scholarly journals Management of Cercospora Leaf Spot in Conventional and Organic Table Beet Production

Plant Disease ◽  
2017 ◽  
Vol 101 (9) ◽  
pp. 1642-1651 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Niloofar Vaghefi ◽  
Julie R. Kikkert
Keyword(s):  
New York ◽  
Disease Control ◽  
Leaf Spot ◽  
Production Systems ◽  
Dry Weight ◽  
Field Trials ◽  
Cercospora Leaf Spot ◽  
Disease Progress ◽  
Shoulder Diameter ◽  
Small Plot

Cercospora leaf spot (CLS; Cercospora beticola) is the most important foliar disease affecting table beet. Epidemics occur annually and fungicides extend the survival of foliage to enable mechanized harvest. However, a high frequency of strobilurin-resistant C. beticola isolates necessitates the identification of fungicides with different modes of action for tactical rotation. There is also substantial demand for organically produced table beet, for which synthetic fungicides are prohibited. Five small-plot, replicated field trials were conducted over two years to evaluate conventional and Organic Materials Review Institute (OMRI)-listed products for CLS control in table beet cv. Ruby Queen at Geneva and Ithaca, New York. Benzovindiflupyr + difenoconazole significantly reduced temporal disease progress (measured by the area under the disease progress stairs; AUDPS) by 86.7 to 97.3% compared with nontreated plots, and mean survival time of leaves was significantly extended. The demethylation inhibitor, propiconazole, also provided significant disease control in two trials in 2016. Disease severity in plots treated with succinate dehydrogenase inhibitors (boscalid, fluxapyroxad + pyraclostrobin, and penthiopyrad) was significantly decreased compared with nontreated plots but less than other fungicides. Efficacious fungicides significantly increased the dry weight of foliage but did not significantly affect the dry weight of roots, and root shoulder diameter. The enhanced longevity of leaves and increased dry weight of foliage may extend opportunities for mechanized harvesting without deleteriously affecting root yield parameters which are strictly regulated for the processing markets. In two trials, copper octanoate + Bacillus amyloliquefaciens strain D747 (as Cueva + Double Nickel LC) resulted in significantly improved disease control in comparison with application of either product alone and provided comparable and reproducible disease control equivalent to conventional fungicides at both locations. The implications of these findings for CLS control in conventional and organic table beet production systems are discussed.

scholarly journals Horticultural Characteristics and Susceptibility of Table Beet Cultivars to Cercospora Leaf Spot in New York

2017 ◽  
Vol 27 (4) ◽  
pp. 530-538 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Niloofar Vaghefi ◽  
Julie R. Kikkert
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Field Trial ◽  
Near Infrared ◽  
Value Added ◽  
Dry Weight ◽  
Disease Assessment ◽  
Canopy Reflectance ◽  
Cercospora Leaf Spot ◽  
Disease Progress

Table beet (Beta vulgaris ssp. vulgaris) production in New York is increasing for direct sale, use in value-added products, or processing. One of the most important diseases affecting table beet is cercospora leaf spot (CLS) caused by the fungus Cercospora beticola. CLS causes lesions on leaves that coalesce and leads to premature defoliation. The presence of CLS may cause buyer rejection at fresh markets. Defoliation from CLS may also result in crop loss because of the inability to harvest with top-pulling machinery. The susceptibility of popular table beet cultivars (Boldor, Detroit, Falcon, Merlin, Rhonda, Ruby Queen, and Touchstone Gold) to CLS was tested using C. beticola isolates representative of the New York population. Two trials were conducted by inoculating 6-week-old plants in the misting chamber. A small-plot replicated field trial was also conducted to examine horticultural characteristics of the cultivars. In the misting chamber trials, disease progress measured by the area under the disease progress stairs (AUDPS) was not significantly different between the red cultivars, Detroit and Ruby Queen, and was significantly higher in ‘Boldor’ than the other yellow cultivar Touchstone Gold. In the field trial, the number of CLS lesions per leaf at the final disease assessment and AUDPS were significantly lower in cultivar Ruby Queen than others and not significantly different between the yellow cultivars. The dry weight of roots was not significantly different among cultivars at first harvest (77 days after planting). At 112 days after planting, the dry weight of roots was significantly higher in cultivar Detroit than Rhonda and Boldor. Leaf blade length and the length:width ratio were cultivar-dependent, which may facilitate selection for specific fresh markets. Significant associations between canopy reflectance in the near infrared (IR) (830 nm), dry weight of foliage, and number of CLS lesions per leaf suggested that this technique may have utility for remote assessment of these variables in table beet research. Implications of these findings for the management of CLS in table beet are discussed.

scholarly journals Phoma Leaf Spot Susceptibility and Horticultural Characteristics of Table Beet Cultivars in New York

2019 ◽  
Vol 20 (2) ◽  
pp. 95-103 ◽  
Author(s):  
Lori B. Koenick ◽  
Julie R. Kikkert ◽  
Sarah J. Pethybridge
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Dry Weight ◽  
Field Trials ◽  
Root Weight ◽  
Fresh Weight ◽  
Fresh Market ◽  
Cultivar Selection ◽  
Small Plot ◽  
Phoma Betae

Phoma leaf spot (PLS), caused by Phoma betae (syn. Neocamarosporium betae), is an important fungal disease affecting table beet (Beta vulgaris L. subsp. vulgaris) production in New York. PLS lesions on the foliage can lead to rejection in fresh market sales and can reduce leaf integrity, which can disrupt mechanized harvesting. Eight popular table beet cultivars were assessed for susceptibility to PLS using P. betae isolates representative of the New York population in two small-plot, replicated field trials in Geneva and Freeville, NY. There were significant differences in PLS incidence, severity, and epidemic progress (as measured by area under the disease progress stairs) and horticultural characteristics among cultivars. Non-red table beet cultivars (Avalanche, Boldor, and Chioggia Guardsmark) were less susceptible to PLS than red cultivars (Falcon, Merlin, Rhonda, Red Ace, and Ruby Queen). Significant differences in fresh weight of roots and dry weight of foliage were detected between cultivars at harvest (86 days after planting [DAP] in Freeville and 91 DAP in Geneva). Falcon had significantly higher root weight than Boldor, and Ruby Queen produced significantly more foliage than Boldor. Information on the performance of these cultivars provides locally valuable information for cultivar selection in a broad range of markets.

scholarly journals Effect of Production System and Pruning on Temporal Development of Cercospora depazeoides and on Berry Yield in Black Elderberry Orchards

Plant Disease ◽  
2009 ◽  
Vol 93 (6) ◽  
pp. 625-631 ◽  
Author(s):  
I. J. Holb ◽  
J. M. Gáll ◽  
B. Fodor
Keyword(s):  
Leaf Spot ◽  
Production Systems ◽  
Disease Incidence ◽  
Organic Production ◽  
Integrated System ◽  
Disease Development ◽  
Temporal Development ◽  
Cercospora Leaf Spot ◽  
Organic System ◽  
Disease Progress

In a 2-year study, the temporal development of Cercospora leaf spot (Cercospora depazeoides) and berry yield were evaluated in two production systems (integrated and organic) and in two winter pruning treatments (trees pruned to four and eight scaffolds) in two black elderberry (Sambucus nigra) orchards in Hungary. Under organic production, leaf spot onset occurred 2 to 4 weeks earlier (mid- and late July) in both years and both orchards compared with the integrated program. Disease then continuously progressed until the final assessment date (late September) in both years, reaching a maximum final disease incidence of 15.9% in the integrated system and of 38.2% in the organic system. In general, disease progress after late August was greater on trees pruned to eight scaffolds than on trees pruned to four scaffolds in both production systems. Both final disease incidence and area under the disease progress curves (AUDPC) were significantly lower (P < 0.001) in the integrated treatments compared with organic ones. Across all treatments, both disease measures were significantly (P < 0.05) lower on trees pruned to four scaffolds compared with trees pruned to eight scaffolds. However, when the effect of pruning on final disease incidence and AUDPC was analyzed separately for integrated and organic systems, pruning caused uniformly significant differences in disease development only for the organic system. Berry yield was significantly higher (P < 0.05) in the integrated system compared with the organic system, but pruning showed no significant effect on yield. Overall, pruning to four scaffolds resulted in consistently lower disease development in organic production compared to integrated. Thus, winter pruning may be useful as a Cercospora leaf spot management practice in organic elderberry orchards.

Optimizing Cercospora Leaf Spot Control in Table Beet Using Action Thresholds and Disease Forecasting

Plant Disease ◽  
2020 ◽  
Vol 104 (6) ◽  
pp. 1831-1840
Author(s):  
Sarah J. Pethybridge ◽  
Sandeep Sharma ◽  
Zachariah Hansen ◽  
Julie R. Kikkert ◽  
Daniel L. Olmstead ◽  
...  
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Field Trials ◽  
Moderate Risk ◽  
Cercospora Leaf Spot ◽  
Risk Threshold ◽  
Current Action ◽  
Action Threshold ◽  
Risk Thresholds ◽  
Control Equivalent

Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, is the dominant foliar disease affecting table-beet production in New York. CLS epidemics occur annually and, if uncontrolled, will rapidly lead to defoliation. In broad-acre production, season-long maintenance of healthy leaves is important to facilitate harvest by top-pulling. Fungicides are the dominant means of CLS control and applications are initiated at an action threshold of 1 CLS lesion/leaf. Regular fungicide application occurs thereafter without regard for scheduling based on weather-based risk. The current action threshold was evaluated with selected fungicides in two replicated field trials. Copper oxychloride + copper hydroxide and propiconazole significantly improved CLS control if initiated prior to infection. Pydiflumetofen + difenoconazole significantly reduced area under the disease progress stairs compared with other fungicides tested and was most efficacious when applications began at 1 CLS lesion/leaf. Six replicated field trials also evaluated the utility of scheduling fungicides on weather-based risk rather than a calendar approach. Two risk thresholds (moderate and high) integrating the accumulation of daily infection values based on temperature and relative humidity from a forecaster for CLS in sugar beet were evaluated. Applications of pydiflumetofen + difenoconazole were reduced from three to two by using the forecaster at either risk threshold compared with calendar applications without affecting CLS control. For propiconazole, the moderate risk threshold provided CLS control equivalent to calendar applications and saved one spray per season. Thus, there was substantial scope to reduce spray frequency by scheduling based on weather-based risk rather than calendar applications. The optimal risk thresholds for pydiflumetofen + difenoconazole and propiconazole were high and moderate, respectively. In these trials, periods of high risk occurred less frequently than moderate risk, increasing the reapplication intervals and, hence, represented a less conservative approach to disease management.

Development of a Sequential Sampling Plan using Spatial Attributes of Cercospora Leaf Spot Epidemics of Table Beet in New York

Plant Disease ◽  
2021 ◽  
Author(s):  
Daniel Winter Heck ◽  
Julie R Kikkert ◽  
Linda Hanson ◽  
Sarah Jane Pethybridge
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Sequential Sampling ◽  
Sampling Plan ◽  
Classification Models ◽  
Cercospora Leaf Spot ◽  
Sample Number ◽  
Sequential Sampling Plan ◽  
True Value

Sampling strategies that effectively assess disease intensity in the field are important to underpin management decisions. To develop a sequential sampling plan for the incidence of Cercospora leaf spot (CLS), caused by Cercospora beticola, 31 table beet fields were assessed in New York. Assessments of CLS incidence were performed in six leaves arbitrarily selected in 51 sampling locations along each of the three to six linear transects per field. Spatial pattern analyses were performed, and results were used to develop sequential sampling estimation and classification models. CLS incidence (p) ranged from 0.13 to 0.92 with a median of 0.31, and beta-binomial distribution, which is reflective of aggregation, best described the spatial patterns observed. Aggregation was commonly detected (>95%) by methods using the point-process approach, runs analyses, and autocorrelation up to the fourth spatial lag. For SADIE, 45% of the datasets were classified as a random pattern. In the sequential sampling estimation and classification models, disease units are sampled until a prespecified target is achieved. For estimation, the goal was sampling CLS incidence with a preselected coefficient of variation (C). Achieving the C = 0.1 was challenging with less than 51 sampling units, and only observed on datasets with an incidence above 0.3. Reducing the level of precision, i.e. increasing C to 0.2, allowed the preselected C be achieved with a lower number of sampling units and with an estimated incidence (p̂) close to the true value of p. For classification, the goal was to classify the datasets above or below prespecified thresholds (pt) used for CLS management. The average sample number (ASN) was determined by Monte Carlo simulations, and was between 20 and 45 at disease incidence values close to pt, and approximately 11 when far from pt. Correct decisions occurred in over 76% of the validation datasets. Results indicated these sequential sampling plans can be used to effectively assess CLS incidence in table beet fields.

Improving fungicide-based management of Cercospora leaf spot in table beet in New York, USA

2019 ◽  
Vol 42 (3) ◽  
pp. 353-366 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Sandeep Sharma ◽  
ZACHARIAH R. Hansen ◽  
Niloofar Vaghefi ◽  
Linda E. Hanson ◽  
...  
Keyword(s):  
New York ◽  
Leaf Spot ◽  
Cercospora Leaf Spot

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 Instrata Fungicide Evaluated for Control of Cercospora Leaf Spot on Crapemyrtle

2013 ◽  
Vol 31 (1) ◽  
pp. 21-26
Author(s):  
A. K. Hagan ◽  
J. R. Arkidge
Keyword(s):  
Disease Control ◽  
Leaf Spot ◽  
Application Rate ◽  
Spot Intensity ◽  
Cercospora Leaf Spot

Efficacy of Instrata™ 3.61E at rates of 0.54, 0.74, and 1.11 g ai·liter−1 was compared with recommended rates of the its component fungicides Daconil Ultrex 82.5WDG (chlorothalonil), Banner MAXX 1.3MEC (propiconazole), and Medallion 50W (fludioxonil) as well as Eagle 40W, Heritage 50WDG, and 3336 4.5F fungicide standards for the control of Cercospora leaf spot (Cercospora lythracearum) on field grown ‘Byer's Wonderful White’ crapemyrtle (Lagerstroemia indica) in 2007 and 2008. Efficacy of Instrata 3.61E for the control of Cercospora leaf spot on crapemyrtle was significantly impacted by application rate. Cercospora leaf spot intensity and defoliation AUDPC values as well as final disease ratings usually were lower for the 1.11 compared with the 0.54 g ai·liter−1 rates of Instrata 3.61E, while those of the 0.74 g ai·liter−1 rate were intermediate. The 1.11 g ai·liter−1 but not lower rates of Instrata 3.61E gave superior Cercospora leaf spot control in both study years when compared with the Daconil Ultrex 82.5WDG, Banner MAAX 1.3MEC, and Medallion 50W component fungicides with the two former fungicides providing some control in one of two years and the latter failing to reduce disease intensity or defoliation. Eagle 40W, Heritage 50WDG, and 3336 4.5F proved equally effective as the 1.11 g ai·liter−1 rate of Instrata 3.61E in controlling Cercospora leaf spot in 2007 but only Eagle 40W gave comparable disease control in 2008, while Heritage 50WDG and 3336 4.5F were generally less efficacious than all rates of Instrata 3.61E. In one of two years, better disease control was obtained with Eagle 40W when compared with the 3336 4.5F and Heritage 50WDG standards. Overall, efficacy of the 1.11 g ai·liter−1 rate of Instrata 3.61E for the control of Cercospora leaf spot on crapemyrtle was superior to not only the label rate of each component fungicide but also to the fungicide standards in one of two study years.

scholarly journals Management of Cercospora Leaf Spot of Groundnut (Cercospora Arachidicola & Cercosporidium Personatum) Through the use of Systemic Fungicides

2014 ◽  
Vol 47 (2) ◽  
pp. 97-102 ◽  
Author(s):  
A.R. Khan ◽  
M. Ijaz ◽  
I.U. Haq ◽  
A. Farzand ◽  
M. Tariqjaved
Keyword(s):  
Field Experiment ◽  
Disease Control ◽  
Analysis Of Variance ◽  
Leaf Spot ◽  
Fungal Diseases ◽  
Cercospora Arachidicola ◽  
Cercospora Leaf Spot ◽  
Pod Yield ◽  
Different Doses ◽  
Better Than

Abstract Various fungal diseases reduce groundnut yield but Cercospora leaf spot commonly called, Tikka disease is most detrimental one. A field experiment was conducted to evaluate the efficacy of different fungicides and their doses on Cercospora leaf spot of groundnut. Five different fungicides (Chlorothalonil, Propineb, Mancozeb, Nativo and Triazole) having three different doses (prescribed, half & prescribed+half) were used to control Cercospora leaf spot of groundnut. Groundnut variety (YH-14) highly susceptible to Cercospora leaf spot was used. The experiment was laid down in RCBD design. The data were analyzed statistically by Fisher's analysis of variance technique. Results showed that maximum disease control with high pod yield was observed with Nativo and Triazole treatments. Efficacy of Chlorothalonil was also better than Mancozeb and Propineb. Maximum disease control and pod yield was observed when Nativo was used @ 0.97g/L of water, followed by @ 0.65g/L and 0.32 g/L, respectively. Propineb was the least effective in controlling Cercospora leaf spot of groundnut as well as having minimum pod yield.

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