EFFECTIVE FUNGICIDE DOSAGE IN RELATION TO INOCULUM CONCENTRATION IN SOIL

1964 ◽  
Vol 42 (3) ◽  
pp. 301-306 ◽  
Author(s):  
Lloyd T. Richardson ◽  
Donald E. Munnecke

A quantitative relationship was established between the fungicide dosage required to control a soil-borne disease and the concentration of mycelial inoculum in soil. The incidence of pre-emergence damping-off was observed in pea seedlings grown in non-sterile soil artifically infested with a series of concentrations of inoculum of Pythium irregulare or Rhizoctonia solani and treated with a dosage series of thiram or methylmercuric dicyandiamide. Parallel linear dosage–control curves were obtained which indicated that the logarithm of the fungicide dosage at the 50% control level increases proportionately with the logarithm of the inoculum density. This linear relationship provides a basis for evaluation of the activity of fungicides against various pathogenic fungi in soil.

Plant Disease ◽  
1997 ◽  
Vol 81 (7) ◽  
pp. 832-832 ◽  
Author(s):  
R. E. Baird ◽  
D. E. Carling

During a study to determine the pathogenic fungi overwintering on dead cotton (Gossypium hirsutum L.) roots, two isolates of Rhizoctonia solani Kühn anastomosis group 7 (AG-7) were identified. Isolate #213 was obtained from dead roots near Tifton, GA, and isolate #219 was cultured from cotton roots near Midville, GA. Rhizoctonia solani AG-7 was previously reported in Arkansas, Indiana, and Asia (1). Isolates #213 and #219 were tested in the greenhouse for pathogenicity by mixing 25 ml of 2-week-old cornmeal sand inoculum (3 g of cornmeal, 100 g of sand, and 20 ml of distilled water) into 20 × 100 cm pots containing 2.25 liters of sterile soil (Tifton loamy sand, pH 6.1) per pot. Pots with noninfested soil were included as a control. Eight seeds of cotton (Delta and Pineland 90 DPL 90) were sown per pot. Each pot was a replicate and each treatment was replicated five times. At 20 days after planting, plant stands in soil infested with isolate #213 or #219 averaged 2 to 3 or 4 to 5 plants per pot, respectively, while stands in noninfested soil averaged 7 to 8 plants per pot. Brownish colored, sunken lesions were observed on roots, hypocotyles, and cotyledons of plants from pots infested with R. solani AG-7. Isolates #213 and #219 were reisolated from plants grown in their respective treatments. This is the first report of R. solani AG-7 in Georgia. Reference: (1) R. E. Baird et al. Plant Dis. 80:1421, 1996.


2012 ◽  
Vol 58 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Jacek Nawrocki

The experiments were carried out in the years 2002 and 2003 on parsley seeds of 6 cultivars: Alba, Berlińska, Cukrowa, Kinga, Lenka, and Vistula. Mycological analysis of parsley seeds showed that the most common inhabitans were fungi from genus <i>Alternaria</i> (mainly <i>A. alternata</i> and <i>A. radicina</i>) and <i>Fusarium</i>, especially <i>F. avenaceum</i> and <i>F. oxysporum</i>. During the glasshouse investigations fungi <i>Alternaria radicina</i>, <i>A. alternata</i> and <i>Fusarium avenaceum</i> were the main reason for parsley damping-off. The highest number of infected seedlings was observed for Berlińska and Kinga, because in both years of experiments these cultivars had the lowest number of healthy seedlings. The highest number of healthy seedlings had cultivars Alba and Lenka, especially in the second year of experiments. In the field experiments not only fungi from genus <i>Alternaria</i> and <i>Fusarium</i> were the most often isolated from diseased parsley seedlings. <i>Fusarium oxysporum</i> was more often isolated from diseased field seedlings than from glasshouse parsley seedlings. Other fungies isolated often from parsley seedlings cultivated in the field were: <i>Pythium</i> spp., <i>Rhizoctonia solani</i>, <i>Cylindrocarpon destructans</i> and <i>Stemphylium botryosum</i>.


2021 ◽  
Vol 9 (6) ◽  
pp. 1285
Author(s):  
Anna Clocchiatti ◽  
Silja Emilia Hannula ◽  
Muhammad Syamsu Rizaludin ◽  
Maria P. J. Hundscheid ◽  
Paulien J. A. klein klein Gunnewiek ◽  
...  

Cellulose-rich amendments stimulate saprotrophic fungi in arable soils. This may increase competitive and antagonistic interactions with root-infecting pathogenic fungi, resulting in lower disease incidence. However, cellulose-rich amendments may also stimulate pathogenic fungi with saprotrophic abilities, thereby increasing plant disease severity. The current study explores these scenarios, with a focus on the pathogenic fungus Rhizoctonia solani. Saprotrophic growth of R. solani on cellulose-rich materials was tested in vitro. This confirmed paper pulp as a highly suitable substrate for R. solani, whereas its performance on wood sawdusts varied with tree species. In two pot experiments, the effects of amendment of R. solani-infected soil with cellulose-rich materials on performance of beetroot seedlings were tested. All deciduous sawdusts and paper pulp stimulated soil fungal biomass, but only oak, elder and beech sawdusts reduced damping-off of beetroot. Oak sawdust amendment gave a consistent stimulation of saprotrophic Sordariomycetes fungi and of seedling performance, independently of the time between amendment and sowing. In contrast, paper pulp caused a short-term increase in R. solani abundance, coinciding with increased disease severity for beet seedlings sown immediately after amendment. However, damping-off of beetroot was reduced if plants were sown two or four weeks after paper pulp amendment. Cellulolytic bacteria, including Cytophagaceae, responded to paper pulp during the first two weeks and may have counteracted further spread of R. solani. The results showed that fungus-stimulating, cellulose-rich amendments have potential to be used for suppression of R. solani. However, such amendments require a careful consideration of material choice and application strategy.


2012 ◽  
pp. 102-109
Author(s):  
Suzana Kristek ◽  
Andrija Kristek ◽  
Dragana Kocevski ◽  
Antonija K. Jankovi ◽  
Dražen Juriši

The experiment was set up on two types of the soil: Mollic Gleysols (FAO, 1998) and Eutric Cambisols where the presence of pathogenic fungi – sugar beet root decay agent – Rhizoctonia solani has been detected since 2005. In a two year study (2008, 2009), the experiment was set up by completely randomized block design in 4 repetitions and 16 different variants. Two beet varieties, Belinda, sensitive to pathogenic fungi R. solani, and Laetitia, tolerant to pathogenic fungi R. solani), were grown. The microbiological preparation BactoFil was applied in different amounts in autumn and spring. In addition, the nitrogen fertilizer application, based on the results of soil analysis, was varied. The following parameters were tested: amount of infected and decayed plants, root yield, sugar content, sugar in molasses and sugar yield. The best results were obtained by applying the microbiological preparation BactoFil, and by 30% reduced nitrogen fertilizer application. Preparation dosage and time of application depended on soil properties.


2006 ◽  
Vol 96 (12) ◽  
pp. 1372-1379 ◽  
Author(s):  
Masahiro Kasuya ◽  
Andriantsoa R. Olivier ◽  
Yoko Ota ◽  
Motoaki Tojo ◽  
Hitoshi Honjo ◽  
...  

Suppressive effects of soil amendment with residues of 12 cultivars of Brassica rapa on damping-off of sugar beet were evaluated in soils infested with Rhizoctonia solani. Residues of clover and peanut were tested as noncruciferous controls. The incidence of damping-off was significantly and consistently suppressed in the soils amended with residues of clover, peanut, and B. rapa subsp. rapifera ‘Saori’, but only the volatile substance produced from water-imbibed residue of cv. Saori exhibited a distinct inhibitory effect on mycelial growth of R. solani. Nonetheless, disease suppression in such residue-amended soils was diminished or nullified when antibacterial antibiotics were applied to the soils, suggesting that proliferation of antagonistic bacteria resident to the soils were responsible for disease suppression. When the seed (pericarps) colonized by R. solani in the infested soil without residues were replanted into the soils amended with such residues, damping-off was suppressed in all cases. In contrast, when seed that had been colonized by microorganisms in the soils containing the residues were replanted into the infested soil, damping-off was not suppressed. The evidence indicates that the laimosphere, but not the spermosphere, is the site for the antagonistic microbial interaction, which is the chief principle of soil suppressiveness against Rhizoctonia damping-off.


Sugar Tech ◽  
2021 ◽  
Author(s):  
Md Ehsanul Haque ◽  
Dilip K. Lakshman ◽  
Aiming Qi ◽  
Mohamed F. R. Khan

2018 ◽  
Vol 40 (1) ◽  
pp. 35075 ◽  
Author(s):  
Alexandre Dinnys Roese ◽  
Paulo Justiniano Ribeiro Junior ◽  
Vanderley Porfírio-da-Silva ◽  
Louise Larissa May De Mio

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