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

2014 ◽  
Vol 20 (1-2) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Biological Control ◽  
Disease Management ◽  
Powdery Mildew ◽  
Chemical Control ◽  
Apple Cultivar ◽  
Apple Orchards ◽  
Cultivar Resistance ◽  
Podosphaera Leucotricha ◽  
Control Options ◽  
Apple Cultivars

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.

scholarly journals Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew [Podosphaera leucotricha (Ell. et Ev.) Salmon]

2013 ◽  
Vol 40 (1-2) ◽  
pp. 87-98
Author(s):  
Zbigniew Borecki
Keyword(s):  
Powdery Mildew ◽  
Chemical Control ◽  
Podosphaera Leucotricha ◽  
Apple Trees ◽  
Complete Field ◽  
Apple Cultivars ◽  
Disease Pressure ◽  
Moderate Susceptibility

Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew was evaluated in 1983-1986. Four groups of susceptibility were distinguished. None of the 13 tested scab-resistant apple trees exhibited complete field immunity to apple powdery mildew. Two cultivars, 'Prima' and 'Primula', were practically resistant. 'Liberty' and two numbered selections, NY-140-9 and NY-158-2, belonged to the group of lower susceptibility. Moderate susceptibility was shown by: 'Novamac', 'Freedom', 'Gavin', 'Prima' and 'Florina'. The group of apple trees most susceptible to <i>Podosphaera leucotricha</i> included: 'Macfree', 'Priscilla' and 'Nova Easygro'. It is not necessary to use chemical sprays to control powdery mildew on 'Prima' and 'Primula'. A reduced spraying program may be recommended only under high disease pressure on less susceptible apple cultivars. A regular spray schedule is needed on moderately susceptible apple trees, but improved chemical control is necessary on the most susceptible ones.

A novel technique for evaluation of apple (Malus × domestica Borkh.) cultivars for susceptibility to powdery mildew

2001 ◽  
Vol 81 (2) ◽  
pp. 289-296 ◽  
Author(s):  
P. L. Sholberg ◽  
W. D. Lane ◽  
P. Haag ◽  
K. Bedford ◽  
L. Lashuk
Keyword(s):  
Powdery Mildew ◽  
Research Centre ◽  
Cultivar Resistance ◽  
Podosphaera Leucotricha ◽  
Malus Domestica Borkh ◽  
Novel Technique ◽  
Food Research ◽  
The Pacific ◽  
Apple Cultivars ◽  
Breeding Selection

A technique for the evaluation of apple cultivars for susceptibility to powdery mildew caused by Podosphaera leucotricha (Ell. & Ev.) E. S. Salmon (anamorph Oidium farinosum Cooke) was tested at the Pacific Agri-Food research Centre (PARC), Summerland, BC. Shoots of test cultivars [Braeburn, Creston, Elstar, Empire, Fuji strain BC2, Gala strain Royal, Jonagold, McIntosh, Delicious red strain Bisbee, Shamrock, Silken, Sunrise, and one breeding selection (11w-17-85)], approximately 6 cm in length, were grafted on to branches of mature Jonagold trees in the spring and evaluated in the summer of the same year and in subsequent years after growth on the host tree. Incidence and severity of powdery mildew were evaluated in 1994, 1995, 1997, and 1998. They were not evaluated in 1996 because approximately half the grafts from the previous year did not grow and had to be replaced. The highest incidence of powdery mildew averaged 84% for Gala, compared with only 15% for Bisbee Delicious with the lowest incidence. Gala had the highest number of P. leucotricha conidia per cm2 of leaf area (4.9 × 104) compared to Bisbee Delicious (1.2 × 104). Some of the grafted cultivars were also evaluated for primary powdery mildew and fruit russetting in 1998 after the growth for three seasons. Jonagold had the highest numbers of primary infections and russetted fruit. Key words: Podosphaera leucotricha, breeding, cultivar resistance, pest management

scholarly journals Development and ultrastructure observations of secondary hyphae of Podosphaera leucotricha on apple cultivars of varying susceptibility to powdery mildew

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 425-428
Author(s):  
E. Rakhimova
Keyword(s):  
Electron Microscopy ◽  
Powdery Mildew ◽  
Light And Electron Microscopy ◽  
Dense Material ◽  
Podosphaera Leucotricha ◽  
Powdery Mildew Fungus ◽  
Full Complement ◽  
Apple Cultivars ◽  
Host Parasite

The development and ultrastructure feature of secondary hyphae of Podosphaera leucotricha were studied using light and electron microscopy. The percentage of development and length of secondary hyphae, differed in compatible and incompatible combinations. In compatible host-parasite combinations, hyphal cells of powdery mildew fungus contained a full complement of fungal organelles. There were differences of hyphal ultrastructure in compatible and incompatible host-parasite combinations, the main one was the appearance of dense material inside the nucleus, in the cytoplasm, and a few mitochondria.

Susceptibility of apple cultivars to apple scab and powdery mildew in Victoria, Australia

1998 ◽  
Vol 38 (6) ◽  
pp. 625 ◽  
Author(s):  
W. S. Washington ◽  
O. N. Villalta ◽  
J. Ingram ◽  
D. Bardon
Keyword(s):  
Powdery Mildew ◽  
Venturia Inaequalis ◽  
Natural Infection ◽  
Apple Scab ◽  
Podosphaera Leucotricha ◽  
Commercial Cultivars ◽  
Apple Cultivars ◽  
High Level

Summary. Twenty apple cultivars were assessed over 3 seasons for their susceptibility to natural infection with scab (caused by Venturia inaequalis) and powdery mildew (caused by Podosphaera leucotricha). It was evident that a number of important commercial cultivars are highly susceptible to leaf scab (average incidence of leaf scab: Pink Lady, 40.2% of leaves; Lady William, 37.1%; Braeburn, 20.0%; and New Jonagold, 18.7%) and powdery mildew (average incidence of leaf mildew: New Jonagold, 23.0%; Pink Lady, 17.8%). There was a high level of resistance to leaf scab in the cultivars Florina-Quérina, Redfree and Jonafree (all less than 1% incidence on leaves) and to powdery mildew in the cultivar Earlidel (no infection observed). The cultivars Jonathan, Bonza and Red Elstar showed a useful level of resistance to scab (average incidence of leaf scab between 1.6 and 3.2%), while the cultivars Red Fuji, HiEarly and Redfree all showed some resistance to powdery mildew (average incidence of mildew between 2.6 and 5.9%). Observations made on the low and variable numbers of fruit produced by some trees in their third year after planting showed that Pink Lady and Lady William were highly susceptible to fruit scab (67.6 or 57.6% scabbed fruit respectively). Twig infection by scab was also observed on shoots of the current season’s growth of Pink Lady.

scholarly journals Types and composition of diseases and pests of restructured forest and pasture plants in the dry part of the Aral Sea

2021 ◽  
Vol 939 (1) ◽  
pp. 012084
Author(s):  
O Khujaev ◽  
D Obidjanov ◽  
O Tursunov ◽  
O Nazarova
Keyword(s):  
Biological Control ◽  
Powdery Mildew ◽  
Dominant Species ◽  
Control Measures ◽  
Aral Sea ◽  
Podosphaera Leucotricha ◽  
Experimental Variant ◽  
Dominant Disease ◽  
Inflammatory Drugs ◽  
Pasture Plants

Abstract Studies on the dried bottom of the Aral Sea have shown that dominant disease from 3 species of them in Haloxylon plant is Podosphaera leucotricha and the dominant species from 34 species of pests is Big Dwarf Haloxylon Locust (D. albidula) and Small Haloxylon Locust (D. annulata roseipen). Chemical and biological control measures were taken against this disease and pests. When using anti-inflammatory drugs Redomil gold, Dnox, Fundazol and Sporagin, their effectiveness is as follows: Redomil gold - 68% sp (2.0–2.5 kg / ha), Fundazol -50% ke (2.0 l / ha), Dnox - 40% ke (2.0 l / ha) and Sporagin (4.0, l / ha) were tested using fungicides in the norms. Of the drugs used in the experimental variant, Redomil gold, 68% s.p. (2.0-2.5 kg / ha) was the highest biological efficacy against powdery mildew in the variant in which the fungicides were applied, was 91.3%.

scholarly journals Disease management in Hawkes Bay apple orchards converting to organic production

2000 ◽  
Vol 53 ◽  
pp. 1-6 ◽  
Author(s):  
K.G. Tate ◽  
D.W. Manktelow ◽  
J.T. Walker ◽  
H. Stiefel
Keyword(s):  
Disease Management ◽  
Powdery Mildew ◽  
Disease Control ◽  
Black Spot ◽  
Organic Production ◽  
Apple Orchards ◽  
Organic Orchards

Disease control achieved by 10 apple growers converting to organics during the 199798 and 199899 seasons is reported Two orchards experienced black spot outbreaks each season while the remainder averaged 05 spotted fruit Powdery mildew was severe in 199798 but acceptable in 199899 Fruit rots after coolstorage averaged 011 for different varieties in 199798 and 030 in 199899 Fungicide applications averaged 116 in 199798 and 184 in 199899 which was a net increase in chemical use Copper use was below 3 kg/ha/year The mostused spray programme was a greentip copper three prebloom limesulphurs sulphur/copper bloom sprays and sulphur or sulphur/ copper sprays thereafter Results showed that acceptable disease control is achievable in organic orchards but summer and core rots remain a concern

scholarly journals Apple powdery mildew caused by Podosphaera leucotricha: some aspects of biology

2013 ◽  
Vol 19 (3-4) ◽  
Author(s):  
I. Holb
Keyword(s):  
Powdery Mildew ◽  
Geographical Distribution ◽  
Causal Agent ◽  
Host Susceptibility ◽  
Podosphaera Leucotricha ◽  
Disease Cycle ◽  
The Past ◽  
The World ◽  
Apple Cultivars ◽  
Resistance Durability

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. Biology of the pathogen is widely investigated all over the world in the past 100 years. In this review, a summary from this enormous research is made for biology of apple powdery mildew in the following aspects: geographical distribution, morphology, taxonomy of the causal agent, symptoms, host susceptibility, resistance durability and disease cycle.

Relative Susceptibility of Selected Apple Cultivars to Powdery Mildew Caused by Podosphaera leucotricha

2009 ◽  
Vol 10 (1) ◽  
pp. 3 ◽  
Author(s):  
Alan R. Biggs ◽  
Keith S. Yoder ◽  
David A. Rosenberger
Keyword(s):  
Powdery Mildew ◽  
Disease Incidence ◽  
Cultivar Differences ◽  
Susceptible Cultivar ◽  
Chronic Effect ◽  
Podosphaera Leucotricha ◽  
Yield Data ◽  
Golden Delicious ◽  
Regional Project ◽  
Apple Cultivars

Apple powdery mildew thrives during dry spring and summer weather wherever apples are grown. The fungus perennates in buds, making it difficult to control and, although it can cause fruit russet, it primarily causes losses due to its chronic effect on tree vigor and yield. Data were collected over several years from 1995 (23 entries) and 1999 (22 entries) plantings of new apple cultivars and selections established at multiple locations as part of regional project NE-183. The cultivars Golden Delicious and McIntosh were the standards in both plantings. Incidence of powdery mildew on leaves and fruit was observed and data were analyzed to determine differences due to location and cultivar. One of the two planting group analyses indicated the significance of cultivar differences due to location. In general, the cultivars Ginger Gold, Suncrisp, GoldRush, Crimson Crisp, and Delblush, and the selection CQR10T17 were the most susceptible, whereas the cultivars Gala Supreme, Enterprise, Zestar, September Wonder, Hampshire, and the selections NY 75414-1 and NY 79507-72 exhibited the lowest incidences of mildew. Pinova was the most highly susceptible cultivar to mildew on fruit in Virginia, followed by Crimson Crisp and the selection NY 65707-19. Percent leaf area with mildew was related to incidence of mildew on leaves; however, fruit symptoms were not significantly related to disease incidence or severity on the foliage. Accepted for publication 11 September 2009. Published 19 November 2009.

scholarly journals High Genetic Diversity in Predominantly Clonal Populations of the Powdery Mildew Fungus Podosphaera leucotricha from U.S. Apple Orchards

2021 ◽  
Author(s):  
Lederson Gañán-Betancur ◽  
Tobin L. Peever ◽  
Kate Evans ◽  
Achour Amiri
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Resistance Gene ◽  
Mating Type ◽  
Genetic Heterogeneity ◽  
Population Biology ◽  
Plant Diseases ◽  
Apple Orchards ◽  
Podosphaera Leucotricha ◽  
Major Resistance Gene

Apple powdery mildew (APM), caused by Podosphaera leucotricha, is a constant threat to apple production worldwide. Very little is known about the biology and population structure of this pathogen in the USA and other growing regions, which impacts APM management. Two hundred fifty-three P. leucotricha isolates, sampled from 10 apple orchards in Washington, New York, and Virginia, were genetically characterized with novel single sequence repeat and mating type markers. Eighty-three multilocus genotypes (MLGs) were identified, most of which were unique to a given orchard. Each isolate carried either a MAT1-1 or MAT1-2 idiomorph at the mating type locus, indicating that P. leucotricha is heterothallic. Virulence tests on detached apple leaves showed that the 10 most frequent P. leucotricha MLGs were not avirulent on a line containing a major resistance gene. Analysis of molecular variance showed significant differentiation (P > 0.001) among populations, a result supported by principal coordinate analysis revealing three genetic groups, each represented by non-overlapping MLGs from Washington, New York, and Virginia. A Bayesian cluster analysis showed genetic heterogeneity between Washington populations, and a relative migration analysis indicated substantial gene flow among neighboring orchards. Random mating tests indicated that APM epidemics during the active cycle were dominated by clonal reproduction. However, the presence of sexual structures in orchards, the likelihood that five repeated MLGs resulted from sexual reproduction, and high genotypic diversity observed in some populations suggest that sexual spores play some role in APM epidemics. IMPORTANCE Understanding the population biology and epidemiology of plant pathogens is essential to develop effective strategies for controlling plant diseases. Herein, we gathered insights into the population biology of P. leucotricha populations from conventional and organic apple orchards in the United States. We showed genetic heterogeneity between P. leucotricha populations in Washington, and structure between populations from different U.S. regions, suggesting that short-distance spore dispersal plays an important role in the disease’s epidemiology. We presented evidence that P. leucotricha is heterothallic, and that populations likely result from a mixed (i.e., sexual and asexual) reproductive system, revealing that the sexual stage contributes to apple powdery mildew epidemics. We showed that the major resistance gene Pl-1 is valuable for apple breeding because virulent isolates have most likely not emerged yet in U.S. commercial orchards. These results will be important to achieve sustainability of disease management strategies and maintenance of plant health in apple orchards.

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