Regression Analyses for Evaluating the Influence of Bacillus cereus on Alfalfa Yield Under Variable Disease Intensity

We developed and tested regression methods to exploit the variability in disease inherent in field experiments, and applied the methods to evaluate strains of Bacillus cereus for biocontrol efficacy. Four B. cereus strains were tested for their effect on alfalfa (Medicago sativa) performance in 16 field trials planted during 1993 to 1996 at multiple sites in Wisconsin. To evaluate performance of the strains, we used the ratio of (metalaxyl response)/(untreated control response) as a measure of disease intensity within the experiments. The ratio of (Bacillus response)/(untreated control response) was then regressed as a function of disease intensity. The slope of the resulting line provides a statistical test to compare performance of the Bacillus strain with that of the untreated seed (Ho: slope = 0) and metalaxyl controls (Ho: slope = 1). Under conditions in which disease occurred, forage yield of plots planted with seed treated with B. cereus strain AS4–12 exceeded yield from the untreated control plots (P = 0.002) and was similar to yield of plots planted with metalaxyl-treated seed (P = 0.14). Yield gain associated with AS4–12 and metalaxyl seed treatment averaged 6.1 ± 2.8% (±standard error) and 3.0 ± 2.8%, respectively. In contrast to the regression approach, means analysis by analysis of variance did not detect differences among treatments. Three other B. cereus strains either did not increase alfalfa yield or increased yield less than did AS4–12. Metalaxyl and three of the Bacillus strains increased seedling emergence, but the improved stands were not predictive of increased forage yield. In six additional studies conducted for one season in 1997, AS4–12 enhanced yield of two cultivars at diverse locations in Wisconsin, but there was an apparent cultivar-location interaction. A strong correlation between response to AS4–12 and metalaxyl treatment suggests that these treatments controlled similar pathogens, most likely the oomycete pathogens Phytophthora medicaginis and Pythium spp.

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Efficacy of Clonostachys rosea strain ACM941 and fungicide seed treatments for controlling the root rot complex of field pea

Canadian Journal of Plant Science ◽

10.4141/p02-078 ◽

2003 ◽

Vol 83 (3) ◽

pp. 519-524 ◽

Cited By ~ 14

Author(s):

A. G. Xue

Keyword(s):

Root Rot ◽

Untreated Control ◽

Seedling Emergence ◽

Field Trials ◽

Field Pea ◽

Seed Treatments ◽

Clonostachys Rosea ◽

Pea Root ◽

Pea Root Rot ◽

Better Than

The efficacy of seed treatments with bioagent ACM941 (a strain of Clonostachys rosea), its formulated products GB116 and ACM941-Pro, and common fungicides for the control of pea root rot complex were examined in six field trials in western Canada from 1996 to 2000. The effects on seedling emergence, root rot severity, and yield varied among years. In trials 1 and 2 (1996–1997), none of the treatments significantly reduced root rot severity or increased yield. ACM941 + Thiram 75WP was the most effective treatment, increasing emergence by 17.4% and was significantly better than that of the untreated controls. In trials 3 and 4 (1997–1998), Apron FL alone and ACM941 + Apron FL were significantly better than the untreated control, increasing emergence by 6.2 and 7.7%, and yield by 10.8 and 11.5%, respectively. In trials 5 and 6 (1999–2000), AC M 941 and GB116 were equally the most effective treatments, increasing emergence by 11.5 and 12.2%, and yield by 8.2 and 6.3%, respectively. These effects were significantly greater than that of the untreated control, but not significantly different from those of Apron FL or Vitaflo-280. ACM941-Pro was developed and tested in 2000 only, and it increased emergence by 17.1% and reduced root rot severity by 29.6%. Key words: Bioagent, Clonostachys rosea, field pea, Pisum sativum, pea root rot complex (PRRC), seed treatment, fungicide

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Beneficial Effects of Solid Matrix Chemo-priming in Okra

Plant Disease ◽

10.1094/pdis.2001.85.5.535 ◽

2001 ◽

Vol 85 (5) ◽

pp. 535-537 ◽

Cited By ~ 2

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.

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Diversity for resistance to a moderately virulent bluegreen aphid (Acyrthosiphon kondoi Shinji) population in Trifolium species

Crop and Pasture Science ◽

10.1071/cp15102 ◽

2016 ◽

Vol 67 (9) ◽

pp. 1009 ◽

Cited By ~ 1

Author(s):

A. W. Humphries ◽

S. S. Robinson ◽

D. Hawkey ◽

D. M. Peck ◽

T. D. Rowe ◽

...

Keyword(s):

Field Experiments ◽

Insect Pest ◽

South Australia ◽

Subterranean Clover ◽

Field Trials ◽

Forage Yield ◽

Severe Damage ◽

Sources Of Resistance ◽

Diverse Range ◽

Crimson Clover

The resistance of a diverse range of Trifolium species (clovers) to a highly virulent bluegreen aphid (BGA, Acyrthosiphon kondoi Shinji) population (Urrbrae 2011) collected in South Australia was assessed in greenhouse and field experiments, with the aims of determining the potential impact of this insect pest on biomass and identifying resistant genotypes for future plant-breeding activities. Resistance to BGA was found in populations of clovers that show some level of outcrossing—white clover (T. repens L.), rose clover (T. hirtum All.), crimson clover (T. incarnatum L.) and red clover (T. pratense L.)—and in one entry of the inbreeding subspecies of subterranean clover, T. subterraneum L. subsp. subterraneum (Katzn. and Morley). Resistance was not found in T. s. brachycalycinum (Katzn. and Morley) or T. s. yanninicum (Katzn. and Morley). In a greenhouse experiment, damage from BGA resulted in forage yield penalties of 72–100% when aphids were inoculated at 14 days after sowing and 13−74% when inoculated at 42 days after sowing, showing that in optimum conditions BGA can be a serious pest of clovers. Observations of severe damage caused by BGA in two regenerating field trials in southern New South Wales confirmed that field damage could occur in seasons favourable to aphid growth and reproduction. The severe damage that BGA can cause to clovers, and the sources of resistance we found, suggest that breeding for BGA resistance in clovers is warranted and feasible.

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Fungicide seed dressings: their effects on emergence of soybean and nodulation of pea and soybean

Australian Journal of Experimental Agriculture ◽

10.1071/ea9800497 ◽

1980 ◽

Vol 20 (105) ◽

pp. 497 ◽

Cited By ~ 7

Author(s):

GE Stovold ◽

J Evans

Keyword(s):

Field Experiments ◽

Soybean Seed ◽

Field Trials ◽

Inhibitory Effect ◽

Alternative Methods ◽

Seedling Disease ◽

Rhizobium Inoculation ◽

Treated Seed ◽

Inoculant Carrier ◽

Seedling Diseases

A range of fungicides was tested for their efficacy as seed treatments for the control of seedling diseases of soybeans. Thiram, captan and captafol at rates of 2000 ppm a.i. w/w or 3000 ppm a.i. w/w provided the most consistent protection in field trials conducted for 3 years at three separate sites. Of these three fungicides, thiram had the least effect on nodulation by Rhizobium applied to the seed, but an inhibiting effect did occur in some years. Several other fungicides had little effect on nodulation but were inconsistent in controlling seedling diseases. In a glasshouse pot trial, the fungicides did not reduce nodulation even though some were consistently toxic in the field experiments. In field trials with peas and soybeans, the inhibitory effect of a toxic fungicide (captan) on nodulation by seed-borne Rhizobium was avoided by using alternative methods of inoculation which separated Rhizobium from the treated seed. A water suspension of peat-based rhizobial inoculant, or sand particles coated with peat inoculant introduced to the furrow together with the seed, were effective methods of inoculation. A large-particle inoculant carrier (heat-killed soybean seed) was unsuitable. For control of soybean seedling disease we recommend the use of thiram fungicide at a rate of 2000 ppm a.i. w/w, and where practicable the use of alternative methods of Rhizobium inoculation to separate the inoculum from the treated seed.

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Effect of Priming and Seed Size on Germination and Emergence of Six Food-Type Soybean Varieties

International Journal of Agronomy ◽

10.1155/2015/859212 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Maru K. Kering ◽

Bo Zhang

Keyword(s):

Seed Size ◽

Field Experiments ◽

Germination Rate ◽

Seedling Emergence ◽

Food Type ◽

Medium Size ◽

Large Seed ◽

Seed Pretreatment ◽

Treated Seed ◽

High Reduction

Soybean (Glycine max(L.) Merr.), a good source of protein and oil, is used to produce nutritious isoflavone-rich soybean-based foods. The objectives of this study were (i) to determine the germination difference among soybean seeds in various seed sizes and (ii) to evaluate effects of seed pretreatment on germination and seedling emergence. Six varieties of different seed size class were used: (i) small size (MFS-561 and V08-4773), (ii) medium size (Glen and V03-47050), and (iii) large size (MFL-159 and V07-1897). Pregermination treatments include 0, 5, or 10 hours soaking and germinating/planting with or without nitrogen fertilizer. Large seed size varieties showed low germination rate and N addition caused the least reduction in germination in these seeds during the first 24 hours. While N had no effect on seed germination after 72 hours, growth in N treated seed was low. Seedling emergence was comparable across varieties in 2013 and water priming and N application had no effect. However, while varieties did not differ in final emergence for nonprimed seeds in 2014, water priming led to a high reduction in seedling emergence of large seed varieties in this study. Application of N fertilizer had no effect on seedling emergence in field experiments.

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Improving vegetable production under semi-arid, saline conditions in south-western Madagascar

Experimental Agriculture ◽

10.1017/s001447972000040x ◽

2020 ◽

Vol 56 (6) ◽

pp. 915-928

Author(s):

Jessica N. Andriamparany ◽

Susan Hanisch ◽

Andreas Buerkert

Keyword(s):

Field Experiments ◽

Seed Quality ◽

Seedling Emergence ◽

Field Trials ◽

Vegetable Production ◽

Saline Irrigation ◽

Manure Application ◽

Soil C ◽

Carrot Seed ◽

Strong Winds

AbstractAgricultural production on the Mahafaly Plateau in SW-Madagascar has traditionally been based on subsistence rain-fed agriculture, with yields declining as a result of low soil fertility, recurrent droughts, and erratic rainfall. Market-oriented vegetable production in this area may help households improve their nutrition and diversify their income. In field trials between the 2013 and 2016 dry cropping seasons, the feasibility of carrot (Daucus carota L.) and onion (Allium cepa L.) production was assessed by testing effects of manure and charcoal amendments, shading, and seed quality on yields. Due to damage caused by cyclones and strong winds, only data from 2013 and 2016 are reported in this paper. Additionally to the field experiments, effects of salinity on seed germination were also examined under laboratory conditions and in the field. Carrot dry matter (DM) yields were 0.24 to 2.76 t·ha−1 while those of onion were 0.15 to 0.99 t·ha−1 DM. While the combination of manure and charcoal application had only minor effects on crop growth, manure alone increased carrot yield by 26% across years. After one cropping season, manure application reduced soil pH from 9.0 to 8.6 and increased soil Corg from 0.87 to 1.76%, N from 0.08 to 0.14%, and P from 10.6 to 15.1 mg·kg−1. Shading reduced carrot yields from 0.87 to 0.58 t·ha−1 DM in 2013 and from 1.87 to 0.85 t·ha−1 DM in 2016, but increased onion yield in 2013 from 0.24 to 0.62 t·ha−1 DM. Carrot seed procured locally performed better in the field than seed imported from the capital which translated into differences in seedling emergence. Saline irrigation water (electrical conductivity = 7.03 mS·cm−1) reduced seedling emergence rate of carrot from 73 to 20% and for onion from 44 to 28% and unprimed seeds performed better than primed ones. Using shading during the dry season is not advisable for carrot and onion production, but improving seed quality and targeted use of soil amendments (time of manure application, manure quality) may enhance vegetable yields.

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Genetic and Seed Treatment Effects in Organic Peanut

Peanut Science ◽

10.3146/ps11-5.1 ◽

2011 ◽

Vol 38 (2) ◽

pp. 115-121 ◽

Cited By ~ 5

Author(s):

E.G. Cantonwine ◽

C.C. Holbrook ◽

A.K. Culbreath ◽

R.S. Tubbs ◽

M.A. Boudreau

Keyword(s):

Seedling Establishment ◽

Seed Treatment ◽

Field Experiments ◽

Plant Biomass ◽

Seedling Emergence ◽

Organic Production ◽

Crown Rot ◽

Stand Establishment ◽

Treated Seed ◽

Low Incidence

ABSTRACT Stand establishment has been a challenge for organic peanut production in the Southeastern United States. Field experiments were conducted in 2007 and 2009 in research plots certified for organic production to evaluate the potential of genotype selection, shelling procedure, and seed treatment with Bacillus subtilis to improve stand establishment and seedling emergence rates, reduce incidence of Aspergillus crown rot, and increase seedling biomass. Seed of 15 peanut genotypes were mechanically shelled or hand-shelled, and treated with B. subtilis or untreated prior to planting in early June. Percent stand was estimated for each plot 17–21 days after planting (DAP), and percent seedlings affected by Aspergillus crown rot and plant biomass were estimated 21–24 DAP. Seed treatment significantly affected stand establishment for three genotypes each year, Georgia-01R both years, C-99R and Tifguard in 2007, and C34-24-69 and C724-19-25 in 2009. In all of these cases, the hand-shelled plots had significantly greater stands than the mechanically shelled plots for untreated and/or B. subtilis treated seed. B. subtilis treatment improved stands for two of the mechanically shelled treatments that significantly responded to hand shelling. Despite low incidence, there was a significant reduction of crown rot in the hand-shelled plots compared to the mechanically shelled plots across years and genotypes. The cultivar Georganic, which has been planted to organic peanut systems in Georgia in recent years, was among the genotypes with the lowest seedling establishment rates and biomass. Based on these results, it is recommended that sorting thresholds for damaged seed be higher for seed destined for organic production, and that breeding efforts that include assessments of factors involved in seedling establishment and growth be prioritized.

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Seedbed preparation, timing of seeding, fertility and root pathogens affect establishment and yield of alfalfa

Canadian Journal of Plant Science ◽

10.4141/p01-121 ◽

2002 ◽

Vol 82 (2) ◽

pp. 371-381 ◽

Cited By ~ 5

Author(s):

S. F. Hwang ◽

B. D. Gossen ◽

G. D. Turnbull ◽

K. F. Chang ◽

R. J. Howard

Keyword(s):

Seed Treatment ◽

Fungal Pathogens ◽

Plant Density ◽

Seedling Emergence ◽

Stand Density ◽

Pathogenic Fungi ◽

Field Trials ◽

Forage Yield ◽

Seedbed Preparation ◽

The Impact

Invasion by grasses and weedy species occurs when plant density in alfalfa fields falls below critical levels. Several soil-borne fungal pathogens can reduce stand density in alfalfa by impeding seedling establishment and by killing older plants weakened by other stresses. Surveys of alfalfa fields were conducted in 1997, and pathogenic fungi from rotted roots were isolated and identified. Isolates of selected pathogens were applied with the seed in field trials to assess the impact of fertilizer and seeding system (conventional vs. sod-seeding, spring vs. dormant-fall seeding) on seedling emergence and subsequent productivity when disease pressure was high. The impact of various fungicide seed treatments was also assessed. Seed treatment improved seedling emergence and initial forage productivity in one of three trials; however, it had little effect on long-term forage yield. Addition of sulphur fertilizer had little effect on seedling emergence or survival, but improved forage productivity at all three trial sites. Sod-seeded plots suffered more winterkill and were less vigorous than plots seeded into a tilled seedbed. Seedling emergence was lower when seedlings were planted in the fall than in the spring. However, fall-seeded treatments showed a less adverse response to inoculum treatments and, in some cases, these seedlings were able to take advantage of early-season moisture to produce higher yields than their spring-seeded counterparts. Key words: Medicago, Fusarium, Pythium, Phoma, fungicide, seed treatment, fertilizer, tillage

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Effect of Application Frequency and Reduced Rates of Acibenzolar-S-Methyl on the Field Efficacy of Induced Resistance Against Bacterial Spot on Tomato

Plant Disease ◽

10.1094/pdis-03-11-0183 ◽

2012 ◽

Vol 96 (2) ◽

pp. 221-227 ◽

Cited By ~ 46

Author(s):

Cheng-Hua Huang ◽

Gary E. Vallad ◽

Shouan Zhang ◽

Amin Wen ◽

Botond Balogh ◽

...

Keyword(s):

Disease Severity ◽

Untreated Control ◽

Systemic Acquired Resistance ◽

Field Experiments ◽

Acquired Resistance ◽

Foliar Spray ◽

Field Trials ◽

Plant Diseases ◽

Bacterial Spot ◽

Field Efficacy

Acibenzolar-S-methyl (ASM), a plant activator known to induce systemic acquired resistance, has demonstrated an ability to manage a number of plant diseases, including bacterial spot on tomato caused by four distinct Xanthomonas spp. The aim of this study was to evaluate application rate and frequency of ASM in order to optimize field efficacy against bacterial spot in Florida, while minimizing its impact on marketable yields. ASM was applied biweekly (once every 2 weeks) as a foliar spray at a constant concentration of 12.9, 64.5, and 129 μM throughout four field experiments during 2007–08. A standard copper program and an untreated control were also included. Overall, biweekly applications of ASM did not significantly reduce disease development or the final disease severity of bacterial spot compared with the copper-mancozeb standard or the untreated control. Only one experiment showed a significant reduction in the final disease severity on plants treated with ASM at 129 μM compared with the untreated control. Three additional field trials conducted during 2009–10 to evaluate the effects of weekly and biweekly applications of ASM at concentrations of 30.3 to 200 μM found that weekly applications provided significantly better disease control than biweekly applications. The tomato yields were not statistically improved with the use of ASM relative to the untreated control and standard copper program. Weekly ASM applications at rates as low as 75 μM (equivalent to 1.58 g a.i./ha in 100 liters of water or 0.21 oz. a.i./acre in 100 gallons of water) to 200 μM (equivalent to 4.20 g a.i./ha in 100 liters of water or 0.56 oz. a.i./acre in 100 gallons of water) were statistically equivalent in managing bacterial spot of tomato without significantly reducing yield compared with the untreated control.

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Biological control of Pythium damping-off of pea and sugar beet by Rhizobium leguminosarum bv. viceae

Canadian Journal of Botany ◽

10.1139/b04-003 ◽

2004 ◽

Vol 82 (3) ◽

pp. 291-296 ◽

Cited By ~ 41

Author(s):

Sylvie D Bardin ◽

Hung-Chang Huang ◽

Joanna Pinto ◽

Eric J Amundsen ◽

R Scott Erickson

Keyword(s):

Biological Control ◽

Sugar Beet ◽

Untreated Control ◽

Rhizobium Leguminosarum ◽

Field Experiments ◽

Biological Control Agent ◽

Root Nodules ◽

Seedling Emergence ◽

Field Pea ◽

Damping Off

Rhizobium leguminosarum Jordan bv. viceae strains from pea and lentil root nodules were tested for control of damping-off of pea (Pisum sativum L., host) and sugar beet (Beta vulgaris L., nonhost) crops caused by Pythium sp. "group G". Of the 18 Rhizobium isolates tested, only strain R5 inhibited mycelial growth of Pythium sp. "group G". None of the strains showed any protease activity. Results of indoor experiments in soil artificially infested with Pythium sp. "group G" showed that 10 strains of R. leguminosarum bv. viceae were effective in increasing sugar beet emergence compared with the untreated control, when bacteria were coated onto seeds. Three of the most promising strains, R12, R20, and R21, were further tested for control of damping-off of field pea and sugar beet in a field naturally infested with Pythium spp. R12 and R20 significantly increased seedling emergence of field pea in the two field tests, compared with the untreated control. The efficacy of strains R12 and R20 was similar to that of Pseudomonas fluorescens Migula 708, a biological control agent of Pythium sp. "group G". Rhizobium leguminosarum bv. viceae strains R12 and R21 were the most effective biological control agents for control of sugar beet damping-off in the field experiments. They were as effective as seed treatment with the fungicide ThiramTM in one field experiment. The present study reveals that some R. leguminosarum bv. viceae strains, in addition to their use as biofertilizer, also have the potential to be used for biological control of Pythium damping-off of field pea and sugar beet.Key words: Rhizobium leguminosarum bv. viceae, Pythium sp. "group G", damping-off, biological control, sugar beet, pea.

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