Fungicidal control of leaf spot (Septoria apiicola) of celery

1989 ◽  
Vol 29 (2) ◽  
pp. 261 ◽  
Author(s):  
TJ Wicks
Keyword(s):  
Leaf Spot ◽  
Field Experiments ◽  
Effective Control ◽  
Severity Of Disease

Ten fungicides were evaluated and compared in glasshouse and field experiments for the control of celery leaf spot caused by Septoria apiicola. In glasshouse experiments propiconazole (25 mg a.i. L-1) inhibited the development of S. apiicola when applied to celery seedlings 2 days after inoculation and in 1 experiment an application 8 days after inoculation reduced by 10-fold the severity of disease as well as the production of pycnidia. Penconazole (25 mg a.i. L-1), myclobutanil (50 mg a.i. L-1), flusilazole (20 mg a.i. L-1), fenarimol (36 mg a.i. L-1), terbuconazole (25 mg a.i. L-1) and triadimenol(25 mg a.i. L-1) also controlled S. apiicola when applied 2, but not 8 days, after inoculation. Anilazine protected celery seedlings for at least 13 days after application and was the most effective of the fungicides applied before infection. In field experiments, the most effective control of leaf spot was achieved with applications, every 7-10 days, of anilazine (1500 mg a.i. L-1), applied either alone or mixed with propiconazole (25 mg a.i. L-1). Similar applications of propiconazole either alone or mixed with chlorothalonil (150 mg a.i. L-1) also controlled leaf spot, whereas penconazole (25 mg a.i. L-1), flusilazole (20 mg a.i. L-1) and myclobutanil (50 mg a.i. L-1) were not effective.

KIH-485 and S-metolachlor Efficacy Comparisons in Conventional and No-Tillage Corn

2006 ◽  
Vol 20 (3) ◽  
pp. 622-626 ◽  
Author(s):  
Patrick W. Geier ◽  
Phillip W. Stahlman ◽  
John C. Frihauf
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Conventional Tillage ◽  
Palmer Amaranth ◽  
Effective Control ◽  
No Tillage ◽  
Green Foxtail

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

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.

scholarly journals Reduced Dosage of Methyl Bromide for Controlling Verticillium Wilt of Potato in Experimental and Commercial Plots

Plant Disease ◽  
1997 ◽  
Vol 81 (5) ◽  
pp. 469-474 ◽  
Author(s):  
A. Gamliel ◽  
A. Grinstein ◽  
Y. Peretz ◽  
L. Klein ◽  
A. Nachmias ◽  
...  
Keyword(s):  
Verticillium Wilt ◽  
Methyl Bromide ◽  
Large Scale ◽  
Field Experiments ◽  
Tuber Yield ◽  
Total Yield ◽  
Effective Control ◽  
Large Scale Field ◽  
Commercial Applications

The use of gas-impermeable films to reduce the dosage of methyl bromide (MB) required to control Verticillium wilt in potatoes was examined in field experiments, conducted in soils naturally infested with Verticillium dahliae. The incidence and severity of Verticillium wilt were significantly reduced (by 74 to 94%) by fumigation with MB at 50 g/m2 under standard low density polyethylene (LDPE) or at 25 g/m2 under gas-impermeable films. Fumigation at 25 g/m2 under LDPE was less effective. Disease severity was inversely correlated (r2 = 0.89 to 0.91) with chlorophyll content in the leaves. Fumigation also reduced (by 89 to 100%) stem colonization by the pathogen. Potato yield in the fumigated plots was significantly higher (26 to 69%), than in their nonfumigated counterparts, and was inversely correlated with disease index (r2 = 0.69 to 0.9). The percentage of high-value tubers (above 45 g) was 52 to 56% of total yield in the fumigated plots as compared with 32 to 40% in the nonfumigated controls. Thus, fumigation also improved the commercial quality of tuber yield. Effective control of V. dahliae and yield increases following MB fumigation at the recommended dosage or at a reduced dosage with gas-impermeable films was also observed in a consecutive crop. These results were verified in a large-scale field experiment using commercial applications, further demonstrating the feasibility of reducing MB dosages under farm conditions, without reducing its effectiveness in terms of disease control and yield improvement.

scholarly journals Control of Volunteer Glyphosate-Resistant Canola in Glyphosate-Resistant Sugar Beet

2015 ◽  
Vol 29 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha
Keyword(s):  
Sugar Beet ◽  
Field Experiments ◽  
Agricultural Research ◽  
Effective Control ◽  
Additional Advantage ◽  
Leaf Stage ◽  
Beet Root ◽  
Control Volunteer ◽  
Sugar Beet Root ◽  
Herbicide Programs

Occurrence of glyphosate-resistant (GR) canola volunteers in GR sugar beet is a management concern for growers in the Northern Great Plains. Field experiments were conducted at the Southern Agricultural Research Center near Huntley, MT, in 2011 and 2012 to evaluate effective herbicide programs to control volunteer GR canola in GR sugar beet. Single POST application of triflusulfuron methyl alone at the two-leaf stage of sugar beet was more effective at 35 compared with 17.5 g ai ha−1. However, rate differences were not evident when triflusulfuron methyl was applied as a sequential POST (two-leaf followed by [fb] six-leaf stage of sugar beet) program (17.5 fb 17.5 or 35 fb 35 g ha−1). Volunteer GR canola plants in the sequential POST triflusulfuron methyl–containing treatments produced little biomass (11 to 15% of nontreated plots) but a significant amount of seeds (160 to 661 seeds m−2). Ethofumesate (4,200 g ai ha−1) PRE followed by sequential POST triflusulfuron methyl (17.5 or 35 g ha−1) provided effective control (94 to 98% at 30 d after treatment [DAT]), biomass reduction (97%), and seed prevention of volunteer GR canola. There was no additional advantage of adding either desmedipham + phenmedipham + ethofumesate premix (44.7 g ha−1) or ethofumesate (140 g ha−1) to the sequential POST triflusulfuron methyl–only treatments. The sequential POST ethofumesate-only (140 fb 140 g ha−1) treatment provided poor volunteer GR canola control at 30 DAT, and the noncontrolled plants produced 6,361 seeds m−2, which was comparable to the nontreated control (7,593 seeds m−2). Sequential POST triflusulfuron methyl–containing treatments reduced GR sugar beet root and sucrose yields to 18 and 20%, respectively. Consistent with GR canola control, sugar beet root and sucrose yields were highest (95 and 91% of hand-weeded plots, respectively) when the sequential POST triflusulfuron methyl–containing treatments were preceded by ethofumesate (4,200 g ha−1) PRE. Growers should utilize these effective herbicide programs to control volunteer GR canola in GR sugar beet. Because of high canola seed production potential, as evident from this research, control efforts should be aimed at preventing seed bank replenishment of the GR canola volunteers.

An experiment in the control of the ground water-level in a fen peat soil

1951 ◽  
Vol 41 (1-2) ◽  
pp. 149-162 ◽  
Author(s):  
H. H. Nicholson ◽  
G. Alderman ◽  
D. H. Firth
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Large Scale ◽  
Field Experiments ◽  
Peat Soil ◽  
Climatic Conditions ◽  
Ground Water Level ◽  
Effective Control ◽  
Soil Conditions ◽  
Local Soil

1. The methods of investigation of the effect of ground water-level on crop growth, together with tho field installations in use, are discussed.2. Direct field experiments are handicapped by the difficulties of achieving close control on a sufficiently large scale, due to considerable variations of surface level and depth of peat within individual fields and to rapid fluctuations in rainfall and evaporation. Many recorded experiments are associated with climatic conditions of substantial precipitation during the growing season.3. Seasonal fluctuations of ground water-level in Fen peat soils in England, in natural and agricultural conditions, are described.4. The local soil conditions are outlined and the implications of profile variations are discussed.5. The effective control of ground water-level on a field scale requires deep and commodious ditches and frequent large underdrains to ensure the movement of water underground with sufficient freedom to give rapid compensatory adjustment for marked disturbances of ground water-level following the incidence of heavy rain or excessive evaporation.6. A working installation for a field experiment in ordinary farming conditions is described and the measure of control attained is indicated.

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.

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.

scholarly journals The in Planta Effective Concentration of Oxytetracycline Against ‘Candidatus Liberibacter asiaticus’ for Suppression of Citrus Huanglongbing

2019 ◽  
Vol 109 (12) ◽  
pp. 2046-2054 ◽  
Author(s):  
Jinyun Li ◽  
Zhiqian Pang ◽  
Shuo Duan ◽  
Donghwan Lee ◽  
Vladimir G. Kolbasov ◽  
...  
Keyword(s):  
Field Experiments ◽  
Foliar Spray ◽  
Effective Control ◽  
Candidatus Liberibacter Asiaticus ◽  
In Planta ◽  
Fresh Tissue ◽  
Minimum Concentration ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Residue Levels

Huanglongbing (HLB) or greening currently is the most devastating citrus disease worldwide. The fastidious phloem-colonizing bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) is the causal agent of citrus HLB in Florida. Bactericides containing the active ingredient oxytetracycline (OTC) have been used in foliar spray to control citrus HLB in Florida since 2016. However, the minimum concentration of OTC required to suppress CLas in planta remains unknown. We developed a new method for evaluating the effects of OTC treatment on CLas titers in infected plants and determined the relationship between OTC residue levels and control levels achieved for CLas using mathematical modeling in greenhouse and field experiments. In both greenhouse and field, OTC spray did not reduce the titers of CLas, and it produced undetectable or mild levels of OTC residue in leaves within 7 days post-application (DPA). In greenhouse, OTC injection at 0.05 g per tree decreased CLas titers to an undetectable level (cycle threshold value ≥ 36.0) from 7 to 30 DPA and produced a residue level of OTC at 0.68 to 0.73 µg/g of fresh tissue over this period. In the field, OTC injection at 0.50 g per tree resulted in the decline of CLas titers by 1.52 log reduction from 14 to 60 DPA, with residue levels of OTC at 0.27 to 0.33 µg/g of fresh tissue. In both trials, a first-order compart model of OTC residue dynamics in leaves of trunk-injected trees was specified for estimating the retention of effective concentrations. Furthermore, nonlinear modeling revealed significant positive correlations between OTC residue levels in leaves and the control levels for CLas achieved. The results suggested that the minimum concentrations of OTC required to suppress CLas populations in planta to below the detection limit are 0.68 and 0.86 µg/g and that the minimum concentrations of OTC required for initial inhibition of CLas growth in planta are ∼0.17 and ∼0.215 µg/g in leaf tissues under greenhouse and field conditions, respectively. This finding highlights that a minimum concentration of OTC should be guaranteed to be delivered to target CLas in infected plants for effective control of citrus HLB.

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.

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