Form Of Inoculum Research Articles

The effect of arbuscular mycorrhizae inoculation on growth and yield of red chili on the highland andisol soil

One effort to improve soil fertility and plant productivity is through the inoculation of arbuscular mycorrhizae. Mycorrhizae plays a role in increasing the absorption of phosphorus elements in the soil. The study aimed to determine the effect of the inoculation of arbuscular mycorrhizae on increasing the growth and production of chili. The experiment was carried out in the highlands of West Bandung in 2017-2018. The experimental design used was a randomized completely block design (RCBD) with 5 treatments and 5 replications. The treatments consisted of control, 2 kg/m2 mycorrhizae in the nursery, 4 kg/m2 mycorrhizae in the nursery, 10 g/plant mycorrhizae at transplanting, and 20 g/plant mycorrhizae at transplanting. The mycorrhizae used was Glomus sp. in the form of inoculum (soil as a carrier). Variables observed included soil chemical properties, degree of root infection, vegetative growth, and yield of chili. Data were analyzed using analysis of variance (anova) and continued with Tukey’s Honestly Significantly Difference (Tukey’s HSD) test at 5% significancy level. The results showed that the inoculation of mycorrhizae to andisol on low P soils increased soil P availability, degree of root infection, vegetative growth, and red chili production, but high doses hurt chili yields. The inoculation of mycorrhizae doses of 2 kg/m2 in the nursery and 10 g/plant at transplanting can increase red chili production by 13.19% and 15.59%. To see the effectiveness of mycorrhizae more clearly, it is suggested to test mycorrhizae on chili in the dry season and on marginal soils.

Soil of the parent plant and AMF mix improve Cerrado’s seedlings growth in forest nurseries

The soil microbiota plays an extremely important role in the growth and survival of plants. The presence of some microorganisms can positively and significantly impact the growth of tree species, which can improve the performance of seedlings after planting for commercial purposes and/or for ecosystem restoration. The present study aimed to evaluate the initial growth of seedlings of Hancornia speciosa and Brosimum gaudichaudii associated with microorganisms from the soil of the parent tree and/or inoculated with arbuscular mycorrhizal fungi (AMF). Four substrates were tested: T1 (control) = Autoclaved dystrophic Red-Yellow Latosol (Aut-dRYL) + autoclaved commercial substrate (Aut-CS); T2 = Aut-dRYL + Aut-CS + inoculum of AMF (Mix); T3 = Aut-dRYL + Aut-CS + soil of the parent plant (SPP); and T4 = Aut-dRYL + Aut-CS + SPP + Mix. The AMF inoculum comprised a mix of the species Gigaspora decipiens, Rhizophagus clarus, and Scutellospora heterogama. Seedling growth was determined 270-350 days after transplanting by measuring the following parameters: mycorrhizal colonization rate (MC), abundance of spores (AS), height (H), stem diameter (D), H/D ratio, volume of roots (VR), dry matter of shoot (SDM), roots (RDM), total (TDM), shoot / root dry matter ratio (SDM/RDM), height / shoot dry matter ratio (H/SDM), and Dickson quality index (DQI). The results showed that the addition of SPP improved the growth and DQI of the seedlings, while the AMF mix minimally changed both growth and DQI. The use of symbiotic microorganisms in the nursery in Brazil is scarse due to the difficulty of acquiring these microorganisms and the lack of commercialization of specific isolates for species native to the Cerrado biome. The present study evaluated the use of soil from naturally occurring areas as a source of inoculum. The higher growth and biomass production of inoculated plants support the use of SPP as a form of inoculum and/or inoculation with native AMF to produce seedlings of H. speciosa and B. gaudichaudii.

Phyllode inoculation provides a rapid protocol for preliminary screening of Acacia species for tolerance to Ceratocystis wilt and canker disease

Ceratocystis wilt and canker disease has devastated Acacia mangium plantations in south-east Asia. Current screening methodologies to identify resistant or tolerant germplasm use potted plants in a greenhouse as a preliminary screening to select material for field trials, but these tests are time-consuming, motivating a search for rapid screening protocols. In this study, inoculation procedures were tested on three species of Acacia, viz. A. mangium, A. crassicarpa and a hybrid of A. auriculiformis and A. mangium, using three isolates of Ceratocystis manginecans. Mycelial plugs were compared with spore suspensions as inoculum to infect artificial wounds on the stems of A. mangium potted plants. The rapid screening protocols involved inoculation of stem segments with mycelial plugs and detached phyllodes with a spore suspension, with susceptibility measured by lesion length on the stems or necrosis length on the phyllodes. Both mycelial plugs and spore suspensions produced a similar level of disease incidence, so either inoculum form can be used for an assay. The stem segments were prone to contamination by other fungi and to desiccation, while results from the potted plant and phyllode protocols showed similar trends of susceptibility among the Acacia clones and species. The ease, rapidity, and reproducibility of the phyllode inoculation protocol makes it a potential replacement for inoculation of potted plants as a preliminary screening protocol to identify disease tolerant A. mangium germplasm prior to field screening.

Impact of the Diet on the Formation of Oxidative Stress and Inflammation Induced by Bacterial Biofilm in the Oral Cavity.

The diet is related to the diversity of bacteria in the oral cavity, and the less diverse microbiota of the oral cavity may favor the growth of pathogenic bacteria of all bacterial complexes. Literature data indicate that disturbances in the balance of the bacterial flora of the oral cavity seem to contribute to both oral diseases, including periodontitis, and systemic diseases. If left untreated, periodontitis can damage the gums and alveolar bones. Improper modern eating habits have an impact on the oral microbiome and the gut microbiome, which increase the risk of several chronic diseases, including inflammatory bowel disease, obesity, type 2 diabetes, cardiovascular disease and cancer. The subject of our consideration is the influence of the traditional diet on the formation of oxidative stress and inflammation caused by bacterial biofilm in the oral cavity. Through dental, biomedical and laboratory studies, we wanted to investigate the effect of individual nutrients contained in specific diets on the induction of oxidative stress inducing inflammation of the soft tissues in the oral cavity in the presence of residual supra- and subgingival biofilm. In our research we used different types of diets marked as W, T, B, F and noninvasively collected biological material in the form of bacterial inoculum from volunteers. The analyzed material was grown on complete and selective media against specific strains of all bacterial complexes. Additionally, the zones of growth inhibition were analyzed based on the disc diffusion method. The research was supplemented with dental and periodontological indicators. The research was supplemented by the application of molecular biology methods related to bacterial DNA isolation, PCR reactions and sequencing. Such selected methods constitute an ideal screening test for the analysis of oral bacterial microbiota. The obtained results suggest that certain types of diet can be an effective prophylaxis in the treatment of civilization diseases such as inflammation of the oral cavity along with periodontal tissues and gingival pockets.

Potential Application of Selected Sulfur-Oxidizing Bacteria and Different Sources of Sulfur in Plant Growth Promotion under Different Moisture Conditions

ABSTRACTThis study aimed to investigate the combined effect of native sulfur-oxidizing bacteria and different sources of sulfur on pH, electrical conductivity, sulfate content in soil, plant growth indices and sulfate uptake by maize under different moisture conditions. A native sulfur-oxidizing bacteria was isolated and identified based on phenotypic characteristics and 16s rDNA sequencing. In this regard, a factorial experiment was conducted in a completely randomized design including Thiobacillus bacteria, sulfur sources, moisture and incubation time as experiment’s factors with three replications. Bacteria in two levels (with and without bacterial isolate), sulfur in three forms (elemental sulfur, granular sulfur and without sulfur), and moisture content in three levels (100%, 75% and 50% of field capacity) were considered. Results obtained from incubation experiment showed that the treatments effect on pH changes, electrical conductivity and the amount of sulfate ion were significant in 1% level and the highest pH changes and sulfur oxidation was related to BS 100% field capacity (inoculated and fertilized with elemental sulfur) treatment in second week. About greenhouse experiment, application of 570 mg sulfur per kg in the form of elemental sulfur and bacterial inoculum significantly increased stem diameter, plant height, shoot weight and sulfate uptake by maize plant. Inoculation of Thiobacillus along with elemental sulfur increases the oxidation of elemental sulfur resulting in increased nutrients availability in soil, consequently increased plant growth.

Elucidation of the Higher Basidiomycetes Enzyme Activity in Dependence on the Medicinal Mushroom Inoculum Form, Precultivation Medium, Age, and Size.

The impact of five mushroom inoculum form, age, size, and precultivation medium on the lignocellulose-deconstracting enzyme (LCDE) production was evaluated in the submerged fermentation of mandarin marc. The results obtained evidence that an adaptation of individual fungi to lignocellulose during maintenance in culture collection and inoculum cultivation may be useful for the production of individual LCDE. Homogenization of submerged mycelium was beneficial for all LCDE production by Cerrena unicolor 305 and Ganoderna lucidum 447 and for LME secretion by Coriolopsis gallica 142 and Trametes multicolor 511. Finely chopped mycelial agar favored CMCase and xylanase production by T. multicolor 511 and LiP secretion by C. unicolor 305 and G. lucidum 447 while homogenized mycelial agar proved to be the worst form of inoculum for the production of most enzymes. Four-days inoculum was the most appropriate for the laccase and MnP production by G. lucidum 447 and T. multicolor 511 while the 7-days mycelium provided the highest yields of these enzymes in the cultivation of C. unicolor 305. Use of the 12-days homogenized mycelium from the late stationary phase resulted in lowest laccase activity of all fungi but provided the highest cellulase activity. Overall, the study showed that the LCDE activity and their accumulation profiles in the cultures with different inoculum size was species dependent.

Rhizopus oligosporus Activity in Crude Extract and Powder Form to Reduce Aspergillus flavus and Aflatoxin Contamination in Corn

Rhizopus oligosporus (RO) in isolate culture was known to reduce contamination toxigenic mold Aspergillus flavus (AF) and aflatoxin B1 in chicken feed. Application in culture form was not effective. The aim of this research was to evaluate RO activities in extract and inoculum form to reduce contamination of AF and aflatoxin B1 in corn. RO was harvested from agar plate, blended, added with water (ratio 1:1 (w/v)) and centrifuged. Supernatant was filtered using Whatman 41. Inoculum was made by inoculation RO in soy powder and incubated at 28oC for 5 days. Inoculum was dried at 40oC for 24-28 hours. Assay was conducted by addition extract or inoculum to corn. Extract and corn ratio were 1:1 (v/w), while inoculum doses were 5, 25, 50, 1000 dan 200 g/kg corn. Assay for aflatoxin B1 was done using kit ELISA aflatoxin. The result of this research showed that extract was able to reduce AF contamination up to 1 log 10, while the less concentration of inoculum which able to inhibit AF up to 6 log 10 was 100 g/kg corn. Extract RO 125 and 250 mL/kg corn was able to reduce aflatoxin contamination by 93.69 % and 85.84 %. Inoculum at dose 5 and 100 g/kg corn was able to reduce aflatoxin 57.58% and 85%. Based on the result, it could be concluded that RO in extract or inoculum form was able to reduce contamination of AF and aflatoxin B1 in corn. Rhizopus as inoculum was easier to be applied than in extract form.

Short Communication: The role of microbial rhizosphere in enhancing plant growth of Jatropha curcas in soil contaminated mercury

Ekyastuti W, Ekamawanti HA. 2018. Short Communication: The role of microbial rhizosphere in enhancing plant growth of Jatropha curcas in soil contaminated mercury. Biodiversitas 19: 701-705. Soil in the area of ex-gold mining, has the chemical-physical constraints to the growth of plants. These chemical-physical constraints are low organic matter, poor of nutrient, acid pH, very low CEC, soil texture dominated by sand, and mercury contamination. This area needs to be rehabilitated. Previous research has found that Jatropha curcas as a plant tolerant to mercury. On the other hand, some types of microbial rhizosphere such as arbuscular mycorrhizal fungi (AMF) and mercury reducing bacteria (MRB) also have an ability to reduce mercury. The purpose of this study was to determine the role of microbial components of AMF and MRB in enhancing the growth of J. curcas in tailings contaminated mercury. The study was conducted in two places, in the greenhouse and in the tailing area of ex-gold mining, using factorial completely randomized design. Results showed that interactions between AMF and MRB were simultaneously able to enhance the growth of J. curcas not only in the greenhouse, but also in the field (tailing area). In the greenhouse (nursery), several isolates of Bacillus sp, Bacillus sp + Glomus SS11 and Bacillus sp + Glomus SS18 in the forms of inoculum were very effective in enhancing the seedling growth of J. curcas. However, results were apparently changed after those seedlings were planted in the field (tailings of ex-gold mining). The combination of Bacillus sp. + Glomus SS18 was the best treatment to enhance the growth of J. curcas of all used treatments. This result proves that the role of microbial rhizosphere, especially AMF and MRB, could effectively enhance the growth of J. curcas in tailings contaminated with mercury.

THE EFFECT OF SOILAGGREGATE SIZE AND P DOSAGE ON AMF SPORES NUMBER IN SHORGUM (Sorghum bicolor L.)

Mycorrhiza is a biological agent to help fertility of soil and plants. Application of mycorrhiza on the land in the form of inoculum is often used in agricultural land in the name of quality of inoculum that also influenced by the content of existing spores. One of them is growing medium. This study aimed to study the effect of soil aggregate size and P dosage on the number of mycorrhizal spores in sorghum plants. The research design used was Randomized Block Design consisting of 2 factors. First factor was soil aggregate size(μm) which consisted of 4 treatments: U1 = < 2000, U2 = 500 - 1000, U3 = 200 - 500, U4 = < 200, and second factor was P dosage: 100 mg/kg and 300mg/kg. Each treatment combination was repeated 3 times so that there were 24 units of experimental unit. Observation parameters included the percentage of the infected root, number of spores, plant height and dry weight of the plant. The research was conducted in Greenhouse and Agronomy Laboratory of Agricultural Faculty of Tadulako University Palu. The various sizes of soil aggregates do not affect the amount of arbuscular mycorrhizal spores in sorghum plants. P 100 mg/kg or f P 300 mg/kg dosage used do not address the effect of the mycorrhizal spores. There is no interaction between soil aggregate size and P dosage to the amount of mycorrhizal spores in sorghum plants.

Variability in parasitic ability of Trichoderma isolates against sclerotia of Sclerotium rolfsii associated with chickpea

Parasitic ability of Trichoderma isolates was tested against Sclerotium rolfsii in two types of soils viz., natural and sterilized soils to assess the ecological adaptability of Trichoderma spp. to a soil. The isolate ATPU 1 (EID50 of 2.1 mycelia/gm of soil) was most effective in parasitization of sclerotia of S. rolfsii when used as live bait, under the natural soil of, when mycelial form of inoculum was used. This isolate was closely followed by KNO 2 and ATPP 6 which had the same EID50 of 2.2 mycelia/gm of soil, the next best isolates were KNP 3 and ATPPE 6 with EID50 of 2.3 mycelia/gm of soil. The isolate KT 6 (EID50 5.7) was rated as poorest competitive colonizer, requiring comparatively highest inoculum level to colonize 50% sclerotia of S. rolfsii . However the conidial form of inoculum from KNK1 (EID50 value of 2.2 conidia/gm of soil) was most aggressive isolate requiring lowest inoculum dose for 50% colonization of sclerotia of S. rolfsii .

Metarhizium brunneum Blastospore Pathogenesis in Aedes aegypti Larvae: Attack on Several Fronts Accelerates Mortality.

Aedes aegypti is the vector of a wide range of diseases (e.g. yellow fever, dengue, Chikungunya and Zika) which impact on over half the world’s population. Entomopathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana have been found to be highly efficacious in killing mosquito larvae but only now are the underlying mechanisms for pathogenesis being elucidated. Recently it was shown that conidia of M. anisopliae caused stress induced mortality in Ae. aegypti larvae, a different mode of pathogenicity to that normally seen in terrestrial hosts. Blastospores constitute a different form of inoculum produced by this fungus when cultured in liquid media and although blastospores are generally considered to be more virulent than conidia no evidence has been presented to explain why. In our study, using a range of biochemical, molecular and microscopy methods, the infection process of Metarhizium brunneum (formerly M. anisopliae) ARSEF 4556 blastospores was investigated. It appears that the blastospores, unlike conidia, readily adhere to and penetrate mosquito larval cuticle. The blastospores are readily ingested by the larvae but unlike the conidia are able infect the insect through the gut and rapidly invade the haemocoel. The fact that pathogenicity related genes were upregulated in blastospores exposed to larvae prior to invasion, suggests the fungus was detecting host derived cues. Similarly, immune and defence genes were upregulated in the host prior to infection suggesting mosquitoes were also able to detect pathogen-derived cues. The hydrophilic blastospores produce copious mucilage, which probably facilitates adhesion to the host but do not appear to depend on production of Pr1, a cuticle degrading subtilisin protease, for penetration since protease inhibitors did not significantly alter blastospore virulence. The fact the blastospores have multiple routes of entry (cuticle and gut) may explain why this form of the inoculum killed Ae. aegypti larvae in a relatively short time (12-24hrs), significantly quicker than when larvae were exposed to conidia. This study shows that selecting the appropriate form of inoculum is important for efficacious control of disease vectors such as Ae. aegypti.

Comparative pathogenicity of sexual and asexual spores of Zymoseptoria tritici (septoria tritici blotch) on wheat leaves

Zymoseptoria tritici ascospores and pycnidiospores are considered the main forms of primary and secondary inoculum, respectively, in septoria tritici blotch epidemics. The pathogenicity of the two types of spores of the same genotypic origin were compared through a two‐stage inoculation procedure in controlled conditions. Adult wheat leaves were inoculated with ascospores collected from field sources, yielding 119 lesions; pycnidiospores collected from 12 lesions resulting from these ascospore infections were then used for inoculation. Lesion development was assessed for 5 weeks; latent period, lesion size, and pycnidium density were estimated for different isolates. The latent period was calculated as the maximum likely time elapsed between inoculation and either the appearance of the majority of the sporulating lesions (leaf scale) or the appearance of the first pycnidia (lesion scale). The latent period was significantly longer (c. 60 degree‐days, i.e. 3–4 days) after infection with ascospores than with pycnidiospores. No difference was established for lesion size and density of pycnidia. A comparison with other ascomycete fungi suggested that the difference in latent period might be related to the volume of spores and their ability to cause infection. Fungal growth before the appearance of lesions may be slower after inoculation with an ascospore than with a pycnidiospore. The mean latent period during the very beginning of epidemics, when first lesions are mainly caused by ascospores, may be longer than during spring, when secondary infections are caused by pycnidiospores. Disease models would be improved if these differences were considered.

Enhanced biohydrogen production from beverage industrial wastewater using external nitrogen sources and bioaugmentation with facultative anaerobic strains

In this work biohydrogen generation and its improvement possibilities from beverage industrial wastewater were sought. Firstly, mesophilic hydrogen fermentations were conducted in batch vials by applying heat-treated (80°C, 30 min) sludge and liquid (LB-grown) cultures of Escherichia coli XL1-Blue/Enterobacter cloacae DSM 16657 strains for bioaugmentation purposes. The results showed that there was a remarkable increase in hydrogen production capacities when facultative anaerobes were added in the form of inoculum. Furthermore, experiments were carried out in order to reveal whether the increment occurred either due to the efficient contribution of the facultative anaerobic microorganisms or the culture ingredients (in particular yeast extract and tryptone) supplied when the bacterial suspensions (LB media-based inocula) were mixed with the sludge. The outcome of these tests was that both the applied nitrogen sources and the bacteria (E. coli) could individually enhance hydrogen formation. Nevertheless, the highest increase took place when they were used together. Finally, the optimal initial wastewater concentration was determined as 5 g/L.

The Impact of the Brassicaceae Plant Materials Added to the Soil on the Population of FUSARIUM SOLANI (Mart.) SACC. and FUSARIUM OXYSPORUM Schlecht

Abstract Soil with the spores of fungi in dormant stage from previous years infections belonging to the genus Fusarium caused significant loss of onion yield in Poland. The most important form of Fusarium inoculum in the field are chlamydospores, which may survive in soil for many years. There are no available methods to eradicate chlamydospores from soil environment. Inspired by data from the literature and own prelimi–nary observation, we evaluated the effect of application of Brassicaceae plant material to the soil infested with F. oxysporum and F. solani isolates, which are pathogenic to onion. Obtained results showed that addition of fresh plant material from B. juncea and B. alba had no effect on amount of Fusarium propagules in the soil. Moreover amendment of infested soil with dry plants or milled seeds of B. juncea or B. nigra significantly stimulated the population of Fusarium in the soil.

Forest farming of shiitake mushrooms: An integrated evaluation of management practices

Two outdoor shiitake ( Lentinula edodes) cultivation experiments, established in Missouri USA in 1999 and 2000, produced mushrooms in 2000–2005. We examined shiitake production in response to substrate species, inoculum form, inoculum strain, and inoculation timing, using total mushroom weight per log as the primary response variable with log characteristics as covariates. The significantly greater mushroom weight produced by sugar maple logs compared with white or northern red oak was attributable to the higher proportion of undiscolored wood volume in the maple logs, rather than to bark thickness or log diameter. The “wide temperature range” shiitake strain produced significantly greater yield compared with the “warm” or “cold” weather strains. Both the wide-range and warm-weather strains were stimulated to fruit by significant rain events, while the cold-weather strain was responsive to temperature. Inoculation with sawdust spawn gave significantly greater yield than colonized wooden dowels or pre-packaged “thimble” plug inoculum. The second and third full years following inoculation were the most productive.

Solid-state Fermentation of Xylanase from Penicillium canescens 10–10c in a Multi-layer-packed Bed Reactor

Xylanase is produced by Penicillium canescens 10-10c from soya oil cake in static conditions using solid-state fermentation. The impact of several parameters such as the nature and the size of inoculum, bed-loading, and aeration is evaluated during the fermentation process. Mycelial inoculum gives more production than conidial inoculum. Increasing the quantity of inoculum enhances slightly xylanase production. Forced aeration induces more sporulation of strain and reduces xylanase production. However, forced moistened air improves the production compared to production obtained with forced dry air. In addition, increasing bed-loading reduces the specific xylanase production likely due to the incapacity of the Penicillium strain to grow deeply in the fermented soya oil cake mass. Thus, the best cultivation conditions involve mycelial inoculum form, a bed loading of 1-cm height and passive aeration. The maximum xylanase activity is obtained after 7 days of fermentation and attains 10,200 U/g of soya oil cake. These levels are higher than those presented in the literature and, therefore, show all the potentialities of this stock and this technique for the production of xylanase.

Seed treatment technology: An attractive delivery system for controlling root parasitic weed Striga with mycoherbicide

Coating sorghum seeds with Fusarium oxysporum (Foxy 2) for control of the root parasitic weed Striga, appears to be an attractive option for minimizing the inoculum amount, establishing the biocontrol agent in the potential infection zone of the host plants, and offering a simple, easy and economical delivery system. Our investigations resulted in the selection of appropriate seed coating materials and a suitable type and form of fungal inoculum. The coating materials tested were arabic gum (AG10%, 20%, 40%), carboxymethylcellulose (CMC1%, 2%) and pectin (LS 440, LM-5 CS) 1%, while the fungal inoculum included microconidia and fresh and dried chlamydospores produced using different substrates. Foxy 2 survived the seed treatment processing and showed excellent viability on seeds for at least 8 months of storage after coating. In general, the performance of 40% arabic gum in combination with dried chlamydospores was the best among the other types of inoculum and coating material tested. Regardless of the type and form of inoculum and coating materials tested, Foxy 2 was able to colonize all roots, even root tips and hairs of the host (sorghum), thereby meeting important criteria of a promising candidate for controlling Striga when applied as a seed treatment. The efficacy of treated sorghum seed with Foxy 2 using different coating materials in reducing S. hermonthica infestation was evaluated in pot and root chamber trials. Foxy 2 markedly reduced Striga emergence and dry weight and increased the percentage of the diseased emerged Striga shoots. However, the efficacy of seed coating varied according to the type and form of fungal inoculum as well as coating material. Coating sorghum seed with dried chlamydospore inoculum homogenized into 20% arabic gum (as adhesive) showed the highest efficacy of 81 and 77% (i.e., percent reduction in healthy emerged Striga shoots compared to the control treatment) against Striga using either sterilized or non-sterilized soil, respectively. In root chamber bioassays, the application of Foxy 2 in combination with AG40% significantly caused disease in 77% of the germinated Striga seeds and in all tubercles after 25 days of sowing. These findings provide an optimized coating protocol as an attractive delivery system for bioherbicides for root parasitic weeds.

Screening techniques and sources of resistance to foliar diseases caused by major necrotrophic fungi in grain legumes

Necrotrophic pathogens of the cool season food legumes (pea, lentil, chickpea, faba bean and lupin) cause wide spread disease and severe crop losses throughout the world. Environmental conditions play an important role in the development and spread of these diseases. Form of inoculum, inoculum concentration and physiological plant growth stage all affect the degree of infection and the amount of crop loss. Measures to control these diseases have relied on identification of resistant germplasm and development of resistant varieties through screening in the field and in controlled environments. Procedures for screening and scoring germplasm and breeding lines for resistance have lacked uniformity among the various programs worldwide. However, this review highlights the most consistent screening and scoring procedures that are simple to use and provide reliable results. Sources of resistance to the major necrotrophic fungi are summarized for each of the cool season food legumes. Marker-assisted selection is underway for Ascochyta blight of pea, lentil and chickpea, and Phomopsis blight of lupin. Other measures such as fungicidal control and cultural control are also reviewed. The emerging genomic information on the model legume, Medicago truncatula, which has various degrees of genetic synteny with the cool season food legumes, has promise for identification of closely linked markers for resistance genes and possibly for eventual map-based cloning of resistance genes. Durable resistance to the necrotrophic pathogens is a common goal of cool season food legume breeders.

Survival of plant pathogens under structural solarization

Structural solarization of greenhouses is a nonchemical sanitation procedure. The method involves dry heating, since maximal temperatures may exceed 60°C and consequent relative humidity (r.h.) is low (ca 15%), under fluctuating temperature and r.h. regimes. Thirty-five structural solarization experiments were performed over 7 years, testing one bacterial and five fungal plant pathogens. Various aspects of pathogen thermal inactivation under this method were studied. Thermal inactivation of the various pathogens differed according to the organism and inoculum form. Sensitivity to heat was highest withClavibacter michiganensis subsp.michiganensis and lowest withFusarium oxysporum f.sp.radicislycopersici inoculum in dry infected tomato stems, with ED80 values of 7 and 47 days, respectively; intermediate values were obtained forPythium sp.,F. oxysporum f.sp.melonis, F. oxysporum f.sp.basilici andSclerotium rolfsii. The maximal ambient temperatures were in the range of 28.2° to 33.1°C. Structural solarization for sanitation can be a useful component of integrated pest management in greenhouses.

Factors affecting symptom production by latent Botrytis cinerea in Primula×polyantha

Latent infection by Botrytis cinerea was frequently detected in young Primula×polyantha (horticultural hybrid polyanthus) plants. Genetically marked isolates were used to demonstrate that conidial inocula applied to young plants generally did not result in disease appearing on the leaves until plants flowered, regardless of when plants were inoculated. The severity of disease was proportional to the length of each day spent at 100% relative humidity during the latent period, regardless of time or form of inoculum. Plants with a prior B. cinerea infection were more susceptible to further infection and also showed symptoms of B. cinerea infection more quickly. Bacteria found to be associated with B. cinerea increased the likelihood of B. cinerea symptoms being seen on the plant, but did not directly assist infection.