Historical review that losses of 3-week-old apple (Malus Compost in the 20th pumila) seedlings, due to Phytophthora Century: A Tool or many years, organic amend- cactorum, were signifi cantly lower in ments, including animal and bark-compost-container medium than to Control Plant Fgreen manures, coupled with in peat medium after inoculation. crop rotation were the principal meth- In the 1990s the effects of sup- Diseases in Nursery ods of fertilization and soilborne disease pressing soilborne pathogens by control (Baker and Cook, 1974). These amending soils with composted sewage and Vegetable Crops management practices were replaced sludge were noted by Lumsden et al. with usage of high quantities of low- (1983) for rhizoctonia root rot (Rhi- cost synthetic nitrogenous fertilizers zoctonia solani) on beans (Phaseolus Gladis M. Zinati1 and soil-sterilizing pesticides (e.g., vulgaris), cotton (Gossypium spp.),spp.), methyl bromide) in the early part of the and radish (Raphanus sativus); sclero- 20th century (De Ceuster and Hoitink, tinia drop (Sclerotinia sclerotiorum) ADDITIONAL INDEX WORDS. biocontrol agents, biological control, mecha- 1999). The latter approaches rendered of lettuce (Lactuca sativa); fusarium nisms of disease suppression, methyl soils more prone to diseases due to wilt (Fusarium oxysporum f.sp. cuc- bromide alternative, Phytophthora, recolonization with plant pathogens umerinum) of cucumber (Cucumis pythium root rot, Rhizoctonia solani, within days of soil treatment (Bollen, sativus); and phytophthora crown rot Trichoderma 1974). Plant pathogen recolonization (Phytophthora capsici) of pepper (Cap- may have signifi cant negative impacts sicum annuum). These diseases were SUMMARY. The discovery of disease suppression in certain bark composts on crop yields in the absence of biocon- all signifi cantly decreased by amending increased the interest in using com- trol agents (De Ceuster and Hoitink, soil with compost. Hadar and Man- post as growing substrate to control 1999). Losses due to soilborne diseases delbaum (1986) showed that licorice root rot diseases caused by Phytoph- on some greenhouse, nursery, and veg- root compost suppressed the damping thora cinnamomi. Disease suppression etable crops can amount to thousands off caused by Pythium aphaniderma- mechanisms include antibiosis, com- of dollars per acre annually. tum in cucumber.cucumber. ThroughoutThroughout the petition, hyperparasitism, and induced In the 1960s the nursery indus- 1980s, various studies showed that systemic resistance. Although abiotic try encountered increasingly serious composted organic residues suppressed factors may infl uence disease sup- problems with root rot disease caused Phytophthora cinnamomi, Rhizoctonia pression, the latter is often based on by Phytophthora cinnamomi due to microbial interactions—the two com- solani, and Fusarium oxysporum inin mon mechanisms being general for the reintroduction of pathogen via many crops (Hoitink, 1980; Hoitink pythium (Pythium spp.) and phytoph- infected plants, after soil fumigation, and Fahy, 1986; Nelson and Hoitink, thora root rot (Phytophthora spp.) and or in irrigation water (Hoitink, 1980). 1982; Spring et al., 1980). specifi c for rhizoctonia (Rhizoctonia The fi rst report on suppression of a Some studies have shown that solani). The discovery of disease sup- soilborne disease by application of tree composted bark may induce suppres- pression agents in compost led to the bark was from Oregon State University sion effects after steam sterilization development of biocontrol agent-for- (Houck, 1962). Observations made in and others may not. For example, tifi ed compost during the last decade nurseries indicated that phytophthora Broadbent et al. (1971) reported that of the 20th century. The suggested root rot of rhododendron (Rhododen- benefi cial bacteria such as Bacillus recommendations for future research dron spp.) was less severesevere on plants and extension outreach may include and Streptomyces species,species, whichwhich areare 1) development of methods to manage produced in media amended with tree antagonistic to fungal root pathogens, bacterial and viral diseases through bark compost than in those amended have been shown to survive steam the use of compost; 2) exploration of with peat (Hoitink, 1980). In addition, treatment of 60.0 °C (140 °F) for 30 the potential effects of fortifi ed com- the search for low-cost substitutes for min, whereas studies by Hardy and post on insect pests suppression; 3) peat in substrate media led the nursery Sivasithampram (1991) have shown improvement of inoculation methods industry to explore the possibility of that potting medium amended with of composts with biocontrol agents using wood waste composts (Hoitink composted eucalyptus (Eucalyptus to produce consistent levels of disease et al., 1991). cinere) bark (CEB) became conducive suppression at the commercial scale; During the 1970s and 1980s to root rot after steam sterilization. 4) development of effective fortifi ed improved procedures in aging and compost teas for suppressing foliar It appeared that the suppression ef- diseases; 5) education of compost composting tree bark led to increased fect of CEB was in decreasing order producers on methods of production compost utilization, and revealed the to Phytophthora cryptogea, P. nicoti- of fortifi ed compost that suppress side benefi ts of reducing losses caused anae var. nicotianae, P. citricola, P. specifi c diseases; and 6) education of by phytophthora root rot (Gugino et drechsleri,and P. cinnamomi infections end-users on uses of fortifi ed compost al., 1973; Hoitink and Fahy, 1986; of the nursery plants waratah (Telopea and its by-products. Hoitink et al., 1977). speciosissima) and banksia (Banksia Hoitink (1980) reported that root occidentalis). Throughout the 1990s, 1Assistant Professor and Nursery Management Special- ist, Rutgers University, Department of Plant Biology rots did not occur in media with 4 nursery industry has, in some cases and Pathology, 166 Foran Hall, 59 Dudley Road, bark : 1 peat ratios. The use of tree bark successfully, replaced methyl bromide New Brunswick, NJ 08901. E-mail: zinati@aesop. compost reduced the incidence of soil- rutgers.edu fumigation with disease suppressive borne diseases not only in nursery crops compost and reduced the uses of Acknowledgments. The author would like to express her appreciation to Ms. Rewa Choueiri and Dr. Kimberly but also in fl oriculture and foliage crops. fungicides (Quarles and Grossman, Klock Moore for editing this manuscript. Similarly, Spring et al. (1980) showed 1995).
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Mechanisms of biological Agrobacterium radiobacter. The most duction of salicylic acid; defense related control in composts widely accepted commercial example is proteins and or other compounds in the use of strain 84 to control of crown plants that eventually lead to a systemic Most compost products sup- gall, one of the most serious diseases resistance to pathogens such as an- press pythium and phytophthora of stone fruit trees in nurseries and of thracnose (Colletotrichum orbiculare) root rot naturally, while only some many other woody plants. Agrobac- in cucumber (Hoitink et al., 1997a). suppress rhizoctonia and very few terium radiobacter a andnd p particularlyarticularly Other studies have shown that peroxi- induce systemic resistance in plants one strain, strain 84, produces large dase activity, an enzyme associated with (Zhang et al., 1996). Abiotic factors quantities of a bacteriocin, now called protection mechanisms against stress, (e.g., high pH and nature of the clays agrocin. was higher in leaves of cucumber plants (montmorillonite) have been shown Competition is when organisms grown in biologically fortifi ed compost to be involved in soilborne disease compete for nutrients (particularly than in the leaves of those grown in a suppression (Amir and Alabouvette, high-energy carbohydrates, nitrogen peat mix. In addition, the activity of an 1993; Hoper et al., 1995), based on and iron) (Duijff et al., 1994; Raaij- enzyme, a “pathogenesis-related (PR) two mechanisms: general and specifi c makers et al., 1995), infection sites, and protein,” was increased more rapidly in microbial interactions. General disease possibly certain environmental factors plants grown in compost than plants suppression (Cook and Baker, 1983), such as oxygen and space (Baker and grown in peat or sterilized compost af- which is based on microbial compe- Cook, 1974). ter being inoculated with the pathogen tition for energy, involves the total Parasitic and predatory fungi are (Hoitink et al., 1997a). soil microfl ora (Serra-Wittling et al., known to parasitize plant pathogens 1996). Propagules of plant pathogens resulting in lysis or death. Such organ- Disease suppression such as Pythium and Phytophthora spe- isms may include Rhizoctonia solani as affected by microbial cies are suppressed through the general on species of Pythium ((Butler,Butler, 11957),957), suppression phenomenon (Boehm et Trichoderma viride onon Armillaria composition al., 1993; Chen et al., 1988a, 1988b; mellea (Duddington(Duddington andand Wyborn,Wyborn, In practice, composts are not Cook and Baker 1983; Hardy and 1972) and Tuberculina maxima aandnd consistently or naturally colonized by Sivasithamparam, 1991; Mandelbaum Fusarium roseum onon rrustust (Cronartium a broad spectrum of biocontrol agents and Hadar, 1990). Specifi c disease ribicola) (Kimmey, 1969). Verticil- because the latter are destroyed by high suppression refers to a specifi c group lium dahliae isis rreportedeported ttoo pparasitizearasitize temperatures during active compost- of microorganisms antagonizing the even itself (Griffi ths and Campbell, ing. To be effective biocontrol agents pathogen. Such group may include 1970). Microorganisms including must recolonize composts during non-pathogenic Fusarium species Trichoderma suchsuch asas T. hamatum the curing process and this does not (Larkin et al., 1993; Serra-Wittling et and T. harzianum areare consideredconsidered always occur. For example, composts al., 1996) and fl uorescent pseudomo- the predominant fungal parasites produced near a forest are much more nas (Pseudomonas fl uorescens) (Scher recovered from composts prepared likely to become colonized by effective and Baker, 1982; Larkin et al., 1993). from lignocellulosic wastes (Kuter et biocontrol agents and more consistent The biological control for Rhizoctonia al., 1983; Nelson et al., 1983) and in suppressing rhizoctonia diseases than solani, by a narrow group of antago- capable of eradicating Rhizoctonia those produced in an enclosed system nistic microorganisms, is described as solani (Hoitink(Hoitink etet al.,al., 1991).1991). WhenWhen (Kuter et al., 1983). Effective control specifi c suppression. suitable antagonists are already pres- of Rhizoctonia solani can be achieved Edaphic microorganisms stimu- ent in the soil or substrate but do by applying isolates of Trichoderma lated by compost amendments con- not provide a satisfactory level of species combined with any of several tribute to the suppressive activity disease control, it may be desirable bacterial biocontrol agents. of the amended soils through four to intensify their activity. This may be Copiotrophic bacteria recolonize control mechanisms: antibiosis, accomplished by one or more of the composts most rapidly (24–48 h) after competition, predation hyperparasit- following methods: 1) crop rotation; peak heating of compost (Chen et ism, and the induction of systemic 2) adding amendments to stimulate al., 1988a; Kwok et al., 1987). The acquired resistance in the host plant antagonists; 3) altering soil pH to favor predominant biocontrol agents in (Lockwood, 1988). the antagonist, inhibit the pathogen, this group include strains of Bacillus, Antibiosis is the inhibition of one or both; 4) employing tillage methods Pseudomonas, and Pantoea s speciespecies organism’s growth by a metabolic that modify soil structure and aera- (Boehm et al., 1997; Kwok et al., product (such as antibiotic) being tion; 5) selection of a planting date to 1987). Oligotrophic bacteria do not produced by another organism (Baker reduce disease incidence; 6) applying reach peak populations until 18–24 and Cook, 1974). Many organisms, organic amendments in such a way as d into the curing phase (Chen et al., especially soil fungi and actinomycetes, to reduce the available nitrogen at the 1988a). Obligate oligotrophs isolated produce antibiotic substances. Three infection side; and 7) managing irriga- from composts are suppressive to diseases have been found to be con- tion practices to maintain soil water pythium root rot and appear ineffec- trolled by antibiosis: armillaria root rot potential favorable to antagonists at tive at inducing biological control of (Armillaria mellea) by Trichoderma infection sites (moist for bacteria, drier pythium damping-off when applied as viride, pythium and rhizoctonia damp- for actinomycetes), and still ensure seed treatments. In contrast to obligate ing off and stem and root rot disease water available for the plant. oligotrophs, facultative oligotrophic by Pseudomonas fl uorescens, and crowncrown Mechanisms of induced systemic strains (as those belong to the genus gall (Agrobacterium tumefaciens) by resistance include activating the pro- Pseudomonas) are highly effective bio-
62 ● January–March 2005 15(1) logical control agents when applied as perparasitism as biocontrol agents for into container media with composted seed treatments. Actinomycetes also Rhizoctonia solani in mature compost biosolids. Schneider (1985) speculated contribute signifi cantly to biological (Chung and Hoitink, 1990; Hoitink that the low C:N in predominantly high control provided by composts (Hardy and Fahy, 1986). ammonium and low nitrate-nitrogen- and Sivasithampram, 1995; You and MOISTURE CONTENT AND PH. The releasing sludge compost enhanced Sivasithampram, 1995). moisture content of compost affects fusarium wilts. Compost with high C: the ability of bacterial mesophiles to N materials, such as tree barks, immo- Compost quality and colonize the substrate after peak heat- bilizes ammonium-N and suppresses biological control ing. Compost with < 34% moisture fusarium diseases if colonized by an Compost must be stable and of w/w could be colonized by fungi appropriate microfl ora (Trillas-Gay et consistent quality to be used success- and are conducive to pythium diseases al., 1986). fully for biological control of diseases in (Hoitink et al., 1997b). Disease sup- LEVEL OF ORGANIC MATTER DE- horticultural crops (Inbar et al., 1993). pression could be induced by increasing COMPOSITION AND MICROBIAL ACTIVITY. Biological control rarely eliminates a moisture content to at least 40%-50% Decomposition of organic matter can pathogen, but rather reduces its num- w/w, for benefi cial bacteria and fungi affect the composition of bacterial bers or its ability to produce disease. to colonize the substrate after peak taxa as well as the populations and Such control may be achieved with heating, whereas a pH <5.0 inhibits activities of biocontrol agents. Green little or no reduction in the pathogen growth of bacterial biocontrol agents manures, stable manures and composts population (Baker and Cook, 1974). (Hoitink et al., 1991). can provide food for biological control Consistent and sustained biologi- IRRIGATION, TEMPERATURE, AND agents if applied well ahead of planting cal control of diseases can be achieved in RATE OF APPLICATION. Irrigation prac- (Lumsden et al., 1983), and can be very different compost-amended growing tices, temperature and of rate of appli- effective in controlling diseases such as media as long as variables such as con- cation of compost can affect losses to Pythium, Phytophthora, Fusarium, and sistency of the parent organic material, diseases. For example, substrate mixes Rhizoctonia solani. moisture content, salinity, carbon to with composted pine bark are used Decomposition level of organic nitrogen ratio and process parameters to suppress fusarium wilt. However, matter in potting mixes or soils is are controlled in the compost (Hoitink such mixes with 45% compost (v/v) overlooked by many specialists work- et al., 1991). have low capillary activity and cannot ing with biocontrol agents. Fresh PARENT MATERIAL OF FEEDSTOCK. be used in an ebb-and-fl ow irrigation (undecomposed) organic matter does Fungal composition seems to be infl u- system to suppress wilt. not support colonization by biocontrol enced by the chemistry of the parent In 1988, a mix formulation made agents. High concentrations of avail- organic material from which the com- of composed of pine bark (25% v/v), able nutrients (glucose, amino acids, post is prepared. Composts prepared light sphagnum and perlite effectively etc.) in fresh crop residues repress the from lignocellulosic substances such suppressed Fusarium oxysporum f. sp. production of enzymes required for as tree barks become colonized pre- cyclaminis disease and performedperformed well parasitism by biocontrol agents such dominantly by Trichoderma speciesspecies in ebb and fl ow system in the U.S. as Trichoderma speciesspecies ((DeDe CCeustereuster (Kuter et al., 1983) which in turn these (Hoitink et al., 1991). and Hoitink, 1999). Flavobacterium benefi cial fungi control Rhizoctonia SALTS. Composts prepared from balustinum 299 and Trichoderma solani (Grebus et al., 1994; Kwok manures contain considerable amounts hamatum 382382 havehave b beeneen identifiidentifi eded et al., 1987; Nelson et al., 1983). In of sodium and chloride (De Ceuster in compost to induce systemic resis- contrast, grape pomace, which is low in and Hoitink, 1999). It has been shown tance in plants. Both microfl ora and cellulosic substances and high in sugars, in fi eld trials that high salinity products organic matter in sphagnum peat can becomes colonized by Penicillium andand must be applied in the fall or winter affect suppression of soilborne dis- Aspergillus speciesspecies (Gorodecki(Gorodecki andand well ahead of planting to allow for eases. Organic matter in sphagnum Hadar, 1990) and consequently these leaching and thus avoid an increase in peat generally does not support high parasitic fungi eradicate sclerotia of phytophthora root rot of certain crops microbial activity because peat resists Sclerotium rolfsii (Hadar and Gor Goro-o- (Hoitink and Schmitthenner, 1988). decomposition. Dark decomposed decki, 1991). The nursery industry uses up to 80% peat is low in activity and is consis- COMPOST MATURITY. Variability of pine bark in potting mixes, bark tently conducive to pythium root rot, in suppression of rhizoctonia damp- composts tend to be lower in salinity whereas light peat is less decomposed ing-off and fusarium wilt encountered than sludge or manure composts, and and has higher microbial activity (De in substrates amended with mature up to 15% (v/v) of compost derived Ceuster and Hoitink, 1999). Peat can composts is due, in part, to random from manure or sludge (Hoitink et be used effectively, if colonized by bio- recolonization of compost by effective al., 1991). control agents, for short production biocontrol agents after peak heating NITROGEN, AND CARBON : NI- cycles such as in plug and fl at mixes (Hoitink et al., 1997b). Rhizoctonia so- TROGEN (C:N) RATIO. Phytophthora used in bedding plant industry. This is lani isis a highlyhighly competitivecompetitive saprophyte.saprophyte. dieback of rhododendron (caused by because the effect of biocontrol agents It can utilize cellulose and colonize P. nicotianae) (Hoitink et al., 1986), in peat is of short duration to suppress fresh bark but cannot colonize mature fusarium wilt of cyclamen (Hoitink pythium root rots. Hence, the “slow bark compost because of low cellulose et al., 1987) and fi reblight (Erwinia release” nature of the organic nutrients content. However, isolates of Tricho- amylovora) are examples of diseases in mature composts and in light peat derma species gr growow as a sapr saprophyteophyte that are increased in severity as a re- supports activity of microfl ora and thus in fresh compost and function via hy- sult of excessive N fertility introduced sustains biocontrol.
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Prediction of disease last relative to biological control. It is was formulated into a potting mix suppression based upon also referred to as “carrying capacity” containing compost, peat and perlite (Boehm et al., 1993). (Grebus et al., 1993). The fortifi ed organic matter decomposition compost consistently suppressed py- Effectiveness of disease suppres- Production of consistent thium root rot of cucumber as well as sion can be estimated by determining fortifi ed compost rhizoctonia damping off and fusarium organic matter decomposition status To produce and maintain com- wilt of radish. The mix continued to in compost. Recalcitrant materials post quality in relation to both plant be suppressive even after 4 months (lignins and lignin-protected cellulose) growth and disease control, produc- of storage. that are resistant to decomposition, sus- ers of composts must understand the tain the activities of biocontrol agents Future opportunities processes involved in this method of (Hoitink et al., 2000). After these biological control. Biocontrol agent- More research and extension recalcitrant materials are decomposed, fortifi ed compost seems to have the outreach on production and usage the benefi cial microorganisms decline greatest opportunities for utilization of compost and compost byproducts in activity, the pathogen population and commercialization as components are needed. In the future, research recovers and increases; and fungicides of commercially manufactured potting should focus on managing bacterial must be applied for sensitive crops to media. Composted pine bark fortifi ed diseases and perhaps reducing the remain disease free (Boehm et al.,1997; with Flavobacterium balustinum 299 severity of some virus diseases by Hoitink et al., 2000). The compost and T. hamatum 382 has been ververyy utilizing fortifi ed composts to induce users can test organic matter content effective in controlling fusarium wilt systemic resistance. In addition, more and compost maturity before compost of cyclamen, rhizoctonia diseases, as research is needed on the effects of is used to estimate likely disease sup- well as phytophthora and pythium root compost on the suppression of insect pression. Nondestructive direct spec- rots of other greenhouse container pests and the mechanisms that might troscopic procedures, utilizing nuclear crops (Krause et al., 1997). Drench- control such suppression. Although resonance spectroscopy (NMR) and ing potting mixes with soil fungicides the rate of hydrolysis of FDA can be Fourier transform infrared (FT-IR), may cost $10/yard3 ($13.08/m3) per used effectively to estimate potential are now being used to determine the application of mix (De Ceuster and suppression of potting mix to pythium amount of undecomposed biode- Hoitink, 1999). Some crops need root rot, more practical procedures gradable organic matter remaining in to be treated more than once, such to quantify suppression based on compost (Chen and Inbar, 1993; Inbar as Easter lily (Lilium longifl orum), microbial activity and organic matter et al., 1989). azalea (Rhododendron macrosepalum), decomposition need to be developed. Improvement in inoculation methods Prediction of disease poinsettia (Euphorbia pulcherrima) and rhododendron. However, bio- of compost with biocontrol agents, to suppression based on control agents can be inoculated into produce consistent levels of disease microbial activity compost-amended mixes for less than suppression at the commercial scale, Effectiveness of disease suppres- 50% of the cost of a single combina- is needed. Furthermore, development sion can be estimated by measuring tion fungicide drench (De Ceuster and of effective compost extracts and teas microbial activity in compost. This can Hoitink, 1999). for enhancing plant growth and foliar be achieved by an enzyme assay based Although treatments with single disease suppression is needed. on the rate of hydrolysis of fl uorescein biocontrol agents have had little effect, Extension education and outreach diacetate (FDA) by lipases, esterases combinations of several Trichoderma should focus on educating compost and proteases (Schnurer and Rosswall, species and bacterial biocontrol agents producers to choose correct feedstocks 1982). The hydrolysis rate of FDA have proved effective in mixes amended for making compost with biological by microorganisms is believed to be with bark compost (Hoitink, et al., agents to suppress disease. Similarly, related to suppression of root rots 1991). Consistent disease suppres- education should be extended to caused by Pythium and Phytophthora sion of both rhizoctonia and pythium compost end-users such on choosing species (Boehm and Hoitink, 1992). damping off was not found among compost that enhances crop yields and High microbial biomass and FDA activ- compost batches in full scale produc- suppresses diseases. ity in readily biodegradable materials tion plants. This suggests that the (such as composted sewage-sludges mechanisms of suppression of these Literature cited and manures) induce suppression in diseases in commercial composted potting mixes at low (10-15% v/v) pine bark mixes differ. Therefore, the Amir, H. and C. Alabouette. 1993. Involve- amendment rates (Boehm and Hoi- addition of biocontrol agents could be ment of soil abiotic factors in the mecha- benefi cial to obtaining and maintain- nisms of soil suppressiveness to fusarium tink, 1992; Chen et al., 1988b; Man- wilts. Soil Biol. Biochem. 25:157–164. delbaum and Hadar 1990; You and ing “quality” by inducing consistent Sivasithamparam, 1994). In contrast, levels of suppression of damping-off Baker, K. F. and R.J. Cook. 1974. Biologi- composts containing more recalcitrant by species of Rhizoctonia, assuming cal control of plant pathogens. Freeman, lignins, such as pine bark and hardwood successful inoculations. San Francisco. bark, must be incorporated at higher Compost made from spruce Boehm, M.J. and H.A.J. Hoitink. 1992. rates (50%). The duration of FDA activ- and hemlock bark and inoculated Sustenance of microbial activity and se- ity in such composts is defi ned as the with Trichoderma hamatum 382 verity of pythium root rot of poinsettia. length of time that suppression effects and Flavobacterium balustinum 299299 Phytopathology 82:259–264.
64 ● January–March 2005 15(1) Boehm, M.J., L.V. Madden, and H.A.J. Duddington, C.L. and C.H.E. Wyborn. sarium wilt—A preliminary report. Ohio Hoitink. 1993. Effect of organic matter 1972. Recent research on the nema- Florist’s Assn. Bul., 693:1–3. decomposition level on bacterial species tophagous Hyphomycetes. Bot. Rev. diversity and composition in relationship 38:545–565. Hoitink, H.A.J., D.M. van Doran, and to pythium damping-off severity. Appl. A.F. Schmitthenner. 1977. Suppression of Environ. Microbiol. 59:4171–4179. Duijff, B.J., P.A.H.M. Bakker, and B. Schip- Phytophthora cinnamomi in a composted pers. 1994. Suppression of fusarium wilt of hardwood bark potting medium. Phyto- Boehm, M.J., T. Wu, A.G. Stone, B. carnation by Pseudomonas putida WWCS358CS358 pathology 67:561–565. Kraakman, D.A. Iannotti, G.E. Wilson, at different levels of disease incidence and L.V. Madden, and H.A.J. Hoitink, 1997. iron availability. Biocontrol Sci. Technol. Hoitink, H.A.J. and P.C. Fahy. 1986. Basis Cross-polarized magic-angle spinning 13 C 4:279–288. for the control of soilborne plant pathogens nuclear magnetic resonance spectroscopic with compost. Annu. Rev. Phytopathol. characterization of soil organic matter Gorodecki, B. and Y. Hadar. 1990. Sup- 24:93–114. pression of Rhizoctonia solani and Sclero- relative to culturable bacterial species Hoitink, H.A.J., M.S. Krause, and A.G. composition and sustained biological con- tium rolfsii in container media containing composted separated cattle manure and Stone. 2000. Disease control induced by trol for pythium root rot. Appl. Environ. composts in container culture and ground Microbiol. 63(1):162–168. composted grape marc. Crop Protection 9:271–274. beds. Orn. Plants Annu. Rpt. Res. Rev. Bollen, G.J. 1974. Fungal recolonization 2000. 18 June 2004.
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