Accumulation of isoflavonoid phytoalexins in leaves of Arachis hypogaea differing in reaction to rust (Puccinia arachidis) and early leafspot (Cercospora arachidicola)

1995 ◽  
Vol 44 (3) ◽  
pp. 573-579 ◽  
Author(s):  
C. EDWARDS ◽  
R. N. STRANGE ◽  
D. L. COLE
Keyword(s):  
Arachis Hypogaea ◽  
Cercospora Arachidicola ◽  
Puccinia Arachidis

Isolation of the Phytoalexin Medicarpin from Leaflets of Arachis hypogaea and Related Species of the Tribe Aeschynomeneae

1985 ◽  
Vol 40 (5-6) ◽  
pp. 313-316 ◽  
Author(s):  
R. N. Strange ◽  
J. L. Ingham ◽  
D. L. Cole ◽  
M. E. Cavill ◽  
C. Edwards ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Arachis Hypogaea ◽  
Related Species ◽  
Natural Infection ◽  
Spore Suspension ◽  
Cercospora Arachidicola

Abstract A phytoalexin produced by the leaflets of seven cultivars of Arachis hypogaea (groundnut) after natural infection by Cercospora arachidicola or Phoma arachidicola has been characterised as the isoflavonoid (+)-medicarpin (3-hydroxy-9-methoxypterocarpan). Treatment of excised ground­nut leaflets with an aqueous solution of CuSO4 or with a spore suspension of the fungus Helmin-thosporium carbonum has also been found to stimulate medicarpin biosynthesis.

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 Night Spraying Peanut Fungicides I. Extended Fungicide Residual and Integrated Disease Management

Plant Disease ◽  
2010 ◽  
Vol 94 (6) ◽  
pp. 676-682 ◽  
Author(s):  
J. Augusto ◽  
T. B. Brenneman ◽  
A. K. Culbreath ◽  
P. Sumner
Keyword(s):  
Disease Management ◽  
Chemical Control ◽  
Sclerotium Rolfsii ◽  
Residual Activity ◽  
Field Trials ◽  
Stem Rot ◽  
Integrated Disease Management ◽  
Cercospora Arachidicola ◽  
Puccinia Arachidis ◽  
Fungicide Efficacy

The efficacy of chemical control of stem rot (caused by Sclerotium rolfsii) of peanut (Arachis hypogaea) relies partially on increasing deposition and residual activity in the lower canopy. Tebuconazole (0.21 kg a.i./ha, four applications) and azoxystrobin (0.31 kg a.i./ha, two applications) were each applied on peanut plants in daylight or at night, when leaves were folded, in two Tifton, GA, field trials in 2007. Both timings of each fungicide provided similar control of early leaf spot (caused by Cercospora arachidicola). Night applications of azoxystrobin and tebuconazole reduced stem rot at digging and increased yield compared with day applications. Night applications of tebuconazole were also tested in Nicaragua from 2005 to 2007. Peanut plants had less stem rot, similar levels of rust (caused by Puccinia arachidis), and higher yield with night applications than with day applications. Residual activity of azoxystrobin and tebuconazole were improved on the bottom shaded leaves (on which fungicides would be better deposited with night application) compared with top, sun-exposed leaves (where most fungicide would be deposited with a day application) according to a bioassay with S. rolfsii. Increased fungicide residual activity within the bottom canopy may increase fungicide efficacy on stem rot and augment peanut yield.

Effect of In-Furrow and Early-Season Banded Applications of Fungicides on Incidence of Early Leaf Spot of Peanut

2015 ◽  
Vol 16 (4) ◽  
pp. 225-229
Author(s):  
Albert K. Culbreath ◽  
Robert C. Kemerait ◽  
Yun-Ching Tsai ◽  
Timothy B. Brenneman ◽  
Katherine L. Stevenson ◽  
...  
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
Cercospora Arachidicola ◽  
Early Season ◽  
Fungicide Application

Field experiments were conducted in Tifton, GA, in 2012-2014 to determine the effect of in-furrow applications of prothioconazole and early-season banded applications of prothioconazole or pyraclostrobin on incidence of early leaf spot (Cercospora arachidicola) of peanut (Arachis hypogaea). In each year, border rows were planted in May as a source of inoculum for plants in the treatment plots. Plots were planted in August or September after epidemics of early leaf spot were severe in the border plots. Fungicide application regimes included two rates (100 and 200 g a.i./ha) of prothioconazole applied in-furrow at planting, and 200 g a.i./ha of prothioconazole or 164 g a.i./ha of pyraclostrobin applied concentrated in a 30-cm band 21 days after planting (DAP). Incidence (percent of leaflets with one or more leaf spot) of early leaf spot was monitored until 54 to 57 days after planting in each year. In all years, disease incidence was below 10% at 28 DAP in plots treated with 200 g a.i./ha of prothioconazole in-furrow compared to over 40% in nontreated plots at the same time. In-furrow applications of 100 g a.i./ha of prothioconazole were less effective, but suppressed leaf spot incidence compared to the control. Banded applications of either fungicide at 21 DAP resulted in a decrease in leaf spot incidence, and prevented increase in leaf spot incidence for 19 days or longer. Accepted for publication 30 November 2015. Published 3 December 2015.

The Choice of Groundnut (Arachis hypogaea) Varieties by Smallholders in South-east Tanzania. I. Observations on Different Varieties

1986 ◽  
Vol 22 (3) ◽  
pp. 269-278 ◽  
Author(s):  
S. R. Preston ◽  
J. H. Simons ◽  
B. R. Taylor
Keyword(s):  
Arachis Hypogaea ◽  
Seed Dormancy ◽  
Moisture Stress ◽  
Yield Losses ◽  
Cercosporidium Personatum ◽  
Varietal Differences ◽  
Puccinia Arachidis ◽  
Short Season

SUMMARYSmallholders in south-east Tanzania grow the groundnut Red Mwitunde (Arachis hypogaea ssp. hypogaea), a long-season variety with seed dormancy, although earlier maturing varieties with no seed dormancy (ssp. hypogaea and fastigiata) usually yielded better in trials, particularly when late sown. Small-seeded, short-season varieties established better in the field than Red Mwitunde and other large-seeded varieties, especially under moisture stress. Trials with selective fungicides to estimate yield losses from leafspots (mainly Cercosporidium personatum) and rust (Puccinia arachidis), jointly and separately, showed no consistent varietal differences.

scholarly journals Selection Indices for Simultaneous Selection for Pod Yield and Leafspot Resistance in Peanut (Arachis hypogaea L.)1

1987 ◽  
Vol 14 (1) ◽  
pp. 51-54 ◽  
Author(s):  
R. N. Iroume ◽  
D. A. Knauft
Keyword(s):  
Arachis Hypogaea ◽  
Breeding Value ◽  
Direct Selection ◽  
Index Selection ◽  
Cercospora Arachidicola ◽  
Pod Yield ◽  
Arachis Hypogaea L ◽  
Yield Gain ◽  
Selection For ◽  
Disease Pressure

Abstract The objective of this study was to investigate the possibility of index selection for pod yield and leafspot resistance, causal organisms Cercospora arachidicola Hori and Cercosporidium personatum (Berk. and Curt.) Deighton, in peanut (Arachis hypogaea L.). Eleven crosses were evaluated in the S1 and S2 generations under natural disease pressure for pod yield and disease reaction. Leafspot severity was measured by leaf necrotic area and defoliation. Variances for each trait and covariances between traits were estimated by progeny analysis. Economic weights assigned to the different characters were derived as the ratio of the pod yield for a genotype to the theoretical pod yield gain from leafspot resistance. Indices were constructed and their efficiency both as predictor of the breeding value and relative to individual selection for either trait was evaluated. Index selection for increased pod yield and reduced leafspot susceptibility was between 87% and 100% as efficient as direct selection for either trait. Combining several leafspot severity readings with pod yield did not improve the efficiency of the index. Fourteen to 17% of the breeding value of the population was accounted for by the traits combined in various indices. This indicated that there is potential for improvement of these indices.

Ultrastructure of the Initial Interaction of Puccinia arachidis and Cercosporidium personatum with Leaves of Arachis hypogaea and Arachis stenosperma

2010 ◽  
Vol 158 (11-12) ◽  
pp. 792-796 ◽  
Author(s):  
Soraya Cristina De Macedo Leal-Bertioli ◽  
Marcelo Picanço De Farias ◽  
Pedro Íalo Tanno Silva ◽  
Patricia Messenberg Guimarães ◽  
Ana Cristina Miranda Brasileiro ◽  
...  
Keyword(s):  
Arachis Hypogaea ◽  
Cercosporidium Personatum ◽  
Puccinia Arachidis ◽  
Initial Interaction

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.

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