The infection of oranges by Trichoderma viride and mixed infection by Trichoderma viride and Penicillium digitatum

Trichoderma viride spores applied in water to apparently uninjured skin of oranges do not cause lesions. Adding orange juice, rind extract, citric acid or orange essential oil did not influence infection. Oranges became infected only when the stem-end cuts or wounds deeper than 6 mm into oil vesicles were inoculated. Sound oranges in contact with decayed oranges did not become infected. Diphenyl-impregnated wrappers reduced infection. A mixed inoculum of T. viride and Penicillium digitatum caused as fast rotting as P. digitatum, which caused faster rotting than T. viride alone. Lesions infected with P. digitatum could become infected by T. viride but those caused by T. viride did not become infected by P. digitatum. T. viride was antagonistic to P. digitatum in vivo and in vitro, possibly because it produces a heat-labile diffusible substance toxic to P. digitatum.     

Green mould of oranges caused by Penicillium digitatutn Sacc.; effect of additives on spore germination and infection

Water extracts of rind, essential oil and juice from oranges, also citrus pectin and citric acid promoted the formation of lesions when spores of Penicillium digitatum were placed in wounds 1·0 mm deep in flavedo of oranges; fructose, glucose and sucrose had little effect. Rind extracts were less effective in wounds 0·5 mm deep but orange juice and pectin still increased infection. None of the substances allowed the parasite to infect fruit through unwounded surfaces. Germination of spores in water increased as spore concentration decreased but was poor even at low concentrations. Almost all spores germinated in aqueous extracts of flavedo, albedo or whole rind, or in wounds on the surface of fruit. Fructose, glucose, sucrose and xylose were less effective but still caused over two-thirds of spores to germinate but only in the presence of phosphate buffer. Without buffer, germination was little different from that in water. Arabinose and galactose stimulated germination to a lesser extent but with the same phosphate effect. Carboxymethylcellulose and pectin did not affect germination. A variety of substances containing nitrogen increased germination but to different degrees, decreasing in the order, casamino acids, yeast extract, ammonium salts, nitrate. Thiamin and to a lesser extent biotin were also effective. Volatile substances from rind infected with P. digitatum stimulated spore germination and growth of germ tubes. The significance of these results is discussed in relation to infection.     

Control of Fusarium solani rot of potato tubers with fungicides

Tecnazene (up to 33 ppm) and dichloran (up to 500 ppm) had little effect on germination of spores or growth of Fusarium solani isolated from and causing a rot of potato tubers; they also did not decrease rotting when applied to wounds later inoculated with the pathogen. Benomyl and thiabendazole (up to 500 ppm) also had little effect on spore germination but did greatly decrease growth at 5 ppm. A pronounced pink coloration developed in cultures growing slowly in the presence of benomyl; a similar though less striking effect appeared in agar cultures containing thiabendazole. Benomyl suspended in water or diluted with Fuller's earth gave good control of rotting when applied to wounds inoculated later with F. solani. Still better control was obtained with thiabendazole; dusts containing 1% a.i. substantially decreased rots and those containing 10 % a.i. gave almost complete control when applied to wounds shortly before inoculation. Thiabendazole was also very effective when used 24 h after inoculation and a fair measure of control was obtained when it was applied 24 h later. Benomyl and thiabendazole placed on apparently intact surfaces of tubers caused tissue 5 mm deep to become toxic to F. solani 10 days later, and, unexpectedly, this tissue prevented spore germination. Fuller's earth alone substantially decreased rotting. The results obtained suggest that dusts containing thiabendazole have some promise for the control of Fusarium rots of potato tubers, especially of early crops.     

The influence of potato harvesting and grading machinery on contact spread of Phoma exigua var. foveata on tubers

The incidence of wounds infected by Phoma exigua var. foveata was increased if freshly damaged tubers (recipients) were shaken in a bag with diseased tubers (donors) to simulate the tuber-to-tuber contact that occurs during potato handling. An increase in the number of gangrene rots on damage points also occurred if the recipient tubers were wounded after contact with the diseased tubers, rather than before, and when the donor tubers were heavily infested with P. exigua var. foveata but were free of gangrene lesions. Increasing the proportion of donor to recipient tubers increased the percentage of infected wounds on recipients. Increased incidences of infection in recipient tubers also occurred after they had been passed over an elevator digger when it was lifting stocks of tubers heavily infested with P. exigua var. foveata. When spores of an E +ve isolate of P. exigua var. foveata were sprayed onto the webs of manned potato harvesters, tubers harvested immediately after developed gangrene rots from many of which the E +ve isolate was cultured. An E +ve isolate was also used to demonstrate the transfer of P. exigua var. foveata inoculum from tubers onto soil on riddles of a potato grader and from these soil-coated surfaces onto other tubers during grading.     

Sources of Gas Gangrene in Hospital

Of four cases of postoperative gas gangrene in three hospitals three followed amputation of legs with gangrenous lesions, and one followed gastrectomy. Clostridium welchii was isolated from the wounds and the faeces of each patient; small numbers of Cl. welchii were found on the floors of the theatres where the operations had been performed.Two infections occurred in one hospital on successive days. Typing of strains of Cl. welchii from these patients showed that they were serologically distinct. Further studies suggested that in each of the four cases infection was probably acquired from the patients'' intestinal flora, probably through faecal contamination of skin.In 76 patients sampling of the skin with surface contact plates showed occasional heavy contamination of the thighs, groins, and buttocks with Cl. welchii, most of which were present as spores or sporing bacilli; Cl. welchii was more commonly found in patients with incontinence of faeces. Compresses of povidone-iodine applied for 30 minutes were found greatly to reduce the numbers of Cl. welchii, and swabbing with 70% alcohol was effective in some cases; washing with soap and water had no effect on the numbers of Cl. welchii on the skin.     

Biological control of postharvest blue mold of oranges by <Emphasis Type="Italic">Cryptococcus laurentii </Emphasis>(Kufferath) Skinner

Cryptococcus laurentii (Kufferath) Skinner was evaluated for its activity in reducing postharvest blue mold decay of oranges caused by Penicillium italicum in vitro and in vivo. The results showed that washed cell suspensions of yeast provided control of blue mold decay better than yeast in culture broth. Autoclaved cell culture and cell-free culture filtrate failed to provide protection against the pathogen. The concentrations of antagonist had significant effects on biocontrol effectiveness. When the washed yeast cell suspension reached the concentration of 1 × 10⁹ CFU/ml, challenged with pathogen spore suspension at 1 × 10⁴ spores/ml, the blue mold decay was completely inhibited during 5 days of incubation at 20 °C. No complete control was obtained when oranges were stored at 4 °C for 30 days, but the decay was distinctly prevented. Efficacy of C. laurentii was maintained when applied simultaneously or prior to inoculation with P. italicum. Efficacy was reduced when C. laurentii was applied after inoculation. In drop-inoculated wounds of oranges, the populations of C. laurentii increased by approximately 50-fold during the first 24 h at 20 °C. The maximum yeast populations, approximately 250-fold over the initial populations, were reached 15 days after inoculation at 4 °C.     

Association of Phoma aquilina and Ascochyta pteridis with curl-tip disease of bracken

Many spores of Phoma aquilina and Ascochyta pteridis were rinsed from dry infected litter obtained from a site where curl tip was prevalent. More spores were released from litter which had been incubated under moist conditions for 24 h before rinsing. P. aquilina, known to cause curl-tip symptoms in bracken when inoculated via wounds (McElwee, 1983), did not damage healthy plants when spores were applied to intact tissues. A. pteridis appeared to infect undamaged plants under humid conditions causing the initial ‘fleck’ symptoms associated with the disease. Flecks formed on plants by A. pteridis may permit subsequent infection by P. aquilina. For bracken control, treating plants with fungal inoculum in disease-free areas may result in disease if inoculum supplements can be found which permit initial infection by A. pteridis or damage plants sufficiently to allow colonisation by P. aquilina directly.     

Soybean and sunflower oils increase the infectivity of Colletotrichum gloeosporioides f. sp. aeschynomene to Northern Jointvetch

Soybean and sunflower oils increased the level of infection of northern jointvetch, Aeschynomene virginica, plants by Colletotrichum gloeosporioides f. sp. aeschynomene. Inoculation of seedlings with spore suspensions containing 10% (v:v) soybean oil or 10% sunflower oil resulted in more disease than when inoculated with suspensions of spores in water alone. The lengths of the dew periods required to establish equivalent levels of disease by spore suspensions containing 10% soybean or 10% sunflower oil were approximately 4–8 h less compared to aqueous suspensions. Incubation of spores in 10% soybean oil followed by removal and resuspension in water did not affect the infectivity of spores when compared to spores incubated in aqueous suspensions. Spore germination and appressoria formation were unaffected by either of the oils tested in in vitro assays; however, in in vivo assays, 10% soybean oil and 10% sunflower oil increased spore germination in comparison to spores that were suspended in water.     

OBSERVATIONS ON APPLE CANKER

Field observations on leaf-scar canker of apple confirm its importance in the southwest of England: on a heavily infected tree more than 5% of the current year's growth may be damaged. Leaf scars may become infected by spores of Nectria galligena which are sucked into the tracheids of a freshly exposed scar where they develop in a relatively protected environment. These freshly exposed scars become much less susceptible to infection after approximately one hour.
Infections established in leaf scars may develop immediately into cankers or they may be confined by a suberized or gum barrier. Mycelium from some of these confined lesions may spread into the surrounding healthy tissue through growth cracks when the buds develop. The lesions extend throughout the winter and spring; usually the scars earliest inoculated are the first to show cankers. It seems possible that infections of this type might be controlled by eradicant sprays applied just before leaf-fall.     

Epidemiology of Cladosporium allii and Cladosporium allii-cepae, leaf blotch pathogens of leek and onion.

Conidia of Cladosporium allii and C. allii-cepae germinated over the temperature range 2–30°C on agar with optimal responses at 15–20°C (C. allii) and 20°C (C. allii-cepae). Conidia of both fungi germinated in water and at c. 100% relative humidity (r.h.) but not at lower humidities on leaf and glass slide surfaces. Germination was more rapid when spores were applied dry to agar or leaves than when applied in water or nutrient solution. More lesions developed when conidia of C. allii-cepae were deposited dry on onion leaf discs or leaf surfaces than when they were applied suspended in water. Conidia of both fungi required 18–20 h at c. 100% r.h. to germinate and infect when applied dry to leaves. Damaging the leaves or the addition of nutrients to the leaf surface increased the incidence of infection by C. allii-cepae compared to controls. Inoculated onion bait plants placed out-of-doors developed infection after at least 17 h at c. 100% r.h. or with leaf wetness. Similar conditions were necessary for infection of bait plants exposed in onion and leek crops infected by C. allii-cepae and C. allii respectively. Disease development and spread of infection occurred at different rates over the same period in two different cultivars of leeks, with spore concentrations increasing in proportion to disease. Spore numbers in the air fell considerably when infected leeks were ploughed under.     

The Potential of Stagonospora sp. as a Mycoherbicide for Field Bindweed

Field bindweed ( Convolvulus arvensis L.) is one of the 12 most important weeds worldwide. Stagonospora sp. Isolate LA39 was isolated from diseased field bindweed plants collected in Europe. No crop tested was susceptible to the fungus, but disease symptoms were observed on other Convolvulaceae species. On field bindweed, the fungus induces disease symptoms (i.e. lesions) mainly on leaves and less severely on stems. The application of spores in an oil emulsion (10% oil in water) enhanced the disease on field bindweed plants compared with spores suspended in a 0.1% aqueous solution of the surfactant agent, Tween 80. The necrotic leaf area of inoculated plants increased as the length of exposure to 100% relative humidity (RH) and the spore density applied increased. Severe disease developed on plants inoculated with 1 107 spores/ml in oil emulsion, even in the absence of exposure to 100% RH. A delay of exposure to 100% RH (up to 8 h) did not have a significant eVect on disease severity. Field bindweed was susceptible to the fungus at all growth stages tested, but older plants were more susceptible than younger ones. It was concluded that isolate LA39 has potential as a biocontrol agent of field bindweed, especially when applied in an oil emulsion. The oil emulsion maintains the aggressiveness of the pathogen during a dew-free period and provides a favourable microenvironment during the infection process.     

Investigations on the causes of upper stem rot (USR) on standing mature oil palms

Three different trials to examine the cause of upper stem rot (USR) infection in oil palm failed to achieve any infection. In the first experiment, inoculum was applied as colonised rubber wood blocks or as spore suspensions. In the second experiment, particular attention was given to ensure that the Ganoderma spores were freshly collected to maintain viability but no infection was observed around the inoculation sites of any of the different oil palm tissues treated. Lastly in the third experiment, both monokaryotic and dikaryotic mycelial cultures were applied directly to cut fronds, which were protected with a moist covering, but no infection was detected after more than two years. Failure to achieve infection by direct inoculation would indicate that USR does not arise from direct infection of living tissues by Ganoderma spores or mycelium, this is probably because of insufficient inoculum potential to cause infection. It is suggested that USR infection is achieved only when a sufficiently large source of inoculum has built up in dead material, probably in frond axils, and this allows invasion of the living tissues.     

Chitosan treatment for skin ulcers associated with diabetes

Infections, ulcerations, gangrene and, in severe cases, extremity amputation, are common complications among diabetic subjects. Various biomaterials have been utilized for the treatment of these lesions. Chitosan is an amino sugar with a low risk of toxicity and immune response. In this study, we evaluated chitosan topical gel and film treatments for subjects with diabetic ulcerations and wounds associated with diabetes mellitus. In a pre-experimental design, we described the result of chitosan gel and film treatment for wounds and skin ulcers among patients with long-standing diabetes mellitus. We studied 8 diabetic patients with wounds and skin ulcers (long duration and Wagner degree 1–2). Initially, most lesions had some degree of infection, tissue damage and ulceration. At the end of the treatment (topical chitosan) period, the infections were cured. All patients experienced a significant improvement in the initial injury and developed granulation tissue and a healthy skin cover. This report represents one of the few published clinical experience regarding the chitosan for the treatment of skin lesions among diabetic subjects. These results are relevant and promising for the treatment of this disease.     

Colonization of wheat roots from seed‐applied spores of Idriella (Microdochium) bolleyi: A biocontrol agent of take‐all

Wheat seedlings were grown in containers of perlite in a glasshouse, and spores of Idriella bolleyi were applied either to the seeds in alginate gel or to the perlite as aqueous suspensions. Growth and sporulation of the fungus on seeds and roots were assessed by plating methods and by retrieval of spores from water that drained from the plant containers. Idriella bolleyi sporulated heavily on seeds for up to 3 weeks when applied to them in alginate gel, andmost of the root system was infected from newly formed spores that were carried in percolating water. Removal of the inoculated seeds from seedlings at 7 days reduced the degree of root infection and temporarily reduced the number of spores in drainage water; however, spore numbers increased to control levels (seeds attached) by 21 days, indicating subsequent sporulation on the roots. When spores were applied to perlite containing young (0–3 days) seedlings I. bolleyi colonized the seeds, sporulated heavily on them and extensively colonized the roots. However, it established poorly on seeds and roots if added to the perlite when seedlings were 11 days or older. The results suggest that early growth on seeds is necessary for establishment of a high population of I. bolleyi, and that cycles of sporulation on seeds and then roots contribute to colonization of the rhizosphere. The features associated with the rhizosphere competence of I. bolleyi are compared with those for systemic colonization of the xylem by vascular wilt fungi, and suggest a new approach to the selection of root‐colonizing biocontrol agents.     

Development of Novel Microemulsion-Based Topical Formulations of Acyclovir for the Treatment of Cutaneous Herpetic Infections

The present investigation aims at developing microemulsion-based formulations for topical delivery of acyclovir. Various microemulsions were developed using isopropyl myristate/Captex 355/Labrafac as an oil phase, Tween 20 as surfactant, Span 20 as cosurfactant, and water/dimethylsulfoxide (1:3) as an aqueous phase. Transcutol, eucalyptus oil, and peppermint oil were used as permeation enhancers. In vitro permeation studies through laca mice skin were performed using Franz diffusion cells. The optimum formulation containing 2.5% Transcutol as the penetration enhancer showed 1.7-fold enhancement in flux and permeation coefficient as compared to marketed cream and ointment formulation. In vivo antiviral studies were performed in female Balb/c mice against induced herpes simplex virus I infection. A single application of microemulsion formulation containing 2.5% Transcutol given 24 h post-injection resulted in complete suppression of development of herpetic skin lesions.     

Observations on blight (Phytophthora infestans) and resistant potatoes at Toluca, Mexico

A late blight epidemic studied at Toluca, Mexico, in 1962 may have started from stems infected at soil level by soil-borne Phytophthora infestans. Its severity was demonstrated by the large differences in the rate foliage was destroyed and in yield of tubers between fungicide-sprayed and unsprayed susceptible and resistant cultivars. The foliage resistances of some Mexican and European cultivars were compared using conventional blight keys and recording the destruction of marked leaves. Cultivars reacted in four ways: (1) Up-to-Date and Alpha leaves were infected and killed soon after plants emerged; (2) Bertita, Conchita and Florita abscissed many infected lower-canopy leaves, and many infections on upper leaves aborted; (3) Elenita leaves had a few lesions in which the fungus grew slowly but remained alive; (4) Greta showed no infection until the potato plants met between rows but then infections developed rapidly and the foliage soon died. Mexican cultivars, except for Elenita, had few blighted tubers; susceptible European cultivars were killed before many tubers formed. Most spores were released during the morning, as in Europe, and leaf infection seemed associated with days with rain when much of the night remained humid. Cool nights lengthened incubation and generation times.     

Cane blight (Leptosphaeria coniothyrium) in mechanically harvested red raspberry (Rubus idaeus)

Leptosphaeria coniothyrium, the cane blight pathogen, was the fungus most commonly isolated from vascular lesions developing from mechanical harvester wounds on first-year red raspberry canes. When inoculated to scalpel wounds, it induced similar lesions which were later associated with bud failure and cane death as were infected wounds on machine damaged canes. Cane resistance increased from May until August, inoculations later than July inducing only small lesions and rarely causing bud failure.     

Tissue changes in cryptococcosis: histologie alteration from gelatinous to suppurative granulomatous tissue response with asteroid body

The histologic variety and transformation in cutaneous cryptococcosis with acute lymphocytic leukemia before antifungal treatment and after the start of treatment were studied by the light and electron microscopic examinations. The initial cutaneous lesions before treatment revealed gelatinous tissue reactions, and Cryptococcus neoformans (serotype A) were isolated from the skin biopsy specimen and blood. However, later recurrent cutaneous lesions receiving antifungal treatment revealed suppurative granulomatous tissue reactions, and fungal cultures of the skin biopsy specimen changed to negative even though numerous yeasts stained with PAS were observed in skin lesions. Moreover, in the later lesion a few giant cells contained asteroid bodies without central spores. Ultrastructure of the later cutaneous lesions is presented.     

Spontaneous zinc deficiency in marmosets, saguinus mystax.

Moustached marmosets, Saguinus mystax, developed alopecia, skin lesions and general debilitation approximately 6 months after being brought into our laboratory. These lesions resembled the signs of zinc deficiency in pigs, rats and squirrel monkeys. The marmosets were fed a commercial monkey diet containing 150 parts per million zinc and about 100 g of apples and oranges per week. The addition of 40 parts per million zinc to the drinking water brought about improvement in hair coat and skin condition.     

Pathogenesis of experimentally induced bacterial cold water disease in ayu Plecoglossus altivelis

Ayu Plecoglossus altivelis were experimentally infected with Flavobacterium psychrophilum, which is the causative agent of bacterial cold water disease (CWD). The fish infected by immersion usually died within an hour after they became moribund. The blood volume and haematocrit values of moribund fish were low, while those values of many infected fish that were not moribund were in the range of controls. Most of the affected fish in the immersion-infected groups had ulcerative lesions on their lower jaw. No histological evidence of haemolysis was observed. These results suggest that rapid bleeding occurred through ulcerative lesions, probably causing hypoxia which killed the fish. Ulcerative lesions developed on the dorsal skin when this area had been slightly abraded artificially prior to immersion challenge. Histologically, F. psychrophilum was initially found on the skin that had microscopic injuries, but not on normal skin. The bacterium then entered the dermis and migrated through connective tissues. The lesions subsequently expanded into the underlying musculature through the myosepta, developed necrotic myositis and formed externally open ulcers. Only in later stages of infection did mild lesions develop in the internal organs and the gill, probably caused by the bacterium migrating through blood vessels. This suggests that infection with CWD through the gill or digestive tract is unlikely. Virtually no open lesions were found in ayu challenged by intramuscular injections except at the injection sites. The results suggest that skin injuries are major portals of entry for F. psychrophilum in ayu, and the bacterium has affinity for collagenous connective tissues.