Three new species and a new record of Diplococcium from plant debris in Spain

Diplococcium dimorphosporum sp. nov., D. racemosum sp. nov., D. singulare sp. nov. and D. pulneyense Subram. & Sekar collected from plant debris in natural areas of Spain are described and illustrated. The first species is characterized principally by the production of branched conidiophores and short chains of conidia. Diplococcium singulare has unbranched conidiophores, and conidia produced usually at the tip of conidiophores and from lateral spherical conidiogenous cells. In addition, both species develop a Selenosporella synanamorph with narrow falcate conidia. Diplococcium racemosum produces branched, verrucose conidiophores, and verrucose conidia in long branched chains. Diplococcium pulneyense is the second record, being described for first time on the natural substratum and re-described in pure culture. A key to currently accepted species of Diplococcium is provided.     

Collection of highly germinative pseudochain conidia of Oidium neolycopersici from conidiophores by electrostatic attraction

A population of simultaneously germinating conidia is an ideal inoculum of the powdery mildew pathogen, Oidium neolycopersici. In conditions of no or low wind velocity, O. neolycopersici successively stacks mature conidia on conidiophores in a chain formation (pseudochain), without releasing the precedent mature conidia. These pseudochain conidia represent a perfect inoculum, in which all conidia used for inoculation germinate simultaneously. However, we found that conidia must be collected before they fall to the leaf surface, because the germination rate was lower among conidia deposited on the leaf surface. We used an electrostatic spore collector to collect the pseudochain conidia, and their high germination rate was not affected by this treatment. The spore collector consisted of an electrified insulator probe, which created an electrostatic field around its pointed tip, and attracted conidia within its electric field. The attractive force created by the probe tip was directly proportional to voltage, and was inversely proportional to the distance between the tip and a target colony on a leaf. Pseudochain conidia were successfully collected by bringing the electrified probe tip close to target colonies on leaves. In this way, conidia were collected from colonies at 3-d intervals. This effectively collected all conidia from conidiophores before they dropped to the leaf surface. A high germination rate was observed among conidia attracted to the probe tip (95.5 ± 0.6 %). Conidia were easily suspended in water with added surfactant, and retained their germination ability. These conidia were infective and produced conidia in pseudochains on conidiophores after inoculation. The electrostatic spore collection method can be used to collect conidia as they form on conidiophores, thus obtaining an inoculum population in which all of the conidia germinate simultaneously.     

Infection process of Colletotrichum dematium on mulberry leaves: An unusual method of sporulation

Abstract

The pre-penetration and infection process of Colletotrichum dematium on mulberry leaf was investigated by scanning electron microscope. Conidia produced on germination appressoria directly or at the end of short germ tubes. Appressoria were formed mostly over cuticle, but sometimes over stomata also. At 72 h post-inoculation, an extensive network of sub-cuticular runner hyphae (RH) was produced. The RH were traceable by the cuticular bulgings on leaf surface. The RH emerged to leaf surface through ruptured cuticle to form secondary infection hyphae (SIH). The SIH re-entered the leaf tissue by sending penetration branches through stomata. Conidia were formed singly on short conidiophores from the RH and SIH, at short intervals. The conidia developed on RH were exposed to leaf surface through ruptured cuticle. Some times conidia were released through stomata also. The RH and SIH had thick knots from which hyphal branches and conidia were developed. Definite acervuli were not developed.     

Dactylella chichisimensis, sp. nov. in the Bonin (Ogasawara) Islands, Japan

ADactylella isolate obtained from soil in the Bonin (Ogasawara) Islands, Japan is described and illustrated as a new species,D. chichisimensis. The fungus is characterized by single terminal multiseptate clavate or ellipsoidal conidia at the apex of simple conidiophores and mycelium that forms chlamydospores and sclerotia. A key is provided for sixDactylella species that produce primary clavate or ellipsoidal conidia at the apex of simple conidiophores.     

马齿苋叉梗孢一中国新记录

<正>Dichotomophthora was erected by Mehrlich & Fitzpatrick in 1935. Its distinctive characteristics are regularly dichotomously branched or lobed at the apex of conidiophores and brown,     

尘白灯蛾的病原真菌新种——福建虫瘴霉

本文报道了采自福建南平尘白灯蛾的病原真菌新种:福建虫瘴霉(Furia fujianaHuang et z.z.Li sp.nov)该菌分生孢子单核,双囊壁,倒卵形,16.0-25.8 ×8.4-18.4μm,平均20.0×9.9μm,长径比1.5-3.0,平均2.0。次生分生孢子梨形,平均18.4×11.7μm。分生孢子梗棍棒状,二歧分枝或单枝。有假根和囊状体,基本等粗于孢子梗。假根不形成明显分化的固着器。休眠孢子光滑,20.3—22.8μm。     

Digitomyces, a new genus of hyphomycetes with cheiroid conidia

The new anamorphic genus Digitomyces, based on Dictyosporium verrucosum, is proposed. It is characterized by micronematous or semimacronematous conidiophores, integrated or discrete, holoblastic, determinate conidiogenous cells, and olivaceous to pale brown, verrucose, cheiroid conidia, with a truncate basal cell and (2-)3 arms. The new taxon is compared with morphologically similar anamorph genera.     

Conidiation of Hirsutella thompsonii var. synnematosa in submerged culture

Fourteen monosporal isolates of Hirsutella thompsonii grew vegetatively in various liquid media producing typical phialidic-like conidiophores. Hirsutella thompsonii var. synnematosa from Ivory Coast (HtIC) was the only pathotype which produced true conidia in submerged culture. HtIC began producing conidia after 3 days incubation reaching a peak ranging from 6.8 × 10⁵ to 9.7 × 10⁷ conidia/ml between 6 and 11 days. A concentration of 10 g/liter of corn steep liquor and 0.2% Tween 80 were essential for maximum conidiation. Submerged conidia had a smooth but somewhat rugose conidial walls, whereas aerially formed conidia were distinctly verrucose. Germination of submerged conidia ranged from 5.2 to 12.9% and were virulent causing 32.5% infection to adult citrus rust mites when sprayed on citrus foliage at 1.2 × 10⁹ conidia/ml.     

<Emphasis Type="Italic">Myrothecium dimorphum</Emphasis>, sp. nov., a soil fungus from beach sand in the Bonin (Ogasawara) Islands,Japan

A new Myrothecium species isolated from beach sand in the Bonin Islands, Japan, is characterized by dark green sporodochia composed of conidiophores with verticillate phialides and ovate and ellipsoidal, often curved conidia on their apexes mixed with erect, straight setae, and seta-like conidiophores with terminal polytomous structures composed of 2–8 digitate polyphialides bearing single globose conidia at each apex.     

Occurrence of a new species of cephalosporium in the rhizosphere of Vitis vinifera L

Summary A new species ofCephalosporium has been described. The colony at maturity turns pink. The conidiophores are straight and long or sometimes curved while the conidia are almost elliptical with an oval apex and a slightly pointed base.     

Infection Process of Botrytis cinerea on Eucalypt Leaves

This study aimed to elucidate the infection process of Botrytis cinerea on eucalypt leaves. Tests were conducted to evaluate the influence of leaf side (adaxial or abaxial), leaf age and luminosity on conidial germination, appressorium formation and grey mould (GM) severity. The adaxial and abaxial surfaces of detached eucalypt leaves were inoculated with a conidial suspension of B. cinerea and kept under constant light or dark. Subsequently, the adaxial surface of young and old leaves was inoculated and kept in the dark. To evaluate the percentage of conidia germination and appressorium formation, leaf samples were collected 6 hours after inoculation (hai), clarified (alcohol and chloral hydrate) and evaluated under a light microscope. The severity of GM was assessed 10 days after inoculation. For scanning electron microscopy analysis, samples were collected from 2 to 168 hai. A higher percentage of conidia germination (92%) and GM severity (21%) occurred on the adaxial surfaces of leaves kept in the dark. There was no statistical difference between the surfaces of young and old leaves for conidia germination. No appressorium was formed by B. cinerea. The GM severity on young leaves (17.3%) was 34 times higher than on old leaves (0.5%). The micrographs showed germinating conidia emitting 1–4 germ tubes in samples at 4 hai. The fungus penetration occurred through intact leaf surfaces, and both extra‐ and intracellular colonization of the mesophyll cells by the hyphae of the pathogen were observed at 120 hai. Sporulation occurred on the adaxial and abaxial surfaces (macronematous conidiophores) and below the epidermis (micronematous conidiophores).     

Entomophthora lampyridarum,a fungal pathogen of the soldier beetle,Chauliognathus pennsylvanicus

In 1974 and 1979 in Clemson, South Carolina, adults of the common soldier beetle, Chauliognathus pennsylvanicus, were found to be infected by the fungal pathogen, Entomophthora lampyridarum. After infected beetles died they remained attached by their mandibles to foliage and flowers. The wings of infected beetles remained open, allowing conidiophores to develop on the upper surface of the abdomen. Primary conidia were elongate and measured 36.5 × 17.1 μm. Two types of secondary spores were formed: Type I spores were similar in form to primary conidia, but were somewhat smaller; Type II spores were formed at the apex of slender stalks and measured 37.7 × 15.3 μm. Resting spores were spherical, hyaline, and 22.3 μm in diameter.     

Two new species of the staurosporous hyphomycetous genera Ceratosporium and Diplocladiella from Taiwan

Ceratosporium verrucosum and Diplocladiella alta are described as new species. Ceratosporium verrucosum was found on a dead bamboo culm and D. alta on rotting wood in Taiwan. Compared with the other species of Ceratosporium, C. verrucosum differs by the verrucose ornamentation covering the arms of the conidia. Diplocladiella alta is easily distinguished by the length of its conidiophores. For comparison with the previously described species of Ceratosporium, type material of C. fasciculare first was reexamined and Bactrodesmium submoniliforme recognized as the correct name for this species.     

Mode of Infection of Phyllosticta maculata on Banana as Revealed by Scanning Electron Microscopy

The initial infection stages of Phyllosticta maculata on banana were studied using scanning electron microscopy. Conidial germination on the banana leaf surface commenced within 3 h postinoculation to produce a long and slender germ tube. The hyphae developed secondary branches and mostly grew randomly across the leaf surface. Appressoria were formed at the apex of the germ tubes within 18 h postinoculation and were variable in shape. A layer of an extracellular matrix surrounded the appressoria at the pathogen–host interface. On the fruit surface, conidia germinated to produce predominantly swollen germ tubes which functioned as lateral appressoria together with some slender ones. These germ tubes were formed within 3 h postinoculation. There was no stomatal penetration apparent on the leaf; instead, direct penetration through the cuticle with and without the formation of appressoria was observed. Cuticular degradation on the leaf surface was evident with a circular, darkened area around the point of penetration by hyphae or appressoria. The significant role of pycnidia and conidia in the epidemiology of the disease was further demonstrated in naturally infected leaf samples.     

The infection process, sporulation and survival of Alternaria helianthi on sunflower

Electron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.     

Surface Ultrastructural Studies on Penetration and Infection Process of Colletotrichum gloeosporioides on Mulberry Leaf Causing Black Spot Disease

Unicelled conidia of Colletotrichum gloeosporioides germinated 3 h after inoculation producing single germ tubes. The orientation of the germ tubes and their lateral branches as they grew was towards the open stomata and away from closed stomata. By 24 h post-inoculation, the lateral branches had developed specialized infection vesicles either over the stomata or within the stomatal cavities. The infection vesicles produced primary infection hyphae which entered the leaves through stomatal openings. The disease symptoms became apparent by 6 days post-inoculation when clusters of abundant conidiophores emerged by rupturing the leaf epidermal layer, forming acervuli mostly near the base of idioblasts. The pressure exerted by the emerging conidiophores caused stretching of epidermal layer leading to the widening of the acervuli. The conidia are borne on the tips of the erect conidiophores.     

A NEW FUNGUS ON CYPERUS IRIA

Thind , K. S., and G. S. Rawla . (Panjab U., Chandigarh, India.) A new fungus on Cyperus iria. Amer. Jour. Bot. 48(10): 859–862. Illus. 1961—Duosporium cyperi gen. et sp. nov., collected on Cyperus iria Linn., is characterized by the production of 2 types of conidia, macroconidia and microconidia. The macroconidia are straight, cylindrical, triseptate, with their middle cells dark brown, long, thick-walled, and end cells much paler or subhyaline, short, thin-walled, the middle and the end cells being equally wide. The microconidia are nonseptate, spherical, dark brown, prominently verrucose, and produced apically on the conidiophores like the macroconidia; occasionally also formed as secondary conidia on germinating 3-septate macroconidia in culture. The formation of 2 distinct types of conidia in Duosporium and the features of its macroconidia characteristically differentiate it from its close relative Helminthosporium, although Duosporium. cyperi is not unique among fungi in producing 2 types of conidia.     

Production and Dispersal of Conidia of Peronospora pisi on Pea Leaves

The number of crops of conidiophores and conidia of Peronospora pisi produced on a single lesion on leaflets of pea (Pisum sativum L.) was determined both in vitro and in vivo by artificial inoculation. Only two crops were produced in vitro whereas five crops were discerned under in vivo conditions. There was a marked difference in the size of conidiophores and conidia formed under the above two conditions. Temperature had a marked effect on the penetration of pea leaflets by conidial germ tubes of P. pisi. The pathogen penetrated the leaf tissues at 12-14°C in 8.0-8.5 h whereas more time (9.5-16.5 h) was required for penetration at higher temperatures (15-18°C). Use of systemic fungicides has been suggested to control downy mildew of pea because of its capacity to produce more than one crop of propagules on the same lesion. Maximum spore discharge in P. pisi was observed from 9.00 to 15.00 hours. However, presence of light, high temperature, lack of moisture on leaf surface and wind velocity affected spore discharge.