Characterization of Antagonistic Bacillus methylotrophicus Isolated From Rhizosphere and Its Biocontrol Effects on Maize Stalk Rot

Stalk rot is one of the most serious and widespread diseases in maize, and effective control measures are currently lacking. Therefore, this study aimed to develop a new biological agent to manage this disease. An antagonistic bacterial strain, TA-1, was isolated from rhizosphere soil and identified as Bacillus methylotrophicus based on morphological and biochemical characterization and 16S ribosomal RNA and gyrB gene sequence analyses. TA-1 exhibited a strong antifungal effect on the growth of Fusarium graminearum mycelium, with 86.3% inhibition at a concentration of 108 CFU per ml. Transmission electron microscopy showed that TA-1 could disrupt the cellular structure of the fungus, induce necrosis, and degrade the cell wall. Greenhouse and field trials were performed to evaluate the biocontrol efficacy of TA-1 on maize stalk rot, and the results of greenhouse experiment revealed that the bacterium significantly reduced disease incidence and disease index. Seeds treated with a 108 CFU ml−1 cell suspension had the highest disease suppression at 86.8%. Results of field trials show that seed bacterization with TA-1 could not only reduce maize stalk rot incidence but also increase maize height, stem diameter, and grain yield. The lipopeptide antibiotics were isolated from the culture supernatants of TA-1 and identified as surfactins and iturins. Consequently, B. methylotrophicus TA-1 is a potential biocontrol agent against maize stalk rot.

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Relative contribution of windbreak, copper sprays and leafminer control for citrus canker management and prevention of crop loss in sweet orange trees

Plant Disease ◽

10.1094/pdis-10-20-2153-re ◽

2020 ◽

Author(s):

Franklin Behlau ◽

José Belasque Junior ◽

RUI LEITE ◽

Armando Bergamin-Filho ◽

Tim Gottwald ◽

...

Keyword(s):

Sweet Orange ◽

Disease Incidence ◽

Citrus Canker ◽

Control Measures ◽

Disease Suppression ◽

Additional Contribution ◽

Crop Losses ◽

Rangpur Lime ◽

Relative Contribution ◽

Orange Trees

The management of citrus canker, caused by Xanthomonas citri subsp. citri, has been widely studied in endemic areas due to the importance of the disease in several citrus producing countries. A set of control measures is well-established, but no study has investigated the efficiency of each measure individually and their combination for disease suppression. This study comprised a 3-year field study to assess the relative contribution of three measures for the control of citrus canker and reduction of crop losses. Windbreak (Wb), copper sprays (Cu), and leafminer control (Lc) were assessed in eight different combinations in a split-split plot design. The orchard was composed of ‘Valencia’ sweet orange trees grafted onto ‘Rangpur’ lime. Casuarina cunninghamiana trees were used as Wb. Cu and Lc sprays were performed every 21 days throughout the year. Individually, Cu showed the highest contribution for canker control, followed by Wb. Lc had no effect on reducing citrus canker. Wb+Cu showed the highest efficiency for control of the disease. This combination reduced the incidence of diseased trees by ~60%, and the incidence of diseased leaves and fruit by ≥ 90% and increased the yield in 2.0 to 2.6-fold in comparison with the unmanaged plots. Cu sprays were important for reducing disease incidence and crop losses, whereas Wb had an additional contribution in minimizing the incidence of cankered, non-marketable fruit. The results indicated that the adoption of these measures of control may depend on the characteristics of the orchard and destination of the production.

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Identification of Novel Sources of Resistance to Sclerotinia Basal Stalk Rot in South African Sunflower Germplasm

Plant Health Progress ◽

10.1094/php-01-17-0007-rs ◽

2017 ◽

Vol 18 (2) ◽

pp. 87-90 ◽

Cited By ~ 1

Author(s):

Gerald J. Seiler ◽

Christopher G. Misar ◽

Thomas J. Gulya ◽

William R. Underwood ◽

Bradley C. Flett ◽

...

Keyword(s):

South African ◽

Research Council ◽

Agricultural Research ◽

Disease Incidence ◽

Field Trials ◽

Sources Of Resistance ◽

Breeding Programs ◽

Stalk Rot ◽

Agricultural Research Council ◽

Moderately Resistant

Sclerotinia basal stalk rot (BSR) is a serious fungal disease that reduces yield of global sunflower (Helianthus annuus L.) production. Because limited chemical and biological controls of BSR are available and the present-day hybrids lack sufficient resistance, identification of new sources of resistance is needed to manage the disease in the future. A total of 59 cultivated oilseed sunflower accessions from the Agricultural Research Council, Grain Crops Institute, Potchefstroom, South Africa sunflower collection were evaluated for resistance to BSR in artificially inoculated field trials. Nine accessions from the South African sunflower collection were identified with a disease incidence less than or equal to the moderately resistant sunflower oilseed hybrid. These lines can be used in breeding programs to introgress the genes for resistance to Sclerotinia BSR into other adapted lines, providing a more efficient, durable, and environmentally friendly host plant resistance.

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Transmission dynamics and control options for Echinococcus granulosus

Parasitology ◽

10.1017/s0031182003003810 ◽

2003 ◽

Vol 127 (S1) ◽

pp. S143-S158 ◽

Cited By ~ 70

Author(s):

P. R. TORGERSON ◽

D. D. HEATH

Keyword(s):

Echinococcus Granulosus ◽

Disease Incidence ◽

Effective Means ◽

Public Health Problem ◽

Control Measures ◽

Transmission Dynamics ◽

Effective Control ◽

Global Public Health ◽

Persistent Problem ◽

Economic Output

Cystic echinococcosis, caused by the larval stage of Echinococcus granulosus, is a global public health problem. Whilst in a few localities, such as New Zealand, the parasite has been effectively controlled or even eradicated, in most endemic regions it remains a persistent problem. In some areas, such as the former Soviet Union, the disease incidence in humans has increased rapidly in recent years. It is important to have an understanding of the transmission dynamics, both between dogs and domestic livestock where the parasite maintains itself and from dogs to people. It is from this knowledge that effective control measures can be devised to reduce the prevalence of the parasite in animals and hence reduce the incidence of human disease. Mathematical models to describe the transmission of the parasite and the effects of different control strategies were first proposed over twenty years ago. Since then further information has been acquired, new technology has been developed and better computing technology has become available. In this review, we summarise these developments and put together a theoretical framework on the interpretation of surveillance information, how this affects transmission and how this information can be exploited to develop new intervention strategies for the control of the parasite. In particular, the parasite remains a persistent or re-emerging problem in countries of low economic output where resources for an intensive control programme, that has been successful in rich countries, are not available. By understanding of the transmission biology, including mathematical modelling, alternative and cost-effective means of control can be developed.

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Comparison of Soil Insecticides Alone and In Combination With PCNB for Suppression of Southern Stem Rot of Peanut1

Peanut Science ◽

10.3146/i0095-3679-15-1-10 ◽

1988 ◽

Vol 15 (1) ◽

pp. 35-38 ◽

Cited By ~ 8

Author(s):

A. K. Hagan ◽

J. R. Weeks ◽

J. A. McGuire

Keyword(s):

Disease Incidence ◽

Sclerotium Rolfsii ◽

Field Trials ◽

Disease Suppression ◽

Stem Rot ◽

Yield Response ◽

Control Disease ◽

Soil Insecticides

Abstract The soil insecticides, chlorpyrifos 15G (2.2 kg a.i./ha), ethoprop 15G (3.3 kg a.i./ha), and fonofos (2.2 kg a.i./ha) were compared with pentachloronitrobenzene (PCNB) 10G (11.2 kg a.i./ha) and PCNB (11.2 kg a.i./ha) + insecticide combinations for suppression of southern stem rot caused by Sclerotium rolfsii on peanut in a series of field trials in 1985, 1986, and 1987 in southeastern Alabama. Stem rot loci counts were reduced each year by chlorpyrifos and two of three years of ethoprop, and fonofos compared to the non-treated control. Disease suppression with chlorpyrifos and ethoprop was similar all three years and two of three years with fonofos to that with the fungicide PCNB. Significant differences (P = 0.05) in yield were noted only in 1986 between each of the soil insecticides and the non-treated control. PCNB and PCNB + insecticide combinations with the exception of PCNB + ethoprop in 1985 significantly increased yields over the non-treated control each year. PCNB + insecticide combinations generally provided better disease suppression and/or yield response than each insecticide but not PCNB applied alone. When data were pooled for all 3 years, all treatments significantly reduced disease incidence and significantly increased yield except fonofos and ethoprop.

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Management of Valsa Canker on Apple with Adjustments to Potassium Nutrition

Plant Disease ◽

10.1094/pdis-09-15-0970-re ◽

2016 ◽

Vol 100 (5) ◽

pp. 884-889 ◽

Cited By ~ 8

Author(s):

H. X. Peng ◽

X. Y. Wei ◽

Y. X. Xiao ◽

Y. Sun ◽

A. R. Biggs ◽

...

Keyword(s):

Disease Incidence ◽

Significant Negative Correlation ◽

Field Trials ◽

Shaanxi Province ◽

Effective Control ◽

Nutrient Analysis ◽

Foliar Nutrient ◽

Valsa Canker ◽

Pathogen Colonization ◽

Valsa Mali

Valsa canker, caused by the fungus Valsa mali, is one of the most destructive diseases of apple in the primary production areas of China and other East Asian countries. Currently, there are no effective control methods for this disease. We investigated the occurrence of Valsa canker in 24 apple orchards in Shaanxi Province in concert with foliar nutrient analysis, and found that there was a significant negative correlation of leaf potassium (K) content with incidence and severity of Valsa canker. Fertilization experiments showed that increasing tree K content enhanced resistance to pathogen colonization and establishment. Apple trees with leaf K content greater than 1.30% exhibited almost complete resistance to Valsa mali. Field trials demonstrated that increasing K fertilization could significantly reduce disease incidence. Improved management of tree nutrition, especially K content, could effectively control the occurrence and development of Valsa canker.

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Managing major diseases of tomato (Solanum lycopersicum L.) using resistance elicitors and protected cultivation

Annals of Tropical Research ◽

10.32945/atr39sb3.2017 ◽

2017 ◽

pp. 40-53

Author(s):

Lucia Borines ◽

Rezel Sagarino ◽

Fely Cañete ◽

Elvira Oclarit ◽

Zenaida Gonzaga ◽

...

Keyword(s):

Acetylsalicylic Acid ◽

Open Field ◽

Bacterial Wilt ◽

Disease Incidence ◽

Field Trials ◽

Control Measures ◽

Vegetable Production ◽

Solanum Lycopersicum L ◽

Protected Cultivation ◽

Wilt Incidence

Diseases, particularly bacterial wilt caused by Ralstonia solanacearum is a major constraint to vegetable production. Protected cultivation has been proven effective in reducing disease incidence but additional control measures need to be integrated in highly infested soils to mitigate the losses due to diseases. This paper reports the effect of resistance elicitors, particularly chitosan, acetylsalicylic acid and SiO2 in mitigating bacterial wilt disease problem and other naturally occurring diseases in two field trials. Two hundred ppm chitosan, acetylsalicylic acid and their combination had reduced bacterial wilt incidence and increased the yield of tomato under protected cultivation, but not in the open field. SiO2 was not able to reduce bacterial wilt incidence in tomato but had reduced the nematode count, especially Rotylenchulus sp. in the roots, particularly when drenched. Protected cultivation still proved effective in reducing bacterial wilt incidence in both experiments. It’s potential to protect crops against bacterial wilt is further enhanced by the application of chitosan and acetylsalicylic acid, most especially the combination of these treatments. The potential of chitosan and acetylsalicylic acid in protecting plants in the open field against bacterial wilt may be enhanced by the addition of a sticker.

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Development of Lettuce Breeding Lines Resistant to Bacterial Leaf Spot

HortScience ◽

10.21273/hortsci.40.4.1098a ◽

2005 ◽

Vol 40 (4) ◽

pp. 1098A-1098 ◽

Cited By ~ 1

Author(s):

Ryan J. Hayes ◽

Carolee T. Bull ◽

Polly H. Goldman ◽

Edward J. Ryder

Keyword(s):

Leaf Spot ◽

Xanthomonas Campestris ◽

Disease Incidence ◽

Field Trials ◽

Control Measures ◽

Bacterial Leaf Spot ◽

Sources Of Resistance ◽

Breeding Lines ◽

Overhead Irrigation ◽

Lettuce Breeding

Bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians (Xcv) is an important lettuce disease in California. No adequate control measures have been found, although resistance exists in several heirloom cultivars. Deployment of cultivars resistant to bacterial leaf spot will reduce these periodic and costly disease events. The objectives of this research were to 1) identify new sources of resistance within modern crisphead cultivars and 2) select for resistance in `Salad Crisp' × `Iceberg' progeny. Field plots were established and grown with overhead irrigation, and a three-strain mixture of Xcv was applied until runoff 1 week after thinning at 1 × 109 CFU/mL. Twenty-six crisphead cultivars were tested in unreplicated field trials and rated on a 1 (susceptible) to 4 (resistant) scale. Selection was carried out between and within families from the F2 to F4 generation. Sixteen F3 families were evaluated in unreplicated plots, and 12 F5 families were tested in replicated plots for disease incidence and severity. No usable levels of resistance were identified in the modern crisphead cultivars tested to date. All F3 families had resistance greater than `Iceberg', and 19 plants from eight families were selected for further breeding. Subsequently, 12 plants from two F4 families were selected. Replicated trials of 12 F5 families indicated that all lines have disease severity comparable to both parents. Breeding lines from crosses to `Salinas 88' are currently being developed.

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Pasteurellaceae members with similar morphological patterns associated with respiratory manifestations in ducks

Veterinary World ◽

10.14202/vetworld.2019.2061-2069 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2061-2069

Author(s):

Samah Eid ◽

Sherif Marouf ◽

Hefny Y. Hefny ◽

Nayera M. Al-Atfeehy

Keyword(s):

Species Identification ◽

Pasteurella Multocida ◽

Biochemical Characterization ◽

Control Measures ◽

Effective Control ◽

Resistance Pattern ◽

Isolation And Identification ◽

Phenotypic Resistance ◽

Avibacterium Paragallinarum

Aim: A total of 112 freshly dead ducks aged from 2 to 20 weeks old with a history of respiratory manifestations were investigated for the implication of Pasteurellaceae family members.. Materials and Methods: Isolation and identification to the family level were conducted by conventional bacteriological methods, including microscopic examination and biochemical characterization. Identification to the species level was conducted by polymerase chain reaction (PCR) and analytical profile index (API) 20E kits. Results: Conventional bacteriological isolation and biochemical characterization revealed the infection of 16/112 examined birds with a prevalence rate of 14.3%. PCR confirmed the detection of Pasteurellaceae family conserved genes RpoB and Bootz in 16/16 (100%) isolates. PCR was also used for genus and species identification of the isolated Pasteurellaceae members; the results revealed that 5/16 (31.3%) of isolates were Gallibacterium anatis and 2/16 of isolates (12.5%) were Pasteurella multocida. Riemerella anatipestifer, Mannheimia haemolytica, and Avibacterium paragallinarum were not detected by PCR. Biotyping by API 20E successfully identified 5/16 (31.3%) isolates that could not be typed by PCR and confirmed their belonging to Pasteurella pneumotropica. Neither the available PCR primer sets nor API 20E succeeded for species identification of 4/16 (25%) isolates. Antibiotic susceptibility profiling of isolates revealed that 16/16 (100%) of isolates demonstrated multidrug resistance (MDR) phenotypes. Moreover, 16/16 (100%) of isolates demonstrated a phenotypic resistance pattern to neomycin. Conclusion: Combined genotypic, phenotypic, biotyping, and virulence characterizations are required for laboratory identification of pathogenic Pasteurellaceae. Moreover, P. multocida was not the prevailed member implicated in respiratory problems in ducks as P. pneumotropica, G. anatis, and unidentified strains were involved with higher prevalence. Chloramphenicol and ampicillin demonstrated the highest in vivo effects on the studied Pasteurellaceae. Furthermore, the prevalence of multidrug-resistant isolates signified the demand to implement targeted surveillance in the ducks' production sector, and MDR survey in poultry sectors in Egypt to apply effective control measures.

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Reduction in Pesticide Use in Plant Disease Control by Integration of Chemical and Non-Chemical Factors

10.32747/1995.7613027.bard ◽

1995 ◽

Author(s):

Dan Shtienberg ◽

William Fry ◽

Amos Dinoor ◽

Thomas Zitter ◽

Uzi Kafkafi

Keyword(s):

Host Resistance ◽

Foliar Application ◽

Disease Incidence ◽

Field Trials ◽

Disease Suppression ◽

Physiological Age ◽

Disease Development ◽

Systemic Fungicides ◽

Age Related ◽

Chemical Factors

The long term goal of this research project was to improve control efficiency of Alternaria diseases while reducing fungicide use, by integration of chemical and non-chemical factors. Non-chemical factors were genotype resistance, age-related resistance and fertilizers. The Specific objectives were: 1) To quantify changes in resistance among genotypes and over time in terms of disease development and specific phases of the disease cycle; 2) To quantify the effects of fertilizers applied to the foliage alone, or in combination with a fungicide, on disease development; 3) To quantify the relative contribution of genotype resistance, age-related resistance and fungicide type to the reduction of disease development; 4) To develop a strategy for integration of chemical and non-chemical factors which will achieve optimal disease suppression. The influence of physiological age of cotton plants and of the individual leaves, on disease incidence and on the rate of lesion expansion of A. macrospora was examined on leaves sampled from the field. Both parameters increased with the physiological age of individual leaves but were not affected by the age of the whole plant. The hypothesis that enrichment of the foliage with nitrogen and potassium may enhance host resistance to Alternaria and thus reduce disease severity, was examined for potato and tomato (A. solani ) and for cotton (A. macrospora ). Under controlled environment conditions, application of urea or KNO3 resulted in some reduction in disease development; however, foliar application of both nutrients (8-10 sprays in total) did not affect Alternaria severity in the field. Systemic fungicides against Alternaria (e.g. , tebuconazole and difenoconazole) are more effective than the commonly used protectant fungicides (e.g. mancozeb and chlorothalonil). Concepts for the integration of genotype resistance, age-related resistances and fungicide for the suppression of Alternaria diseases were developed and evaluated. It was found that reduction in host resistance, with age and among genotypes, can be compensated for by adjusting the intensity of fungicide applications, i.e. by increasing the frequency of sprays and by spraying systemic fungicides towards the end of the season. In, moderately resistant cultivars protection can be achieved by spraying at longer intervals than susceptible cultivars. The concepts for integration were evaluated in field trials for cotton, potatoes and tomatoes. By following these concepts it was possible to save up to five sprays out of 8-10 in a growing season.

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Fluazinam: A New Fungicide for Control of Sclerotinia Blight and Other Soilborne Pathogens of Peanut1

Peanut Science ◽

10.3146/i0095-3679-19-2-14 ◽

1992 ◽

Vol 19 (2) ◽

pp. 115-120 ◽

Cited By ~ 24

Author(s):

F. D. Smith ◽

P. M. Phipps ◽

R. J. Stipes

Keyword(s):

Disease Incidence ◽

Effective Means ◽

Sclerotium Rolfsii ◽

Field Trials ◽

Effective Control ◽

Cercospora Arachidicola ◽

Advisory Program ◽

Sclerotinia Blight ◽

Better Than

Abstract Fluazinam provided effective control of Sclerotinia blight (Sclerotinia minor Jagger) of peanut in six field trials during a 4-yr period. Applications of fluazinam (0.56 kg/ha) at the onset of Sclerotinia blight and 4 wk later provided an average of 69% suppression of disease incidence and increased yields by 1598 kg/ha compared to untreated plots. Performance of fluazinam was significantly better than iprodione, the material currently used for control of Sclerotinia blight. Two applications of iprodione at 1.12 kg/ha provided only 31% suppression of disease incidence and increased yield by 718 kg/ha. Fungicides were also evaluated in 1990 as tank-mixes with chlorothalonil (1.26 kg/ha) that were applied in foliar sprays according to the Virginia peanut leafspot advisory program. Treatments consisted of no fungicide, chlorothalonil alone, and tank-mixes of chlorothalonil plus either dicloran at 2.10 kg/ha, fluazinam at 0.56 kg/ha, or iprodione at 0.84 kg/ha. Sclerotinia blight at harvest in untreated plots and plots treated with chlorothalonil alone averaged 27.8 and 35.8 disease foci per plot, whereas yields averaged 3624 and 2251 kg/ha, respectively. Compared to plots treated with chlorothalonil alone, Sclerotinia blight was suppressed by 92, 25, and 25%, and yield was increased by 4020, 1925, and 1684 kg/ha in plots treated with chlorothalonil plus either fluazinam, iprodione, or dicloran, respectively. Applications of tank-mixes containing fluazinam plus chlorothalonil in 1991 provided additional evidence that this approach was a highly effective means of controlling both Sclerotinia blight and early leafspot, a previously unattainable goal. Fluazinam did not control early leafspot (Cercospora arachidicola S. Hori) in field trials; however, the fungicide was fungitoxic in vitro to Sclerotium rolfsii Sacc. and Rhizoctonia solani Kühn.

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