Wound Parasite Research Articles

Diplodia pinea . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Diplodia pinea . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Pinus species. Also on Abies excelsa, Araucaria cunninghamii, Chamaecyparis lawsoniana, Cupressus macrocarpa, Cupressus lusitanica, Cupressus sempervirens, Picea abies, Pseudotusga menziesii, P. taxifolia and Thuja orientalis [Platycladus orientalis] . DISEASES: Tip and twig blight, stag-head, red top, bud-wilt and seedling collar rot of conifers. Causes stunting of new growth, browning of needles, bending or curling of young shoots and discoloration and death of parts of the crown. Also affecting germination of Pinus seed and causing blight and dieback of coniferous seedlings in the nursery. Frequently found as a wound parasite of injured or weak trees causing bark cankers and dieback of branches and as a saprophyte causing blue-stain of sap-wood of fallen or freshly cut timbers (17: 150; 36: 436; 41: 339). GEOGRAPHICAL DISTRIBUTION: Africa (Kenya, Malawi, Mauritius, Mozambique, Rhodesia, S. Africa, Tanzania, Uganda); Asia (Japan, Malaysia, Thailand); Australasia & Oceania (Australia, New Zealand); Europe (Austria, Belgium, France, Germany, Italy, Portugal, Rumania, Spain, Sweden, U.K.); North America (Canada, U.S.A.); Central America & West Indies (Jamaica), South America (Argentina, Brazil, Chile, Paraguay). (CMI Map 459, 1969). TRANSMISSION: The pathogen is disseminated as spores by wind, rain and in fluid secreted by the pine spittle-bug, Aphrophora parallela and as mycelium on seed of Pinus (16: 219; 21: 398). Infection may take place through natural infection courts such as leaf traces or cones and cone-stalks (5: 708; 48, 3187) as well as through living tissues following wounding (31: 1; 44, 889; 48, 3187) or damage from hail (8: 535; 16: 219; 20: 150), frost (21: 398; 40: 388) or insects (pine spittle-bug, 21: 398; bark beetles, Myelophilus piniperda [Tomicus piniperda] , 14: 727) or attack by rust, Cronartiurn ribicola , causing progressive wilt in Pinus halepensis (25: 493) or by drought (14: 65) or other unfavourable growing conditions (13: 426, 553; 16: 148). Gilmour found that the amount of infection in P. radiata appeared to be correlated with trunk wounding and varied with the type of pruning tool used: secateurs, 12%; axe, 48%, slasher, 68% (44, 889). The pathogen may persist in infected tissues up to 400 days (48, 3187) and is commonly saprophytic on forest debris which provides a source of abundant spores during periods of rain (41: 339).

Testing onions (Allium cepa L.) and otherAllium species for resistance toBotrytis allii Munn.

While various methods of testing for neck rot resistance were compared, it was found thatBotrytis allii behaves as a wound parasite and that its pathogenicity is rather low. The degree of infection was strongly influenced by the amount of inoculum by the temperature at which the cultures were stored and by storage duration. Besides, infection appeared to be much influenced by pre-treating, the inoculated bulbs, the method of inoculation and finally the environmental conditions after inoculation.

Penicillium digitatum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Penicillium digitatum . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On decaying citrus fruit. DISEASE: Green mould of citrus fruit. Growth is rapid atter infection, the fruit surface becoming covered in a white mould which quickly becomes olive due to the production of the conidia. The fruit then softens and begins to shrink and if exposed to the air becomes a hollow mummified shell. Distinct from Penicillium italicum (see CMI Descript. 99) which is blue-green and finally reduces the fruit to a slimy mass. GEOGRAPHICAL DISTRIBUTION: Common in all citrus producing areas, but widespread as a storage rot of citrus fruit. TRANSMISSION: Common in soil of citrus producing areas and enters the fruit as a wound parasite but will not penetrate undamaged fruit. Said to occur more frequently than P. italicum on fallen fruit on light soil in Israel (31: 603). Spores also particularly abundant in air of citrus packing houses and fruit conditioning rooms (40: 400; 41: 89).

A canker and wilt disease of pimento ( Pimenta officinalis) caused by Ceratocystis fimbriata in Jamaica

The symptoms of this widely occurring disease are described. The disease is shown to be caused by a strain of Ceratocystis fimbriata Ell. & Halst. which is a wound parasite probably specific to pimento since inoculation experiments carried out on cacao, coffee, and sweet potato gave negative results. The disease can be controlled by careful pruning and the removal of the infected limbs; these measures are discussed in relation to the habits of the parasite and methods of cultivation. Comparisons are made between this and other similar diseases of tree crops.

Appressoria of Gloeosporium musarum Cke. and Massee on Banana Fruits

Gloeosporium musarum is one of the most important fungi causing rotting of banana fruits during transport and storage1,2. Although the fungus is of greatest commercial concern when acting as a post-harvest wound parasite, it also infects unwounded immature fruit in the field2–4. These early infections do not become manifest until the fruit starts to ripen after harvest; such infections are known as ‘latent infections’. The basis of latency in G. musarum was elucidated by Simmonds3 and Chakravarty5. In a water film on the fruit surface, conidia of G. musarum germinate within 4 h. After elongating for a variable distance, the germ tube swells at the tip to form an appressorium. After 24–72 h, a fine infection hypha grows from the appressorium and pierces the cuticle by mechanical means. No further penetration occurs until the fruit starts to ripen. Simmonds3 concluded that this subcuticular hypha is the form in which the fungus survives its period of latency, which may exceed 5 months in Australia. When the fruit is mature, the subcuticular hypha resumes activity and penetrates the cellulose wall of the epidermis cell; the fungus then spreads through the tissues to cause a typical anthracnose lesion.

BRANCH AND STEM CANKERS OF WHITE AND NORWAY SPRUCES IN ONTARIO

A branch and stem canker disease of white and Norway spruce was investigated in southern Ontario. The disease was found to be associated with the occurrence of Valsa Kunzei var. picea, a wound parasite commonly occurring on spruce in central and eastern United States and Canada. A study of tree growth in relation to the development of stem cankers revealed that stem-cankered trees had been predisposed to the attack, as indicated by a sudden decrease in diameter growth one or more years in advance of the infection.The predisposing factor is believed to be drought, which weakens trees with a poorly developed root system, thus causing the reduced diameter growth and permitting fungus infection of the main stem and the later developmnet of stem cankers.Spruce grown on sites with a continuous supply of aerated soil water will not be affected by the disease if crowding of trees in the stand is avoided.

Botryodiplodia Theobromae and its Association with Musa Species

Botryodiplodia theobromae Pat. is a common and widespread fungus in tropical areas, where it is well-known as a wound parasite on a wide range of host plants. A partial list of the recorded hosts includes citrus (Nowell, 1923; Pole-Evans, 1910), rubber (Cook, 1913; Petch, 1921), tea (Cook, 1913; Johnston, 1960), cacao (Charles, 1906; Cook, 1913; Griffon and Maublanc, 1909; Petch, 1921; Urquhart, 1961), sugar cane (Howard, 1901; Nowell, 1923), cotton (Johnston, 1960; Patouillard, 1922), tung (Large, 1948), oil palm (Johnston, 1960; Zambettakis, 1950), mango (Charles, 1906; Zambettakis, 1950), coffee (Massee, 1909, Riley, 1960), papaya (Petch, 1921; Zambettakis, 1950), castor bean (Riley, 1960), cashew (Riley, 1960), tobacco (Averna-Sacca, 1922), peanut (Wilson, 1947), and banana (Wardlaw, 1935). B. theobromae is considered by most authors to be a weak pathogen, invading its hosts only through wounds or necrotic tissue. It occurs as a seedborne fungus in rubber, cotton, and cacao (Noble et al., 1958), and has also been isolated from soil in Central America (Farrow, 1954) and Africa (Meyer, 1959), and from decaying military materiel in a number of tropical areas (Reese et al., 1950). Botryodiplodia theobronmae has been known to occur on banana since 1913 when Ashby (1913) reported finding it associated with a rhizome disease in Jamaica. Wardlaw (1931) isolated the fungus from decaying banana fruit in Jamaica, and through inoculation trials demonstrated that it was capable of causing rapid decay of banana fruit in storage. Von Becze (1932) isolated B. theobromae from Jamaican and Brazilian fruit, but did not regard it as a serious rot pathogen, apparently because of its infrequency among the fungi isolated. Roy and Sharma (1952) reported that B. theobromae attacked most of the table varieties of banana in Punjab and Bihar, and Chona (1933) cited it as the cause of pseudostem rot, main stalk (inflorescence axis) rot, and a black or

Preliminary study on the varictal resistance of Standing cane to Pine apple disease and the influence of the discase on the juice quality

Pine apple disease caused by Ceratostomella paradoxa do synes was for the first time noticed by Wont in Java in 1893. Since then this has been reported in every sugar producing country through out the world. This is primarily a disease of the stalk. The causal organism is a wound parasite and once it invades the cane stalk it develops rapidly in the parenchyma of the tissue and destroys it. Since the cut ends of the cane setts are exposed, this explains why the disease is very commonly found in the sugar cane setts used for planting. The occurence of this disease is not very common in the standing canes. In 1933 it was reported to have been found in the standing canes in Coimbatore by Subramaniam (L. S.) Incidence, of this disease though reported to be of rare occurence, of late it has been found in several varieties of the standing canes in some places of the sugarcane areas of this tract. The incidence varying from 3.9% to 21.8% was recorded in some varieties of the standing eanes in Nellikuppam area by Subramaniam (C. L.) during the year 1955-'56.

The Ascocarps of Aspergillus Alliaceus

Aspergillus alliaceus, described in 1926 by Thom and Church (4) as a new species in the A. wentii Group, was based upon two strains: C.T. 4660, isolated by Eddy from a decaying garlic bulb sometime prior 1924 when it was discussed without name by Walker and Lindegren (6) as a wound parasite of onions; and C.T. 4656, isolated from a dead blister beetle (Macrobasis albida) by Cohen and High of the Bureau of Chemistry and submitted Thom for identification in 1922. Thom and Church recognized that A. alliaceus, as exemplified by these strains, might develop a perfect stage, and in their original description reported unsuccessful attempts to induce the development of an ascogenous phase in these sclerotia whose appearance is so suggestive of perithecia. The discovery by Raper, Fennell, and Tresner (3) of an ascosporic stage in the sclerotioid parenchymatous structures of Aspergillus citrisporus and A. ornatus, members of the sclerotial A. tamarii section of the genus, further suggested that the development of a perfect stage by other sclerotium-producing species of Aspergillus could be anticipated. Although careful examination of sclerotia from numerous cultures of the A. wentii and A. flavus Groups over a period of many years had failed disclose a single ascosporic strain, these authors recognized the possibility of their existence and concluded that extension of our search for additional forms, and the introduction of new procedures for isolating them, may in time justify our optimistic hope. During an investigation of the fungous flora of Australian soils by one of us (J. H. W.), many species of Aspergillus were isolated. All such isolates were held for extended periods and, following publication of the description of A. ornatus, these forms were re-examined for the presence of a perfect stage. The sclerotia of two isolates, SA 15 and SA 117, in cultures about a year old were discovered be full of spores. In order determine their nature, new cultures were prepared and examined at regular intervals; after three months,

FURTHER OBSERVATIONS ON THE PATHOGENICITY OF CALONECTRIA RIGIDIUSCULA (BERK. & BR.) SACC. TO THEOBROMA CACAO L

Quantitative data are provided for the occurrence of Calonectria rigidiuscula and other fungi in occluded Mirid lesions and other sites in shoots of cacao plants. Mirid lesions appear to be particularly favourable for the development of C. rigidiuscula. The fungus also occurs as a saprophyte on cacao pods, and as a wound parasite in woody plants other than cacao; it was successfully introduced into plants of varied affinities by inoculation. C. rigidiuscula spreads from inoculations in cacao stems much more rapidly than other fungi. The results confirm that it is the most important fungus infecting Mirid lesions and causing dieback of cacao in West Africa.Inoculation tests with a range of Amelonado and Trinitario clones suggested that the clones vary in their susceptibility to C. rigidiuscula, but the plant‐to‐plant variation was too great to conclude that any one is highly resistant. Various types of introduced cacao were also tested; preliminary experiments indicate that certain types of Upper Amazon cacao may be resistant, but they need further investigation.

Two new species of fungi on clove trees in the Zanzibar Protectorate

Two species of fungi pathogenic to clove (Eugenia aromatica) are described from the Zanzibar Protectorate. Valsa eugeniae sp.nov. occurs in constant association with clove trees which have died of the Sudden-death disease, and also causes a die-back. Cryptosporella eugeniae Nutman & Roberts is a severe wound parasite of clove trees of all ages, and often causes the sudden death of young trees.

Some effects of host-plant physiology on resistance to viruses

Although the subject for discussion is the physiology of disease resistance, I propose to take a more restricted topic and to deal only with variations in the degree and type of resistance shown towards viruses by susceptible hosts. I do this because we know a little of some of the conditions that affect the reactions of susceptible plants, but we know nothing of the causes that render most plants immune from most viruses. With viruses, as with other kinds of pathogens, immunity is the common state of plants and susceptibility is the exceptional. Indeed, all uninjured plants appear to be immune from all viruses, and though there are a few viruses that can infect a wide range of different plants through suitable wounds, most viruses have only a narrow host range even as wound parasites. Presumably immunity is con­ferred on most species because their cells either contain substances that are antagonistic towards individual viruses or they lack substances that are essential for multiplication of the viruses. Extracts of many plants do contain substances that act as inhibitors of infectivity when mixed with viruses in vitro , but whether such substances play any part in conferring resistance in vivo is uncertain. We know nothing of the growth requirements of any viruses that attack flowering plants, but it is perhaps worth noting that there are bacterial viruses that lyse certain bacteria only when specific amino-acids are supplied to the culture media. When we consider the types of resistance shown by susceptible hosts towards viruses, we find some that are common to other forms of infectious diseases but also additional ones peculiar to virus diseases. This could be expected, for viruses possess an unusual combination of properties. They are the only pathogens that are both obligate and wound parasites. For their spread from plant to plant most of them depend on the activities of certain vectors, of which the most common are leaf­-sucking insects. A further peculiarity is their ability to cause systemic infections, for in most hosts viruses spread from a single entry point to invade all the vegetative parts of the plant that are still actively growing. It is this ability to permeate the whole system of infected plants that gives us with virus diseases the only authentic examples in plant pathology of acquired resistance to disease and provides perhaps the biggest contrast between virus and other types of disease. There are two rather different types of behaviour that come under this heading, both of which simulate conditions usually considered more typical of diseases of animals than of plants.

Observations on the perennial canker fungus: Gloeosporium perennans Zeller & Childs

1. A fungus isolated from canker and dieback of branches and apple rots in this country is shown to be Gloeosporium perennans Zeller & Childs. 2. Cross inoculations demonstrated the identity of the fungus causing branch lesions with that infecting fruits. 3. Some morphological characteristics of G. perennans are described. 4. Controlled infection experiments, show that G. perennans is an active wound parasite of apple branches, but is unable to penetrate uninjured bark ; it cannot penetrate the unbroken skin of the fruit but can traverse the skin through a lenticel. 5. The rate of growth of the fungus and the rate of decay it causes in apple fruits are compared with those of G. album and G. fructigenum . G. perennans grows at ápproximately the same rate as G. album and much more slowly than G. fructigenum .

A New Pseudonectria on Pachysandra

SUMMARYThe canker-blight disease of pachysandra is caused by a new species of ascomycete, Pseudonectria pachysandricola, which is a wound parasite. The perithecia usually arise from stornata which ...

A New Pseudonectria on Pachysandra

SUMMARYThe canker-blight disease of pachysandra is caused by a new species of ascomycete, Pseudonectria pachysandricola, which is a wound parasite. The perithecia usually arise from stornata which represent the basal remains of sporodochia of the Volutella stage. The perithecial stage follows closely the conidial stage which is most in evidence during May and June, at least during periods where moisture is plentiful.The connection between the two stages has been established culturally and by inoculation tests.

RHIZOPUS ROOT ROT OF SUGAR BEET

During the summer of 1942 sugar beets growing in an experimental plot at the Harrow laboratory were destroyed by a root rot of a type that apparently has been reported only once previously on this host in North America. Wilting of the foliage first attracts attention to affected plants, the roots of which show, externally, grayish-brown discoloured areas and, internally, fairly sharply-delimited, grayish to coffee-coloured lesions, affected tissues being more or less spongy in consistency. The causal organism, found to be a wound parasite, has been identified as Rhizopus arrhizus Fischer. The effect of temperature on the growth in culture and on the pathogenicity of this fungus and of representatives of the species, R. oryzae and R. nigricans, has been studied. It has been found that R. arrhizus and R. oryzae are relatively high temperature organisms, showing optimum growth at about 34° to 36 °C., and each capable of infecting and destroying artificially injured sugar beets most rapidly between 30° and 40 °C. R. nigricans, also a wound parasite is, on the other hand, a relatively low temperature organism showing optimum growth in culture at about 24° and displaying highest infection capability at about 14° to 16 °C.

Studies on two Strains of Aphano—Myces Laevis found Occurring as Wound Parasites on Crayfish

Studies on two Strains of Aphano—Myces Laevis found Occurring as Wound Parasites on Crayfish

Studies on Two Strains of Aphanomyces laevis Found Occurring as Wound Parasites on Crayfish

During 1937 and 1938 a number of young crayfish (Cambarus Clarkii Girard) which had recently been operated upon in these laboratories 3 died, apparently as the result of infection with a water mould which after isolation was tentatively identified as Aphanomyces laevis De Bary. Since this species is not very clearly defined, and has never been reported as parasitic upon animals, and because of the fact that a severe, recurring epidemic disease of European crayfish is caused by a species of Aphanomyces (A. astaci -magnusi Schikora), which is, however, quite different from A. laevis, the following studies were made to determine more carefully the morphology, development, and taxonomic position of the present fungus. Two strains, A and B, believed to be A. laevis have been isolated, each from a different lot of crayfish. These isolates, although morphologically very similar, show important' physiological differences which are of interest in view of the varying descriptions of A. laevis that have previously been given. The hyphae of both strains are slender and whitish, rather straight, with occasional side branches given off nearly at right

A STUDY OF POLYPORUS BETULINUS (BULL.) FRIES

SUMMARY An introductory survey is given of the distribution, synonyms, etc., of Polyporus betulinus (Bull.) Fries. In an investigation of the parasitism of the fungus negative results were obtained from infection experiments, but field observations force the writer to the opinion that the organism is a wound parasite. The effect of the fungus on attacked wood was traced in nature and in culture. The type of breakdown produced is regarded as a red‐brown cubical rot, attacking both sapwood and heartwood. A study of the enzyme content of the fungus showed that it contained ferments capable of attacking lignin. The characters of the mvcelium were investigated and the fungus is classified according to Fritz's work. Black lines are formed in culture. They are frequently related in position to bulbils (sclerotia). It is suggested that here, as elsewhere, the hyphae of the black line may be regarded as forming the limiting layer of a resting stage of the fungus. The fertile portion of the sporophore consists of a hymenium lining very numerous pores. The basidia form a continuous row of club‐shaped cells, interspersed with cystidia. These latter appear to be the terminal portions of fibre hyphae. The sequence of nuclear phenomena in the basidium was traced. The period of spore discharge was determined for the species and for individual sporophores. The life of the fungus has been observed from spore to spore in culture during a space of 3 months. Monospore cultures were obtained. The fungus is heterothallic. The spores were shown to fall into two groups when twelve monospore colonies were paired in every possible way. Monosporous mycelia have single nuclei and no clamp connexions. Mycelia which are polysporous in origin contain conjugate nuclei and bear clamp connexions.

Sporulation of the Phialophora Type in Hormodendrum

Hormodendrum is an important genus of the Fungi Imperfecti. Its species have a wide geographical distribution and are commonly present in soil and decaying vegetation. Because of the ubiquity of its wind-blown spores it is a familiar culture weed of the laboratory. M/ost species of the genus are saprophytes, but at least two are facultative pathogens of man and there cause a skin disease known as dermatitis (chromoblastomycosis). This disease apparently is not contagious, and the evidence at hand indicates that the fungus is a wound parasite capable of growing in animal tissue only after its introduction upon some foreign body such as a thorn. In this respect it is like some of the other mycotic diseases in which the parasitic agent requires certain special, and in some cases, unknown conditions before it becomes pathogenic, but once established in the human body, it is extremely difficult to dislodge. Dermatitis verrucosa occurs chiefly in the tropics, and more rarely in temperate climates. Three cases have been reported from the United States. The disease is generally characterized in man by the formation on an extremity, usually a leg, of warty or cauliflower-like outgrowths of the skin (FIG. 1). In some cases it has been possible to obtain from the patient a history of some slight injury to the foot, followed by the slow appearance and development of a small initial lesion. By slow extension of this primary lesion the entire lower leg may become involved. Extension of the pathologic process is not rapid, and a duration of several years, without metastatic spread, and without serious interference with the activities of the patient is the rule. Sections of the infected tissue show the fungus present in the form of subspherical pigmented cells often occurring in pairs or short chains. In spite of