Development of Anthracnose on Grain Sorghum Hybrids Inoculated with Recently Described Pathotypes of Colletotrichum sublineolum Found in Arkansas

Sorghum anthracnose, caused by Colletotrichum sublineolum, is found in most grain-sorghum-producing areas, including Arkansas. Yield losses can be severe in susceptible sorghum hybrids, suggesting that host resistance will continue to be critical for maintaining high yields. However, genetic control is often unsuccessful because of haplotype and pathotype variability within the C. sublineolum population. The objective of this research was to assess the levels of resistance of selected grain sorghum hybrids to isolates of the recently described pathotypes of C. sublineolum found in Arkansas. Field experiments were conducted in 2005 and 2006 to evaluate the reaction of 10 sorghum hybrids to eight C. sublineolum pathotypes by collecting anthracnose severity ratings at 7, 14, 21, and 28 days after inoculation. Based on these disease severity ratings, the area under the disease progress curve was calculated for each pathotype by hybrid interaction. These data showed that different levels of resistance are available in the current grain sorghum hybrids to different pathotypes. Cargill 888Y was resistant to all pathotypes in both years. However, Asgrow A571, DEKALB DKS53-11, FFR 318, and Pioneer 84G62 were moderately susceptible to susceptible to all pathotypes tested in both years. Pathotype 9 caused the most disease on 7 of the 10 hybrids evaluated in 2005 but, in 2006, pathotypes 12 and 13 surpassed pathotype 9 for disease severity on 9 of the 10 hybrids. More work is needed to assess host resistance and the effect of sorghum anthracnose on yield parameters of grain sorghum hybrids planted in Arkansas.

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Alternative Products to Control Soybean Downy Mildew in the Field

Journal of Agricultural Science ◽

10.5539/jas.v12n8p160 ◽

2020 ◽

Vol 12 (8) ◽

pp. 160

Author(s):

Gislaine Gabardo ◽

Maristella Dalla Pria ◽

Henrique Luis da Silva ◽

Mônica Gabrielle Harms

Keyword(s):

Downy Mildew ◽

Disease Severity ◽

Field Experiments ◽

Ascophyllum Nodosum ◽

Phenological Stages ◽

Manganese Zinc ◽

Growing Seasons ◽

Progress Curve ◽

Copper Manganese ◽

Diagrammatic Scale

Soybean mildew caused by Oomycota Peronospora manshurica, is a disease widely spread in Brazil. In order to study the efficiency of soybean mildew control due to the application of alternative products and fungicide in the field, experiments were conducted in Ponta Grossa, PR, Brazil, during the 2013/2014 and 2014/2015 growing seasons. The design used was randomized blocks with four replications. The treatments were: 1-witness; 2-acibenzolar-S-methyl; 3-calcium; 4-micronutrients: copper, manganese and zinc; 5-micronutrients: manganese, zinc and molybdenum; 6-NK fertilizer; 7-Ascophyllum nodosum and 8-azoxystrobin + cyproconazole with the addition of Nimbus adjuvant. Four applications of alternative products (phenological stages V3, V6, R1 and R5.1) and two of fungicide (phenological stages R1 and R5.1) were performed. The mildew severity was estimated using a diagrammatic scale. The severity data made it possible to calculate the area under the disease progress curve (AUDPC). In the 2014/2015 harvest the disease was more severe. The control of downy mildew by the use of fungicide did not reduce the epidemic. The fungicide was not efficient in the two evaluated seasons. All tested alternative products reduced the disease severity and AUDPC in both seasons. The best results in reducing downy mildew were found with the application of acibenzolar-S-methyl, micronutrients (Cu, Mn, Zn) and A. nodosum.

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Nitrogen Level and Irrigation Interval on Mitigating Stemphylium Blight and Downy Mildew in Onion

International Journal of Applied Sciences and Biotechnology ◽

10.3126/ijasbt.v6i1.18795 ◽

2018 ◽

Vol 6 (1) ◽

pp. 17-22

Author(s):

Bibek Acharya ◽

Ram Kumar Shrestha

Keyword(s):

Downy Mildew ◽

Disease Severity ◽

Growth Stage ◽

Block Design ◽

Nitrogen Level ◽

Yield Parameters ◽

Progress Curve ◽

Irrigation Interval ◽

Randomized Block Design ◽

Stemphylium Blight

Field trial was conducted on horticultural farm of Lamjung Agriculture Campus, Lamjung, Nepal between December-April 2016/17 on onion (Allium cepa), following two factorial Randomized Block Design with three replications and fifteen treatments to assess disease severity of Stemphylium blight (Stemphylium vesicarium) and Downy mildew (Peronospora destructor). The onion cultivar Red Creole, widely grown in this locality and susceptible to these diseases was used for trial. The disease intensity for Stemphylium leaf blight and Downy mildew was rated on weekly basis. Disease severity of both the disease significantly varied with nitrogen level and irrigation interval during initial and middle growth stage of onion, but in contrary, was found non-significant during later days as the plant approached harvesting stage. Area under Disease Progress Curve (AUDPC) also significantly varied in both treatments for both disease. Yield parameters recorded viz. bulb diameter and bulb yield significantly varied with nitrogen level and irrigation interval. The interaction effect of both the treatment was found non-significant for disease severity, AUDPC level and yield parameters during entire growth stage of onion. The results indicated that 7 days irrigation interval and government recommended dose of nitrogen i.e. 235 kg/ha were significantly better over other level of treatments in reducing Stemphylium blight and Downy mildew disease severity and also increasing yield parameters.Int. J. Appl. Sci. Biotechnol. Vol 6(1): 17-22

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Pathotypes of Colletotrichum sublineolum in Arkansas

Plant Disease ◽

10.1094/pdis-92-10-1415 ◽

2008 ◽

Vol 92 (10) ◽

pp. 1415-1420 ◽

Cited By ~ 20

Author(s):

J. W. Moore ◽

M. Ditmore ◽

D. O. TeBeest

Keyword(s):

Grain Sorghum ◽

Inbred Lines ◽

The State ◽

Delta Region ◽

Breeding Lines ◽

Colletotrichum Sublineolum ◽

Sorghum Anthracnose ◽

Sorghum Breeding

Sorghum anthracnose, caused by Colletotrichum sublineolum, is widely distributed in most grain sorghum-producing areas in Arkansas, and localized epidemics continue to occur across the state. The objectives of this research were to determine the number of pathotypes of C. sublineolum in Arkansas and to determine where these pathotypes are located within the state. Ninety-eight isolates were collected from research stations and production fields located in the Delta region of Arkansas from 2003 through 2005 and were tested for virulence to eight differential grain sorghum breeding lines. Of these, 11 isolates produced conflicting and unreliable results and were excluded from further analysis. Among the remaining 87 isolates, 13 pathotypes were identified. Eleven of these pathotypes were previously unreported, with 53% of the isolates consisting of pathotype 9. Pathotype 9 was distinguished from all other pathotypes by its virulence to all eight differential lines. Pathotype diversity appeared to be more closely associated with the year than with the locations where isolates were collected. Although all host differential lines were susceptible to at least 50% of the isolates evaluated, inbred lines SC326-6, TAM428, and TX2536 were susceptible to more than 90% of the 87 isolates evaluated. These results showed that the C. sublineolum populations in Arkansas are diverse based on the comparisons of pathogenicity to previously published host differentials, and it appears that these field populations varied from year to year.

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Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia

Tropical Drylands ◽

10.13057/tropdrylands/t020102 ◽

2018 ◽

Vol 2 (1) ◽

pp. 5-11 ◽

Cited By ~ 2

Author(s):

YOSEP SERAN MAU

Keyword(s):

Disease Severity ◽

Sweet Potato ◽

Field Experiments ◽

Block Design ◽

Scab Resistance ◽

Resistance Level ◽

Resistance Response ◽

Progress Curve ◽

Randomized Block Design ◽

Study Results

Mau YS. 2018. Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia. Trop Drylands 2: 5-11. Field experiments were carried out in two growing locations involving potential sweet potato clones from East Nusa Tenggara Province, Indonesia to: (i) evaluate scab resistance levels of the sweet potato clones, and (ii) identify sweet potato clones with good resistance level to scab disease. The experiment was carried out in the fields employing a Randomized Block Design with a mono-factorial treatment design in each location. The treatment assigned was sweet potato genotype, each consisted of two replicates. The variables observed were disease severity that was assessed at 2, 4, 6, and 8 weeks after inoculation (WAI), which then was used to calculate the Area Under the Disease Progress Curve (AUDPC) of the disease severity. The ANOVA of AUDPC was used to determine the treatment effect, and the disease severity at 8 WAI was used to assess scab resistance level of the sweet potato genotypes tested. The study results showed highly significant differences of disease severities among the tested sweet potato genotypes within each trial location. The majority of the genotypes tested were classified "resistant" or "moderately resistant" to scab disease, except the check clone SLM-01 and KRA-01 that were, respectively, "susceptible" and "moderately susceptible" to scab disease. The majority of sweet potato genotypes evaluated were consistent in their resistance performance in the two trial locations.

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Epidemiological Criteria to Support Breeding Tactics Against the Emerging, High-Consequence Wheat Blast Disease

Plant Disease ◽

10.1094/pdis-12-19-2672-re ◽

2020 ◽

Vol 104 (8) ◽

pp. 2252-2261 ◽

Cited By ~ 1

Author(s):

M. Fernández-Campos ◽

C. Góngora-Canul ◽

S. Das ◽

M. R. Kabir ◽

B. Valent ◽

...

Keyword(s):

Field Experiments ◽

Temporal Dynamics ◽

Blast Disease ◽

Disease Progress Curve ◽

Disease Progress ◽

Wheat Blast ◽

Progress Curve ◽

Cultivar Selection ◽

Different Levels ◽

Epidemiological Parameters

Plant disease epidemiology can make a significant contribution for cultivar selection by elucidating the principles of an epidemic under different levels of resistance. For emerging diseases as wheat blast (WB), epidemiological parameters can provide support for better selection of genetic resources. Field experiments were conducted at two locations in Bolivia in 2018–2019 to characterize the temporal dynamics of the disease on 10 cultivars with different levels of reaction to WB. Logistic models best (R2 = 0.70–0.96) fit the disease progress curve in all cultivars followed by Gompertz (R2 = 0.64–0.94), providing additional evidence of a polycyclic disease. Total area under disease progress curve (tAUDPC), final disease severity (Ymax), and logistic apparent infection rates (rL*) were shown to be appropriate epidemiological parameters for describing resistance and cultivar selection. Cultivars that showed a high spike AUDPC (sAUDPC) showed a high leaf AUDPC (lAUDPC). tAUPDC, Ymax, and rL* were positively correlated among them (P < 0.01) and all were negatively correlated with grain weight (P < 0.01). Based on the epidemiological parameters used, cultivars that showed resistance to WB were Urubó, San Pablo, and AN-120, which were previously reported to have effective resistance against the disease under field conditions. The information generated could help breeding programs to make technical decisions about relevant epidemiological parameters to consider prior to cultivar release.

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Effect of different levels of nitrogen and potassium against leaf spots disease of groundnut in different fertility gradient soil in field

Legume Research - An International Journal ◽

10.18805/lr-3957 ◽

2018 ◽

Author(s):

Trina Sandham ◽

Sunita Mahapatra ◽

Srikanta Das

Keyword(s):

Disease Severity ◽

Leaf Spot Disease ◽

High Fertility ◽

Kernel Number ◽

Yield Attributes ◽

Fertility Gradient ◽

Leaf Spots ◽

Yield Parameters ◽

Different Levels ◽

Kernel Yield

The occurrence of early and late leaf spots of groundnut under influence of variable soil fertility states with further interaction to different levels of nitrogen and potassium was measured and the same was correlated with the yield attributing parameters. Two different nitrogen and potassium combinations (20; 40 kg ha-1) applied on four different fertility gradient soil (low ,S1; medium ,S2 ; moderate ,S3 and high ,S4) showed minimum leaf spot disease severity and maximum diseases reduction in (S1) N40K20 (AUDPC 34.48 and 16.06% reduction); (S2) N40K40 (AUDPC- 32.88 and 13.68% reduction ); (S3) N20K40 (AUDPC 31.51 and 11.44% reduction) and (S4) N20K20 (AUDPC-25.40 and 11.58% reduction). The yield attributes like kernel number and weight per plant and kernel yield were also high in above combinations and fertility gradient soil. The linear regression value between disease severity and yield parameters showed a high co-relation regression and negatively significant at all fertility gradient soil and more responsive at low, medium and high fertility gradient soil irrespective of different N and K levels.

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Economic Management of Late Blight (Phytophthora infestans L.) of Potato in Eastern Tarai of Nepal

Nepal Agriculture Research Journal ◽

10.3126/narj.v6i0.3365 ◽

1970 ◽

Vol 6 ◽

pp. 57-61 ◽

Cited By ~ 3

Author(s):

Prem CP Chaurasia

Keyword(s):

Late Blight ◽

Disease Severity ◽

Field Experiments ◽

Tuber Yield ◽

Block Design ◽

Winter Season ◽

Cost Ratio ◽

Research Station ◽

Terminal Disease ◽

Progress Curve

Field experiments were carried out at Regional Agriculture Research Station, Tarahara in threeconsecutive years (1997-2000) during winter season to know the economic sprays of differentfungicides to manage late blight disease of potato. Late blight susceptible cultivar of potatoKufri Sindhuri was used for the experiment. Krinoxyl gold (metalaxyl 8% and mancozeb 64%)at the rate of 1.5 g/l, Dithane M- 45 (mancozeb 75%) @ 0.3% and Bordeaux mixture @ 10 gcopper sulfate and 10 g lime/l of water and their different combinations were tested inrandomized complete block design with three replications. Terminal disease severity was thehighest (7.9) on 0-9 scale disease rating in unsprayed check and it was significantly higher thanthose of other fungicides sprays. Plots with three sprays of Dithane M- 45 @ 0.3% recorded thelowest (2.4) terminal disease severity. Disease development was the fastest in the unsprayed plotcompared to all other treatments. Similarly apparent infection rate was the highest in unsprayedtreatment. Area Under the Disease Progress Curve was also the highest in unsprayed plot and itwas significantly higher than those of other treatments. Tuber yield was the lowest (3.93 kg/4.5m2 plot in unsprayed and the highest (6.08 kg), in the plot receiving four sprays of Dithane M-45@ 0.3 % and this was at par with the tuber yield of plots receiving two and three sprays ofDithane M-45. Benefit cost ratio was the highest (1.54) in case of two sprays of Dithane M-45@ 0.3% at 10 days intervals. All others fungicide spays were uneconomical under Eastern Taraicondition.Key words: Eastern Tarai; economic spray; Dithane M-45; late blight management; potatoDOI: 10.3126/narj.v6i0.3365Nepal Agriculture Research Journal Vol.6 2005 pp.57-61

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REACTION OF POTATO CULTIVARS AND CLONES TO Phytophthora infestans

Revista Caatinga ◽

10.1590/1983-21252019v32n212rc ◽

2019 ◽

Vol 32 (2) ◽

pp. 390-398

Author(s):

VICTOR HUGO CASA-COILA ◽

CESAR BAUER GOMES ◽

ISRAEL LIMA-MEDINA ◽

DEDIEL JUNIOR AMARAL ROCHA ◽

ARIONE DA SILVA PEREIRA ◽

...

Keyword(s):

Phytophthora Infestans ◽

Disease Severity ◽

Field Experiments ◽

Tuber Yield ◽

Field Tests ◽

Potato Cultivars ◽

In Vitro Test ◽

Progress Curve ◽

Vitro Test

ABSTRACT The in vitro and field reactions of 23 potato cultivars and clones to two isolates of Phytophthora infestans were tested. The in vitro test used the detached potato leaflets method, and disease severity was evaluated 6 days after inoculation. Field experiments were conducted in autumn of 2013, in two locations in Pelotas City, Rio Grande do Sul State, Brazil. Seven evaluations of the disease severity were performed. From the severity values, the area under the disease progress curve (AUDPC) was calculated. Tubers were harvested to determine the yield (g plot-1). The A2 mating type isolate was the most aggressive for the majority of the potato genotypes. It was possible to group the different reactions of the potato genotypes based on the AUDPC values. Clones C2553-1-06, C2573-4-06, C2550-4-06, C2551-2-06, and CIP392,617.54 showed moderate-to-high resistance to the two isolates of P. infestans. The values of severity and AUDPC obtained in vitro and field tests were positively correlated for both P. infestans isolates, but in some interactions, inconsistencies were observed. Tuber yield was negatively correlated with AUDPC.

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Impact of Fungicide Program and Powdery Mildew Resistance in Three Varieties of Pumpkin

HortTechnology ◽

10.21273/horttech.21.5.533 ◽

2011 ◽

Vol 21 (5) ◽

pp. 533-538 ◽

Cited By ~ 3

Author(s):

Timothy Coolong ◽

Kenneth Seebold

Keyword(s):

Powdery Mildew ◽

Cucurbita Pepo ◽

Powdery Mildew Resistance ◽

Fruit Weight ◽

Podosphaera Xanthii ◽

Varietal Resistance ◽

High Input ◽

Yield Parameters ◽

Progress Curve ◽

Different Levels

The effects of fungicide program and varietal resistance on the development of cucurbit powdery mildew [PM (Podosphaera xanthii)] in pumpkin (Cucurbita pepo) were tested in 2009 and 2010 in Lexington, KY. Three fungicide programs consisted of a no-fungicide control, low input (chlorothalonil), and high input (chlorothalonil alternated with myclobutanil) were applied to three varieties of pumpkin with different levels of cucurbit PM resistance. Varieties tested were Howden, Aladdin, and Camaro, which had no, moderate, and high levels of cucurbit PM resistance, respectively. There were no significant variety by fungicide program interactions for yield, number fruit per acre, and average fruit weight in both years. In 2009 and 2010, variety significantly affected yield. Yield increases corresponded to the level of cucurbit PM resistance. The high-resistance variety, Camaro, had the greatest yields in both years, while Howden, with no PM resistance, had the lowest yields. In 2010, yield significantly increased with the intensity of fungicide program. With the exception of cull percentage in 2009, there were no fungicide program by variety interactions for yield parameters. In both years, PM disease severity, characterized by the area under the disease progress curve (AUDPC), was lowest on ‘Camaro’ and highest on ‘Howden’. In 2009, unsprayed ‘Camaro’ had similar AUDPC values as ‘Aladdin’ and ‘Howden’ treated with low- or high-input fungicide programs. In 2010, unsprayed ‘Camaro’ had less disease than ‘Aladdin’ or ‘Howden’ that had received the high-intensity fungicide program. These results suggest that yields can be maintained with a minimal fungicide program when using a variety with high cucurbit PM resistant in some environments. A high-input fungicide program may be necessary to maintain yields of varieties with low cucurbit PM resistance.

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Interference of Three Annual Grasses with Grain Sorghum (Sorghum bicolor)

Weed Technology ◽

10.1017/s0890037x00025343 ◽

1990 ◽

Vol 4 (2) ◽

pp. 245-249 ◽

Cited By ~ 19

Author(s):

Brenda S. Smith ◽

Don S. Murray ◽

J. D. Green ◽

Wan M. Wanyahaya ◽

David L. Weeks

Keyword(s):

Linear Regression ◽

Grain Yield ◽

Field Experiments ◽

Grain Sorghum ◽

Grass Species ◽

Row Spacing ◽

Yield Data ◽

Weed Density ◽

Annual Grasses ◽

Wide Row Spacing

Barnyardgrass, large crabgrass, and Texas panicum were evaluated in field experiments over 3 yr to measure their duration of interference and density on grain sorghum yield. When grain yield data were converted to a percentage of the weed-free control, linear regression predicted a 3.6% yield loss for each week of weed interference regardless of year or grass species. Grain sorghum grown in a narrow (61-cm) row spacing was affected little by full-season interference; however, in wide (91-cm) rows, interference increased as grass density increased. Data from the wide-row spacing were described by linear regression following conversion of grain yield to percentages and weed density to log10. A separate nonlinear model also was derived which could predict the effect of weed density on grain sorghum yield.

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