scholarly journals Relationship Between Nitrogen Fertilization and Cercospora Leaf Spot and Alternaria Leaf Blight of Carrot

HortScience ◽  
2008 ◽  
Vol 43 (5) ◽  
pp. 1522-1527 ◽  
Author(s):  
Sean M. Westerveld ◽  
Alan W. McKeown ◽  
Mary Ruth McDonald
Keyword(s):  
Leaf Spot ◽  
Field Experiments ◽  
Field Trials ◽  
Application Rate ◽  
Leaf Blight ◽  
Cercospora Leaf Spot ◽  
N Application ◽  
Alternaria Leaf Blight ◽  
N Application Rate ◽  
Alternaria Dauci

Alternaria leaf blight (ALB) and Cercospora leaf spot (CLS) are economically important diseases of carrot in Ontario. Field experiments were conducted in the Holland Marsh, Ontario, to determine the effect of nitrogen (N) application rates on both diseases. Five rates of N were applied to organic and mineral soils in which two carrot cultivars, Idaho and Fontana, were grown in each of 2002, 2003, and 2004. Both diseases were rated every 2 weeks on a scale of 0 (healthy) to 10 (tops destroyed), and the number of live (green) leaves per plant was assessed at harvest. In addition, three N rates were applied to carrot plants grown in the greenhouse, and the plants were inoculated with Alternaria dauci (Kühn) Groves and Skolko. Disease severity, senescence, and sap nitrate-N concentration were assessed. In the field trials, the response of ALB and CLS to N application rate was relatively consistent across cultivar, soil type, and year. Area-under-the-disease-progress curves typically increased with decreasing N rate for both diseases. In lower N treatments, this resulted in fewer live leaves per plant at harvest. In the greenhouse, ALB severity increased with increasing amount of leaf senescence at final assessment. The results suggest that N application rate could be used to reduce the need for fungicide applications to control these diseases in the field.

scholarly journals Optimization of Chemical Suppression of Alternaria dauci, the Causal Agent of Alternaria Leaf Blight in Carrots

Plant Disease ◽  
2001 ◽  
Vol 85 (11) ◽  
pp. 1149-1156 ◽  
Author(s):  
E. Ben-Noon ◽  
D. Shtienberg ◽  
E. Shlevin ◽  
H. Vintal ◽  
A. Dinoor
Keyword(s):  
Field Experiments ◽  
Threshold Model ◽  
Disease Onset ◽  
Leaf Blight ◽  
Copper Hydroxide ◽  
Control Efficacy ◽  
Alternaria Leaf Blight ◽  
Major Constraint ◽  
Action Threshold ◽  
Alternaria Dauci

Alternaria leaf blight, caused by Alternaria dauci, is a major constraint to carrot production in Israel. Israeli carrot growers apply prophylactic sprays at 3- to 10-day intervals throughout the season until harvest, up to 30 sprays in a growing season. In this study, we attempted to optimize the chemical suppression of the disease, in order to reduce fungicide use. The efficacy of nine fungicides was determined in two field experiments. All fungicides reduced disease severity, but there were significant differences in efficacy among them. The most effective were difenoconazole and chlorothalonil; less effective were copper hydroxide, tebuconazole, trifloxystrobin, and mancozeb; the least effective in our experiments were flutrifol, propineb, and iprodione. The effect of the time of spray initiation on fungicide efficacy was determined in three field experiments. Qualitative (analysis of variance) and quantitative (regression) analyses of the data revealed that initiating sprays after disease onset reduced control efficacy. Thus, an action threshold model could not be developed for A. dauci in carrots. The time before harvest at which sprays could be terminated was tested in two field experiments and it was found that terminating sprays 14 days before harvest did not significantly affect the overall control efficacy. The main conclusions derived from these experiments were tested and corroborated in two additional field experiments.

scholarly journals Foliar Zn Spraying Simultaneously Improved Concentrations and Bioavailability of Zn and Fe in Maize Grains Irrespective of Foliar Sucrose Supply

Agronomy ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 386 ◽  
Author(s):  
Haiyong Xia ◽  
Weilin Kong ◽  
Lan Wang ◽  
Yanhui Xue ◽  
Wenlong Liu ◽  
...  
Keyword(s):  
Agronomic Traits ◽  
Application Rate ◽  
Deionized Water ◽  
Control Treatment ◽  
Agricultural Practice ◽  
N Application ◽  
Application Rates ◽  
N Application Rate ◽  
Maize Grain ◽  
Sucrose Supply

Zinc (Zn) deficiency is a global nutritional problem that is reduced through agronomic biofortification. In the current study, the effects of foliar spraying of exogenous ZnSO4·7H2O (0.2% in Quzhou and 0.3% in Licheng, w/v) and/or sucrose (10.0%, w/v) on maize (Zea mays L.) agronomic traits; concentrations of Zn, iron (Fe), calcium (Ca), total phosphorus (P), phytic acid (PA) P, carbon (C), and nitrogen (N); C/N ratios; and Zn and Fe bioavailability (as evaluated by molar ratios of PA/Zn, PA × Ca/Zn, PA/Fe and PA × Ca/Fe) in maize grains were studied under field conditions for two years at two experimental locations. The results confirmed that there were no significant differences in maize agronomic traits following the various foliar treatments. Compared with the control treatment of foliar spraying with deionized water, foliar applications of Zn alone or combined with sucrose significantly increased maize grain Zn concentrations by 29.2–58.3% in Quzhou (from 18.4–19.9 to 25.2–29.6 mg/kg) and by 39.8–47.8% in Licheng (from 24.9 to 34.8–36.8 mg/kg), as well as its bioavailability. No significant differences were found between the foliar spraying of deionized water and sucrose, and between Zn-only and “sucrose + Zn” at each N application rate and across different N application rates and experimental sites. Similar results were observed for maize grain Fe concentrations and bioavailability, but the Fe concentration increased to a smaller extent than Zn. Foliar Zn spraying alone or with sucrose increased maize grain Fe concentrations by 4.7–28.4% in Quzhou (from 13.4–17.1 to 15.2–18.5 mg/kg) and by 15.4–25.0% in Licheng (from 24.0 to 27.7–30.0 mg/kg). Iron concentrations were significantly and positively correlated with Zn at each N application rate and across different N application rates and experimental locations, indicating that foliar Zn spraying facilitated the transport of endogenous Fe to maize grains. Therefore, foliar Zn spraying increased the Zn concentration and bioavailability in maize grains irrespective of foliar sucrose supply while also improving Fe concentrations and bioavailability to some extent. This is a promising agricultural practice for simultaneous Zn and Fe biofortification in maize grains, i.e., “killing two birds with one stone”.

Crop rotation and N application rate affecting the performance of winter wheat under deficit irrigation

2018 ◽  
Vol 210 ◽  
pp. 330-339 ◽  
Author(s):  
Wenli Qin ◽  
Xiying Zhang ◽  
Suying Chen ◽  
Hongyong Sun ◽  
Liwei Shao
Keyword(s):  
Winter Wheat ◽  
Crop Rotation ◽  
Deficit Irrigation ◽  
Application Rate ◽  
N Application ◽  
N Application Rate

scholarly journals Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 572 ◽  
Author(s):  
Weijin Wang ◽  
Glen Park ◽  
Steven Reeves ◽  
Megan Zahmel ◽  
Marijke Heenan ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Yield Loss ◽  
N Uptake ◽  
Management Strategies ◽  
Application Rate ◽  
Sugar Yield ◽  
N2o Emissions ◽  
N Application ◽  
N Application Rate ◽  
Coated Urea

Nitrous oxide (N2O) emissions from sugarcane cropped soils are usually high compared with those from other arable lands. Nitrogen-efficient management strategies are needed to mitigate N2O emissions from sugarcane farming whilst maintaining productivity and profitability. A year-long field experiment was conducted in wet tropical Australia to assess the efficacy of polymer-coated urea (PCU) and nitrification inhibitor (3,4-dimethylpyrazole phosphate)-coated urea (NICU). Emissions of N2O were measured using manual and automatic gas sampling chambers in combination. The nitrogen (N) release from PCU continued for >5–6 months, and lower soil NO3– contents were recorded for≥3 months in the NICU treatments compared with the conventional urea treatments. The annual cumulative N2O emissions were high, amounting to 11.4–18.2kg N2O-Nha–1. In contrast to findings in most other cropping systems, there were no significant differences in annual N2O emissions between treatments with different urea formulations and application rates (0, 100 and 140kgNha–1). Daily variation in N2O emissions at this site was driven predominantly by rainfall. Urea formulations did not significantly affect sugarcane or sugar yield at the same N application rate. Decreasing fertiliser application rate from the recommended 140kgNha–1 to 100kgNha–1 led to a decrease in sugar yield by 1.3tha–1 and 2.2tha–1 for the conventional urea and PCU treatments, respectively, but no yield loss occurred for the NICU treatment. Crop N uptake also declined at the reduced N application rate with conventional urea, but not with the PCU and NICU. These results demonstrated that substituting NICU for conventional urea may substantially decrease fertiliser N application from the normal recommended rates whilst causing no yield loss or N deficiency to the crop. Further studies are required to investigate the optimal integrated fertiliser management strategies for sugarcane production, particularly choice of products and application time and rates, in relation to site and seasonal conditions.

Effects of tillage, crop rotation and N application rate on labile and recalcitrant soil carbon in a Mediterranean Vertisol

2017 ◽  
Vol 169 ◽  
pp. 118-123 ◽  
Author(s):  
Veronica Muñoz-Romero ◽  
Rafael J. Lopez-Bellido ◽  
Purificacion Fernandez-Garcia ◽  
Ramon Redondo ◽  
Sergio Murillo ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Crop Rotation ◽  
Application Rate ◽  
N Application ◽  
N Application Rate

Yield, nutritive value and ensilage characteristics of whole-crop maize, and of the separated cob and stover components – nitrogen, harvest date and cultivar effects

2012 ◽  
Vol 151 (3) ◽  
pp. 347-367 ◽  
Author(s):  
J. P. LYNCH ◽  
P. O'KIELY ◽  
E. M. DOYLE
Keyword(s):  
Nutritive Value ◽  
Application Rate ◽  
Harvest Date ◽  
N Application ◽  
Forage Maize ◽  
Maize Cultivars ◽  
Harvest Dates ◽  
N Application Rate ◽  
Main Plot ◽  
Silage Production

SUMMARYThe objectives of the present study were to determine the effects of nitrogen (N) application rate, harvest date and maize cultivar on the yield, quality and the subsequent conservation characteristics of whole-crop, cob and stover silages. The experiment was organized in a spilt-plot design, with harvest date (15 September, 6 October and 27 October) as the main plot, and a three (maize cultivars: Tassilo, Andante and KXA 7211)×two (N application rate: 33 and 168 kg N/ha) factorial arrangement of treatments as the sub-plot, within three replicate blocks, and was conducted at Grange, Dunsany, Co. Meath, Ireland in 2009. The three harvest dates represented early, normal and late harvests, respectively, for a midland site in Ireland. Of the three maize cultivars selected, cvars Tassilo and Andante represent conventional cultivars sown by commercial livestock farmers in Ireland, while cvar KXA 7211 is categorized as a high biomass cultivar. No effect of N application rate was observed on the dry matter (DM) yield, nutritive value or ensiling characteristics of maize whole-crop or cob. Whole-crop and stover harvested on the later date had a lower digestible DM (DDM) content and the silages underwent a more restricted fermentation, compared to silages produced from herbage harvested on earlier dates. Cob silages produced from crops harvested on 15 September had lower DDM content and higher DM loss during ensiling than later harvest dates. Despite higher whole-crop DM yields, the later maturing cultivar KXA 7211 did not improve the DM yields of cob and also resulted in increased DM losses from the ensilage of cob, when compared with the other cultivars. In addition to the DM yield and nutritive value of forage maize at harvest, the subsequent fermentation profile during ensilage influences the optimum choice of cultivar and date for crop harvest in a maize silage production system.

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