scholarly journals Beneficial Effects of Fungicide Seed Treatments for Soybean Cultivars with Partial Resistance to Phytophthora sojae

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1063-1068 ◽  
Author(s):  
A. E. Dorrance ◽  
S. A. McClure
Keyword(s):  
Partial Resistance ◽  
Seed Treatment ◽  
Phytophthora Sojae ◽  
Soybean Seeds ◽  
Damping Off ◽  
Seed Treatments ◽  
Beneficial Effects ◽  
Rps Gene ◽  
Greenhouse Assay ◽  
Zoospore Suspension

Phytophthora sojae is a yield-limiting soybean pathogen in areas where soils remain saturated for long periods of time. P. sojae has been successfully managed with single dominant resistance genes (Rps genes). The proportion of fields with populations of P. sojae capable of causing susceptible interactions with many of the Rps genes has increased in number. The fungicides metalaxyl and mefenoxam have been used both as in-furrow and seed treatments to provide protection against damping-off caused by P. sojae. To determine the plant age when partial resistance and Rps genes are effective against P. sojae, we evaluated a greenhouse assay in which soybean seeds were planted and inoculated with a zoospore suspension to compare the disease reaction of soybean seeds and seedlings. Efficacy of different fungicide rates also was evaluated using the cultivar with partial resistance with this inoculation technique. Seeds and seedlings of a cultivar with high levels of partial resistance were susceptible to infection by P. sojae while those of a cultivar with an Rps gene were resistant. For the cultivar with partial resistance, reductions in percent emergence and the number of damped-off seedlings were significantly higher for plants inoculated at the day of planting compared to inoculations of plants with unifoliates present (5 days after planting). Results also indicate that fungicide seed treatment on cultivars with partial resistance may be beneficial when the environmental conditions that favor P. sojae infections occur prior to soybean emergence. This greenhouse assay appears to be useful in examining overall fungicide efficacy; however, it did not detect consistent and quantifiable differences in rates of seed treatment fungicides.

Effect of Resistance and Ethaboxam Seed Treatment on the Management of Phytophthora Root Rot in Illinois and Iowa

2021 ◽  
Author(s):  
Daniel G. Cerritos-Garcia ◽  
Juan P. Granda ◽  
Rashelle Matthiessen ◽  
Brian W. Diers ◽  
Alison E. Robertson ◽  
...  
Keyword(s):  
Partial Resistance ◽  
Seed Treatment ◽  
Field Experiments ◽  
Limiting Factor ◽  
Seed Selection ◽  
Seed Treatments ◽  
Phytophthora Root Rot ◽  
Early Season ◽  
Rps Gene ◽  
Different Levels

Phytophthora root and stem rot (PRR) is a limiting factor for soybean production. Seed treatments are used for early-season management, but efficacy can depend on seed selection and the local environment. Ethaboxam is a new fungicide commercially available as a seed treatment to control oomycetes. Field experiments were established in Illinois and Iowa in 2017 and 2018 to evaluate the effect of ethaboxam + metalaxyl on PRR. Experiments included soybean lines with no resistance gene, Rps1c or Rps1k, and different levels of partial resistance. Seed treatments increased soybean stands in all locations and years. Significant yield effects were observed only in two locations that were inoculated with Phytophthora spp. Groups of soybean lines with the same Rps gene responded differently in each location, showing how Rps gene usefulness depends on the field. A comparison of the effect of seed treatment on lines with different levels of partial resistance showed that partial resistance alone cannot always protect against stand losses. Soybean lines with high levels of partial resistance had consistently higher yields than those with low levels of partial resistance across Illinois locations. These results show that ethaboxam seed treatment can protect early-season stands and that selection of cultivars with high levels of partial resistance is important for PRR management.

Phytophthora sojae pathotype distribution and fungicide sensitivity in Michigan

Plant Disease ◽  
2021 ◽  
Author(s):  
Austin Glenn McCoy ◽  
Zachary Albert Noel ◽  
Janette L Jacobs ◽  
Kayla M Clouse ◽  
Martin I Chilvers
Keyword(s):  
Resistance Genes ◽  
Phytophthora Sojae ◽  
Significant Shift ◽  
Seed Treatments ◽  
Fungicide Sensitivity ◽  
History Of ◽  
Plant Stand ◽  
Rps Gene ◽  
Major Resistance Genes ◽  
Pathogen Populations

Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P. sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize the current pathotype structure and fungicide sensitivity of P. sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P. sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b and 6, compared to a previous survey conducted in Michigan from 1993-1997. Three effective resistance genes were identified for P. sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% (EC50) was determined. No P. sojae isolates were insensitive to the tested chemistries with mean EC50 values of 2.60x10-2 µg/ml for ethaboxam, 3.03x10-2 µg/ml for mefenoxam, 2.88x10-4 µg/ml for oxathiapiprolin, and 5.08x10-2 µg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.

scholarly journals The Efficacy of Ethaboxam as a Soybean Seed Treatment Toward Phytophthora, Phytopythium, and Pythium in Ohio

Plant Disease ◽  
2020 ◽  
Vol 104 (5) ◽  
pp. 1421-1432 ◽  
Author(s):  
Kelsey Scott ◽  
Meredith Eyre ◽  
Dair McDuffee ◽  
Anne E. Dorrance
Keyword(s):  
Seed Treatment ◽  
Soybean Seed ◽  
Primary Objective ◽  
Phytophthora Species ◽  
Damping Off ◽  
Seed Treatments ◽  
Seedling Disease ◽  
Seed Decay ◽  
Fungicide Mixtures ◽  
Seed Rot

Phytophthora, Phytopythium, and Pythium species that cause early-season seed decay and pre-emergence and post-emergence damping off of soybean are most commonly managed with seed treatments. The phenylamide fungicides metalaxyl and mefenoxam, and ethaboxam are effective toward some but not all species. The primary objective of this study was to evaluate the efficacy of ethaboxam in fungicide mixtures and compare those with other fungicides as seed treatments to protect soybean against Pythium, Phytopythium, and Phytophthora species in both high-disease field environments and laboratory seed plate assays. The second objective was to evaluate these seed treatment mixtures on cultivars that have varying levels and combinations of resistance to these soilborne pathogens. Five of eight environments received adequate precipitation in the 14 days after planting for high levels of seedling disease development and treatment evaluations. Three environments had significantly greater stands, and three had significantly greater yield when ethaboxam was used in the seed treatment mixture compared with treatments containing metalaxyl or mefenoxam alone. Three fungicide formulations significantly reduced disease severity compared with nontreated in the seed plate assay for 17 species. However, the combination of ethaboxam plus metalaxyl in a mixture was more effective than either fungicide alone against some Pythium and Phytopythium species. Overall, our results indicate that the addition of ethaboxam to a fungicide seed treatment is effective in reducing seed rot caused by these pathogens commonly isolated from soybean in Ohio but that these effects can be masked when cultivars with resistance are planted.

scholarly journals Electrical conductivity test in the evaluation of the physiological potential of treated and stored soybean seeds

2021 ◽  
Vol 42 (6) ◽  
pp. 3135-3148
Author(s):  
Ana Paula Silva Couto ◽  
◽  
Cristian Rafael Brzezinski ◽  
Julia Abati ◽  
Ronan Carlos Colombo ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Seed Treatment ◽  
Seed Quality ◽  
Soybean Seed ◽  
Accelerated Aging ◽  
Control Treatment ◽  
Soybean Seeds ◽  
Seed Treatments ◽  
Chemical Treatments ◽  
Soybean Cultivars

Soybean seed treatment contributes to the maintenance of seed quality, but the effect of commercial formulations and chemical products on the effectiveness of the electrical conductivity test based on electrolyte leaching has been frequently questioned. This study aimed to verify the interference of the chemical seed treatment of two soybean cultivars on the effectiveness of the electrical conductivity test in evaluating the vigor of freshly treated and stored seeds. The experimental design was completely randomized, consisting of seven seed treatments and two evaluation periods (0 and 60 days after storage), with four replications. The used seed treatments consisted of 1) fipronil + pyraclostrobin + thiophanate-methyl, 2) imidacloprid + thiodicarb + carbendazim + thiram, 3) abamectin + thiamethoxan + fludioxonil + mefenoxam + thiabendazole, 4) carbendazim + thiram, 5) fludioxonil + mefenoxam + thiabendazole, 6) carboxin + thiram, and 7) control (no treatment). The cultivars were BRS 360 RR and BRS 284, which were analyzed separately. Germination, accelerated aging, emergence, and electrical conductivity tests were carried out. No differences were detected between the control and chemical treatments performed on seeds of the two freshly treated soybean cultivars regarding germination, accelerated aging, and emergence tests. The germination test stood out after storage with the cultivar BRS 360 RR, showing the maintenance of germination potential for seeds treated with carbendazim + thiram and the control treatment. Therefore, the chemical treatment of soybean seeds interferes with the result of the electrical conductivity test. The electrical conductivity test is effective in segregating seed lots in terms of vigor level. The electrical conductivity test correlates with the other vigor tests used to identify the reduction in the physiological seed quality with storage.

scholarly journals Insecticide Seed Treatments Reduced Crop Injury from Flumioxazin, Chlorsulfuron, Saflufenacil, Pyroxasulfone, and Flumioxazin + Pyroxasulfone + Chlorimuron in Soybean

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
N. R. Steppig ◽  
J. K. Norsworthy ◽  
R. C. Scott ◽  
G. M. Lorenz
Keyword(s):  
Seed Treatment ◽  
Residual Activity ◽  
Unintentional Injury ◽  
Field Trials ◽  
Soybean Seeds ◽  
Seed Treatments ◽  
Injury Reduction ◽  
Crop Injury ◽  
Postemergence Herbicides ◽  
Weed Resistance

With increased instances of weed resistance to applications of postemergence herbicides, the use of soil-applied herbicides that offer residual activity is becoming popular. Unfortunately, under some conditions, the use of residual herbicides can result in unintentional injury to crops. However, there are a number of ways to reduce these risks, including the use of in-crop herbicide safeners. Based on previous research conducted on rice, the potential may exist for crop injury from certain soil-applied herbicides to be reduced (safened) in seeds treated with insecticides. Field trials were conducted in Marianna, Arkansas, in 2015 and 2016, and near Colt, Arkansas, in 2016, to explore this possibility in soybean. Soybean seeds were treated with the insecticide thiamethoxam and subsequently the herbicides metribuzin, saflufenacil, pyroxasulfone, sulfentrazone, chlorimuron, flumioxazin, flumioxazin + pyroxasulfone + chlorimuron, mesotrione, and chlorsulfuron were applied immediately after planting. Of the nine herbicides evaluated, the insecticide reduced crop injury for flumioxazin, chlorsulfuron, saflufenacil, pyroxasulfone, and flumioxazin + pyroxasulfone + chlorimuron. The highest degree of injury reduction was seen 1 week after emergence (WAE) at Marianna, where injury from flumioxazin + pyroxasulfone + chlorimuron was reduced from 15% to 5%. Based on the results from this study, the insecticide seed treatment thiamethoxam may have the potential to safen soybean to applications of some soil-applied herbicides.

scholarly journals Beneficial Effects of Solid Matrix Chemo-priming in Okra

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 535-537 ◽  
Author(s):  
K. E. Conway ◽  
R. Mereddy ◽  
B. A. Kahn ◽  
Y. Wu ◽  
S. W. Hallgren ◽  
...  
Keyword(s):  
Untreated Control ◽  
Seed Treatment ◽  
Seedling Emergence ◽  
Pythium Ultimum ◽  
Field Trials ◽  
Solid Matrix ◽  
Damping Off ◽  
Untreated Seed ◽  
Beneficial Effects ◽  
Emergence And Reduction

Two field trials at Stillwater and Bixby, OK, evaluated the efficacy of solid matrix priming techniques, alone or in combination with fungicide seed treatment on seedling emergence and reduction of damping-off of okra in field soil naturally infested with Pythium ultimum. The following treatments were evaluated: thiram + carboxin (chemo-primed) (commercially applied), biological seed treatment (bio-primed) (Trichoderma harzianum isolate OK-110, 1 g suspended in 1% carboxymethylcellulose [CMC]), untreated seed (control), and a 1% CMC control. Chemo-primed seeds had a more uniform and faster emergence compared with untreated seeds at both field sites. Within 3 days, 92 and 78% of chemo-primed seeds had emerged at Stillwater and Bixby, respectively, compared with 84 and 71% emergence in the untreated control. Mean emergence of chemo-primed seeds was lower (P ≤ 0.05) than the untreated control. Chemo-primed seeds had greater vigor (P≤ 0.05) at both locations compared with either fungicide-treated or priming alone, at both locations. There were no differences (P ≤ 0.05) in yield among treatments at both locations. P. ultimum was consistently isolated from damped-off seedlings and surrounding soil at both locations. Isolates of P. ultimum were more pathogenic on okra in laboratory tests than isolates of Rhizoctonia spp., Fusarium spp., and other Pythium spp. also isolated from seed or soil.

scholarly journals Pathotype Diversity of Phytophthora sojae in Eleven States in the United States

Plant Disease ◽  
2016 ◽  
Vol 100 (7) ◽  
pp. 1429-1437 ◽  
Author(s):  
A. E. Dorrance ◽  
J. Kurle ◽  
A. E. Robertson ◽  
C. A. Bradley ◽  
L. Giesler ◽  
...  
Keyword(s):  
United States ◽  
Partial Resistance ◽  
The United States ◽  
Phytophthora Sojae ◽  
Soil Samples ◽  
The State ◽  
Soybean Seedling ◽  
Northern Regions ◽  
Rps Gene

Pathotype diversity of Phytophthora sojae was assessed in 11 states in the United States during 2012 and 2013. Isolates of P. sojae were recovered from 202 fields, either from soil samples using a soybean seedling bioassay or by isolation from symptomatic plants. Each isolate was inoculated directly onto 12 soybean differentials; no Rps gene or Rps 1a, 1b, 1c, 1k, 3a, 3b, 3c, 4, 6, 7, or 8. There were 213 unique virulence pathotypes identified among the 873 isolates collected. None of the Rps genes were effective against all the isolates collected but Rps6 and Rps8 were effective against the majority of isolates collected in the northern regions of the sampled area. Virulence toward Rps1a, 1b, 1c, and 1k ranged from 36 to 100% of isolates collected in each state, while virulence to Rps6 and Rps8 was less than 36 and 10%, respectively. Depending on the state, the effectiveness of Rps3a ranged from totally effective to susceptible to more than 40% of the isolates. Pathotype complexity has increased in populations of P. sojae in the United States, emphasizing the increasing importance of stacked Rps genes in combination with high partial resistance as a means of limiting losses to P. sojae.

scholarly journals Infection of Soybean Seed by Fusarium graminearum and Effect of Seed Treatments on Disease Under Controlled Conditions

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 401-407 ◽  
Author(s):  
M. L. Ellis ◽  
K. D. Broders ◽  
P. A. Paul ◽  
A. E. Dorrance
Keyword(s):  
Fusarium Graminearum ◽  
Seed Treatment ◽  
Soybean Seed ◽  
Disease Development ◽  
Damping Off ◽  
Optimum Conditions ◽  
Seed Treatments ◽  
Seedling Disease ◽  
Seed Decay ◽  
Recent Emergence

Fusarium graminearum causes seed decay and damping-off of soybean. This study evaluated the effect of inoculum density of F. graminearum, temperature, and fungicide seed treatments on disease development. To determine the optimum conditions for disease development, individual soybean seed was inoculated with 100 μl of a suspension of 2.5 × 102, 2.5 × 103, 2.5 × 104, or 2.5 × 105 macroconidia/ml in a rolled-towel assay at temperatures of 18, 22, and 25°C. Inoculum concentrations of 2.5 × 104 macroconidia/ml or higher were necessary for optimum disease development at all temperatures. The efficacy of captan, fludioxonil, mefenoxam + fludioxonil, azoxystrobin, trifloxystrobin, and pyraclostrobin as seed treatments was then evaluated with the same assay at 2.5 × 104 and 2.5 × 105 macroconidia/ml. Seed treated with captan at 61.9 g a.i. or fludioxonil at 2.5 or 5.0 g a.i. per 100 kg developed smaller lesions than other seed treatments and the nontreated control. Based on these results, there are limited choices in fungicide seed treatments for managing this seedling disease, and it is possible that shifts in seed treatment products may have played a role in the recent emergence of this soybean pathogen.

scholarly journals Storage of Soybean Seeds and Addition of Insecticide and Micronutrients

2018 ◽  
Vol 11 (1) ◽  
pp. 553
Author(s):  
Gustavo H. Demari ◽  
Vinícius J. Szareski ◽  
Ivan R. Carvalho ◽  
Tuane A. da Silva ◽  
Vânia M. Gehling ◽  
...  
Keyword(s):  
Significant Interaction ◽  
Seed Treatment ◽  
Primary Root ◽  
Dry Mass ◽  
Shoot Length ◽  
Soybean Seeds ◽  
Seed Treatments ◽  
Storage Times ◽  
And Storage ◽  
Primary Root Length

The objective of this work was to evaluate the effects on the physiological attributes of soybean seeds submitted to the seed treatment with addition of insecticide, polymers and micronutrients throughout the storage. The experimental design was completely randomized in a factorial scheme, with four seed treatments per two seasons of storage of the seeds. The analysis of variance revealed a significant interaction among seed treatments and storage times for both cultivars at 5% of probability, referring to the characteristics of shoot length (SL), primary root length (RL), shoot dry mass (SDM) and dry mass of the primary root (RDM) for the cultivar Fundacep 37 RR. Addition of seed treatments influences the physiological performance of seedlings originated from soybean seeds stored for 240 days. The shoot and primary root lenghts, and shoot dry mass express the isoenzyme esterase through the aerial part and primary root of the seedling, the malate dehydrogenase is expressed in the primary root while in the peroxidase it is evident in the shoot of the seedlings.

scholarly journals Greenhouse Evaluation of Seed and Drench Treatments for Organic Management of Soilborne Pathogens of Spinach

Plant Disease ◽  
2009 ◽  
Vol 93 (12) ◽  
pp. 1281-1292 ◽  
Author(s):  
Jaime A. Cummings ◽  
Carol A. Miles ◽  
Lindsey J. du Toit
Keyword(s):  
Seed Treatment ◽  
Pythium Ultimum ◽  
Organic Production ◽  
Compost Tea ◽  
Damping Off ◽  
Seed Treatments ◽  
Greenhouse Study ◽  
Greenhouse Evaluation ◽  
Equivalent Control ◽  
Bacillus Pumilis

The efficacy of 14 seed and drench treatments for control of soilborne damping-off pathogens in organic production of spinach was evaluated in a greenhouse study. The efficacy of each treatment was compared with nontreated seed and seed treated with a conventional fungicide for control of Fusarium oxysporum f. sp. spinaciae, Pythium ultimum, and Rhizoctonia solani. Two experimental seed treatments, GTG I and GTG II (each comprised of a proprietary organic disinfectant and the latter also containing Trichoderma harzianum T22), provided equivalent control to the conventional fungicide, mefenoxam, against P. ultimum in one trial and significant reduction of damping-off in the second trial. Natural II and Natural X (Streptomycete products), and Subtilex (Bacillus subtilis) seed treatments each suppressed damping-off significantly in one of the two trials. For R. solani, GTG I and Natural II seed treatments reduced damping-off as effectively as a drench with the fungicide Terraclor (pentachloronitrobenzene). A soil drench with Prestop (Gliocladium catenulatum) suppressed postemergence wilt caused by F. oxysporum in both trials; a compost tea drench and seed treatment with Yield Shield (Bacillus pumilis) each suppressed postemergence wilt in only one of two trials. GTG I and GTG II significantly increased seed germination compared to nontreated seed. No treatment was effective against all three pathogens, and some treatments exacerbated damping-off.

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