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Contamination of grain products by fungus can lead to economic losses and is deleterious to human and livestock health. Detection and quantification of fungus-infected corn kernels would be advantageous for producers and breeders in evaluating quality and in selecting hybrids with resistance to infection. This study evaluated the performance of single-kernel near-infrared reflectance spectroscopy (NIRS) and color imaging to discriminate corn kernels infected by eight fungus species at different levels of infection. Discrimination was done according to the level of infection and the mold species. NIR spectra (904 to 1685 nm) and color images were used to develop linear and nonlinear prediction models using linear discriminant analysis (LDA) and multi-layer perceptron (MLP) neural networks. NIRS was able to accurately detect 98% of the uninfected control kernels, compared to about 89% for the color imaging. Results for detecting all levels of infection using NIR were 89% and 79% for the uninfected control and infected kernels, respectively; color imaging was able to discriminate 75% of both the control and infected kernels. In general, there was better discrimination for control kernels than for infected kernels, and certain mold species had better classification accuracy than others when using NIR. The vision system was not able to classify mold species well. The use of principal component analysis on image data did not improve the classification results, while LDA performed almost as well as MLP models. LDA and mean centering NIR spectra gave better classification models. Compared to the results of NIR spectrometry, the classification accuracy of the color imaging system was less attractive, although the instrument has a lower cost and a higher throughput.

White corn grown in southern Texas was collected for characterization and evaluation of the feasibility of sorting kernels containing mycotoxins. Kernels were grouped into one of six symptom categories depending on the degree of visible discoloration and bright green-yellow fluorescence (BGYF) or bright orange fluorescence (BOF). Kernels visibly discolored (= 25% of their surface) and having BGYF contained over 57% of the aflatoxin. However, kernels approximately 50% discolored without BGYF contained over 35% of the aflatoxin. Over 33% of the fumonisin was found in kernels that were visibly discolored and had BOF. The remaining fumonisin was in asymptomatic kernels at low levels. Sorting tests for removing mycotoxin-contaminated kernels were performed using a dual wavelength high-speed commercial sorter. In one pass through the sorter, aflatoxin was reduced by an average of 46%, and fumonisin was reduced by 57% while removing 4% to 9% of the corn. Re-sorting accepted kernels a second time resulted in an 88% reduction in aflatoxin while removing approximately 13% of the corn. Approximately half of the aflatoxin missed by the optical sorter was found in larger kernels showing BGYF but no other symptoms, with the remaining aflatoxin in smaller kernels where the germ was damaged by insect feeding.

Single-kernel reflectance spectra (550 to 1700 nm), visible color reflectance images, x-ray images, multi-spectral transmittance images (visible and NIR), and physical properties (mass, length, width, thickness, and cross-sectional area) were analyzed to determine if they could be used to detect fungal-infected corn kernels. Kernels were collected from corn ears inoculated with one of several different common fungi several weeks before harvest, and then collected at harvest time. It was found that two NIR reflectance spectral bands centered at 715 nm and 965 nm could correctly identify 98.1% of asymptomatic kernels and 96.6% of kernels showing extensive discoloration and infected with Aspergillus flavus, Aspergillus niger, Diplodia maydis, Fusarium graminearum, Fusarium verticillioides, or Trichoderma viride. These two spectral bands can easily be implemented on high-speed sorting machines for removal of fungal-damaged grain. Histogram features from three transmittance images (blue and red components of color images and another at 960 nm) can distinguish 91.9% of infected kernels with extensive discoloration from 96.2% of asymptomatic kernels. Similar classification accuracies were achieved using x-ray images and physical properties (kernel thickness, weight, length). A neural network was trained to identify infecting fungal species on single kernels using principle components of the reflectance spectra as input features.

This study was undertaken to investigate the feasibility of using Paecilomyces lilacinus NRRL 13 866, chitin, and cellulose amendments, in order to reduce survival and prevent germination of sclerotia from Aspergillus flavus NRRL 6556, NRRL 13 048, and A. parasiticus NRRL 13 005, NRRL 13 539 buried in sandy soil in Georgia and Illinois (April–October, 1990). The number of sclerotia that germinated sporogenically in moist chambers following burial in Illinois was twice that of sclerotia buried in Georgia and varied among the four sclerotium-producing Aspergillus spp. strains. Sclerotium viability, as measured by Aspergillus spp. colony formation on potato dextrose agar, was high (>84%) for all strains and treatments (e.g. amendment, location). Even so, A. parasiticus NRRL 13 539 sclerotia were apparently more susceptible to P. lilacinus colonization than sclerotia from other strains. Treatment with Paecilomyces sp. caused a small but significant reduction in germination among sclerotia buried in Georgia.

Microflora in wound sites of preharvest maize (including bacteria, yeasts, and filamentous fungi) may play a role in attracting insects to maize plants and may also interact with growth and mycotoxin production by filamentous fungi. As little data are available about the yeasts occurring on maize from the U.S. corn belt, samples of milled maize from experimental plantings at the University of Illinois River Valley Sand Field were analyzed. Yeast counts showed slight yearly fluctuation and varied between 3.60 and 5.88 (log cfu/g maize). The majority of the yeasts were Candida guilliermondii (approximately 55%), Candida zeylanoides (24 %), Candida shehatae (11%), and Debaryomyces hansenii (3%). Also present were Trichosporon cutaneum, Cryptococcus albidus var. aerius, and Pichia membranifaciens. The occurrence of killer yeasts was also evaluated. Killer yeasts were detected in maize for the first time and were identified as Trichosporon cutaneum and Candida zeylanoides. These were able to kill some representative yeasts isolated from maize, including Candida guilliermondii, Candida shehatae, and Cryptococcus albidus var. aerius. Other maize yeasts (Candida zeylanoides, Debaryomyces hansenii, Pichia membranifaciens) were not affected. The majority of yeasts found on maize were unable to ferment its major sugars, i.e., sucrose and maltose. Some (e.g., Candida zeylanoides) were not even able to assimilate these sugars. The importance of these properties in relation to insect attraction to preharvest ears of maize is discussed.Key words: corn, maize, yeast, killer.

Normally innocuous forages are sporadically associated with hepatogenous photosensitization outbreaks at certain times of the year or when grown and harvested during unusual environmental conditions, such as periods of excessive rainfall. Allegations of livestock illness following consumption of such moldy hays are associated with clinical syndromes uncharacteristic of known forage-related diseases, suggesting that unidentified toxin(s) may be responsible. This study was instigated by field observations of hepatogenous photosensitization in cattle fed alfalfa-grass forage. To document the toxic nature of the hay, large bales of hay (450 kg) were fed, ad libitum, to 3 groups of 2 calves each. Elevated serum liver enzymes provided evidence of hepatobiliary disease. Gamma glutamyl transferase activities in serums of the calves sustained at least a 10-fold increase above baseline during the feeding trials. Histologic examination of liver biopsies and postmortem sections revealed mild periportal fibrosis and biliary hyperplasia. Culture material from 12 fungal isolates from the hay failed to induce liver disease in calves.

Species of Aspergillus have been isolated from living, diseased and dead insects. They colonise discrete nutrient-rich substrates for which insects and fungi may compete (e.g. seeds, fruit, dung, etc.). There are numerous examples of antiinsectan effects attributed to Aspergillus, including symptoms of fungal infection (Madelin, 1963; Charnley, 1984; Moore and Erlandson, 1988), observations of insect response to fungal cultures (Loschiavo and Sinha, 1966; Sinha, 1971; Hill, 1978), moulded grain (Sinha, 1966, van Bronswijk and Sinha, 1971, mould contaminated diets (Wicklow and Dowd, 1989), and toxicity studies with specific fungal secondary metabolites (Wright et. al., 1982; Dowd et al.., 1988; Wicklow, 1988; Dowd, 1992). The antiinsectan effects include growth retardation, reduced pupal and adult size, lower fecundity, loss of fertility, mortality, repellency, and genetic changes. In nature, these entomotoxic fermentation products of Aspergillus may prevent loss of substrate to insects and/or discourage arthropod fungivores (Janzen, 1977; Wicklow, 1988). Experiments to test the suitability of Aspergillus species as food for the grain beetle Ahasverus advena revealed that beetle larvae consumed the Aspergillus conidial heads of Eurotium (syn. Aspergillus glaucus) but did not eat the ascomata (Hill, 1978). Eurotium ascomata are covered with a felt of sterile aerial hyphae encrusted with yellow, orange, or red granules which, if toxic or unpalatable, could make such fungal structures less attractive to arthropodes.

A nematicidal toxin was purified fromPleurotus ostreatus NRRL 3526 grown on moistened, autoclaved wheat straw for 30 days at room temperature (21-33°C). The active compound, at a concentration of 300 ppm, immobilized 95% of test nematodes (Panagrellus redivivus) within 1 hr. Immobilized nematodes did not recover, even after being rinsed with deionized water. The toxin was identified astrans-2-decenedioic acid.

Ribosomal RNA sequences were determined for terverticillate Penicillia by the dideoxy nucleotide chain termination method and oligonucleotide primers. The sequences of individual isolates were compared for base differences upon proper alignment. Prior experience in other fungi suggests that a single nucleotide difference in the sequence of two Penicillium isolates may indicate that they are not the same species. A second baseline for data interpretation was provided by comparisons involving: Penicillium, Saccharomyces, and Urnula. These intergeneric comparisons revealed >100 base differences.

The fungus, Aspergillus flavus, secretes lipases while parasitizing oilseed hosts and may contaminate the seed with aflatoxin. We found that exogenous lipase applied to soybean cotyledons results in the generation of volatile aldehydes by the lipoxygenase pathway that halts the growth of fungi. Volatiles generated from untreated homogenized soybeans did not affect the germination of A. flavus spores in a closed petri plate assay in which spores were streaked on corn-meal agar and soybean homogenate was placed on the lid of the inverted plate. When lipase (500 units/ml) was added to the soybean homogenate, all fungal spore germination was inhibited [...]

Three hundred and sixty-eight isolated of Penicillium were recovered from water collected from flotation tanks in four apple packinghouses i southeastern New York. The 345 isolates, which caused blue mold in inoculated apples (Malus domestica), were identified to species and tested for sensitivity to methyl 2-benzimidazolecarbamate (MBC) and diphenylamine (DPA). Sixty-five isolates were P. expansum, 277 were P. auantiogriseum, two were P. citreonigrum, and one was P. dendriticum. Thirty-one isolates of P. expansum were sensitive to MBC (...)

We describe the histology of fungal development in maize ears wound inoculated with Aspergillus flavus. Plants were inoculated 21 days after style emergence; wounded grains and adjacent spikelets (with their rachis segments) were harvested at intervals up to 28 days later. Tissues were processed for plastic embedding and 1.5-μm thick sections were examined by bright field microscopy. The fungus spread from the wound sometime after 14 days postinoculation, and at 28 days postinoculation it could be found in small amounts throughout all rachis tissues except the pith and lignified fibers (...)

This research examines the distribution of aflatoxins among conidia and sclerotia of toxigenic strains of Aspergillus flavus Link and Aspergillus parasiticus Speare cultured on Czapek agar (21 days, 28 °C). Total aflatoxin levels in conidia and sclerotia varied considerably both within (intrafungal) and among strains. Aspergillus flavus NRRL 6554 accumulated the highest levels of aflatoxin (conidia: B1 84 000 ppb; G1; 566 000 ppb; sclerotia: B1, 135 000 ppb; G1, 968 000 ppb). Substantial aflatoxin levels in conidia could place at risk those agricultural workers exposed to dust containing large numbers of A. flavus conidia. Cellular ratios of aflatoxin B1 to aflatoxin G1 were nearly identical in conidia and sclerotia even though levels of total aflatoxins in these propagule types may have differed greatly. Aflatoxin G1 was detected in sclerotia of all A. flavus strains but in the conidia of only one strain. Each of the A. parasiticus strains examined accumulated aflatoxin G1 in both sclerotia and conidia. These results are examined in the context of current evolutionary theory predicting an increase in the chemical defense systems of fungal sclerotia, propagules critical to the survival of these organisms.

This laboratory study was designed to examine the response of a postfire ascomycete community to elevated temperatures and treatment intervals corresponding to those recorded during the burning of a tallgrass prairie. Aerated steam treatment of prairie soil samples (35, 40, 55, 70, 85, or 100 °C) for intervals of 60, 100, 140, or 180 s enabled us to examine the response of individual species comprising the carbonicolous ascomycete community.Simulation of a grassland fire by aerated steam treatment of prairie soils promoted the development of 20 species of ascomycetes. Generalists such as Sporomiella subtilis Ahmed and Cain occurred at high frequencies over most of the temperature range while specialists Podospora curvispora (Cain) Cain, Sordaria macrospora Awd., and Leptosphaeria sp. were important at only one temperature. Species diversity, richness, and number of species per sample were significantly affected by the temperature of the steam treatment. The temperature–treatment interval combination allowing for the greatest expression of diversity in the carbonicolous ascomycete community was 55 °C for 60 s. Since a grassland fire does not uniformly heat the soil surface, the environmental patchiness created by this physical perturbation may be an important factor in determining the composition of the carbonicolous ascomycete community in prairies.

A survey was made of the kinds of fungi which developed fructifications on different coprophilous substrates from a semiarid grassland in Colorado. Fifty-three species were found on approximately 6...

The distribution and relative abundance of coprophilous Ascomycetes having certain ascocarp morphologies [e.g., cleistothecium; multi-spored ascus (>8 spores), and distinct bristles or hairs on neck of perithecium] was contrasted for rabbit and cattle feces collected from a semi-arid short-grass prairie, a mixed-grass prairie, and a tall-grass prairie. Species with non-ostiolate ascocarps were most frequently recorded from dung in semi-arid shortgrass prairie (p p > 0.05); and species with bristles or hairs on the perithecial neck and surrounding the ostiole showed no significant variation among prairies.

A field study was designed to compare the attractiveness of pre-aged (laboratory incubated) and fresh rabbit feces to potential arthropod colonists. Laboratory collected rabbit feces were incubated on moist peat for intervals of 0, 10, 20, 30, and 40 days before exposure (48 h) in one of four field sites in northwestern Pennsylvania. Greater numbers and kinds of arthropods were attracted to 0-day-old dung samples than to fecal pellets that were preincubated for 10 or more days in the laboratory. Furthermore, numbers and kinds of arthropods attracted to fecal pellets increased with increasing habitat complexity. The results indicate that loss in attractiveness of aged feces to potential arthropod colonists cannot be attributed entirely to the drying of the substrate or to prior arthropod colonization. It is suggested that microfloral activity contributes to chemical changes in the incubating feces which render them less attractive to potential early colonists.

Twelve species of Cyathus and two additional taxa included in the Nidulariaceae (i.e., Crucibulum laeve (Bull. ex DC) Kambly and Nidula niveo-tomentosa (Henn.) Lloyd) were examined for their ability to differentially modify the lignin and cellulose components of wheat (Triticum aestivum L.) straw (WS) and a silver maple (Acer saccharinum L.) hardwood (HW) log. Our results indicate that the rate and pattern of biological modification of native lignocellulose differs according to substrate and fungal species chosen for the fermentation. The ecological specialization or substrate preferences of the species selected for study was not always an accurate predictor of how each fungus ranked in its ability to degrade WS or HW.

Gross decomposition (wt./cal) losses of rabbit feces colonized by larvae of the sciarid flyLycoriella maliFitch as contrasted with feces incubated without fly larvae were studied in the laboratory. Under conditions of high larval density and intense grazing pressure, fecal weight and calorie losses (30 days) were double those from fecal samples incubated without flies. Decomposition losses among the samples in a given treatment showed limited variation although the number of emergent adults varied greatly. Although published caloric values obtained for microflora and flies are significantly higher than those recorded for the rabbit feces used in this study (4837 cal/g), feces colonized by flies and feces incubated without flies had caloric values equivalent to that of the unincubated control. Larvae consumed both the mycelium and sporocarps of coprophilous fungi.

The role of certain abiotic and biotic factors in determining the structure of a post-fire ascomycete community was studied by the laboratory simulation of soil conditions occurring during and following a prairie fire. Aerated steam treatment of prairie soil (35, 40, 55, 70, or 85 °C for 60 s) was used to simulate the elevated soil temperatures generated during a grassland fire. Further manipulations included: (1) addition of ashed remains of prairie grasses to steamed soil surfaces, (2) the incubation of steam-treated soil samples layered over untreated prairie soil, and (3) addition of ash to steamed soil underlain with a layer of untreated soil to create a simulated burn.Across all treatments, species diversity and total number of species were significantly higher in soils steamed at 35, 55, or 70 °C than soils steamed at 40 or 85 °C. The greatest number of species per sample for steaming alone occurred in samples treated at 55 °C. The addition of ash to steamed samples or layering with untreated prairie soil significantly reduced species diversity and total number of species as compared with steamed soil alone. When ash and a subsurface layer of untreated soil were applied together, species diversity, total number of species, and mean number of species for samples steamed at 55 or 70 °C, were significantly greater than when either treatment was added separately. It was found that a simulated burn at 55 or 70 °C promoted the development of a community which most closely resembled a naturally occurring post-fire ascomycete community. This suggested that the structure of the post-fire ascomycete community was in part determined by (1) species responses to elevated soil temperatures, (2) ash deposition, and (3) biotic factors associated with the subsurface soil layers.

Aspergillus niger, a mold commonly associated with Aspergillus flavus in damaged corn, interferes with the production of aflatoxin when grown with A. flavus on autoclaved corn. The pH of com-meal disks was adjusted using NaOH–HCl, citric acid–sodium citrate, or a water extract of A. niger fermented corn. Aflatoxin formation was completely inhibited below pH 2.8–3.0, irrespective of the system used for pH adjustment. When grown in association with A. flavus NRRL 6432 on autoclaved corn kernels, A. niger NRRL 6411 lowered substrate pH sufficiently to suppress aflatoxin production. The biodegradation of aflatoxin B1or its conversion to aflatoxin B2a were eliminated as potential mechanisms by which A. niger reduces aflatoxin contamination. A water extract of corn kernels fermented with A. niger caused an additional inhibition of aflatoxin formation apart from the effects of pH.

SynopsisThe evolutionary significance of natural fire disturbance regimes in the development of post-fire fungal and herb communities is examined. Before a fire the soil microflora exhibits a general fungistasis, microbial competition is great, nutrients are limiting, and carbonicolous ascomycetes are in a dormant phase. Also in mature chaparral shrub communities the soil microflora is implicated in soil toxicity that prevents seeds of some species from germinating in the interval between burns. Fire results in the deposition of ash and charred wood, a release of nutrients, the elimination of competitors (e.g. shrub cover, soil microflora), an increase in soil alkalinity, the removal of soil toxicity/fungistasis, and cues the germination of constitutively dormant ascospores and seeds. The cue for germination of the chaparral fire annuals appears to be components of the hemicellulose fraction, produced during the charring of wood, but this fraction has not been tested for its ability to cue ascospore germination. Germination in the absence of fire would be “suicidal” because neither the carbonicolous ascomycetes nor the post-fire annuals are able to compete successfully in these pre-burn habitats. The frequency of burning and the uneven heating of the soil surface creates patchiness with a corresponding increase in the species richness of the post-burn community.

Terverticillate penicillia were important colonists of the underground seed caches and the external cheek pouches of the banner-tailed kangaroo rat (Dipodomys spectabilis) from the North American desert. Two taxa representing the dominant Penicillium populations are described as new varieties of well-known ubiquitous species. Penicillium chrysogenum var. dipodomyis var.nov. produces the antibiotic penicillin but does not produce mycotoxins (PR-toxin and roquefortine C) known from P. chrysogenum. The new variety is further distinguished by having rough-walled stipes. Penicillium aurantiogriseum var. neoechinulatum var.nov. isolates produce penicillic acid, viridicatin, and cyclopenin, metabolites with antibiotic properties, but not the potent nephrotoxins xanthomegnin and viomellein or tremorgenic mycotoxins (e.g., penitrem A). The variety is also distinguished by conspicuously rough-walled conidia. Three additional new varieties which do not produce mycotoxins normally associated with their species are also reported: P. griseofulvum var. dipodomyicola var.nov. produced the antibiotically active compounds patulin and griseofulvin but not cyclopiazonic acid and roquefortine C; P. glandicola var. mononematosa var.nov. and P. glandicola var. confertum var.nov. did not produce roquefortine C, penitrem A, or patulin. Infrequently isolated strains of the species P. viridicatum and P. griseofulvum duplicated the mycotoxin profiles of the cultures ex type. It is suggested that the evolution of seed-caching behaviour in D. spectabilis may have guided the selection of less-toxic terverticillate penicillia as colonists in rodent seed caches.

Exposure of laboratory-collected rabbit feces in different habitats associated with a dune succession in Presque Isle State Park, Erie, Pennsylvania, USA, affected the structure and composition of the coprophilous fungal communities developing on these feces. Nylon mesh litter bags containing 4-g samples of rabbit feces, the latter incorporating a similar fungal inoculum, were exposed in the field for either 2- or 4-wk intervals throughout the summer of 1975. This was followed by a 40-d incubation in laboratory moist chambers, during which time the development (sporulation) of fungal populations was studied and the frequency of occurrence of fungal taxa recorded. Com- munity analysis was accomplished by position vectors ordination, and analysis of species diversity values. Experimental evidence is offered for the first time that microclimatic amelioration and sta- bilization in later stages of ecosystem development can be important in determining microfungal diversity. Community diversity increased when dune habitat and/or exposure interval were associated with a less stressful environment (i.e., presence of vegetational cover or greater available moisture).

Aflatoxin-producing ability medium was tested for its ability to distinguish aflatoxin-positive from aflatoxin-negative strains of Aspergillus flavus in naturally occurring populations from corn at harvest. All of the aflatoxin-positive strains and some of the aflatoxin-negative strains produced aflatoxins when cultured on cracked corn. Although the data indicate that aflatoxin-producing ability medium is not entirely reliable in distinguishing potential aflatoxin-producing strains of A. flavus from nontoxigenic strains, it is significant that the medium did not yield false-positives.

A study was made to determine whether Aspergillus flavus (QM 380; NRRL 3537; ATCC 9643) and Aspergillus versicolor (QM 432; NRRL 573; ATCC 16,020), mold strains routinely combined in fungus resistance tests for United States military specification (MIL-STD-810B; MIL-STD-331A), were capable of producing aflatoxins or sterigmatocystin when grown separately or in mixed culture fermentations of cracked corn (11 days at 25 °C or 28 °C). Substantial quantities of sterigmatocystin (average of 3 replicates= 1,895 ppb) were detected when A. versicolor was the sole colonist. No sterigmatocystin was detected when A. versicolor was simultaneously inoculated with other molds. Aflatoxins were not detected in any of the treatment combinations.

Faeces of cattle, pronghorn and rabbit were collected from the Central Plains Experimental Range, Colorado, 6, 18 and 30 months after being excreted. The faecal material was placed in moistened potting soil and seedling emergence observed. Bouteloua gracilis (blue grama grass) and Sporobolus cryptandrus (sand drop seed), emerged in abundance from cattle dung. Emergence of B. gracilis decreased with increasing period of exposure before collection, but emergence of S. cryptandrus increased with exposure. Forbs dominated the seedling populations in pronghorn dung, and few seedling populations of any species emerged from rabbit dung. The results are discussed in relation to the effect of large herbivores on the establishment of species from seed in rangeland.

Wicklow. D. T. 1988. Patterns of fungal association within maize kernels harvested in North Carolina. Plant Disease 72:113-115. Eleven common maize-infecting fungi grew out from surface-disinfected maize kernels that were collected at harvest in North Carolina in 1977 and plated on malt extract agar. The fungal species were compared for significant association between pairs in all possible combinations. A negative association was observed for 21 ofthe 55 pairings offungal species. whereas only three species pairs were positively associated. Fusarium moniliforme infected 52% of the kernels and was negatively associated in pairings with all 10 of the other kernel-invading fungi. This finding lends support to the hypothesis that initial kernel infection by F. moniliformeserves as a deterrent to the subsequent establishment ofother fungi. In contrast. Aspergillusflavusand A. niger frequently grew out from the same kernel and showed a highly significant positive association (chi-square = 147.37).

An experiment was designed to determine whether certain fungi commonly isolated from maize at harvest can affect aflatoxin development when inoculated with Aspergillus flavus (NRRL 6412) onto individual sterilized maize kernels (incubation 8 days at 28 deg C). No aflatoxins were detected when A. niger (NRRL 6411) or Trichoderma viride (NRRL 6418) were paired with A. flavus. Aflatoxin contamination was substantial (mean value for B1 ranging from 676 p.p.b. to 3765 p.p.b.) in 11 other simultaneous pairings. When inoculation with A. flavus followed by 5 days that of the other test fungi, aflatoxin was detected only in pairings with Candida guilliermondii (B1, 16 p.p.b.; B2, 1 p.p.b.). However A. flavus invaded a number of the other preinoculated kernels in this series, as evidenced by its abundant sporulation on kernel surfaces and/or the formation of a bright greenish-yellow (BGY) fluorescence in kernel tissues examined under black light (365 nm). The status of individual fungal colonists as interference competitors and the order in which spp. colonize a kernel (i.e. prior to, or simultaneous with, the introduction of A. flavus), are examined as factors contributing to variation in aflatoxin levels among field samples.

Inability to compete directly with other members of the carbonicolous community is examined as a factor contributing to the stratification of fungal sporocarp appearance in a heterotrophic successi...