scholarly journals Integrated Control of Rhizoctonia Crown and Root Rot of Sugar Beet with Fungicides and Antagonistic Bacteria

Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 718-722 ◽  
Author(s):  
Sebastian Kiewnick ◽  
Barry J. Jacobsen ◽  
Andrea Braun-Kiewnick ◽  
Joyce L. A. Eckhoff ◽  
Jerry W. Bergman
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Integrated Control ◽  
The United States ◽  
Field Trials ◽  
Sugar Yield ◽  
Economic Losses ◽  
Yield Increase ◽  
Leaf Stage ◽  
Crown And Root Rot

Rhizoctonia crown and root rot, caused by the fungus Rhizoctonia solani AG 2-2, is one of the most damaging sugar beet diseases worldwide and causes significant economic losses in more than 25% of the sugar beet production area in the United States. We report on field trials in the years 1996 to 1999 testing both experimental fungicides and antagonistic Bacillus sp. for their potential to reduce disease severity and increase sugar yield in trials inoculated with R. solani AG 2-2. Fungicides were applied as in-furrow sprays at planting or as band sprays directed at the crown at the four-leaf stage, or four- plus eight-leaf stage, while bacteria were applied at the four-leaf stage only. The fungicides azoxystrobin and tebuconazole reduced crown and root rot disease by 50 to 90% over 3 years when used at rates of 76 to 304 g a.i./ha and 250 g a.i./ha, respectively. The disease index at harvest was reduced and the root and sugar yield increased with azoxystrobin compared with tebuconazole. The combination of azoxystrobin applied at 76 g a.i./ha and the Bacillus isolate MSU-127 resulted in best disease reduction and greatest root and sucrose yield increase.

scholarly journals Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
The United States ◽  
Damping Off ◽  
Growth Assay ◽  
The Mean ◽  
Crown And Root Rot ◽  
Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

scholarly journals Interaction of Sugar Beet Host Resistance andRhizoctonia solaniAG-2-2 IIIB Strains

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1175-1180 ◽  
Author(s):  
Carl A. Strausbaugh ◽  
Imad A. Eujayl ◽  
Leonard W. Panella
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Weak Interactions ◽  
Block Design ◽  
Field Studies ◽  
Preliminary Evidence ◽  
Economic Losses ◽  
Resistant Lines ◽  
Crown And Root Rot ◽  
Different Strains

Rhizoctonia crown and root rot caused by Rhizoctonia solani can cause serious economic losses in sugar beet fields. Preliminary evidence suggests that there could be interactions between different strains and resistance sources. Thus, field studies were conducted to determine whether nine R. solani AG-2-2 IIIB strains varied for virulence when compared with a noninoculated check and interacted with five sugar beet lines (four resistant lines and a susceptible check). The studies were arranged in a randomized complete block design with six replications. Roots were evaluated for surface rot and internal fungal and bacterial rot in September. All strains were virulent on the susceptible check, FC901/C817, and had a similar ranking (r = 0.80 to 0.97; P = 0.0096 to <0.0001) regardless of disease variable. Line FC709-2 was resistant (response not different from noninoculated check, P ≥ 0.1042) to all strains, while the strain responses resulted in weak interactions with less-resistant lines in 14 of 19 variable-year combinations. Because most commercial sugar beet cultivars contain low to intermediate resistance to Rhizoctonia crown and root rot, the strain used to screen should be considered in order to maintain consistent responses between nurseries and commercial fields.

scholarly journals Interaction of Rhizoctonia solani and Rhizopus stolonifer Causing Root Rot of Sugar Beet

Plant Disease ◽  
2010 ◽  
Vol 94 (5) ◽  
pp. 504-509 ◽  
Author(s):  
L. E. Hanson
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Management Practices ◽  
The United States ◽  
Disease Diagnosis ◽  
Rhizopus Stolonifer ◽  
Rhizoctonia Root Rot ◽  
Crown And Root Rot ◽  
Growing Conditions ◽  
Production Areas

In recent years, growers in Michigan and other sugar beet (Beta vulgaris) production areas of the United States have reported increasing incidence of root rot with little or no crown or foliar symptoms in sugar beet with Rhizoctonia crown and root rot. In addition, Rhizoctonia-resistant beets have been reported with higher levels of disease than expected. In examining beets with Rhizoctonia root rot in Michigan, over 50% of sampled roots had a second potential root rot pathogen, Rhizopus stolonifer. Growing conditions generally were not conducive to disease production by this pathogen alone, so we investigated the potential for interaction between these two pathogens. In greenhouse tests, four of five sugar beet varieties had more severe root rot symptoms when inoculated with both pathogens than when inoculated with either pathogen alone. This synergism occurred under conditions that were not conducive to disease production by R. stolonifer. Host resistance to Rhizoctonia crown and root rot reduced diseases severity, but was insufficient to control the disease when both pathogens were present. This raises concerns about correct disease diagnosis and management practices and indicates that a root rot complex may be important on sugar beet in Michigan.

scholarly journals Integrated Control of Root and Crown Rot in Sugar Beet: Combined Effects of Cultivar, Crop Rotation, and Soil Tillage

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Cord Buhre ◽  
Christian Kluth ◽  
Klaus Bürcky ◽  
Bernward Märländer ◽  
Mark Varrelmann
Keyword(s):  
Sugar Beet ◽  
Crop Rotation ◽  
Integrated Control ◽  
Field Trials ◽  
Sugar Yield ◽  
Crop Rotations ◽  
Crown Rot ◽  
Soil Tillage ◽  
Sugar Beet Cultivar ◽  
Root And Crown Rot

Rhizoctonia solani (AG 2-2IIIB), causing root and crown rot in sugar beet, poses an increasing problem in Europe. Agronomic measures have to be optimized to control disease and minimize yield and quality loss, because no fungicides can be applied. Resistant sugar beet cultivars have been introduced to reduce disease occurrence. Furthermore, crop rotation can influence R. solani occurrence. In contrast to other cereals, maize serves as a host of the fungus. In order to study the combined effect of these factors, a series of four field trials was established with crop rotations varying in the proportion of maize and comparing a resistant with a susceptible sugar beet cultivar in 2001–02 in southern Germany. Within crop rotations, cultivation methods were varied in the form of soil tillage, intercrops, or both. Sugar beet cultivar and crop rotation had the main impact on disease severity and sugar yield. With increasing proportion of maize, sugar yield decreased, whereas cultivation method had only a minor impact. Plowing directly before sugar beet increased sugar yield only within the unfavorable maize-maize-sugar beet rotation compared with mulching. These results give strong evidence that crop rotation of sugar beet with nonhost plants and cultivation of resistant sugar beet cultivars are adequate means for integrated R. solani control.

scholarly journals First Report of Pythium aphanidermatum Crown and Root Rot of Industrial Hemp in the United States

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 1038 ◽  
Author(s):  
J. Beckerman ◽  
H. Nisonson ◽  
N. Albright ◽  
T. Creswell
Keyword(s):  
United States ◽  
Root Rot ◽  
The United States ◽  
Pythium Aphanidermatum ◽  
First Report ◽  
Crown And Root Rot ◽  
Industrial Hemp

scholarly journals A transgenic approach for controlling Lygus in cotton

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Anilkumar Gowda ◽  
Timothy J. Rydel ◽  
Andrew M. Wollacott ◽  
Robert S. Brown ◽  
Waseem Akbar ◽  
...  
Keyword(s):  
Insecticidal Activity ◽  
The United States ◽  
Field Trials ◽  
Transgenic Cotton ◽  
Economic Losses ◽  
Bt Cotton ◽  
Transgenic Event ◽  
Plant Feeding ◽  
Whole Plant ◽  
Further Development

Abstract Lygus species of plant-feeding insects have emerged as economically important pests of cotton in the United States. These species are not controlled by commercial Bacillus thuringiensis (Bt) cotton varieties resulting in economic losses and increased application of insecticide. Previously, a Bt crystal protein (Cry51Aa2) was reported with insecticidal activity against Lygus spp. However, transgenic cotton plants expressing this protein did not exhibit effective protection from Lygus feeding damage. Here we employ various optimization strategies, informed in part by protein crystallography and modelling, to identify limited amino-acid substitutions in Cry51Aa2 that increase insecticidal activity towards Lygus spp. by >200-fold. Transgenic cotton expressing the variant protein, Cry51Aa2.834_16, reduce populations of Lygus spp. up to 30-fold in whole-plant caged field trials. One transgenic event, designated MON88702, has been selected for further development of cotton varieties that could potentially reduce or eliminate insecticide application for control of Lygus and the associated environmental impacts.

Tolerance of 12 Sugarbeet Varieties to Applications ofs-Metolachlor and Dimethenamid-P

2008 ◽  
Vol 22 (4) ◽  
pp. 699-706 ◽  
Author(s):  
Scott L. Bollman ◽  
Christy L. Sprague
Keyword(s):  
Disease Resistance ◽  
Weed Control ◽  
Herbicide Tolerance ◽  
Field Trials ◽  
Sugar Yield ◽  
Varietal Differences ◽  
Leaf Stage ◽  
Variety Selection

Sugarbeet varieties vary in their response to herbicides.s-Metolachlor and dimethenamid-P were recently registered for use in sugarbeet. Field trials were conducted in Michigan in 2004, 2005, and 2006 to evaluate the response of 12 sugarbeet varieties tos-metolachlor and dimethenamid-P applied PRE and POST to two-leaf and four-leaf stage sugarbeet.s-Metolachlor and dimethenamid-P reduced sugarbeet density when rainfall occurred within 7 d of the PRE applications. Dimethenamid-P PRE caused the most injury across all varieties followed bys-metolachlor PRE. Applying dimethenamid-P POST to two-leaf sugarbeet injured plants more thans-metolachlor applied POST to two- and four-leaf stage sugarbeet. The least amount of sugarbeet injury from dimethenamid-P was from POST applications at the four-leaf stage. Sugarbeet varietal differences were most pronounced from PRE applications of both herbicides and from the POST two-leaf application of dimethenamid-P. Of the 12 sugarbeet varieties evaluated, Hilleshog 2771RZ and Beta 5833R were the most tolerant, whereas Hilleshog 7172RZ was typically the most sensitive variety to these herbicides. Growers will probably not choose varieties based on herbicide tolerance alone, but instead base variety selection on sugar yield and disease resistance. However, if a grower has chosen a particular variety, this information could assist in assessing the risk of usings-metolachlor or dimethenamid-P for weed control.

scholarly journals Remote Sensing for Assessing Rhizoctonia Crown and Root Rot Severity in Sugar Beet

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 497-505 ◽  
Author(s):  
Gregory J. Reynolds ◽  
Carol E. Windels ◽  
Ian V. MacRae ◽  
Soizik Laguette
Keyword(s):  
Remote Sensing ◽  
Sugar Beet ◽  
Root Rot ◽  
Near Infrared ◽  
Vegetation Indices ◽  
Root Surface ◽  
Near Infrared Reflectance ◽  
Initial Appearance ◽  
Crown And Root Rot ◽  
Field Plots

Rhizoctonia crown and root rot (RCRR), caused by Rhizoctonia solani AG-2-2, is an increasingly important disease of sugar beet in Minnesota and North Dakota. Disease ratings are based on subjective, visual estimates of root rot severity (0-to-7 scale, where 0 = healthy and 7 = 100% rotted, foliage dead). Remote sensing was evaluated as an alternative method to assess RCRR. Field plots of sugar beet were inoculated with R. solani AG 2-2 IIIB at different inoculum densities at the 10-leaf stage in 2008 and 2009. Data were collected for (i) hyperspectral reflectance from the sugar beet canopy and (ii) visual ratings of RCRR in 2008 at 2, 4, 6, and 8 weeks after inoculation (WAI) and in 2009 at 2, 3, 5, and 9 WAI. Green, red, and near-infrared reflectance and several calculated narrowband and wideband vegetation indices (VIs) were correlated with visual RCRR ratings, and all resulted in strong nonlinear regressions. Values of VIs were constant until at least 26 to 50% of the root surface was rotted (RCRR = 4, wilting of foliage starting to develop) and then decreased significantly as RCRR ratings increased and plants began dying. RCRR also was detected using airborne, color-infrared imagery at 0.25- and 1-m resolution. Remote sensing can detect RCRR but not before initial appearance of foliar symptoms.

scholarly journals Control of Rhizoctonia solani in Sugar Beet and Effect of Fungicide Application and Plant Cultivar on Inoculum Potential in the Soil

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 941-947 ◽  
Author(s):  
Anika Bartholomäus ◽  
Stefan Mittler ◽  
Bernward Märländer ◽  
Mark Varrelmann
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Natural Infection ◽  
Resistance Management ◽  
The United States ◽  
Similar Efficacy ◽  
Field Trials ◽  
Crown Rot ◽  
Inoculum Potential ◽  
Fungicide Application

Rhizoctonia solani (AG 2-2 IIIB) is the causal agent of Rhizoctonia root and crown rot, a disease that causes severe economic problems in sugar beet growing areas worldwide. In the United States, azoxystrobin is the most important active ingredient for fungicidal control of R. solani in sugar beet, showing efficacy superior to other substances. First reports on resistance development in R. solani, however, underline the importance of a careful fungicide resistance management. For this reason, the efficacy of a new fungicide mixture of azoxystrobin and difenoconazole was compared with a fungicide containing only azoxystrobin. Field trials were carried out under natural infection conditions as well as with inoculation in the years 2012, 2013, and 2014. Evaluation of the disease severity and the obtained white sugar yield of different sugar beet cultivars demonstrated that both fungicide treatments possess a similar efficacy, reducing the diseased beet surface by up to 78% and preventing yield losses. Additionally, a real-time PCR assay, based on DNA extracts from representative soil samples (250 g), was used to directly determine the effect of chemical treatment and plant cultivar on the soil-borne inoculum. Fungicide application significantly reduced the concentration of soil-borne inoculum by up to 97%. Furthermore, the results demonstrated that the cultivation of a susceptible cultivar significantly increases the concentration of R. solani in the soil by a factor of 200. In conclusion, the study implies that only a combination of resistant cultivar and fungicide application can prevent an accumulation of R. solani inoculum under conducive conditions in infested fields.

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