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Sclerotium delphinii is a common pathogen that causes wilting in a number of plants. In recent years, the genus Sclerotium has been reported as one of those responsible for leaf spots in Piper nigrum in the Amazonian humid tropical regions. In 2017–2018, several black pepper plants presented symptoms of concentric leaf spots. Five isolates were obtained in this study for morphological and phylogenetic characterizations and pathogenicity test. Initially, the gene regions (ITS and LSU) were amplified and sequenced. Phylogenetic analysis confirmed the grouping of the five isolates with the S. delphinii reference isolate (CBS 672.71). The isolates produced sclerotia in all culture media, but some of them altered their capacity to produce sclerotia. The inoculated isolates induced irregular necrotic lesions in the pathogenicity assay using detached leaves. The symptomatic leaves were re-isolated and the fungus culture obtained. No fungus growth was observed in the leaves used as control. This study is the first record of S. delphinii causing leaf spots on P. nigrum in Brazil.

This study is a unique report of the utilization of Trichoderma strains collected from even tree barks for rice plant growth, its health management, and paddy straw degradation. Seven different spp. of Trichoderma were characterized according to morphological and molecular tools. Two of the isolated strains, namely Trichoderma hebeiensis and Trichoderma erinaceum, outperformed the other strains. Both of the strains controlled four important rice pathogens, i.e., Rhizoctonia solani (100%), Sclerotium oryzae (84.17%), Sclerotium rolfsii (66.67%), and Sclerotium delphinii (76.25%). Seed bio-priming with respective Trichoderma strains reduced the mean germination time, enhanced the seedling vigor and total chlorophyll content which could be related to the higher yield observed in two rice varieties; Annapurna and Satabdi. All the seven strains accelerated the decomposition of rice straw by producing higher straw degrading enzymes like total cellulase (0.97–2.59 IU/mL), endoglucanase (0.53–0.75 IU/mL), xylanase (145.35–201.35 nkat/mL), and laccase (2.48–12.60 IU/mL). They also produced higher quantities of indole acetic acid (19.19–46.28 μg/mL), soluble phosphate (297.49–435.42 μg/mL), and prussic acid (0.01–0.37 μg/mL) which are responsible for plant growth promotion and the inhibition of rice pathogen populations. Higher expression of defense enzymes like catalase (≥250% both in shoot and root), peroxidase (≥150% in root and ≥100% in shoot), superoxide dismutase (≥ 150% in root and ≥100% in shoot), polyphenol oxidase (≥160% in shoot and ≥120% in shoot), and total phenolics (≥200% in root and ≥250% in shoot) as compared to the control indicates stress tolerance ability to rice crop. The expression of the aforementioned enzymes were confirmed by the expression of corresponding defense genes like PAL (>3-fold), DEFENSIN (>1-fold), POX (>1.5-fold), LOX (>1-fold), and PR-3 (>2-fold) as compared to the non-treated control plants. This investigation demonstrates that Trichoderma strains obtained from tree bark could be considered to be utilized for the sustainable health management of rice crop.

Euonymus fortunei is an evergreen shrub-vine in the family Celastraceae, widely used as a groundcover or a vine to climb walls, or traditional herbal medicine in China. In August 2019, typical southern blight symptoms that included basal stem rot and the presence of sclerotia in rotted tissue were observed on E. fortunei in Kunshan city, Jiangsu province, China. Disease incidence was estimated at approximately 15 to 20%; meanwhile, approximately 30 to 40% of diseased plants died. The infected plants showed brown to dark stem necrosis near the base, leaf yellowing and wilting. White mycelia and white to dark reddish-brown sclerotia were observed at the base of the stem and rotten tissue. To isolate the causal organism, infected stem tissue and sclerotia collected from diseased plants in a median strip in Kunshan (31°23'40"N, 120°54'57"E) were disinfected with 70% ethanol for 2 to 3 sec, followed by 2 min in 5% NaClO, rinsed three times with sterile water, then plated on potato dextrose agar (PDA) medium, and incubated at 25°C. Isolated colonies were subcultured by needle tip transfer 3 days later. Isolates had white mycelia on PDA, with a radial growth rate of 15.2 to 18.7 mm/day. White and orange sclerotia were developed after 5 to 8 days and eventually turned dark reddish-brown. The sclerotia were globoid or irregular with surface markings (1.4 to 4.3 mm diam.; mean = 2.59 mm; n = 50) on PDA, and the average number of sclerotia produced per Petri dish ranged from 35 to 85 (mean = 52; n = 10). Microscopic observations found septal hyphae and clamp connections. These morphological features were identical to the description of Sclerotium delphinii (syn. Sclerotium rolfsii var. delphinii) (Mukherjee et al. 2015; Punja and Damiani 1996; Stevens 1931). A representative isolate YKY2020.01 was stored in the Key laboratory of National Forestry and Grassland Administration on Ecological Landscaping of challenging Urban Sites in Shanghai. For molecular identification, DNA of the isolate YKY2020.01 was extracted using the Fungal DNA Kit (OMEGA bio-tek, China). The internal transcribed spacer region (ITS fragment including ITS1, 5.8S rDNA, and ITS2 region) was amplified with primers ITS1/ITS4 (White et al. 1990), and then sequenced by Sangon Biotech (Shanghai, China). BLAST analysis in NCBI found the ITS sequence of YKY2020.01 (MW916955) was 99.84% similar to S. delphinii strain CBS272.30 (MH855140). Phylogenetic analysis using maximum likelihood (ML) method placed isolate YKY2020.01 in the same clade as S. delphinii. To evaluate pathogenicity, hyphal blocks (0.7 cm diam.) were placed at the base of the stem of healthy E. fortunei (n = 5 plants). Five healthy plants were inoculated by uncolonized agar blocks as controls. All plants were kept in a greenhouse with a temperature range from 21 to 25.6°C (mean = 24.9°C) and relative humidity of 50%. Inoculated plants were symptomatic after 3 days and wilted after 12 days. Symptoms in inoculated plants were similar to those observed under natural conditions, whereas the control group remained asymptomatic. The fungal pathogen was reisolated from symptomatic tissue and confirmed as S. delphinii. To the best of our knowledge, this is the first report of S. delphinii causing southern blight on E. fortunei in China and worldwide. This finding provides concise and practical information on the newly emerged disease of E. fortunei, which is beneficial for future disease management. References: Mukherjee, A. K., et al. 2015. J. Plant Pathol. 97:303. Punja, Z. K. and Damiani, A. 1996. Mycologia 88:694. Stevens, F. L. 1931. Mycologia 23:204. White, T. J., et al. 1990. Page 315 in PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Funding: This work was supported by the Key Project of Science and Technology Commission of Shanghai Municipality (19DZ1204102).

Green chireta (Andrographis paniculata) a popular medicinal plant found infected with Sclerotium delphinii causing stem rot disease with 5 to 20% incidence. The rotting symptoms were first observed on outer surface of the stem base along with white mycelium and sclerotia. The causal organism was identified as Sclerotium delphinii based on its morphological and molecular characterization. Sclerotium delphinii causing stem rot disease in Green chireta is being reported for the first time in India and worldwide.

Mosses are ecologically important plants also used for greening, gardening, and decorative purposes. Knowledge of the microbial flora associated with mosses is expected to be important for control and preservation of global and local environments. However, the moss-associated microbial flora is often poorly known. Moss-associated fungi and bacteria may promote plant growth and pest control, but they may be alternative hosts for pathogens of vascular plants. In this study, the fungus Sclerotinia delphinii was identified for the first time as a pathogen that causes severe damage to Sunagoke moss (Racomitrium japonicum). This moss is used for greening roofs and walls of buildings in urban environments owing to its notable tolerance of environmental stresses. Inoculation with the S. delphinii strain SR1 of the mono- and dicotyledonous seed plants Hordeum vulgare, Brassica rapa var. pekinensis, Lactuca sativa, and Spinacia oleracea, in addition to the liverwort Marchantia polymorpha and the moss Physcomitrella patens, showed that the fungus has a wide host range. Colonization with SR1 progressed more rapidly in non-vascular than in vascular plant species. Studies with P. patens under controlled conditions showed that SR1 secreted a fluid during colonization. Treatment with the secretion induced production of reactive oxygen species in the moss. Endogenous peroxidase partially inhibited SR1 colonization of P. patens. A bacterial isolate, most likely Bacillus amyloliquefaciens, that coexists with R. japonicum was antagonistic to SR1 growth. Taken together, the present results suggest that fungal colonization of mosses may be prevented by a peroxidase secreted by the moss and an antagonistic bacterium coexisting in the moss habitat. The findings suggest that there is potential to apply biological control measures for protection of mosses against fungal pathogens.

Dendrobium officinale is a valuable and rare Chinese herb, which is easy to suffer from various diseases during its growth. Thus early diagnosis of those diseases is crucial to increase the yield of D. officinale. In this study, we compared the internal transcribed spacer regions of the ribosomal DNA sequences of four widely disseminated pathogens in D. officinale (Sclerotium delphinii, Colletotrichum gloeosporioides, Alternaria alternata, and Cladosporium cladosporioides), designed specific primers for A. alternata and C. cladosporioides, and established a four-seat nested multiplex PCR assay. The sensitivity for S. delphinii, C. cladosporioides, A. alternata was found to be 10 fg/μL, and 10 pg/μL for C. gloeosporioides. In the actual application test, our established nested multiplex PCR can detect pathogens more quickly and accurately than conventional culture method. This method combines the advantages of nested and multiplex techniques, and it considerably improves the sensitivity and specificity of the detection results. Therefore, we hope that this method can provide a tool for diagnosing D. officinale diseases.

In August 2013, a severe disease that caused collar rot of Cynanchum paniculatum plants was observed in Shandong province, China. Diseased stems were water-soaked, grey-green or light brown in color, and displayed both silky mycelium and numerous tan or reddish brown sclerotia on the basal part of the stems and the surrounding soil. Based on morphological traits and molecular analysis of the internal transcribed spacer sequences, the casual agent was identified to be Sclerotium delphinii, and its pathogenicity was confirmed on healthy potted seedlings of C. paniculatum. Thus, the present study represents the first report of S. delphinii-infection of C. paniculatum both in China and internationally.

Variability among four isolates of Sclerotium delphinii isolated from infected diseased Khirni (Manilkara hexandra); chafa (Plumeria rubra acutifolia) and Jackfruit (Artocapus heterophyllus) plants of Western Maharashtra region of India were studied. This is the first report on presence of S. delphinii species in India. These isolates varied in colony morphology, mycelial growth rate, sclerotia formation period, sclerotia size and color. On the basis of morphological characters, these isolates were identified as S. delphinii and were also confirmed in Indian type culture collection (ITCC), New Delhi. In mycelial compatibility study, isolates of S. delphinii did not intermingle with Sclerotium rolfsii isolates indicating genetic variation among the species. The isolates of S. delphinii also showed distinct differences in their oxalic acid content. The classification and variability was further confirmed using molecular studies. It was observed that only morphological features and MCGs differentiated the Sclerotium species rather than molecular characterization because they shared some common bands of DNA at genetic level, but showed distinctness in morphological and MCGs study. Key words: Variation, cultural; biochemical, Sclerotium delphinii, RAPD-PCR.

We have isolated three novel strains of Trichoderma (two T. harzianum and one T. atroviride) from wild mushroom and tree bark, and evaluated their biocontrol potential against Sclerotium delphinii infecting cultivated cotton seedlings. T. harzianum strain CICR-G, isolated as a natural mycoparasite on a tree-pathogenic Ganoderma sp. exhibited the highest disease suppression ability. This isolate was formulated into a talcum-based product and evaluated against the pathogen in non-sterile soil. This isolate conidiated profusely under conditions that are non-conducive for conidiation by three other Trichoderma species tested, thus having an added advantage from commercial perspective.

The phylogenetic relationships of the stem rot pathogens Sclerotium rolfsii and S. delphinii were examined, based on their rDNA ITS sequences. The ITS regions were cloned and sequenced to identify three distinct ITS types: r-1, r-2, and r-3. Two different ITS types exist within S. rolfsii and S. delphinii strains. Japanese strains and one strain of S. rolfsii from the USA contain types r-1 and r-2, whereas another strain from the USA and one from Chile have only one ITS type, r-2. S. delphinii strains have types r-1 and r-3. We discuss the implications of the common presence of ITS type r-1 for the taxonomy and evolution of this species complex.

The genetic relationships among 132 isolates of Sclerotium rolfsii (teleomorph Athelia rolfsii) collected during 1967–97 from 36 different host species over a wide geographic range representing 13 countries were investigated using mycelial compatibility groupings and RAPD analysis. A smaller group of 15 Sclerotium delphinii isolates from five host species and a limited geographic distribution was also studied. The development of aversion reactions following mycelial pairings of isolates in all possible combinations on potato dextrose agar was used to differentiate 71 mycelial compatibility groups (MCG) in S. rolfsii and five MCG in S. delphinii. Many MCG were unique single-member groups and these generally were found in widely separated geographic regions or countries. There was no clear relationship between host of origin and MCG, except for a majority of isolates of S. rolfsii from turfgrass that belonged to MCG 1. Within a specific geographic region, e.g. California, there usually were several different MCG present, some of which were recovered from the same host species. In addition, specific MCG of S. rolfsii were recovered from widely separated geographic regions as well as different host species, e.g. MCG 1 was recovered from turfgrass, carrot, tobacco, and tomato in California, Georgia, North Carolina, and Mexico, respectively. The extent of genetic diversity within and among MCG of S. rolfsii and S. delphinii was studied using RAPD analysis. Isolates from different MCG could be differentiated by their unique banding patterns using six primers. There were no discernible relationships among the various MCG using UPGMA analysis. Isolates within a particular MCG were also genetically diverse, but shared greater numbers of common bands and clustered together. Only a few members of some MCG in S. rolfsii and S. delphinii that had identical RAPD patterns were considered to be clonally derived. The extent of genetic diversity among isolates of S. delphinii was lower than that observed in S. rolfsii.

Sixty-seven isolates of the southern blight fungus from Japan were divided into five groups based on ITS-RFLP analysis of nuclear rDNA. Morphological characters of sclerotia varied between groups. Three groups were reidentified asSclerotium rolfsii, and two resembledS. delphinii in RFLP patterns and/or in having large sclerotia and relatively low optimal growth temperature (28°C). Sclerotia of the latter, however, varied in size according to temperature and became indistinguishable from those ofS. rolfsii at high temperatures. Hyphal anastomosis (imperfect fusion) was observed between different ITS-RFLP groups, as well as between different isolates belonging to the same groups. These results indicate that populations of this fungus in Japan consists of several different subgroups, although morphological differences are not always evident.

The effect of sclerotia from a host species, Sclerotinia sclerotiorum and three non-host species, Rhizoctonia tuliparum, Sclerotium delphinii and Typhula incarnata on conidial germination, germ tube and mycelial growth of Coniothyrium minitans was examined. Both live and autoclaved sclerotia of all species except S. delphinii stimulated conidial germination and germ tube growth of C. minitans on distilled water or mineral salts agar. Mycelial growth of C. minitans was stimulated by all sclerotia but there was no clear specificity in response to any of the sclerotia tested. The implications of these results to the activity of C. minitans as a mycoparasite of sclerotia are discussed.

Honeysuckle flower (Lonicera japonica Thunb.) is a perennial, traditional Chinese medicine plant, widely cultivated in China. In early June 2013, heavy branch rot infection was observed on L. japonica in an approximately 10,000-m2 field in Linyi, Shandong, China. The disease incidence was 30 to 40%. Early symptoms appeared as small, elliptoid, pale brown lesions on the branches. Lesions expanded into 50 to 100 mm long and 3 to 7 mm wide, brown, elongated spots. The upper branches wilted after the lesions expanded around the stems. A fungus was consistently isolated from stem lesions on potato dextrose agar (PDA) that was morphologically similar to S. delphinii, with white mycelium, round to irregularly shaped reddish-brown sclerotia that were 2 to 4 mm diameter (2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. KJ145328), which was 99% homologous to those of other S. delphinii isolates (JN241578 and AB075314) (1). Pathogenicity tests were conducted with three 2-year-old seedlings grown in 20-cm-diameter pots at 25 to 30°C during experiments in greenhouse. Ten branches from the three plants pricked by needle were inoculated with a mycelial plug (0.4 cm diameter) harvested from the periphery of a 4-day-old colony. An equal number of branches pricked by needle serving as controls were mock-inoculated with plugs of PDA medium. Inoculated branches were covered with plastic bags for 24 h to maintain high relative humidity and incubated at about 25°C. Plugs were removed 48 h after inoculation. After 3 days, nine inoculated branches showed symptoms identical to those observed in the field under natural conditions, whereas controls remained symptom-free. Re-isolation of the fungus from lesions on inoculated branches confirmed that the causal agent was S. delphinii. Pathogenicity tests were repeated three times by the same methods with the same results. To our knowledge, this is the first report of S. delphinii infecting Lonicera japonica in China. References: (1) I. Okabe and N. Matsumoto. Mycol. Res. 107:164, 2003. (2) Z. K. Punja and A. Damiani. Mycologia. 88:694, 1996.

Pairings among 119 isolates of Sclerotium rolfsii, 11 of S. delphinii, and two of S. coffeicola on potato-dextrose agar to establish mycelial compatibility groups (MCGs) revealed 49, 3, and 2 MCGs, respectively, in a worldwide collection. Within an MCG, isolates were often from the same host and geographical area ; however, widely diverse isolates also were grouped within the same MCG. The host of origin of the isolate was not correlated with the MCG except in S. delphinii. Many MCGs were comprised of only one isolate. Variation in nuclear rDNA [internal transcribed spacer (ITS) regions] was examined following restriction enzyme digests. Restriction fragment length polymorphisms (RFLPs) were obtained with AluI, HpaII, RsaI, and MboI and could distinguish amongst the three Sclerotium spp. and three Athelia spp. (an outgroup). Combined banding patterns for the four enzymes were used to characterize intraspecific variation in the three Sclerotium spp. There were 12 subspecific groupings in S. rolfsii, one in S. delphinii, and two in S. coffeicola; some of these groupings correlated with their MCG. However, isolates within an MCG could show different ITS-RFLP patterns and certain patterns were also dispersed among different MCGs. The total sum of digested fragment sizes exceeded the undigested polymerase chain reaction product in several S. rolfsii isolates. This length discrepancy was not due to artifacts or incomplete digestion and, therefore, must have resulted from variation among rDNA copies in the presence of restriction sites. Furthermore, segregation of two MboI restriction patterns in the ITS region among 29 single-basidiospore strains, derived from four parental field isolates of S. rolfsii with one pattern, suggested the presence of two distinct rDNA types in the field isolates. The rDNA types may reflect a heterokaryotic nuclear condition in field isolates of S. rolfsii. Restriction maps and phylogenetic analyses supported a close affinity of the three Sclerotium spp., which may be more appropriately designated as subspecific varieties of S. rolfsii.

Dried sclerotia of Sclerotium delphinii rotted in moist soil whereas those of Sclerotium cepivorum. Botrytis cinerea and Botrytis tulipae did not. A number of fungi invaded dried sclerotia of S. delphinii in soil, the principal coloniser found in the first sampling being Trichodermu hamatum . Leakage of 14 C compounds from dried labelled sclerotia placed in water was rapid and was little affected by variation in leakage temperature from 1 to 25°C or by prolonging the drying period beyond a day. Leakage from dried sclerotia which were allowed to imbibe water through a small part of their surface was much reduced. Sclerotia which were redried after leakage leaked again when returned to water but with all four fungi the first of three leakage cycles gave the highest 14 C levels. Loss in dry weight in the first leakage cycle was greater with S. delphinii than with the other three fungi and this may be related to the poor survival of dried sclerotia of S. delphinii in moist soil. Substances lost during leakage appear to originate from within sclerotial hyphae rather than from the hyphal free space.

SUMMARY The survival in soil of sclerotia of Sclerotinia trifoliorum, S. sclerotiorum, Sclerotium delphinii and S. rolfii was studied. Those of S. rolfsii disintegrated in less than 1 month, while 95% of those of S. delphinii and Sclerotinia sclerotiorum were recovered after 2 years. Sclerotia of S. trifoliorum placed in soil in March slowly diminished in numbers over the summer months, and in late autumn there was a rapid decrease in those near the surface, as a consequence of apothecial formation. This rapid fall did not occur when sclerotia were buried under clover. Over the winter, sclerotia 1 and 2 in. deep increased in numbers by the formation of secondary sclerotia. Secondary sclerotia also occurred in samples of Sclerotinia sclerotiorum. Soil moisture content affected sclerotial survival, an accelerating decline in numbers being noted up to a soil moisture-holding capacity of 30%. Above this level, increasing numbers of secondary sclerotia were formed, so that the numbers of sclerotia recovered were sometimes greater than those originally buried. Sclerotia became more liable to decay after producing apothecia, but they did not invariably disappear, and some were capable of forming two or possibly three crops of apothecia in successive years.

Experiments on the desiccation sclerotia of Sclerotinia sclerotiorum, Sclerotium delphinii and S. rolfsii demonstrate that the sclerotium rind does not effectively restrict water loss. Observations on rate of rehydration show that drying of the outer sclerotial tissues does not make them impermeable. The data suggest that survival of sclerotia under desiccating conditions is a property of the individual sclerotial cells.

Sclerotium formation in Sclerotium delphinii, S. rolfsii and Sclerotinia sclerotiorum is influenced both by light intensity and the duration of the light treatment. Removal of matured sclerotia from colonies results in the production of a further crop of sclerotia. In S. sclerotiorum the time of Sclerotium production by a colony appears to be determined endogenously. The observations suggest that a complex of different factors may be involved in sclerotium morphogenesis.

SCHOPFER (1934a, 1934b) reported that Phycomyces Blakesleeanus Burgeff does not grow upon a medium of mineral salts, pure dextrose, asparagine, and water, but grows normally on the same medium to which a minute quantitv of crystalline vitamin B, is added. Schopfer's discovery resulted from a suggestion made to him by Burgeff (Schopfer, 1934c) based on the latter's observation of the effect of crystalline vitamin B1 on the growth of Phycomyces. Other fungi found by Schopfer (1935) to require vitamin B1 include Absidia ranosa, Parasitella simplex, Mucor Ramanmnianus, Dicranophora fulva, Chaetocladium Brefeldi, Choanephora cucurbita, Choan,ephora persicaria, and Pilaria anomala. Earlier reports on the importance of vitamin B1 as a growth factor for the lower plants have been published by various investigators including R. J. Williams (1920, 1930), Lepeschkin (19'24), and others. The conclusive evidence of the importance of vitamin B, (aneurin or thiamin) for the growth of plants depended upon a supply of the pure vitamin, which became available in 1934. We have confirmed Schopfer's report of the effect of vitamin B1 on the growth of Phycomyces BRakcesleeanus, and since there are many organisms which do not grow, or grow poorly, on the common synthetic media (those lacking some natural organic supplement), we have determined the effect of vitamin B1 on a number of fungi. MATERIALS AND METHODS.-In addition to Ph ycomyces Blakesleeanus, a plus strain kindly furnished by A. F. Blakeslee, we have used other organisms secured through the courtesy of W. E. Maneval, J. T. Middleton, or C. M. Tucker. Those furnished by Maneval were Absidia glauca Hagem, Basidiobolus ranarum Eidam, Mortierella sp. no. 11, Mortierella candelabrum v. Tiegham and le Monnier, Mucor circinelloides v. Tiegham, Mucor griseolilacinus Povah, Mucor sp. no. 103, Mucor sp. no. 115, Circinella aspera Lendner, Cunninghamella sp. no. 102, Thamnidium elegans Link, Zygorhynchus Moelleri Vuill, Zygorhynchus sp. no. 111, Rhizopus nigricans Ehrenberg, + and -, Phycomyces nitens (Agardh) Kunze and Schmidt, +, Sphaerulina trifolii Rostr. From Tucker we secured cultures of Phytophthora Boehmeriae Saw., P. cactoram (L. and C.) Schwet, P. cambivora (Petri) Buis, P. capsici Leon., P. cinnamoni Rands, P. colocasiae Racib., P. cryptogea Pethyb. and Laff., P. Drechsleri Tuck., P. palmivora Butler, P. parasitica Dast., P. fagopyri Takimoto; Agaricus campestris Linn., Schizophyllum commune Fr., Sclerotium delphinii Welch, and S. Rolfsii Sac. Middleton furnished cultures of Pythium arrhenomanes Drechsler, P. polycladon Sideris, P.

(1931). A Comparative Study of Sclerotium Rolfsii and Sclerotium Delphinii. Mycologia: Vol. 23, No. 3, pp. 204-222.

Sclerotium delphinii Welch is recognized as a highly destructive pathogen of a large number of vegetables and ornamental plants. Efforts during the past twenty-five years to develop practical control of this fungus have met with failure. Some investigators reported a slight benefit with chemicals, but the control achieved was far from satisfactory. Chemical tests by Davey and Leach in 19411, on a closely related organism, Sclerotium rolfsii, revealed that, of the seventeen water-soluble chemicals tested, only formalin at dilutions of 1 : 100 and applied at 3 gallons per sq. ft. of soil surface was effective. More recently, chemicals were also tried by Thomas Laskaris, while working on diseases of delphinium at the New York Botanical Garden. Because these and other workers were unsuccessful in finding a chemical control for this highly destructive fungus, an attempt has therefore been made, at the suggestion of Dr. P. P. Pirone, plant pathologist of the New York Botanical Garden, to achieve control by biological methods.

IN 1952, I reported1 the inhibition in vitro of the crown-rot fungus, Sclerotium delphinii Welch, by two species of Penicillium, P. brevi-compactum and P. charlesii. In vivo experiments were set up to demonstrate the practical utilization of these penicillia as agents in combating the crown-rot fungus disease. For this purpose the penicillia were grown in large quantities in Czapek–Dox medium for seventeen to eighteen days on a rotary shaker at room temperature. The culture fluid was then filtered and the filtrate was poured into standard greenhouse flats, containing soil which had been artificially infested three days before with sclerotia of S. delphinii. Controls were also set up, using Czapek–Dox medium, in flats of similarly infested soil. A few days after filtrates of different concentrations were added to the flats, nine plants of Mazus reptans and Ajuga reptans (two rock-garden plants extremely susceptible to S. delphinii) were planted in each of the different flats.

In the summer of 1933 there was observed in a rock garden in Lawrence a fungus parasitizing a patch of Ajuga reptans L. The following summer the fungus had spread to various parts of the garden, and in addition to Ajuga reptans, was parasitizing Lysimachia nummularia L. and Sedum acre L. Dr. A. J. Mix made isolations from Ajuga on August 9, 1934, and obtained an organism that appeared to be Sclerotium delphinii Welch.1 Growing on potato dextrose agar this fungus exhibited those characteristics that distinguish it from Sclerotium rolfsii Sacc., a closely related species, as listed by Stevens.2 These characteristics include ropy mycelium and concave sclerotia varying widely in size from 0.8 to 5.18mm. in diameter. These sclerotia frequently have pits or depressions on their surface, and are of a buff to tawny to Hay's brown color. A comparison of the fungus from Ajuga made with authentic cultures of Sclerotium rolfsii Sacc. obtained from H. H. Whetzel, L. D. Leach, G. F. Weber, and C. W. Edgerton, and cultures of Sclerotium delphinii Welch from H. H. Whetzel, also proved without doubt that it was Sclerotium delphinii Welch. This is the first time this species has been found in this vicinity, and as far as the literature reveals, in Kansas.

In a note published previously (8) the writer mentioned that A. J. Mix had made an isolation of Sclerotium delphinii Welch from Ajuga reptans. The organism was observed in a rock garden where in addition to Ajuga it was parasitizing Sedum acre and Lysimachia nummularia. This marked the first time this species had been isolated in Kansas, although Sclerotium rolfsii Sacc., a closely related species, is listed by Bartholomew (1) as occurring in the state. Figure 1, left, is a photograph of the strain of S. delphinii isolated from Ajuga, and, right, a typical culture of S. rolfsii growing on potato dextrose agar slants. In the course of a general study of this isolate from Ajuga it was decided to investigate the host range and make a few comparisons with S. rolfsii. The latter, because of its wide geographical distribution and economic importance as a plant pathogene, has received considerable mention in the literature and is known to be parasitic on nearly two hundred hosts. Sclerotium delphinii, on the other hand, has been reported on only about forty species. These have been compiled and are listed in Table I. Unfortunately some workers gave only the common names for some of the hosts, and where there was doubt as to the correct scientific name, either just the genus name or common name is listed.

Sclerotia of Sclerotium delphinii Welch buried at different depths in the field showed little sign of activity but did not survive as well as has been claimed previously. Soil temperatures in this country are always below the optimum for germination and below the minimum for much of the year. Sclerotia are subject to soil fungistasis but are less sensitive than those of many other fungi. Germination was suppressed by volatile materials arising from soil and carbon dioxide was shown to be partly responsible for this effect. Germination of sclerotia on soil was enhanced after a period of desiccation and exudation by sclerotia was similarly affected. Previously dried sclerotia did not rot quickly on soil and some were able to germinate vigorously up to twenty times. Their capacity to do this was dependent upon their size. Germination of sclerotia was stimulated by puncturing the rind and by certain chemical treatments. The rind apparently acts as a physical barrier to germination but stereoscan electron microscope studies of the surface of dried sclerotia did not reveal any cracks through which germination hyphae might emerge.