scholarly journals Late Leaf Spot Severity and Yield of New Peanut Breeding Lines and Cultivars Grown Without Fungicides

Plant Disease ◽  
2017 ◽  
Vol 101 (11) ◽  
pp. 1843-1850 ◽  
Author(s):  
Brian S. Jordan ◽  
Albert K. Culbreath ◽  
Timothy B. Brenneman ◽  
Robert C. Kemerait ◽  
William D. Branch
Keyword(s):  
Leaf Spot ◽  
Vegetation Index ◽  
Field Experiments ◽  
Organic Production ◽  
Canopy Reflectance ◽  
Cercospora Arachidicola ◽  
Early Season ◽  
Late Leaf Spot ◽  
Breeding Lines ◽  
Width Measurements

Peanut (Arachis hypogaea) cultivars with resistance or tolerance to Cercospora arachidicola and/or Cercosporidium personatum, the causes of early and late leaf spot, respectively, are needed for organic production in the southeastern U.S. To determine the potential of new breeding lines for use in such production systems, field experiments were conducted in Tifton, GA, in 2014 and 2015 in which nine breeding lines and two cultivars, Georgia-06G and Georgia-12Y, were grown without foliar fungicide applications. In one set of trials, cultivar Georgia-12Y and most of the breeding lines evaluated had early season vigor ratings, early-season canopy width measurements, final plant populations, and pod yield that were greater than those of standard cultivar Georgia-06G. In those trials, final late leaf spot Florida scale ratings were lower and canopy reflectance measured as the normalized difference vegetation index (NDVI), was higher all the breeding lines than those of Georgia-06G. In another set of trials, two of those same breeding lines had final late leaf spot ratings similar to those of Georgia-12Y in 2014, whereas in 2015, six of those breeding lines had final leaf spot ratings that were lower than those of Georgia-12Y. Yields were similar for Georgia-12Y and all the breeding lines in the Gibbs Farm trials. Across years and breeding lines at the Lang Farm, the relationship between visual estimates of defoliation and NDVI was described by a two sector piecewise regression with NDVI decreasing more rapidly with increasing defoliation above approximately 89%. The utility of NDVI for spot comparisons among breeding lines appears to be limited to situations where there are differences in defoliation. Georgia-12Y and multiple breeding lines evaluated show potential for use in situations such as organic production where acceptable fungicides available for seed treatment and leaf spot control are limited.

scholarly journals Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 263-268 ◽  
Author(s):  
S. K. Gremillion ◽  
A. K. Culbreath ◽  
D. W. Gorbet ◽  
B. G. Mullinix ◽  
R. N. Pittman ◽  
...  
Keyword(s):  
United States ◽  
Disease Resistance ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
The United States ◽  
Yield Potential ◽  
Cercospora Arachidicola ◽  
Breeding Lines ◽  
Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

Effect of In-Furrow Application of Fluopyram on Leaf Spot Diseases of Peanut

Plant Disease ◽  
2021 ◽  
Author(s):  
Albert Culbreath ◽  
Robert Kemerait ◽  
Timothy Brenneman ◽  
Emily Cantonwine ◽  
Keith Rucker
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Fungal Pathogens ◽  
Field Experiments ◽  
Resistance Management ◽  
Feeding Damage ◽  
Early Season ◽  
Late Leaf Spot ◽  
Frankliniella Fusca ◽  
Tobacco Thrips

In peanut (Arachis hypogaea) production, in-furrow applications of the pre-mix combination of the SDHI fungicide/nematicide, fluopyram, and the insecticide, imidacloprid are used primarily for management of nematode pests and for preventing feeding damage on foliage caused by tobacco thrips (Frankliniella fusca). Fluopyram is also active against many fungal pathogens. However, the effect of in-furrow applications of fluopyram on early leaf spot (Passalora arachidicola) or late leaf spot (Nothopassalora personata) has not been characterized. The purpose of this study was to determine the effects of in-furrow applications of fluopyram + imidacloprid or fluopyram alone on leaf spot epidemics. Field experiments were conducted in Tifton, GA in 2015, 2016, and 2018-2020. In all experiments in-furrow applications of fluopyram + imidacloprid provided extended suppression of early leaf spot and late leaf spot epidemics compared to the nontreated control. In 2020, there was no difference between the effects of fluopyram + imidacloprid and fluopyram alone on leaf spot epidemics. Results indicated that fluopyram could complement early season leaf spot management programs. Use of in-furrow applications of fluopyram should be considered as an SDHI fungicide application for resistance management purposes.

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.

Efficacy of Organically Acceptable Fungicides for Management of Early and Late Leaf Spot Diseases on Partially Resistant Peanut Cultivars

2008 ◽  
Vol 9 (1) ◽  
pp. 19 ◽  
Author(s):  
E. G. Cantonwine ◽  
A. K. Culbreath ◽  
B. B. Shew ◽  
M. A. Boudreau
Keyword(s):  
North Carolina ◽  
Copper Sulfate ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Suppression ◽  
Yield Response ◽  
Cercospora Arachidicola ◽  
Late Leaf Spot ◽  
Cupric Hydroxide ◽  
Affect Disease Severity

Field experiments were carried out in Georgia and North Carolina to evaluate the efficacy of fungicides approved for the organic management of early leaf spot, caused by Cercospora arachidicola, and late leaf spot, caused by Cercosporidium personatum, in peanut (Arachis hypogaea) fields planted to cultivars with partial resistance to one or both pathogens. Copper treatments alone or in mixtures resulted in less disease than a non-treated control. In Georgia, sulfur provided some disease suppression, but not as much as treatments with copper sulfate. Neem oil did not affect disease severity. Mean pod yields across years were significantly greater than the non-treated control only for copper sulfate in Georgia and cupric hydroxide in North Carolina. The minimal yield response to treatments suggests that under similar situations, the frequency of copper-based fungicide applications may be reduced with little affect on yield. Accepted for publication 16 January 2008. Published 17 March 2008.

scholarly journals Management of Late Leaf Spot of Peanut with Benomyl and Chlorothalonil: A Study in Preserving Fungicide Utility

Plant Disease ◽  
2002 ◽  
Vol 86 (4) ◽  
pp. 349-355 ◽  
Author(s):  
A. K. Culbreath ◽  
K. L. Stevenson ◽  
T. B. Brenneman
Keyword(s):  
Leaf Spot ◽  
Fungicide Resistance ◽  
Field Experiments ◽  
Resistance Management ◽  
Model System ◽  
Systemic Fungicide ◽  
Cercospora Arachidicola ◽  
Pathogen Population ◽  
Late Leaf Spot ◽  
Sterol Biosynthesis Inhibitor

Recent registration of sterol biosynthesis inhibitor and strobilurin fungicides for control of early (Cercospora arachidicola) and late (Cercosporidium personatum) leaf spot diseases of peanut (Arachis hypogaea) has renewed interest in the potential for loss of disease control due to fungicide resistance. The objectives of this study were to use the systemic fungicide benomyl, the protectant fungicide chlorothalonil, and late leaf spot of peanut as a model system to compare fungicide application strategies for fungicide resistance management. Field experiments were conducted at Tifton and Plains, GA, in 1995 and 1996 to determine the effects of alternate applications, mixtures, and alternating block applications of chlorothalonil and benomyl compared with full-season applications of two rates of chlorothalonil and two rates of benomyl alone on late leaf spot of peanut and on the proportion of the pathogen population resistant to benomyl following the various regimes. Tank mix combinations of half rates of the two fungicides and alternations of the full rates of the two fungicides provided better (P ≤ 0.05) control of late leaf spot than full-season applications of either rate of benomyl alone, and were comparable to full rates of chlorothalonil alone. Neither tank mixes nor alternating sprays prevented an increase in the relative frequency of benomyl-resistant isolates compared with other treatments in which benomyl was used. Both mixtures and alternate applications of chlorothalonil and benomyl were effective for management of leaf spot in fields where benomyl alone did not provide season-long leaf spot control.

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.

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 Comparison of Trimble GreenSeeker and Crop Circle (Model ACS-210) Reflectance Meters for Assessment of Severity of Late Leaf Spot

2019 ◽  
Vol 46 (2) ◽  
pp. 110-117
Author(s):  
B.S. Jordan ◽  
W.D. Branch ◽  
A.W. Coffin ◽  
C.M. Smith ◽  
A.K. Culbreath
Keyword(s):  
Leaf Spot ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Field Experiments ◽  
Linear Functions ◽  
Quadratic Functions ◽  
Coefficient Of Determination ◽  
Late Leaf Spot ◽  
Significant Regression ◽  
Circle Model

ABSTRACT Four field experiments conducted in 2015 were used to examine the relationships among normalized difference vegetation index (NDVI) measurements from two canopy crop sensors and visual estimates of defoliation by late leaf spot (Nothopassalora personata) of peanut (Arachis hypogaea) the predominant foliar disease in this study. For each evaluation, reflectance was measured with each the two meters, and leaf spot severity was measured visually within as short a time as possible. Linear and quadratic regression models were used to characterize the relationships between percent defoliation from late leaf spot and NDVI measured with the GreenSeeker (NDVIGS) and Crop Circle (NDVICC) instruments and the relationships between NDVIGS and NDVICC. NDVIGS decreased with increasing percent defoliation according to linear or quadratic functions in three of the four trials, NDVICC decreased with increasing percent defoliation according to linear functions in three of four trials. In two of the four trials, NDVICC increased with increasing NDVIGS according to quadratic functions, but there was no significant regression for those variables in two trials. In three of the four trials, NDVICC linear regression had a better fit for predicting percent defoliation according to the coefficient of determination (R2). There was no indication for either instrument that the same NDVI reading corresponded with the same level of defoliation across trials. Results indicated that NDVI measurements from the two instruments are not interchangeable.

Influence of Broadleaf Weeds on Chlorothalonil Deposition, Foliar Disease Incidence, and Peanut (Arachis hypogaea) Yield

1997 ◽  
Vol 11 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Stanley S. Royal ◽  
Barry J. Brecke ◽  
Frederick M. Shokes ◽  
Daniel L. Colvin
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Yield Loss ◽  
Disease Incidence ◽  
Weed Biomass ◽  
Late Leaf Spot ◽  
Foliar Disease ◽  
Weed Density ◽  
Weed Plants

Field experiments were conducted at Jay and Marianna, FL in 1988 and 1989 to determine the effects of sicklepod, Florida beggarweed, and common cocklebur density on chlorothalonil deposition to peanut foliage, peanut foliar disease incidence, and peanut yield. At a density of four weed plants per 8 m of row, Florida beggarweed and sicklepod reduced chlorothalonil deposition on peanut foliage by 20%, while common cocklebur reduced fungicide deposition by 34%. At the same density, incidence of the foliar diseases early leaf spot and late leaf spot increased 10% with Florida beggarweed, 14% with sicklepod, and 20% with common cocklebur compared with weed-free peanut. The predicted peanut yield loss from a weed density of four plants per 8 m was 16 to 19% for Florida beggarweed, 23 to 25% for sicklepod, and 31 to 39% for common cocklebur. Weed biomass increased with increasing weed density.

Screening Groundnut (Arachis hypogeae) Genotypes for Resistance to Early and Late Leaf Spot Diseases

2019 ◽  
pp. 1-9
Author(s):  
M. S. Alidu ◽  
S. Abukari ◽  
M. Abudulai
Keyword(s):  
Leaf Spot ◽  
Agricultural Research ◽  
Block Design ◽  
Northern Region ◽  
Limiting Factors ◽  
Leaf Spot Disease ◽  
Cercospora Arachidicola ◽  
Late Leaf Spot ◽  
Arachis Hypogaea L ◽  
Significant Difference

Background for the Study: Groundnut (Arachis hypogaea L.) is an important crop both in subsistence and commercial agriculture in Ghana. Early leaf spot (Cercospora arachidicola) and late leaf spot (Cercosporidium personata) are major limiting factors to groundnut productivity in Ghana. Aim: The objective of the study was to screen groundnut genotypes for resistance to Early and Late leaf spot diseases. Study Design: The treatments were arranged in a randomized complete block design and replicated three (3) times. Place and Duration of Study: The research was conducted from May to December 2013 at the Savanna Agricultural Research Institute experimental site at Nyankpala in the Northern Region. The site lies between latitude 9°25´141 North and longitude 0°58’142 West and an altitude of 183 m. Methodology: The land was done using a tractor and field divided into plots of 2 m x 5 m with 1 m interval between plots. Sowing was done on 3rd June 2013. One seed was planted per hole at a depth of approximately 4 cm. Early and late leaf spot ratings were recorded at 30, 60 and 90 days after planting, using a ten-point scale. At pod maturity, plants from the middle two rows of each plot were hand-harvested and weights of the above ground foliage and underground pods were oven-dried to obtain dry haulm weight and pod yield respectively. Data collected were subjected to analysis of variance using Genstat statistical package (12th edition). Means were separated using the least significant difference at 5%. Results: The were significant differences (P < .001) among the groundnut genotypes in terms of severity for both early and late leaf spot diseases. F-Mix, NC 7, PC 79-79, F-Mix × SINK 24 and NKATIE-SARI had lowest score for both early and late leaf spot diseases. Among the 21 groundnut genotypes, F-Mix recorded the highest pods yield of 1100kg/ha and haulm weight of 5867 kg/ha followed by NC 7 with total pods yield of 900 kg/ha and haulm weight of 5373 kg/ha. PC 79-79 had a total pods yield of 666.7 kg/ha and haulm weight of 4867kg/ha. The pods yield of F-Mix × SINK 24 was 533.3 kg/ha and haulm weight of 4600 kg/ha. NKATIE-SARI recorded pods yield of 500 kg/ha and haulm weight of 4633 kg/ha. Conclusions: From the study, the genotypes F-Mix, NC 7, PC 79-79, F-Mix × SINK 24 and NKATIE-SARI were found to be resistance to both early and late leaf spot disease whereas Chinese, Doumbala, GM 120, GM 324 and ICGV 86015 were susceptible to both diseases.

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