The effect of soil fumigation on microbial recolonization and mycorrhizal infection

doi:10.1016/0038-0717(72)90025-9

Soil Biology and Biochemistry

Volume 4, Issue 3, August 1972, Pages 295-305

https://doi.org/10.1016/0038-0717(72)90025-9 Get rights and content

Abstract

The fungal populations of two forest nursery soils were greatly reduced by fumigation with methyl bromide or dazomet (Basamid). Fungal recolonization was rapid, but original numbers were not attained even 7 months after fumigation. Some fungi not detected in untreated soil colonized the fumigated soil. Seedling pine roots were always colonized by larger numbers of fungal species and individuals in control than in treated soil. Infection of roots by a seedinoculated mycorrhizal fungus was increased by fumigation at one site but not at the other.

Aerobic bacteria in fumigated soils were initially reduced in number but rapidly rose to 10 times that of control soil. Dazomet had a more persistent effect on bacteria than did methyl bromide. Counts of fluorescent pseudomonads from soils treated with methyl bromide, after an initial fall, rose quickly to constitute up to 78 per cent of the total aerobic count, then slowly declined. Bacterial spore numbers were initially reduced 50–90 per cent by methyl bromide but not by dazomet. The effectiveness of methyl bromide differed in the two soils.

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Cited by (29)

Significance of Microbial Interactions in the Mycorrhizosphere
2006, Advances in Applied Microbiology
Citation Excerpt :
Such MHB may also suppress pathogens in mycorrhizosphere soil (Budi et al., 1999; Schelkle and Peterson, 1996). The helper effect of soil bacteria on mycorrhiza formation was initially investigated in nursery soils (Garbaye, 1983; Ridge and Theodorou, 1972). In these soils, ECM formation was reduced following fumigation with methyl bromide, suggesting that bacteria are important in the formation of mycorrhiza.
There are several major types of mycorrhiza that are classified according to morphology and the types of fungi involved. The dominant type of mycorrhiza in terms of plant species and distribution are the Arbuscular mycorrhizas (AM) that form between fungi from the Glomeromycota and angiosperms, gymnosperms, pteridophytes, and bryophytes. Based on taxonomy, approximately 160 species of AM fungus have been described, although this is likely to be a considerable underestimate of actual diversity. In AM associations, the fungus penetrates root cortical cells in which it proliferates and forms arbuscules through which materials are exchanged between the symbionts. In addition, the biological and chemical interactions that take place within the mycorrhizosphere are still largely unexplored, and furthermore the relative importance of the host and mycorrhizal fungus mycelium for directing interactions largely remains to be resolved. This information should provide new possibilities to exploit biological interactions within the mycorrhizosphere for agricultural and environmental management.
Greenhouse gas production and emission from a forest nursery soil following fumigation with chloropicrin and methyl isothiocyanate
2005, Soil Biology and Biochemistry
Soil fumigation is commonly used to control soil-borne pathogens and weeds. Our aim was to examine the effects of soil fumigation with chloropicrin (CP) and methyl isothiocyanate (MITC) on CH₄, N₂O and CO₂ production and emission. These effects on a SE USA forest nursery soil were examined in field and laboratory experiments. Following field fumigation, CH₄ surface emissions and concentrations in the soil atmosphere were unaffected. Both fumigants increased N₂O emissions rates significantly compared to non-fumigated controls, and the effects were still evident after 48 d. These findings are in contrast to fertilizer-induced N₂O emissions, which generally return to background within 2 wk after application. Depths of N₂O production were different for the two fumigants as determined by soil gas sampling, suggesting fumigant-specific stimulation mechanisms. CO₂ emissions (0–15 d) were not altered significantly, although sub-surface CO₂ concentrations did increase following fumigation with CP or MITC and remained elevated for CP treatment on d 48. CP-induced N₂O production was also stimulated in aerobic laboratory incubation studies, with surface soils exhibiting 10 to 100-fold greater production rates. MITC and a combination of CP/MITC also stimulated N₂O production, but the effect was significantly less than for CP alone. MITC suppressed and CP did not effect CO₂ production in the laboratory incubation. By comparing sterilized to non-sterile soils, >95% of these effects appear to be of biotic origin.
From Lamarckian fertilizers to fungal castles: Recapturing the pre-1985 literature on endophytic and saprotrophic fungi associated with ectomycorrhizal root systems
2005, Studies in Mycology
Citation Excerpt :
The abilities of ectomycorrhizal fungi to secrete acids are unremarkable, at least in pure culture (Harley & Smith 1983). Although at least one ectomycorrhizal fungus, Boletus felleus Bulliard [= Tylopilus felleus (Bulliard : Fries) P. Karsten], was shown to render rock phosphates available to plants (Rosendahl 1942, Wilde 1954), this appeared to be an exceptional case (Wilde 1954). Some experiments on mycorrhizae vs. inorganic phosphates (Stone 1950, Bowen & Theodorou 1967) showed some breakdown of the phosphates in the presence of mycorrhizal roots.
The endophytic, mantle-inhabiting and rhizosphere-inhabiting microorganisms associated with ectomycorrhizal roots have been studied for over 100 years, but a surprising amount of the information obtained prior to the mid-1980's is difficult to access and understand. In large part, this is because research investigating local ecosystems and silvicultural practices was often considered regional in nature. It tended to be written up in many different languages and to be published in journals that were not widely distributed. After 1985, this scientific isolationism was broken up by the ubiquitous trend towards impact factor measurement and international publishing. The goal of the present review is to make still-relevant information from the pre-1985 ectomycorrhizosphere literature, especially its more strongly obscured elements, readily accessible to modern researchers. Also, some publications that fell into relative obscurity for historical reasons – in particular, studies seeming to reflect the brief association of Soviet mycorrhizal research of the early 1950's with the Lamarckian plant improvement ideas of T. D. Lysenko – are re-examined from current perspectives. The scattered data reveal considerable coherence despite the high ecological diversity they reflect. Endophytes such as members of the Mycelium radicis atrovirens complex – most prominently the species now known as Phialocephala fortinii – feature especially prominently in this area of study, and they received considerable attention beginning in the very early years of the 20^th century. They were variously interpreted as potential symbionts or weak pathogens, an ambiguity that continues to the present day for many of these taxa despite the recent molecular clarification of species and population boundaries. The predominance of P. fortinii and other (normally) non-mycorrhizal “dark (or hyaline) sterile endophyte” fungi from stringently washed or surface-disinfected ectomycorrhizae in most ecosystems was shown repeatedly beginning with the studies of Elias Melin in the early 1920's. The adjacent rhizosphere soil typically contained sporulating fungi dominated by Penicillium, Umbelopsis and Mortierella species, sometimes accompanied by Trichoderma spp., Cylindrocarpon destructans, and various other microfungi. Microbiological investigations into whether ectomycorrhizae exerted a positive “rhizosphere effect” on numbers of fungal propagules in the surrounding soil showed that such effects were often less prominent in natural forests than in planted forests. Several studies showed a general reduction in microbial activity in the zone of ectomycorrhizal influence, and a particularly strong inhibition of soil organisms was shown in the symbiorhizosphere of Tricholoma matsutake and members of the genus Tuber. In relation to such cases, the adoption by mycologists of M. Ogawa's term “shiro”, (castle, fortress) for the delimited, three-dimensional analogue of a fairy ring formed in soil by many ectomycorrhizal mycobionts is advocated. As relatively highly co-adapted communities, ectomycorrhizosphere organisms appeared to aid in root disease control, in part by harmlessly stimulating roots to produce defensive tannic materials. The production of these materials then appeared to favour the predominance of tannin-degrading Penicillium species in the rhizosphere. Rhizosphere inhabitants were shown to be involved in many types of nutrient and growth factor exchanges, but perhaps to be most important as solubilizers of refractory nutrients like inorganic phosphorus compounds and complex proteinaceous materials. Some potential pathogens like Fusarium spp. tended to be excluded from established forest soils, while Cylindrocarpon destructans, if present, tended to be confined to lower soil regions by microbial acidification of the upper soil zones. The complexity of microfungal communities and their known and potential interactions was high, and seemingly contradictory results often needed to be rationalized, e.g., Trichoderma spp. appeared to be favoured in the root zone in some ecosystems and partially excluded in others, and seemed to abet mycorrhiza formation and tree growth in some habitats but to cause damage to seedlings and mycorrhizal inoculum both in vitro and in the nursery. Modern techniques and bioinformatics methodologies will be needed to make progress towards understanding this complexity, but the multilingual and sometimes overlooked pre-1985 studies provide a very strong initial basis supporting further development.
Comparison of substrate induced respiration, selective inhibition and biovolume measurements of microbial biomass and its community structure in unamended, ryegrass-amended, fumigated and pesticide-treated soils
1999, Soil Biology and Biochemistry
Two UK grassland soils, one from Rothamsted (24% clay) and the other from Woburn (8% clay) were incubated at 25°C, unamended or amended with ryegrass followed by fumigation 20 d later followed by a further 20 d incubation. Other portions of the Rothamsted grassland soil were treated separately with a fungicide (Captan), a bacteriocide (Bronopol), or a herbicide (Dinoseb). The substrate-induced respiration (SIR) method coupled with use of antibiotics (selective inhibition) and biovolume measurements by direct microscopy were used to comparatively measure total microbial biomass and the proportions of fungal and bacterial biomass in these two treated soils. Both methods gave similar estimates of total microbial biomass and the proportions of bacteria and fungi in the two soils. The different treatments did not significantly change the proportions of bacteria and fungi in the soil microbial biomass. It was concluded that both SIR and biovolume measurements are equally valid in measuring total biomass as are selective inhibition and biovolume measurements in measuring the proportions of fungi and bacteria in soils which are either unamended or undergoing rapid changes in metabolism due to substrate amendment, fumigation or biocidal treatments.
Population responses of target and non-target forest soil organisms to selected biocides
1994, Soil Biology and Biochemistry
Oxytetracycline-penicillin (combined), captan, fumigillan and dimethoate-carbofuran (combined) were applied to forest soils to test their effects on soil populations of active and total bacteria, active and total fungi, protozoa, nematodes and microarthropods. All biocides significantly reduced the populations of target organisms, except dimethoate-carbofuran, which failed to reduce the number of microarthropods. All biocides also affected populations of non-target organisms. Oxytetracycline-penicillin reduced lengths of active hyphae. Captan reduced nematode and bacterial numbers. Fumagillin reduced active hyphal lengths and the number of nematodes and total bacteria. Dimethoate-carbofuran reduced active hyphal lengths and the number of active bacteria.
Selective influence of volatiles purged from coniferous forest and nursery soils on microbes of a nursery soil
1989, Soil Biology and Biochemistry
Numerous genera of ectomycorrhizal fungi and other soil microbes produce volatile compounds in vitro. The consequence of in vivo volatile production by soil microorganisms is unknown largely due to difficulties in separating volatile effects from other microbially mediated effects. An apparatus which slowly purges volatiles from a “donor” test soil into a “receiver” soil was used to determine differential effects of volatiles from “donor” forest or nursery soils on Fusarium and other microbial populations of a “receiver” nursery soil. “Donor” soils were either treated or not with methyl bromide and aerated-steam, and were planted or not with Douglas-fir seedlings. “Donor” soil origin and tree presence significantly altered populations of several taxonomic and functional microbial groups in “receiver” nursery soils, demonstrating for the first time that soil volatiles selectively influence soil microbe populations in vivo. Though functional microbial group populations were differentially altered by volatiles from forest and nursery soils, the importance of this phenomenon in relation to Fusarium exclusion from coniferous forest soils is not readily determinable.

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Soil Biology and Biochemistry

Abstract

References (22)

A method of studying active mycelia on living roots and other surfaces in the soil

Trans. Brit. mycol. Soc.

Illustrated Genera of Imperfect Fungi

The Genera of Hyphomycetes from Soil

The Natural Occurrence of Mycorrhizal Fungi for Pinus radiata in South Australian Soils

CSIRO Division of Soils, Adelaide, Australia. Divisional Report 6/63

Origin of a toxicity of mycorrhiza in Wareham Heath

Nature, Lond.

Microbiological studies of some sub-antarctic soils

J. Soil Sci.

Soil disinfection and nutrient status of spruce seedlings

Physiol. Plant.

The effects of soil fumigation, sucrose application and inoculation of sugar fungi on the growth of forest tree seedlings

Pl. Soil

Antagonistic effects of Altemaria tenuis on certain root-fungi of forest trees

Nature, Lond.

Influence of pesticide residues on soil microbiological and chemical properties

Res. Rev.

Cited by (29)

Significance of Microbial Interactions in the Mycorrhizosphere

Greenhouse gas production and emission from a forest nursery soil following fumigation with chloropicrin and methyl isothiocyanate

From Lamarckian fertilizers to fungal castles: Recapturing the pre-1985 literature on endophytic and saprotrophic fungi associated with ectomycorrhizal root systems

Comparison of substrate induced respiration, selective inhibition and biovolume measurements of microbial biomass and its community structure in unamended, ryegrass-amended, fumigated and pesticide-treated soils

Population responses of target and non-target forest soil organisms to selected biocides

Selective influence of volatiles purged from coniferous forest and nursery soils on microbes of a nursery soil