2.14 In vitro methods for monitoring flusilazole sensitivity in populations of Venturia inaequalis (apple scab) and Cercosporidium personatum (peanut late leaf spot)

EPPO Bulletin ◽  
1991 ◽  
Vol 21 (2) ◽  
pp. 323-328 ◽  
Author(s):  
C. M. SMITH ◽  
A. E. TRIVELLAS ◽  
L. E. B. JOHNSON
Keyword(s):  
Leaf Spot ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Cercosporidium Personatum ◽  
Late Leaf Spot ◽  
In Vitro Methods

scholarly journals Effect of Timing of Application of the Biological Control Agent Microsphaeropsis ochracea on the Production and Ejection Pattern of Ascospores by Venturia inaequalis

2004 ◽  
Vol 94 (12) ◽  
pp. 1305-1314 ◽  
Author(s):  
O. Carisse ◽  
D. Rolland
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Control Agent ◽  
Sterile Leaf ◽  
Ascospore Production ◽  
Fall Application ◽  
Leaf Disks

Field and in vitro trials were conducted to establish the influence of the biological control agent Microsphaeropsis ochracea on the ejection pattern of ascospores by Venturia inaequalis and on apple scab development, and to establish the best timing of application. The ejection pattern of ascospores was similar on leaves sprayed with M. ochracea and on untreated leaves. Fall application of M. ochracea combined with a delayed-fungicide program was evaluated in orchards with intermediate and high scab risk. For both orchards, it was possible to delay the first three and two infection periods in 1998 and 1999, respectively, without causing significant increase or unacceptable leaf and fruit scab incidence. To evaluate the best timing of application, sterile leaf disks were inoculated with V. inaequalis and then with M. ochracea 0, 2, 4, 6, 8, 10, 12, 14, and 16 weeks later. After incubation under optimal conditions for pseudothecia development, the number of ascospores was counted. Similarly, M. ochracea was sprayed on scabbed leaves on seven occasions from August to November 1999 and 2000. Leaves were overwintered on the orchard floor and ascospore production was evaluated the following spring. Ascospore production was reduced by 97 to 100% on leaf disks inoculated with M. ochracea less than 6 weeks after inoculation with V. inaequalis, but ascospore production increased with increasing period of time when M. ochracea was applied 8 to 16 weeks after the inoculation with V. inaequalis. In the orchard, the greatest reduction in production of ascospores (94 to 96% in 2000 and 99% in 2001) occurred on leaves sprayed with M. ochracea in August. The production of ascospores was reduced by 61 to 84% in 2000 and 93% in 2001 on leaves sprayed with M. ochracea in September, reduced by 64 to 86% in 2000 and 74 to 89% in 2001 on leaves sprayed in October, and reduced by 54 and 67% in 2000 and 2001, respectively, on leaves sprayed in November. It was concluded that M. ochracea should be applied in August or September and that ascospore maturation models and delayed-fungicide program could be used in orchards treated with this biological control agent.

Applications of Mixtures of Copper Fungicides and Chlorothalonil for Management of Peanut Leaf Spot Diseases

2001 ◽  
Vol 2 (1) ◽  
pp. 1 ◽  
Author(s):  
A. K. Culbreath ◽  
T. B. Brenneman ◽  
R. C. Kemerait
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Cercospora Arachidicola ◽  
Copper Oxychloride ◽  
Copper Hydroxide ◽  
Cercosporidium Personatum ◽  
Late Leaf Spot ◽  
Copper Fungicides

Management of early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum) of peanut (Arachis hypogaea) in the southeastern U.S. is dependent upon multiple applications of foliar fungicides. Field experiments were conducted from 1997 to 2000 to compare the efficacy of mixtures of copper hydroxide or copper oxychloride and reduced rates of chlorothalonil with that of full rates of chlorothalonil alone or chlorothalonil + propiconazole. In all tests, rates per ha of 0.70 kg of chlorothalonil + 0.70 kg of copper oxychloride or higher provided leaf spot control that was similar (P > 0.05) to that achieved with standard rates of chlorothalonil (0.84 kg/ha) + propiconazole (0.063 kg/ha). Application of chlorothalonil at 0.56 kg/ha + copper oxychloride at 0.56 kg/ha controlled leaf spot as well as (P > 0.05) chlorothalonil alone at 1.26 kg/ha in five of six tests in which that treatment was evaluated. In three of four tests in 1998 and 1999, application of chlorothalonil at 0.63 kg/ha + copper hydroxide at 0.63 kg/ha controlled leaf spot as well as chlorothalonil alone at 1.26 kg/ha. In both tests in 2000, application of chlorothalonil at 0.84 kg/ha + copper hydroxide at 0.63 kg/ha controlled leaf spot as well as chlorothalonil alone at 1.26 kg/ha. There were no consistent yield differences among the chlorothalonil, chlorothalonil + propiconazole, or chlorothalonil + copper treatments. Accepted for publication 8 November 2001. Published 16 November 2001.

scholarly journals Sweet Immunity: The Effect of Exogenous Fructans on the Susceptibility of Apple (Malus × domestica Borkh.) to Venturia inaequalis

2020 ◽  
Vol 21 (16) ◽  
pp. 5885 ◽  
Author(s):  
Anze Svara ◽  
Łukasz Paweł Tarkowski ◽  
Henry Christopher Janse van Rensburg ◽  
Evelien Deleye ◽  
Jarl Vaerten ◽  
...  
Keyword(s):  
Complex Dynamics ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Fungal Growth ◽  
Production Costs ◽  
Future Research ◽  
Leaf Ontogeny ◽  
Disease Symptoms ◽  
Potential Use

There is an urgent need for novel, efficient and environmentally friendly strategies to control apple scab (Venturia inaequalis), for the purpose of reducing overall pesticide use. Fructans are recently emerging as promising “priming” compounds, standing out for their safety and low production costs. The objective of this work was to test a fructan-triggered defense in the leaves of apple seedlings. It was demonstrated that exogenous leaf spraying can reduce the development of apple scab disease symptoms. When evaluated macroscopically and by V. inaequalis-specific qPCR, levan-treated leaves showed a significant reduction of sporulation and V. inaequalis DNA in comparison to mock- and inulin-treated leaves, comparable to the levels in fosetyl-aluminum-treated leaves. Furthermore, we observed a significant reduction of in vitro mycelial growth of V. inaequalis on plates supplemented with levans when compared to controls, indicating a direct inhibition of fungal growth. Variations in endogenous sugar contents in the leaves were followed during priming and subsequent infection, revealing complex dynamics as a function of time and leaf ontogeny. Our data are discussed in view of the present theories on sugar signaling and fructan-based immunity, identifying areas for future research and highlighting the potential use of fructans in apple scab management in orchards.

Resistance to Myclobutanil in Populations of Venturia inaequalis in Winchester, Virginia

2007 ◽  
Vol 8 (1) ◽  
pp. 3 ◽  
Author(s):  
Sasha C. Marine ◽  
David G. Schmale ◽  
Keith S. Yoder
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Apple Orchards ◽  
The Mean ◽  
Moderately Resistant

Sterol-inhibiting (SI) fungicides are widely used to manage apple scab, caused by Venturia inaequalis. However, recent observations indicate that populations of V. inaequalis in orchards in Virginia have developed resistance to myclobutanil and other SI fungicides. Little is known about the frequency and distribution of fungicide resistance in apple scab populations in Virginia. Isolates of V. inaequalis were collected from three different apple orchards in Winchester, VA in 2006. Orchards were treated with myclobutanil on 12 April, 19 April, 1 May, 30 May, and 7 July. The sensitivity of 87 single-spored isolates of V. inaequalis to myclobutanil was determined by monitoring their growth on agar dishes amended with 0, 0.1, 0.5, or 1.0 μg/ml myclobutanil. A relative continuum of fungicide resistance was observed: 16 isolates were resistant, 40 isolates were moderately resistant, and 31 isolates were sensitive to myclobutanil. After 28 days, the mean growth of isolates collected from trees treated with myclobutanil was significantly greater than that of isolates collected from non-treated trees at all concentrations of myclobutanil tested in vitro. High levels of fungicide resistance found in populations of V. inaequalis suggest that replacement programs may need to be developed to manage apple scab in Virginia. Accepted for publication 4 September 2007. Published 13 November 2007.

scholarly journals KETAHANAN TIGA SPESIES ARACHIS TERHADAP BERCAK DAUN AKHIR (CERCOSPORIDIUM PERSONATUM BERK. ET CURT.) PADA PEMBERIAN DAN TANPA PEMBERIAN MANKOZEB

2004 ◽  
Vol 4 (2) ◽  
pp. 75-82
Author(s):  
Setyo Dwi Utomo ◽  
Hasriadi Mat Akin
Keyword(s):  
Wild Species ◽  
Leaf Spot ◽  
Effective Means ◽  
Yield Losses ◽  
Cercosporidium Personatum ◽  
Resistant Parent ◽  
Late Leaf Spot ◽  
Fungicide Treatment ◽  
Cultivated Peanut ◽  
Resistant Genotypes

The resistance of three species of Arachis to late leaf spot (Cercosporidium personatum) with and without application of mankozeb.  The use of  resistant cultivars and application of fungicide are effective means to control late leafspot.  Resistant genotypes of peanut is required as a parent for hibridization to develop high-yielding cultivars resistant to late leaf spot.  The objective of this study were to evaluate the resistance of 11 genotypes from three species of Arachis to  late leaf spot (C. personatum) with and without application of mankozeb.  The experiment was arangged ia a split splot design with three replications.  The main plots were  fungicide treatment (treated and untreated).  Fungicide mankozeb ( 4 g/l, 500 l/ha) was applied at 28, 40, 52, 64 and 76 days after planting.  The sub-plots were genotypes of species Arachis, i.e.,   7 lines of cultivated peanut (Archis hypogaea) from ICRISAT, 2 national varieties (Gajah and Kelinci),  and two wild species (A. cardenasii, and A. pintoi).  The two wild species were imune to late leaf spot so that they can be utilized as resistant parent in wide hybridization to develop a superior cultivars.  ICGV 88262 was more resistant than Gajah and Kelinci.  Because its yield tend to be lower than Gajah and Kelinci, ICGV 88262 also can be utilized as resistant parent in hibridization.  Mankozeb was efective and substantially reduced yield losses of cv. Gajah.  Mankozeb should be aplied in cultivation of cv. Gajah to control late leafspot.

scholarly journals Evaluation of Improved Valencia Peanut Varieties for Production in Haiti

2020 ◽  
Vol 47 (1) ◽  
pp. 1-8
Author(s):  
A.M. Fulmer ◽  
T.B. Brenneman ◽  
R.C. Kemerait ◽  
R. Macajoux ◽  
D.A. Carroll ◽  
...  
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Yield Potential ◽  
Average Increase ◽  
Cercosporidium Personatum ◽  
Central Plateau ◽  
Late Leaf Spot ◽  
Puccinia Arachidis ◽  
Arachis Hypogaea L ◽  
Plot Design

ABSTRACT Late leaf spot (Cercosporidium personatum) and peanut rust (Puccinia arachidis) are the most important diseases of peanut (Arachis hypogaea L.) in Haiti. Traditional Haitian peanut varieties are not only susceptible to these diseases but are also typically grown without benefit of a fungicide program. Five trials were conducted from 2015 to 2017 to evaluate the performance of six Valencia varieties in Quartier-Morin, Haiti (with an additional trial in 2017 at the Central Plateau) with respect to yield, resistance to rust and leaf spot diseases, and response to a fungicide program. A split-plot design with four or six replications was used in these studies. In each, “variety” was the whole plot and presence or absence of a fungicide program was the subplot. Valencia market types 309 Red, 309 Tan, M2, M3, SGV0801 and a local landrace were compared with and without Muscle ADV (tebuconazole + chlorothalonil, Sipcam) (2.3 L/ha) applied at 45, 60 and 75 days after planting (DAP). Final disease ratings (late leaf spot and peanut rust) were assessed approximately 94 DAP and plots were harvested the day following. In all trials, 309 Tan variety had the least amount of leaf spot and rust, but resulted in the lowest yield in four out of five trials, averaging 1727 kg/ha across fungicide treatments. M3, M2 and 309 Red were generally the numerically highest-yielding varieties, averaging 2906, 2864 and 2541 kg/ha across fungicide treatments, respectively, but were not statistically higher than the local Haitian Valencia, averaging 2374 kg/ha. Three fungicide applications during the season significantly increased yields in most trials for all varieties except 309 Tan. The highest and lowest average increase in yield from fungicide was for 309 Red (1126 kg/ha) and 309 Tan (103 kg/ha), respectively. The results from this study conducted over 2 years and 4 seasons document that while resistance to late leaf spot and rust is available in Valencia varieties, yield potential is not directly associated with that resistance. Also, use of fungicide improves yield potential in more susceptible varieties.

scholarly journals Evaluation of Essential Oils and Their Components for Broad-Spectrum Antifungal Activity and Control of Late Leaf Spot and Crown Rot Diseases in Peanut

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 375-379 ◽  
Author(s):  
G. Krishna Kishore ◽  
S. Pande ◽  
S. Harish
Keyword(s):  
Leaf Spot ◽  
Foliar Spray ◽  
Crown Rot ◽  
Curvularia Lunata ◽  
Infested Soil ◽  
Clove Oil ◽  
Cercospora Arachidicola ◽  
Cinnamon Oil ◽  
Late Leaf Spot

Clove oil, cinnamon oil, and five essential oil components (citral, eugenol, geraniol, limonene, and linalool) were tested for growth inhibition of 14 phytopathogenic fungi. Citral completely inhibited the growth of Alternaria alternata, Aspergillus flavus, Curvularia lunata, Fusarium moniliforme, F. pallidoroseum, and Phoma sorghina in paper disc agar diffusion assays. Cinnamon oil, citral, and clove oil as low as 0.01% (vol/vol) inhibited the spore germination of Cercospora arachidicola, Phaeoisariopsis personata, and Puccinia arachidis by >90% in vitro. Limonene and linalool were observed to be the least antifungal against the test fungi and were not used in further studies. Clove oil (1% vol/vol) applied as a foliar spray 10 min before Phaeoisariopsis personata inoculation reduced the severity of late leaf spot of peanut up to 58% when challenge inoculated with 104 conidia ml-1. This treatment was more effective (P = 0.01) than 0.5% (vol/vol) citral, cinnamon oil, or clove oil and 1% (vol/vol) eugenol or geraniol. Seed treatment with the test compounds had no effect on the incidence of crown rot in peanut in Aspergillus niger-infested soil. However, soil amendment with 0.25% (vol/wt) clove oil and cinnamon oil reduced the preemergence rotting by 71 and 67% and postemergence wilting by 58 and 55%, respectively, compared with the nontreated control. These two treatments were more effective (P < 0.01) than geraniol on preemergence rotting, and more effective than citral, eugenol, and geraniol on postemergence wilting. All treatments significantly outperformed the nontreated control but none were as effective as thiram treatment.

Management of Leaf Spot Diseases of Peanut With Prothioconazole Applied Alone or in Combination With Tebuconazole or Trifloxystrobin

2008 ◽  
Vol 35 (2) ◽  
pp. 149-158 ◽  
Author(s):  
A. K. Culbreath ◽  
R. C. Kemerait ◽  
T. B. Brenneman
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Yield Response ◽  
Cercospora Arachidicola ◽  
Cercosporidium Personatum ◽  
Late Leaf Spot ◽  
Similar Series

Abstract Field experiments were conducted in Tifton and Plains, GA in 2001–2007 to determine the efficacy of prothioconazole on early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personatum) of peanut (Arachis hypogaea). In five of six experiments, application of one or both rates (0.18 and 0.20 kg ai/ha) of prothioconazole in sprays 3–6 (chlorothalonil at 1.26 kg ai/ha in sprays 1, 2, and 7) provided leaf spot control superior to tebuconazole (0.23 kg ai/ha) in a similar regime, and superior to chlorothalonil at 1.26 kg ai/ha applied full season (seven times) in four of six experiments. In a similar series of six experiments, application of 0.085 kg ai/ha of prothioconazole + 0.17 kg ai/ha of tebuconazole provided better leaf spot control than tebuconazole (0.23 kg ai/ha) applied in regimes similar to those described above. Leaf spot control with prothioconazole + tebuconazole was similar to chlorothalonil applied at 1.26 kg ai/ha full season in five of eight experiments, but was less effective in the remaining three experiments. Fungicide effects on yield were inconsistent, but in all experiments, yield response with either rate of prothioconazole was similar to or greater than that obtained with 0.23 kg ai/ha tebuconazole on the same schedule. In a third series of four experiments, full-season (seven sprays) application of mixtures of prothioconazole at 0.063 kg ai/ha with trifloxystrobin at 0.063 kg ai/ha gave similar or better leaf spot control than chlorothalonil full season.

scholarly journals Characterization of rust, early and late leaf spot resistance in wild and cultivated peanut germplasm

2009 ◽  
Vol 66 (1) ◽  
pp. 110-117 ◽  
Author(s):  
Alessandra Pereira Fávero ◽  
Sérgio Almeida de Moraes ◽  
Antonio Augusto Franco Garcia ◽  
José Francisco Montenegro Valls ◽  
Natal Antonio Vello
Keyword(s):  
Wild Species ◽  
Leaf Spot ◽  
Fungal Diseases ◽  
Cercospora Arachidicola ◽  
Cercosporidium Personatum ◽  
Late Leaf Spot ◽  
Pests And Diseases ◽  
Puccinia Arachidis ◽  
Oil Crops ◽  
Late Leaf Spot Resistance

Groundnut (Arachis hypogaea) has an AB genome and is one of the most important oil crops in the world. The main constraints of crop management in Brazil are fungal diseases. Several species of the genus Arachis are resistant to pests and diseases. The objective of our experiments was to identify wild species belonging to the taxonomic section Arachis with either A or B (or " non-A" ) genomes that are resistant to early leaf spot (Cercospora arachidicola), late leaf spot (Cercosporidium personatum) and rust (Puccinia arachidis). For the identification of genotypes resistant to fungal diseases, bioassays with detached leaves were done in laboratory conditions, with artificial inoculation, a controlled temperature of 25ºC and a photoperiod of 10 h light/14 h dark, for 20-42 days, depending on the fungi species. Most of the accessions of wild species were more resistant than accessions of A. hypogaea for one, two or all three fungi species studied. Arachis monticola, considered to be a possible tetraploid ancestor or a derivative of A. hypogaea, was also more susceptible to Cercosporidium personatum and Puccinia arachidis, as compared to most of the wild species. Therefore, wild germplasm accessions of both genome types are available to be used for the introgression of resistance genes against three fungal diseases of peanut.

EFFECTS OF SEASONAL FUNGICIDE SPRAYS ON PERITHECIUM FORMATION AND ASCOSPORE PRODUCTION IN VENTURIA INAEQUALIS

1975 ◽  
Vol 55 (3) ◽  
pp. 737-742 ◽  
Author(s):  
R. G. ROSS ◽  
R. J. NEWBERY
Keyword(s):  
Venturia Inaequalis ◽  
Apple Scab ◽  
Malus Pumila ◽  
In Vitro Production ◽  
Ascospore Discharge ◽  
Malus Pumila Mill ◽  
Terminal Shoot ◽  
Vitro Production ◽  
Ascospore Production

Seasonal sprays of the systemic fungicides benomyl, thiophanate-methyl, Bay Dam 18654 and Bavistin applied for the control of apple scab, Venturia inaequalis (Cke.) Wint., either completely or almost completely suppressed the production of ascospores in apple (Malus pumila Mill.) leaves overwintered in the orchard. In vitro production of perithecia on leaves sterilized with propylene oxide was also inhibited by these sprays, although some treatments suppressed ascospore discharge in overwintered leaves that failed to inhibit perithecium formation on the sterile leaves. Ascospore production was also reduced in leaves from spur clusters that had been sprayed with Dikar and metiram. In terminal shoot leaves from Dikar-sprayed trees, ascospore production was higher in leaves collected from near the tip than in leaves collected from near the base of the terminal growth.

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