litter in the spring is a critical step in the disease cycle of Venturia inaequalis Leaf litter management is potentially an important component of an integrated pest and disease management strategy An orchard study was carried out in Hawkes Bay to investigate the relationships between the incidence of black spot on leaves in autumn the density of apple leaf litter on the orchard floor in spring and the number of ascospores produced in spring A total of 22 blocks on eight orchards were surveyed for black spot incidence in autumn 2000 The following spring remaining leaf litter was measured and ascospore production was quantified using spore traps Autumn black spot levels and spring litter levels were accurate predictors of spring ascospore production Management strategies employed on different blocks influenced spring leaf litter and ascospore levels Blocks with high autumn black spot generally had high spring ascospore production Management practices that substantially reduced litter levels resulted in reduced V inaequalis inoculum

scholarly journals Effect of Fall Application of Fungal Antagonists on Spring Ascospore Production of the Apple Scab Pathogen, Venturia inaequalis

2000 ◽  
Vol 90 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Odile Carisse ◽  
Vincent Philion ◽  
Daniel Rolland ◽  
Julie Bernier
Keyword(s):  
Large Scale ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Leaf Fall ◽  
Natural Conditions ◽  
Fungal Isolates ◽  
Trichoderma Sp ◽  
Ascospore Production ◽  
Fall Application ◽  
Leaf Disks

The influences of Microsphaeropsis sp., M. arundinis, Ophiostoma sp., Diplodia sp., and Trichoderma sp., all antagonists of Venturia inaequalis, on ascospore production were evaluated under natural conditions and compared with urea and Athelia bombacina, a known antagonist. In the autumn, the fungi were applied to leaf disks artificially inoculated with V. inaequalis and to scabbed apple (Malus domestica) leaves incubated under controlled and natural conditions. In addition, large-scale trials were conducted with Microsphaeropsis sp. applied either as a foliar postharvest spray or as a ground application at 90% leaf fall. All fungal isolates, except Ophiostoma sp., were recovered from the leaf material that overwintered in the orchard. All treatments, except those with Ophiostoma sp., resulted in a significant reduction in V. inaequalis ascospore production on the leaf disks incubated under controlled conditions or in the orchard. In 1997, leaves with apple scab lesions treated with urea or Microsphaeropsis sp. produced significantly fewer ascospores of V. inaequalis than did nontreated leaves, with a reduction of 73.0 and 76.3%, respectively. In 1998, leaves treated with Microsphaeropsis sp., urea, Trichoderma sp., A. bombacina, and M. arundinis reduced ascospore production by 84.3, 96.6, 75.2, 96.6, and 52.2%, respectively. Based on all tests combined, the most efficient isolate was Microsphaeropsis sp. Postharvest applications of Microsphaeropsis sp. reduced the total amount of airborne ascospores trapped by 70.7 and 79.8% as compared with the nontreated plots in 1997 and 1998, respectively. Microsphaeropsis sp. provided a significant and consistent reduction in ascospore production in all tests.

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