Responses of Peanut Genotypes to Fungicidal Control of Early Leaf Spot in Malawi1

Abstract Early leaf spot (Cercospora arachidicola Hori.) is the most destructive disease of peanut (Arachis hypogaea L.) in Malawi. Fifteen peanut genotypes were examined for their response to fungicidal control of early leaf spot during the 1990/91 (year 1), 1991/92 (year 2), and 1992/93 (year 3) growing seasons at Chitedze, Malawi. Total rainfall and its distribution in these years were variable, with the most favorable pattern in year 3. Early leaf spot was most severe in year 2, although there was a severe midseason drought during this year. Fungicide application gave excellent control of the disease in all growing seasons. The cultivar Malimba had the most damage and the breeding line ICGV-SM 85053 had the least damage from early leaf spot. Pod yields were higher in year 3 than in the other two growing seasons. Pod yields were significantly higher in fungicide-sprayed (treated) plots than in water-sprayed (control) plots in years 1 and 3. Most peanut genotypes had positive yield responses to disease control in years 1 and 3. However, there were no significant differences in pod yields between treated and control plots of most genotypes in year 2. Although the pod yields were lower in year 2 than in year 1, total biomass production was higher in year 2. It was apparent that biomass partitioning was severely affected in year 2 due to the midseason drought stress that reduced pod yields and vitiated the beneficial effects of fungicidal application. Investment in fungicidal control of early leaf spot on genotypes with low yield potential may not be economical under less than optimal rainfall conditions.

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

Plant Disease ◽

10.1094/pdis-06-10-0454 ◽

2011 ◽

Vol 95 (3) ◽

pp. 263-268 ◽

Cited By ~ 4

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.

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

Journal of Experimental Agriculture International ◽

10.9734/jeai/2019/v37i430274 ◽

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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Combination of Early Maturity and Leaf Spot Tolerance Within an Advanced Georgia Peanut Breeding Line1

Peanut Science ◽

10.3146/i0095-3679-22-2-6 ◽

1995 ◽

Vol 22 (2) ◽

pp. 106-108 ◽

Cited By ~ 7

Author(s):

W. D. Branch ◽

A. K. Culbreath

Keyword(s):

Leaf Spot ◽

Genetic Resistance ◽

Field Tests ◽

Cercospora Arachidicola ◽

Early Maturity ◽

The Past ◽

Leaf Spots ◽

Arachis Hypogaea L ◽

Cultivated Peanut ◽

Efficient Alternative

Abstract In the past, genetic resistance to both early and late leaf spots [Cercospora arachidicola Hori and Cercosporidiumpersonatum (Berk. & Curt.) Deighton] has been found to be negatively or inversely correlated with early maturity in the cultivated peanut (Arachis hypogaea L.). For example, the late leaf spot resistant cultivar Southern Runner is approximately 2 wk later in maturity than the susceptible Florunner cultivar. Recently, an advanced runner-type breeding line (GA T-2844) has been developed by the Georgia peanut breeding program which combines early maturity and leaf spot tolerance. For the past 3 yr (1991–1993), GA T-2844 has been evaluated in replicated field tests without fungicides. Results show that GA T-2844 has on the average >30% yield advantage and a 30-d earlier maturity than Southern Runner. Leaf spot ratings also showed GA T-2844 to be intermediate between Southern Runner and Florunner. Such a combination of early maturity and leaf spot tolerance could significantly enhance U.S. peanut production by providing an environmentally safer and efficient alternative to costly pesticides not previously available among runner-type cultivars.

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Sowing time affecting the development of common bean cultivars in Lichinga, Province of Niassa, Mozambique

Revista CERES ◽

10.1590/0034-737x201764050011 ◽

2017 ◽

Vol 64 (5) ◽

pp. 532-539

Author(s):

Maria da Conceição Santana Carvalho ◽

Adriano Stephan Nascente ◽

Gilvan Ferreira Barbosa ◽

Celso Américo Pedro Mutadiua ◽

José Eloir Denardin

Keyword(s):

Grain Yield ◽

Common Bean ◽

Rainy Season ◽

Agricultural Research ◽

Yield Potential ◽

Sowing Time ◽

Growing Seasons ◽

Sowing Dates ◽

In The Beginning ◽

And Control

ABSTRACT The demonstration of yield potential of crops depends on genetic factors, favorable conditions of envi ronment, and management. The sowing time can significantly affect the common bean grain yield. The aim of this research was to study the behavior of Brazilian cultivars and sowing times on the yield components and grain yield of common bean grown in the environmental conditions of Lichinga, Province of Niassa, Mozambique. The field trial was performed for two growing seasons, using the experimental as a randomized block in factorial 5 × 3 × 2, with four replications. The treatments consisted of the combination of five common bean cultivars (BRS Pontal, BRS Agreste, Perola, and BRS Requinte, developed by Brazilian Agricultural Research Corporation (Embrapa), and a local variety, Encarnada) with three sowing dates (beginning of the rainy season, and 15 and 30 days after), during two growing seasons. The Brazilian cultivar of common beans BRS Pontal was the most productive in all sowing times, followed by BRS Agreste, which was not the most productive only in the second sowing time of 2013/2014 growing season. The cultivar Encarnada, from Mozambique, was the less productive cultivar in all sowing times and in all growing seasons. The best sowing time for common bean cultivars is in the beginning of the rainy season. The use of technologies such as use of seeds of new cultivars, proper sowing time, fertilization, and control of weeds allow significant increase of common bean grain yield in Lichinga, Mozambique.

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Evaluation of Improved Valencia Peanut Varieties for Production in Haiti

Peanut Science ◽

10.3146/ps18-13.1 ◽

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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Geographical Distribution of Genetic Diversity in Arachis hypogaea

Peanut Science ◽

10.3146/i0095-3679-28-2-8 ◽

2001 ◽

Vol 28 (2) ◽

pp. 80-84 ◽

Cited By ~ 11

Author(s):

C. C. Holbrook ◽

T. G. Isleib

Keyword(s):

Disease Resistance ◽

Arachis Hypogaea ◽

Leaf Spot ◽

Germplasm Collection ◽

Cercospora Arachidicola ◽

Root Knot Nematode ◽

Sources Of Resistance ◽

Arachis Hypogaea L ◽

Race 1 ◽

The U.S

Abstract The U.S. maintains a large (> 8000 accessions) and genetically diverse collection of peanut (Arachis hypogaea L.) germplasm. It is costly to screen all accessions within this collection for traits that could be useful in cultivar development. The objective of this research was to identify countries of origin that are rich sources of resistance to important peanut diseases. This would allow peanut breeders to focus their efforts on smaller subsets of the germplasm collection. Accessions in the peanut core collection were evaluated for resistance to late (Cercosporidium personatum Berk. & M. A. Curtis) and early (Cercospora arachidicola Hori) leaf spot, tomato spotted wilt Tospovirus (TSWV), the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1], and Cylindrocladium black rot (CBR)[Cylindrocladium crotalarie (Loos) Bell & Sobers]. These data then were examined to determine if genes for resistance clustered geographically. Several geographical areas that appear to be rich sources for disease-resistant genes were identified. China had a relatively large number of accessions with resistance to the peanut root-knot nematode. Peru appeared to be a rich source of material with resistance to CBR. Resistance to late leaf spot was more frequent than expected in accessions from Bolivia and Ecuador. Bolivia was also a valuable source of resistance to early leaf spot. Early leaf spot resistance also was more prevalent than expected in accessions from India, Nigeria, and Sudan. India, Israel, and Sudan were valuable origins for material with resistance to TSWV. Accessions with multiple disease resistance were most common in India, Mozambique, and Senegal. This information should enable plant breeders to utilize more efficiently the genes for disease resistance that are available in the U.S. germplasm collection.

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The biology and control of termites damaging field crops in Tanganyika

Bulletin of Entomological Research ◽

10.1017/s0007485300056509 ◽

1966 ◽

Vol 56 (3) ◽

pp. 417-444 ◽

Cited By ~ 23

Author(s):

M. Bigger

Keyword(s):

Good Control ◽

Field Trials ◽

The Other ◽

Growing Seasons ◽

Fungus Combs ◽

Termite Attack ◽

Excellent Control ◽

Small Clusters ◽

And Control ◽

Population Counts

Many crops in southern Tanganyika are attacked by termites, especially those grown in the miombo woodland (Brachystegia-Pseudoberlinia), which covers much of the southern and western parts of the country. The termites chiefly concerned are Microtermes albopartitus (Sjöst.), M. redenianus (Sjöst.), Ancistrotermes latinotus (Hlmgr.) and Allodontermes tenax (Silv.). A pit dug to investigate their nest systems showed that M. albopartitus was the most numerous, 425 occupied cells being recovered from an area 50 × 24 ft. excavated to a depth of 6 ft. Cells of the other species included 166 of M. redenianus, 54 of Ancistrotermes latinotus and 49 of Allodontermes tenax. The cells of Ancistrotermes latinotus were aggregated into small clusters connected by long runways; those of the other species were more or less randomly scattered. The greatest concentration of cells of all species was within the top 2 ft. of the soil, but a number of cells were found at greater depths and it is certain that 6 ft. is not the maximum nesting depth. Descriptions of the nest systems and fungus combs are given.Observations at Nachingwea in 1959–63 showed that loss of maize stands from termite attack averaged 27 per cent, over the five years, and that of soya 33 per cent. The damage was often great on individual plots, as much as 90 per cent, being recorded from one plot of maize. Plant-population counts over three growing seasons showed that maize is lost mainly towards the end of the season, whereas soya may be attacked any time after planting, increased losses occurring during dry spells and at the end of the season.Control was achieved by the use of aldrin or dieldrin applied as dusts to the soil before planting or used in seed dressings. It was found in a series of field trials that good control of termites was afforded by aldrin worked into the soil along the planting ridges at a rate of 1 lb. active ingredient per acre, but that in practice ½ lb. per acre gave nearly as good results when measured by yields. In spite of the considerable losses, it was considered uneconomic to use aldrin to protect soya from termite attack, but the increased yields of 200–400 lb. maize per acre justified the expenditure on insecticide. The aldrin dust protected both crops for at least one further year after application, the effects on yield being of the same order as before.A seed dressing of 75 per cent, dieldrin gave excellent control and was considerably cheaper than soil application of aldrin. The cost was only a few shillings an acre when the dressing was used at the rate of 0·1 oz. per 1 lb. seed, and the effect was to raise yields of maize by 330–500 lb. and of soya by 110–180 lb. per acre.Trenches were dug to investigate the effects of soil treatment with aldrin on the nest systems of the termites. There was little effect on cell density eight months after application, but after 20 months there were signs of a reduction, especially in the top 9 in. of the soil.

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Evaluation of Detached Leaf Culture for Screening Peanuts for Leafspot Resistance1

Peanut Science ◽

10.3146/i0095-3679-7-2-10 ◽

1980 ◽

Vol 7 (2) ◽

pp. 98-100 ◽

Cited By ~ 8

Author(s):

D. J. Foster ◽

J. C. Wynne ◽

M. K. Beute

Keyword(s):

Arachis Hypogaea ◽

Leaf Spot ◽

Leaf Age ◽

Field Tests ◽

Cercospora Arachidicola ◽

Simple Method ◽

Detached Leaf ◽

Arachis Hypogaea L ◽

The Relationship ◽

Resistant Genotypes

Abstract A detached leaf culturing technique has been proposed as a rapid and simple method for screening peanut (Arachis hypogaea L.) genotypes for leafspot resistance. This study was conducted to (a) determine the effect of both leaf age and outdoor plant weathering on infection with Cercospora arachidicola Hori as measured by the detached leaf technique, (b) evaluate the resistance to early leafspot of several peanut genotypes in the field and in the greenhouse using the detached leaf technique, and (c) determine the relationship between leafspot resistance measured in the field and the greenhouse. The age of the leaf had a significant effect on leafspot resistance when evaluated using the detached leaf technique. Younger leaves averaged 11.4 lesions per leaflet compared to 5.6 lesions per leaflet for older leaves. The number of lesions per leaflet was similar for weathered and greenhouse-grown plants. PI 270806, PI 109839, Kanyoma, and PI 259679, four Virginia (ssp. hypogaea var. hypogaea) types, were the most resistant genotypes evaluated in these tests. The number of lesions per leaflet caused by early leaf-spot for the 16 genotypes measured by the detached leaf technique was significantly correlated (r = 0.85) with the same trait measured in the field. PI 109839 had the fewest number of lesions per leaflet in both greenhouse and field tests.

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Evaluation of Peanut Agrochemical Efficacy in Situations where Spray Solution Application is Delayed

Peanut Science ◽

10.3146/ps12-5.1 ◽

2013 ◽

Vol 40 (1) ◽

pp. 52-61

Author(s):

P.M. Eure ◽

D.L. Jordan ◽

L.R. Fisher ◽

A.C. York

Keyword(s):

Leaf Spot ◽

Time Interval ◽

Cercospora Arachidicola ◽

Application Performance ◽

Spray Solution ◽

Sclerotinia Blight ◽

Arachis Hypogaea L ◽

Solution Preparation ◽

Tobacco Thrips ◽

Prohexadione Calcium

ABSTRACT The effect of delayed application of spray solutions is poorly understood with respect to efficacy of fungicides, insecticides, inoculants, and plant growth regulators commonly used in peanut (Arachis hypogaea L.). Research was conducted in North Carolina during 2009 and 2010 to determine if tobacco thrips (Frankliniella fusca Hinds) control by acephate; early leaf spot (caused by Cercospora arachidicola Hori) and late leaf spot (caused by Cercosporidium personatum Berk. and Curt.) control by chlorothalonil, prothioconazole plus tebuconazole, pyraclostrobin, and tebuconazole; Sclerotinia blight (caused by Sclerotinia minor Jagger) control by boscalid and fluazinam; and improvement in row visibility by prohexadione calcium were affected by the time interval between solution preparation and application. Performance of the inoculant Bradyrhizobium was also compared when prepared in 25 different sources of water when application was delayed after preparation of solutions. Agrochemicals and prohexadione calcium solutions were prepared the d of application or 3, 6, and 9 d prior to application with all solutions applied on the same d. Similarly, inoculant solutions were prepared the d of application or 4 and 8 d prior to application and applied on the same d. Performance of fungicides, insecticides, inoculant, and prohexadione calcium was not reduced in most instances when left in spray solution up to 8 or 9 d. The magnitude of difference in efficacy was minor when differences were observed.

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Effects of Postemergence Herbicides on Cercospora arachidicola Hori and Early Leaf Spot of Peanut1

Peanut Science ◽

10.3146/i0095-3679-26-1-2 ◽

1999 ◽

Vol 26 (1) ◽

pp. 4-8 ◽

Cited By ~ 2

Author(s):

J. A. Baysinger ◽

H. A. Melouk ◽

D. S. Murray

Keyword(s):

Arachis Hypogaea ◽

Leaf Spot ◽

Untreated Control ◽

Conidial Germination ◽

Leaf Spot Disease ◽

Common Disease ◽

Cercospora Arachidicola ◽

Spot Disease ◽

Arachis Hypogaea L ◽

Postemergence Herbicides

Abstract Early leaf spot is a common disease of peanut caused by the fungus Cercospora arachidicola Hori. Experiments were conducted to evaluate the effect of postemergence herbicides on the conidial germination of C. arachidicola and on the incidence of early leaf spot disease in peanut (Arachis hypogaea L.) in a greenhouse. Conidial germination was enhanced (≥ 100%) at concentrations of 1, 100, and 1000 mg/L of 2,4-DB compared with the untreated control. Lactofen reduced conidial germination by 42% compared with the control at concentrations as low as 100 mg/L and completely inhibited germination at concentrations ≥ 5000 mg/L. A concentration of 10,000 mg/L acifluorfen and 2,4-DB completely inhibited conidial germination. Acifluorfen, acifluorfen plus 2,4-DB, and lactofen decreased the sporulation of early leaf spot lesions. Lactofen reduced leaf spot incidence 12% and decreased sporulation of lesions 22% compared with the control. None of the herbicides increased the incidence of early leaf spot on peanut plants or the number of early leaf spot lesions per leaflet when compared with plants that received no herbicide.

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