scholarly journals Development of a Fungicide-Based Management Strategy for Foliar Disease Caused by Phoma ligulicola in Tasmanian Pyrethrum Fields

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1114-1120 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Frank S. Hay ◽  
Calum R. Wilson ◽  
Tim Groom
Keyword(s):  
Mycelial Growth ◽  
Management Strategy ◽  
Cost Effective ◽  
Field Trials ◽  
Early Spring ◽  
Effective Management ◽  
Ray Blight ◽  
Low Concentrations ◽  
Demethylation Inhibitor

The efficacy of a range of fungicides were assessed under in vitro conditions in four field trials over three seasons for the management of ray blight of pyrethrum, caused by the fungus Phoma ligulicola in Tasmania. Fungicides belonging to the demethylation inhibitor group, including prochloraz, tebuconazole, difenoconazole, and cyproconazole, produced the most significant reduction in mycelial growth in vitro compared with unamended controls. Significant reductions in germination of conidia resulted from low concentrations of azoxystrobin. In the field, azox-ystrobin (as Amistar) at a rate of 300 g of product/ha significantly decreased disease intensity and increased pyrethrin yield (kg/ha) in all seasons. Applications of either azoxystrobin or difenoconazole (as Score) at a rate of 250 ml of product/ha in early spring were the most effective, whereas no significant benefit was demonstrated from applications in autumn. Over all seasons, azoxystrobin applications resulted in double the weight of flowers produced compared with nontreated areas, whereas increases in pyrethrin content within the flowers were season and location specific. Application of azoxystrobin and chlorothalonil (as Bravo 720) at a rate of 1.4 liters of product/ha resulted in a 45 to 48% increase in flowers, reduced defoliation, and increased stem diameter. The weight of individual flowers and flower maturity was not significantly affected by fungicide application. These data provide the basis for cost-effective management of this disease.

scholarly journals Improving Fungicide-Based Management of Ray Blight Disease in Tasmanian Pyrethrum Fields

Plant Disease ◽  
2008 ◽  
Vol 92 (6) ◽  
pp. 887-895 ◽  
Author(s):  
Sarah J. Pethybridge ◽  
Frank S. Hay ◽  
Tim Groom ◽  
Calum R. Wilson
Keyword(s):  
Dry Weight ◽  
Field Trials ◽  
Early Spring ◽  
Primary Objective ◽  
Canopy Reflectance ◽  
Resistance Development ◽  
Ray Blight ◽  
The Difference ◽  
Blight Disease

Ray blight disease, caused by Phoma ligulicola var. inoxydablis, is a serious threat to the Tasmanian pyrethrum industry. The management of this disease relies upon the strategic application of fungicides in early spring. A range of fungicides were assessed for their efficacy in controlling ray blight disease in Tasmanian pyrethrum fields, and the primary objective of this study was to increase fungicide options available to growers in different resistance groups. Fungicides were assessed under in vitro conditions, within five replicated-plot field trials over three seasons (2004 to 2006) and in single-plot trials over eight fields in 2005. In each of the field trials, regular assessments of disease intensity (defoliation severity and the incidence of stems with ray blight), stem height, and the number of flowers produced on each stem were made using stems as the primary sampling unit. Canopy reflectance at 830 nm and the Difference Vegetative Index, measured using a handheld multispectral radiometer, also were used to compare fungicide effects on green leaf area. The effect of fungicides on the dry weight of flowers, pyrethrin content within the flowers, flower maturity, and pyrethrin yield were determined. Under in vitro conditions, boscalid reduced both conidial germination and mycelial growth at concentrations of at least 0.16 μg/ml. In field trials 1 and 2 (in 2004), the premixed formulation of pyraclostrobin + boscalid (Pristine) increased pyrethrin yield by an average of 79% compared with nontreated plots over the two locations. Furthermore, in single-plot trials, pyraclostrobin + boscalid increased pyrethrin yield by 134 and 60% compared with the industry-recommended protocol (single application of azoxystrobin at 150 g a.i./ha [Amistar WG] and two additional applications of a tank mixture of difenoconazole at 125 g a.i./ha [Score] and chlorothalonil at 1,008 liters a.i./ha [Bravo 720] at 14- to 21-day intervals) and nontreated plots, respectively. In field trials 3 (in 2005) and 4 and 5 (in 2006), similar yield benefits also were produced by applying pyraclostrobin (Cabrio SC) or boscalid (Filan) alone or in combination with chlorothalonil (Bravo 720) at 1.4 liters of product per hectare, regardless of the rates of pyraclostrobin (250 and 125 g a.i./ha) and boscalid (500 and 250 g a.i./ha) used. These data were used to recommend the incorporation of boscalid to improve the fungicide-based management of ray blight disease. This decreases the number of applications of both strobilurin and triazole fungicides which have been used extensively for the management of ray blight and other diseases in Tasmanian pyrethrum fields and are prone to fungicide resistance development.

scholarly journals In vitro effects of fungicides on conidium germination of Spilocaea oleagina the cause of olive leaf spot

2005 ◽  
Vol 58 ◽  
pp. 278-282
Author(s):  
E.O. Obanor ◽  
M. Walter ◽  
E.E. Jones ◽  
M.V. Jaspers
Keyword(s):  
Leaf Spot ◽  
Copper Hydroxide ◽  
Olive Leaf ◽  
Olive Leaves ◽  
Benzimidazole Fungicides ◽  
Low Concentrations ◽  
Conidium Germination ◽  
In Vitro Effects ◽  
Demethylation Inhibitor

Twenty fungicides were tested in vitro for their effects on the germination of conidia of Spilocaea oleagina the fungus that causes olive leaf spot Conidia used in this evaluation were obtained from naturally infected olive leaves in Canterbury Of the fungicides tested kresoximmethyl and captan were the most effective in preventing conidium germination at low concentrations with EC50 values of 0002 and 0003 g/ml respectively The newer fungicides boscalid and boscalid/pyraclostrobin were also effective (EC500031 and 0006 g/ml respectively) Of the benzimidazole fungicides tested carbendazim was effective (EC500005 g/ml) but thiophanatemethyl was not (EC5026 g/ml) None of the demethylation inhibitor fungicides tested were very effective (EC50 values gt;1 g/ml) except flusilazol (EC500075 g/ml) Two coppercontaining fungicides copper hydroxide and copper sulphate were ineffective for preventing conidium germination (EC5030 and 443 g/ml respectively) This study has identified candidate fungicides for further evaluation as tools for management of olive leaf spot

scholarly journals Suppression of Fusarium moniliforme in Rice by Rice-Associated Antagonistic Bacteria

Plant Disease ◽  
1997 ◽  
Vol 81 (1) ◽  
pp. 49-52 ◽  
Author(s):  
A. M. Rosales ◽  
T. W. Mew
Keyword(s):  
Seed Germination ◽  
Fusarium Moniliforme ◽  
Mycelial Growth ◽  
Field Trials ◽  
The Philippines ◽  
The Other ◽  
Antagonistic Bacteria ◽  
Seedling Vigor ◽  
Bacterial Strains

The potential of antagonistic bacteria from paddy water, rhizosphere soils, sclerotia, and rice plants to control “bakanae” caused by Fusarium moniliforme was assessed. Experiments were conducted to determine the in vitro antibiosis and effect of bacteria on seed germination. Out of 441 isolates, 113 were inhibitory to mycelial growth of the pathogen. Bacterial strains were classified into three groups based on effect on seed germination: (i) those that promoted germination and enhanced seedling vigor; (ii) those that had no effect on germination; and (iii) those that were deleterious and inhibited germination. Bacterization of naturally infected seeds reduced bakanae incidence in seedbox and seedbed tests. In a seedbed experiment with IR 58 seeds soaked in suspensions of bacterial strains, bakanae incidence and disease control ranged from 0.9 to 6.8% and 71.7 to 96.3%, respectively. From the 3 years of field trials, 10 strains reduced bakanae. Five strains consistently reduced bakanae, but the other five exhibited variable effects among trials. Specificity of suppression by antagonistic bacteria against different pathogenic isolates of F. moniliforme from various locations in the Philippines was observed.

scholarly journals Fungicide Seed Treatment Effects on Seedling Damping-off of Pumpkin Caused by Phytophthora capsici

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 63-68 ◽  
Author(s):  
M. Babadoost ◽  
S. Z. Islam
Keyword(s):  
Seed Germination ◽  
Untreated Control ◽  
Mycelial Growth ◽  
Seed Treatment ◽  
Culture Medium ◽  
Phytophthora Capsici ◽  
Field Trials ◽  
Seedling Vigor ◽  
Damping Off

Apron XL LS (mefenoxam) and Allegiance FL (metalaxyl) were highly inhibitory to growth of mycelium of Phytophthora capsici in vitro. Effective dose (ED50) of mefenoxam and metalaxyl for 50% inhibition of mycelial growth, for all five isolates of P. capsici tested, was 0.98 and 0.99 μg a.i./ml of culture medium, respectively. For mefenoxam at 200 μg a.i./ml, sporangium and zoospore germination were reduced by 92 and 96%, respectively, and 21 and 24%, respectively, for metalaxyl. In greenhouse studies, seed treatment with mefenoxam (0.42 ml of Apron XL LS/kg of seed) and metalaxyl (0.98 ml of Allegiance FL/kg of seed) significantly reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars (Dickinson, Hybrid-401, and Hybrid-698) tested. Thirty-one days after seeding, at inoculum levels of 0, 90, 600, 1,400, and 4,000 CFU/g of soil, the average seedling stands for mefenoxam treatment were 98.4, 93.8, 88.3, 77.8, and 64.8%; for metalaxyl, 99.1, 85.3, 85.8, 73.5, and 59.3; and for the untreated control, 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after seeding were 76.7, 74.7, and 44.9% for mefenoxam, metalaxyl, and untreated control, respectively. Seed treatment with mefenoxam or metalaxyl did not have any significant effect on either seed germination or seedling vigor.

scholarly journals Weed Control in Organic Vegetable Production: The Use of Sweet Corn Transplants and Vinegar

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1093A-1093
Author(s):  
Albert H. Markhart ◽  
Milton J. Harr ◽  
Paul Burkhouse
Keyword(s):  
Acetic Acid ◽  
Weed Control ◽  
Sweet Corn ◽  
Cost Effective ◽  
Field Trials ◽  
Vegetable Production ◽  
Poor Control ◽  
Corn Production ◽  
Low Concentrations ◽  
Organic Vegetable Production

Weed control in organic vegetable production is a major challenge. During Summer 2004, we conducted field trials to manage weeds in organic sweet corn, carrots and onions. In sweet corn, we evaluated the efficacy of transplanting greenhouse-grown sweet corn seedlings. In carrots and onions, we tested vinegar and several concentrations of acetic acid. Studies were conducted in southwestern Minnesota at the Lamberton Research and Outreach Center and in eastern Minnesota at Foxtail Farm in Shaefer. Ten-day-old corn transplants were effective at both locations. Stand establishment was greater, less tillage was needed, and yield was greater than in the seeded plots. Straight vinegar was not very effective in controlling weed populations. Although there was greater damage to broadleaf weeds than grasses, straight vinegar did not reduce the need for tillage. Although 10% to 20% acetic acid did provide better weed control, it significantly damaged carrot and onion seedlings. These results suggest that using sweet corn transplants is time and cost effective for small acreage sweet corn production such as CSAs. Vinegar and acetic acid are problematic. Nonselectivity, potential danger in handling, and poor control at low concentrations were all considered significant disadvantages.

scholarly journals Biocontrol of Chickpea Fusarium Wilt by Bacillus Spp. Rhizobacteria

2013 ◽  
Vol 53 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Souad Zaim ◽  
Lakhdar Belabid ◽  
Miloud Bellahcene
Keyword(s):  
Disease Control ◽  
Fusarium Wilt ◽  
Mycelial Growth ◽  
Field Trials ◽  
Inhibitory Effect ◽  
In Vitro Assays ◽  
Beneficial Effects ◽  
Volatile Metabolites ◽  
Bacillus Spp

Abstract Among 131 rhizobacteria isolates, 29 potentially antagonistic strains were screened in in vitro assays. The five antagonistic Bacillus spp. Rb29, Rb6, Rb12, Rb4, and Rb15 showed the most inhibitory effect against FOC1 (from 25.63 to 71.11%), mycelial growth, and FOC2 (from 28.43 to 60.65%) in vitro. Results also revealed that production of volatile metabolite, components and inhibition of the test pathogen by volatile metabolites varied among different antagonistic rhizobacteria. Isolates Rb29, Rb6, Rb12, Rb4, and Rb15 produced more volatile metabolites which inhibited mycelial FOC growth by 40%. Chickpea Fusarium wilt severity caused by FOC1 was reduced from 60 to 99% in the susceptible cultivar ILC 482 treated with antagonistic Bacillus spp. (Rb29, Rb6, Rb12, Rb4, and Rb15) in pot assays and by 98, 81, 68, 64, 57.20%, respectively, in the field trials. As for their beneficial effects on disease control, the results revealed that Bacillus spp. may improve plant growth and disease control.

scholarly journals Effect of Fungicide Application on the Management of Avocado Branch Canker (Formerly Dothiorella Canker) in California

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 897-902 ◽  
Author(s):  
M. Twizeyimana ◽  
V. McDonald ◽  
J. S. Mayorquin ◽  
D. H. Wang ◽  
F. Na ◽  
...  
Keyword(s):  
Field Experiment ◽  
Mycelial Growth ◽  
Fungal Pathogens ◽  
Field Experiments ◽  
Field Trials ◽  
Persea Americana ◽  
Lesion Length ◽  
Length Data ◽  
Branch Canker

Members of the Botryosphaeriaceae family have been associated with branch cankers of avocado trees (Persea americana) in California. Canker infections are initiated by spores entering the host plant through fresh wounds such as pruning wounds. With high-density planting becoming more common in the California avocado industry, more intensive pruning may increase the occurrence of branch canker. The objective of this study was to evaluate the preventive ability of some commercial fungicides belonging to different chemical families against fungal pathogens associated with avocado branch canker. Initially, 12 fungicides were tested in vitro for their effect on the inhibition of mycelial growth of three isolates of Dothiorella iberica and isolates (five per species) of Neofusicoccum australe, N. luteum, N. parvum, and Phomopsis sp. Subsequently, azoxystrobin, fludioxonil, metconazole, and pyraclostrobin, selected because of their low effective concentrations that reduce 50% of mycelial growth (EC50 values), and myclobutanil, selected for its high EC50 value, were tested in two field experiments. Azoxystrobin and fludioxonil were used in a premix with propiconazole and cyprodinil, respectively, in field trials. Significant differences (P < 0.05) were observed among fungicides in field trials. Azoxystrobin + propiconazole had the highest percent inhibition at 52 and 62% (internal lesion length) in trial 1 and trial 2, respectively, although this level of inhibition was not significantly different from that of metconazole. A significant correlation (r = 0.51, P < 0.05) was observed between internal lesion length data in the field experiment and EC50 data from in vitro fungicide screening. Application of azoxystrobin + propiconazole and metconazole can play a key role in protecting Californian avocado against fungi causing avocado branch canker.

Population biology of coppicing plants: survival of mallee (Eucalyptus spp.) populations exposed to contrasting fire and cutting regimes

2013 ◽  
Vol 61 (7) ◽  
pp. 552 ◽  
Author(s):  
James C. Noble ◽  
Peter J. Diggle
Keyword(s):  
Prescribed Fire ◽  
Population Biology ◽  
Management Strategy ◽  
Field Experiments ◽  
Cost Effective ◽  
Management Tool ◽  
Effective Management ◽  
Domestic Livestock ◽  
Second Year ◽  
Cutting Regimes

We examined data obtained from two experiments running concurrently over an 8-year period, designed to investigate the survival of mallee eucalypts exposed to various decapitation treatments applied by either fire or axe at contrasting frequencies. Annual autumn decapitation, with or without combined spring decapitation, gave the most rapid rates of depletion. The estimated half-life, i.e. time to 50% mortality, ranged from 278 days when both autumn and spring fires were applied annually, up to 3366 days when plants were cut by axe every fourth autumn. These were followed in turn by autumn decapitation every second year, then spring annually and autumn every third year and finally autumn decapitation imposed every fourth year. With the marginal exception of one treatment (burnt every third autumn), the estimated rates of depletion were greater for the burning treatments than for their cutting counterparts. The ranking of the six treatments by estimated rates of depletion was the same in both the fire and cutting trials. Prescribed fire is a powerful and cost-effective management tool for manipulating semiarid woodlands in temperate Australia. In addition to reducing grass and litter fuel, prescribed fire has the potential to promote herbage production for domestic livestock. We provide clear evidence based on field experiments that a management strategy based on relatively frequent fires applied in the autumn will significantly reduce mallee density, thereby promoting herbage productivity.

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