bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance to 3,5‐dichlorophenyl‐N‐cyclic imide (‘dicarboximide’) fungicides in the grey mould pathogen Botrytis cinerea on protected crops*
Authors: KATAN TALMA
Published: April 2007

Spores of laboratory isolates of Botrytis cinerca did not germinate on potato‐dextrose agar (PDA) containing 5 μg/ml dicarboximide fungicides (iprodione, vinclozolin, procymidone, Serinal, Co 4462, Co 6054). Spores from diseased cucumbers, tomatoes, strawberries and eggplants, from greenhouses where iprodione and vinclozolin failed to control grey mould, germinated normally on PDA containing 100 μg/ml vinclozolin. The fungicide concentrations that reduced the mycelial growth rate of these resistant strains by 50% ranged from 1‐0 to 4‐9 μg/ml for six dicarboximides and dicloran. These values were between nine and 26 times greater than the values for sensitive strains (0.10‐0.27 μg/ml). Mycelial growth of resistant strains was inhibited at lower fungicide concentrations than was spore germination. On average, resistant strains grew 25‐30% slower than sensitive strains. Dicarboximide‐resistant strains were all resistant to benomyl but sensitive to prochloraz. Of 37 resistant strains transferred four to 19 times on fungicide‐free PDA, 36 were stable in their resistance. In four in vivo systems, various plant parts were treated with dicarboximide fungicides (500–2500 μg/ml) and then inoculated with mycelial plugs. Protection was observed against sensitive strains of B. cinerea but not against dicarboximide‐resistant strains. Lesion development of resistant strains was often slower than that of sensitive strains. The emergence of resistant strains apparently resulted from selection pressure imposed on the pathogen population by exclusive and extensive use of dicarboximides under conditions favouring grey mould epidemics on protected crops.
Laboratory assessments of the susceptibility of potato tubers to gangrene (Phoma exigua var. foveata)
Authors: JELLIS G. J.
Published: April 2007

Disease incidence was recorded in tubers of various cultivars following inoculation with macerated mycelium of Phoma exigua var. foveata and wounding in various ways. A method which produced predominantly crush wounds gave most rots and the most consistent results. The length of time between inoculation and wounding did not significantly affect the incidence of disease but disease severity did increase with damage infliction time. Inoculated, undamaged tubers produced rots but the incidence was low and discrimination between cultivars was poor when compared with damaged tubers. In some tests the resistance to gangrene could be measured by the proportion of tubers affected, in others all tubers had lesions but the extent of infection was different, The latent period of the disease differed between cultivars. Rate of lesion development was constant over a period of 12 wk within cultivars but differed between them.
Effects of pollination on smut development in pearl millet*
Authors: THAKUR R. P. , RAO K. V. SUBBA , WILLIAMS R. J.
Published: April 2007

In field and screenhouse experiments, pollination of inflorescences of three pearl millet F1 hybrids and two male‐sterile (ms) lines with fresh viable pollen 5–8 days after inoculation with a Tolyposporium penicillariae sporidial suspension reduced smut severities significantly compared with inoculated, non‐pollinated control plants. Smut development was not significantly reduced in a ms line following pollination of inoculated inflorescences with pollen of low viability. The implications of these findings in developing an effective screening technique for smut resistance and in controlling this disease in pearl millet are discussed.
Incidence of tuber diseases in classified seed potatoes harvested In England and Wales, 1974–77
Authors: EBBELS D. L.
Published: April 2007

Seed potato tuber inspections were inaugurated in England and Wales as a training exercise daring 1974–77, preparatory to the operation of seed potato classification under statutory authority as from 1978. The number of stocks inspected varied from 359 for the 1976 harvest (38% of those classified) to 536 for the 1975 harvest (52%). The proportion of stocks meeting the required standards progressively increased from 82% for 1974 crops to 91% for 1977 crops. The diseases most commonly causing the failure of stocks to meet the required standards were gangrene (Phoma exigua var. foveata) for crops harvested in 1974, 1975 and 1977, and non‐bacterial soft rots for 1976 crops. Over the 4 years the proportion of stocks failing to meet the required standards for diseases were respectively: 1.2% for tuber blight (Phytophthora infestans); 0.6% for bacterial soft rots (Erwinia carotovora subspp.); 2.0% for non‐bacterial soft rots (including Phytophthora erythroseptica and Pythium ultimum); 0.8% for dry rots (Fusarium spp.); 4.0% for gangrene; 0.1% for skinspot (Polyscytalum pustulans); 0.1% for black scurf (Rhizoctonia solani); 0.1% for powdery scab (Spongospora subterranea) and 1.6% for common scab (Streptomyces spp.).
The inheritance of specific virulence in Bremia lactucae (downy mildew) to match resistance factors 1, 2, 4, 6 and 11 in Lactuca sativa (lettuce)
Authors: NORWOOD JUDITH M. , MICHELMORE R.W. , CRUTE I.R. , INGRAM D. S.
Published: April 2007

The inheritance of specific virulence in Bremia lactucae was studied by hybridizing two isolates which differed in their virulence on host cultivars carrying the resistance factors R1, R2, R4, R6 and R11. Avirulence on R1, R2, R4 and R11 was dominant to virulence and the segregation conformed to that expected for alleles at single loci, although reactions on R4 were not always dearly defined. The loci conditioning avirulence on R2 and R11 were probably linked. It was difficult to classify the reactions of isolates on R6 and the ratios obtained could not readily be interpreted in Mendelian terms. Since no segregation was observed for reaction on R3, R5, R7, R8, R9 and R10 it was concluded that the genes determining virulence on these factors occurred at the same loci in both isolates, Sexual compatibility type (B1 and B2) segregated with a ratio of 1:1.
Inheritance of resistance to benomyl in isolates of Venturia inaequalis from Israel*
Authors: SHABI E. , KATAN TALMA , MARION KELA
Published: April 2007

Ten single‐spore cultures of benomyl‐resistant Venturia inaequalis were isolated from apple scab lesions at two sites in Israel. According to the ability of the isolates to germinate and grow at varying benomyl concentrations, three levels of resistance were determined in vitro: two moderately resistant (MR) isolates were resistant to 5 μg/ml but sensitive to 50 μg/ml benomyl; five highly resistant (HR) isolates, grew and sporulated at 50 μg/ml more slowly than at 5 μg/ml; and three isolates with very high resistance (VHR) grew and sporulated as freely at 50 μg/ml as at 5 μg/ml. Crosses between resistant isolates and sensitive wild types, as well as between different resistant isolates, showed that the various levels of benomyl resistance are conferred by three allelic mutations that constitute a polymorphic series in a single Mendelian gene. In these isolates benomyl resistance is not affected by modifying genes or cytoplasmic components.
The estimation of yield losses in wheat from severity of infection by Septoria species
Authors: KING J. E. , JENKINS J. E. E. , MORGAN W. A.
Published: April 2007

Equations to assist the estimation of national losses from the results of disease surveys carried out at GS75 were derived from five fungicide trials and two inoculation experiments in the field. The equations indicate that the percentage loss in grain yield is equal to 5.412xi0.6, 1.011xior 0.551xii where xi and xii are the percentage area infected on the flag and second leaves respectively.
The annual leatheijacket survey in Northern Ireland, 1965–82, and some factors affecting populations
Authors: BLACKSHAW R. P.
Published: April 2007

An annual leatherjacket survey was made each winter in Northern Ireland from 1965 to 1982. Over this period the mean population was 520,130/ha and showed less annual variation than in some parts of Britain. This appears to be due to the regulation of populations by rainfall in July, August and November rather than in September and October as has been shown elsewhere.

It is concluded that in Northern Ireland 18,096 ha of grassland would benefit from an insecticide treatment each year. Grassland with leatheijacket populations of 1 × 106/ha or more may suffer damage and up to 100,000 ha are at risk each year. Leatherjackets are therefore considered to be serious pests of grassland in Northern Ireland.
Toxicity of methyl bromide to soil‐borne fungi
Authors: EBBEN MARION H. , GANDY DOREEN G. , SPENCER D. M.
Published: April 2007

Nineteen fungal isolates, mostly plant pathogens cultured on agar, were subjected to fumigation with methyl bromide at known concentration x time product (CTP, concentration in mg/1 x time in h) in a fumigation chamber at controlled temperature. Survival of the fungi was determined by sub‐culturing on fresh agar. An order of methyl bromide tolerance of the fungi was cetermined and it was shown that at low concentrations of the fumigant, prolonged exposure, to give a normally toxic CTP, did not kill important soil‐borne pathogens. The implication of this in relation to field fumigations is discussed.
Control of benomyl‐resistant strains of Colletotrichum coffeanum, the cause of coffee berry disease
Authors: JAVED Z. U. R.
Published: April 2007

Sprays containing difolatan, dithianon, chlorothalonil and cuprous oxide were tested for the control of coffee berry disease (CBD) in 1979 and 1980 at an estate in Kenya with abundant benomyl‐resistant strains of Colletotrichum coffeanum. In 1979 all fungicides gave good CBD control and increased yields of coffee. In 1980 only difolatan increased yield. Isolates of C. coffeanum capable of growing on agar with 8 μg/ml benomyl were detected throughout the 2 years of these trials.
Comparison of laboratory methods for assessing numbers of apple rust mite (Aculus schlechtendali) overwintering on apple
Authors: LOW L. R. WARD , JACKSON A. W.
Published: April 2007

During the winter of 1980/81 apple shoots from the preceding season's growth were collected from 19 orchards in Kent and East Sussex. Five buds from each of 10 shoots per orchard were dissected under a stereoscopic microscope at × 30 magnification and apple rust mites (Aculus rchlechtendali) were counted. These dissected buds were then used to test a more rapid method of extraction and counting. The buds were added to methanol and mixed with a vibrating machine, mites were then collected in sieves and counted. Counts of mites by this method were similar to those of the first method when there were fewer than 100 mites on 50 buds, but there was greater variation when mites were more numerous.

An even more rapid method using five other buds from the same 10 shoots was also tested; the buds were bisected, then vibrated in methanol, and the mites were collected in sieves and counted. Results were comparable with those obtained by the dissection/methanol method and can be used with similar confidence in advisory work on apple rust mite.
Fungal development and plant response in detached onion, onion bulb scales and leaves inoculated with Botrytis allii, B. cinerea, B. fabae and B. squamosa
Authors: STEWART ALISON , MANSFIELD J. W.
Published: April 2007

Fungal development and plant responses were examined in detached leaves and mid‐bulb scales of Allumcepa. Following inoculation with suspensions of 105 conidia/ml distilled water Botrytis squamosa consistently produced spreading lesions in leaves and bulb scales. B. allii produced spreading lesions at most sites in bulbs but was very inconsistent in its infection of leaves; lesions were often confined to inoculation sites. Limited lesions were usually produced by B. cinerea but R. fabae failed to produce symptoms at most sites. Extensive colonization by B. allii and B. tauamosa required rapid penetration and totally necrotrophic fungal growth. During development of a spreading lesion, plant cell walls became very swollen around intramural hyphae and wall swelling appeared to precede epidermal cell death. Resistance to colonization was due to poor germination, failure to produce distinct infection hyphae (associated with accumulation of deposits of granular reaction material [RM] in underlying live cells) or restriction of infection ryphae amongst small groups of dead cells (limited lesion formation). Only B. fabae germinated poorly, and germ‐tubes produced often failed to attempt penetration but grew over the leaf or bulb scale surface. Reducing numbers of conidia increased the frequency of sites associated with RM accumulation; granular deposits being particularly common at sites inoculated with low numbers of B. allii conidia. Electron microscopy revealed that RM granules were osmiophilic aggregates formed between the plasma membrane and epidermal cell wall. In the absence of RM, growth of avirulent species was restricted within the swollen walls of dead epidermal cells. Results ae compared with those from studies on tulip and broad bean leaves.
Virus infection and reproductive losses in faba bean (Vicia faba L.)
Authors: BAILISS K. W. , SENANANYAKE S.
Published: April 2007

The viruses, bean yellow mosaic (BYMV), Echtes Ackerbohnenmosaik (EAMV) and bean (pea) leaf roll (BLRV) reduced seed yield in faba bean particularly when plants were infected at the pre‐and mid‐bloom stage. EAMV and BYMV, but not BLRV, delayed senescence and increased branching on glasshouse‐grown plants so that more inflorescences were produced on diseased plants; most of the additional flower buds necrosed. All three viruses increased the proportion of flower buds that became necrotic thus reducing the number of mature flowers available for pollination. This, together with enhanced abscission of recently set flowers, diminished pod production. Flower set per se was unaffected by infection. The number of ovule sites per pod and weight of individual mature seeds were also unaffected by these diseases but productivity per pod declined because of increased ovule abortions. Patterns of pod production on the inflorescence and location of mature seeds within the pod were unaffected by virus infection.
The influence of the primary germ tube on infection of barley by Erysiphe graminis f. sp. hordei
Authors: WOOLACOTT B. , ARCHER S. A.
Published: April 2007

In each of three separate genotype combinations of Erysiphe graminis f. sp. hordei and barley the probability of infection success by an appressorium was reduced by close proximity to a primary germ tube interacting with the same host cell, whether this germ tube was produced by the same or another conidium. Infection success of appressoria was unaffected by events in an adjacent cell, whether associated with other conidia or with the primary germ tube of the same conidium. This interaction between germ tubes and underlying host cells should be considered when mechanisms of resistance to E. graminis f. sp. hordei are investigated.
Effects of avirulent bacteriocin‐producing strains of Pseudomonas solanacearum on the control of bacterial wilt of tobacco
Authors: CHEN W. Y. , ECHANDI E.
Published: April 2007

Root systems of tobacco dipped in suspensions containing 2 × 109 colony forming units (CFU)/ml of avirulent bacteriocin‐producing strains (ABPS) of Pseudomonas solanacearum and assayed immediately after planting in steam‐sterilized soil had 8 × 106 CFU/root system of ABPS. The bacterial population declined to an average of 5·3 × 105 CFU/root system after 30 days. Roots of seedlings dipped in bacterial suspensions of ABPS were more effectively protected against wilt caused by P. solanacearum than those dipped in suspensions of an avirulent nonbacteriocin‐producing strain (ANBPS). Lipopolysaccharide (LPS) isolated from one ABPS (121) inhibited the attachment of bacteria on roots by 70% but had no effect on the reduction of wilt, whereas bacterial cells significantly reduced the disease severity as compared to LPS or water treatment. In steam‐sterilized soil containing a 1:1 mixture (5 × 105 CFU/g of oven‐dried soil) of ABPS 121 or 237 and the virulent strain K‐60, ABPS 121 reduced multiplication of the virulent strain in soil and in the rhizosphere of seedlings. When roots of seedlings were dipped in a suspension of 2 × 109 CFU/ml of ABPS before planting, root colonization by the virulent strain added to steam‐sterilized soil at 2 × 106 CFU/g of oven‐dried soil was significantly reduced. When roots were dipped in a suspension of ABPS and assayed 20 days after planting, 98% of the bacterial population was found in the original zone of inoculation and only 2% was detected in new growths of the root system. Plants which were grown in soil infested with ABPS 121 or K‐60 had both strains present at variable populations along all sections of roots.
Barley net blotch: influence of straw disposal and cultivation methods on inoculum potential, and on incidence and severity of autumn disease
Authors: JORDAN V. W. L , ALLEN ELIZABETH C.
Published: April 2007

Effects of ploughing or direct drilling with three methods of straw disposal on amounts of inoculum of Pyrenophora teres, and on frequency of infection and severity of net blotch in the autumn, were studied in winter barley. Prior to ploughing, many conidia of P. teres were caught above areas where infected straw from a previous crop of winter barley had been bated and removed leaving culm bases, or where barley straw had been chopped and left in situ, but relatively few were caught above areas where straw had been burnt. Thereafter, where ploughing had buried surface residues, irrespective of the method of straw disposal, conidia were not caught for at least 3 weeks, and subsequently were substantially fewer than in direct‐drilled areas where many spores were caught. Production of conidia (measured as numbers per unit length of straw) was greatest on chopped straw, less on culm bases and least on burnt straw residues. Sporulation on volunteer barley plants was much reduced by application of paraquat + diquat, but some still occurred on visually‘dead’volunteer barley.

All direct‐drilled barley plants were diseased within 27 days of sowing, whereas 42 days elapsed before all plants sown in ploughed areas were diseased. Disease on individual plants was also more severe in direct‐drilled areas: 20% of the area of the first leaf to emerge was diseased 19 days after crop emergence in direct‐drilled plots, whereas less than 9% was diseased in ploughed areas 50 days after emergence.

There was an additive effect of straw disposal methods and direct‐drilling on disease, which in turn affected plant vigour. The adverse effect of direct‐drilling on the incidence and severity of net blotch appeared to be far greater than that of the straw disposal methods.
Variation for isozymes and double‐stranded RNA among isolates of Puccinia striiformis and two other cereal rusts
Authors: NEWTON A. C. , CATEN C. E. , JOHNSON R.
Published: April 2007

Gel electrophoresis was used to examine the variation in isozymes and dsRNA within and between the rust species Puccinia striiformis, P. recondita and P. hordei. No differences in isozyme phenotype were found among 29 diverse isolates of the wheat‐attacking form of P. striiformis (WYR). Smaller numbers of isolates of the barley‐attacking form (BYR) of P. recondita and of P. hordei showed similar intra‐group uniformity. There were major differences in isozyme phenotypes between the three species, while WYR and BYR differed for two of 12 enzymes. Double‐stranded RNA was detected in each species and in all 26 isolates examined. For WYR and BYR, all isolates within each group had the same or a similar phenotype. In contrast, each isolate of P. recondita and P. hordei had a unique phenotype. There were differences in dsRNA phenotypes both between the three species and between WYR and BYR.

The uniformity of these rust populations and species for isozyme phenotype is contrasted with their variability in pathogenicity and with the variability in isozymes encountered in higher organisms. Uniformity may result from a feature of the biology of the rust species and populations examined, or from the relative homogeneity of the environment of biotrophic pathogens. Consistent differences in isozyme and dsRNA phenotype between the WYR and BYR isolates of P. striiformis indicate that these are two discrete populations, supporting the view that they should be recognized as f.sp. tritici and f.sp. hordei, respectively.
Production and characterization of single‐spore isolates of Plasmodiophora brassicae
Authors: SCOTT E. S.
Published: April 2007

An improved procedure for inoculating Brassica seedlings with single resting spores of Plasmo‐diophora brassicae is described. Using this procedure, eight out of a total of 600 seedlings inoculated with single spores developed severe symptoms of clubroot disease. Seven isolates of P. brassicae derived from single spores were characterized using the European Clubroot Differential (ECD) series. Four distinct pathotypes were obtained. The original populations of P. brassicae were shown t o be heterogeneous; this supports the findings of other workers. The isolates have been used to establish a reference collection of single‐spore isolates of P. brassicae of known pathotype for use in Brassica breeding.
Phenotypic influences on the incidence of infection by Ascochyta fabae in spring varieties of faba beans (Vicia faba)
Authors: JELLIS G. J. , LOCKWOOD G. , AUBURY R. G.
Published: April 2007

Spring beans with a range of different growth habits were assessed for resistance to Ascochyta fabae. Variation in the incidence of both foliar and pod infection was recorded but there was no association between the two. The larger‐podded broad bean types had a higher incidence of pod infection relative to foliar infection than the smaller‐podded field beans. The effect of straw length on the incidence of A. fabae was investigated using exogenously applied gibberellin to sensitive and insensitive cultivars. This confirmed the association between long straw and low incidence of pod disease.
Resistance of Venturia nashicola to thiophanate‐methyl and benomyl: build‐up and decline of resistance in the field
Authors: ISHII HIDEO , UDAGAWA HIDEO , YANASE HARUO , YAMAGUCHI AKIRA
Published: April 2007

Changes in the proportion of benzimidazole‐resistant strains in populations of Venturia nashicola were monitored in pear orchards. Successive applications of thiophanate‐methyl increased the level of resistance in the populations. When the application of benzimidazoles was stopped and other fungicides were applied, the proportion of highly resistant strains gradually decreased and the proportion of intermediately resistant, weakly resistant and sensitive strains increased. It is suggested that this phenomenon is an example of genetic homeostasis within microbial populations.
Zearalenone production in Fusarium culmorum after transformation with DNA of F. graminearum
Authors: MADHOSINGH CLARENCE , ORR WINSON
Published: April 2007

Total DNA from a cycloheximide‐resistant mutant of Fusarium graminearum producing zearalenone was incubated with the protoplasts of a non‐zearalenone‐producing cycloheximide‐susceptible isolate of F. culmorum. The regenerated protoplasts were inoculated on a 5‐mM cycloheximide medium. The cultures which developed were examined for zearalenone production. Sixty‐five cycloheximide‐resistant isolates, including two isolates producing zearalenone, were obtained from approximately 3.6 × 104 viable F. culmorum protoplasts. Similar incubations with homologous F. culmorum DNA and non‐fungal DNA did not elicit zearalenone production. The results suggest the transformation of F. culmorum by the genetic factors responsible for cycloheximide resistance and zearalenone production from F. graminearum. The epidemiological and taxonomic significance of these observations is discussed.
ELISA indexing of commercial carnations for carnation mottle virus using a urease‐antibody conjugate
Authors: MORAN JANE R. , WILSON JENNY M. , GARRETT R. G. , SMITH P. R.
Published: April 2007

The high sensitivity of the urease form of enzyme‐linked immunosorbent assay (ELISA) system allowed the use of pooled samples for the detection of carnation mottle virus (CarMV) with greater sensitivity than the phosphatase system. The urease‐ELISA was used for a field assessment of the effectiveness of a Plant Improvement Programme (PIP) for carnations operated by the Victorian Department of Agriculture for the control of carnation mottle virus. On properties growing only PIP carnations, infection with CarMV averaged 0.95%. whereas cm properties growing carnations from ordinary commercial sources, all plants sampled contained the virus. The Plant Improvement Programme provided effective control of CarMV in Sim carnations.
Further characterization of field resistance in lettuce to Bremia lactucae (downy mildew)
Authors: NORWOOD JUDITH M. , CRUTE I. R.
Published: April 2007

The development of five Bremia lactucae isolates on the field‐resistant crisphead lettuce cultivar Iceberg was compared under field conditions with that on the more susceptible crisphead cultivar Ithaca. With each of five isolates, the epidemic developed more rapidly on Ithaca than Iceberg; lesions on Ithaca were more numerous, larger and sporulated more profusely than on Iceberg. There was no evidence for adaptation of isolates to Iceberg, which provides some additional evidence that the resistance of this cultivar could be non‐differential (horizontal). There was, however, evidence of non‐specific differences between isolates in their quantitative virulence.
Interaction of red raspberry cultivars with isolates of Phragmidium rubi‐idaei
Authors: ANTHONY VIVIENNE M. , SHATTOCK R. C. , WILLIAMSON B.
Published: April 2007

Seven cultivars of red raspberry (Rubus idaeus) showed different susceptibility to infection by yellow rust (Phragmidium rubi‐idaei) at two commercial plantations in Scotland and North Wales, The cultivars Latham, Chief and Boyne were completely resistant. Mailing Delight and Glen Clova supported more telial more than Mailing Jewel. In contrast the last named was the most susceptible cultivar at the aecial stage in Scotland but developed similar numbers of aecia to Glen Clova and Mailing Delight in Wales.

Meeker had an extended latent period, fewer and smaller pustules and a very small yield of urediniospores compared to the other susceptible cultivars, thus showing the characteristics of slow‐rusting genotypes. At the Scottish site in 1982, where rust was less than in Wales, Meeker and Mailing Jewel performed differently to the other cultivars at the telial stage. Inoculation studies under controlled environmental conditions with urediniospores from each site revealed an interaction between cultivars and isolates suggesting that variation in pathogenicity is present in populations of P. rubi‐idaei in the UK.
The control of Penicillium corymbiferum on crocus and its effect on corm production
Authors: SUTTON M. W. , WALE S. J.
Published: April 2007

Crocus corms with different amounts of infection by Penicillium corymbiferum were planted in field plots in October 1982 and harvested in the following July. Differences in infection at planting had no effect on the development of the disease on harvested stored corms. Corms with 40–60% surface area infected by P. corymbiferum at planting had a reduced mean weight of harvested corms and yield (kg corms harvested per kg corms planted) compared with corms with 4–10% surface area infected at planting. Dipping corms in benomyl, captafol, tnancozeb or thiram solutions after harvesting failed to control the disease. The severity of disease was increased by damage occurring before storage and was reduced by delaying harvesting.
Characteristics of alginate pellets formulated with Trichoderma and Gliocladium and their effect on the proliferation of the fungi in soil
Authors: LEWIS J. A. , PAPAVIZAS G. C.
Published: April 2007

Pelletized formulations of wheat bran or kaolin clay in an alginate gel containing conidia, chlamydospores, or fermentor biomass (FB) of several isolates of the biocontrol fungi Trichoderma spp. and Gliocladium virens were prepared. The ability of fungal propagules within the pellets to proliferate in soil was determined. Higher population densities were obtained when alginate pellets added to soil contained chlamydospores rather than condia, and bran rather than kaolin as the bulking agent. The active ingredient in pellets prepared from FB was approximately 5% biomass by weight and contained many chlamydospores. Colony‐forming units (cfu) ranged from 106’to 1010/g of soil after soil amendment with FB pellets of 12 Trichoderma and G. virens isolates. Population densities were high during the first 3 weeks of incubation and declined only gradually during 9 weeks. Propagules in FB pellets were more viable at 5° than at 25°C. Viability at 25°C remained high (> 70%) after 1 week, but declined to less than 10% after 24 weeks. Despite reduction in propagule viability in stored pellets, numbers of cfu formed after adding these pellets to soil were comparable with those formed from freshly prepared pellets.
The composition of wall alterations and appositions (reaction material) and their role in the resistance of onion bulb scale epidermis to colonization by Botrytis allii
Authors: STEWART ALISON , MANSFIELD J.W.
Published: April 2007

Ultrastructural examination of deposits of reaction material (RM) showed them to be composed of paramural granules (osmiophilic to varying degrees) lying within amorphous electron–dense material. Epidermal cell walls per se became increasingly electron–dense around the short infection hyphae produced by Botrytis allii. Fluorescence microscopy, histochemical tests and microautoradiography showed the accumulation of phenolic compounds at infection sites. Use of phenylalanine and cinnamate for E.M. autoradiography demonstrated the accumulation of phenolics within paramural granules, amorphous aggregates and within the penetrated cell wall, Paramural deposits were soluble in organic solvents and probably represented reservoirs of low MW phenolics which were progressively incorporated into insoluble polymers within the cell wall. Initial synthesis or accumulation of phenolics appeared to take place in rough endoplasmic reticulum during the first 2 h after cuticle penetration. Suppression of RM deposition and wall alterations was achieved by treatment of bulb scales with cycloheximide. Tissues treated with the protein synthesis inhibitor became susceptible to colonization by B. allii. Accumulation of phenolics at infection sites rendered the onion cell walls resistant to attack by a mixture of cell wall–degrading enzymes, Methanolic extracts of epidermal strips containing RM deposits contained very weakly active inhibitors of B. allii germ–tube growth. The role of RM deposits and wall alterations in the resistance of onion epidermis to colonization by Botrytis is discussed.
Scanning electron microscopy of early infection in the uredial stage of Puccinia sorghi in Zea mays
Authors: HUGHES FIONA L. , RIJKENBERG F. H. J.
Published: April 2007

An SEM study was made of the infection process of Puccinia sorghi in Zea mays. A uredospore germ tube grows across epidermal cells and along their anticlinal walls, often branching and altering direction of growth. The fungus, on attaining a stoma, delimits an appressorium over it. Infection peg initials enlarge linearly and centripetally along the appressorium base, forcing open the stomatal slit. Having penetrated the stomatal aperture, the infection peg develops a substomatal vesicle. From the vesicle, two short primary infection hyphae develop synchronously, a septum later forming between the vesicle body and each hyphal base. A further septum divides the primary hypha into two cells. Secondary infection hyphae emerge later from the fully expanded vesicle on the proximal side of each vesicle/primary hypha septum. Secondary hyphae are narrower than primary hyphae, form their proximal septum some distance along the hypha, develop asynchronously, and proliferate to form the intercellular mycelium. Infection processes and epidermal stripping are discussed.
Pathogenicity and colonization studies on wild–type and auxotrophic isolates of Verticillium albo–atrum from hop
Authors: CLARKSON JOHN M. , HEALE J. B.
Published: April 2007

Three fluctuating (M18, M33 and M50) and three progressive (PVl, PV2 and PV3) hop wilt isolates of Verticillium albo–atrum Reinke and Berthold were tested against the hop (Humulus lupulus L.) cultivars, Fuggle, Wye Challenger and Wye Target. Significant differences in pathogenicity were observed between progressive and fluctuating isolates and although wilt symptoms varied in intensity from season to season, the relative order of pathogenicity and host resistance usually remained the same. Using a detached leaf procedure, differences were observed in the frequency of successful re–isolations of Vertieillium from hop plants infected with wild–type isolates. This procedure is discussed as a possible additional method for distinguishing between progressive and fluctuating hop wilt isolates. Auxotrophic and morphological mutants derived from these six wild–type isolates were tested under glasshouse conditions against hop and the non–selective alternative host Antirrhinum majus L. (cv. Maximum). Although auxotrophic mutants generally showed a reduction in pathogenicity to, and ability to colonize, both hop and Antirrhinum, certain auxotrophs retained near–parental levels of colonization and were therefore suitable for studies on possible parasexual recombination in these hosts.
Integrated control ofRhizoctonia solaniby methyl bromide andTrichoderma harzianum
Authors: STRASHNOW Y. , ELAD Y. , SIVAN A. , CHET I.
Published: April 2007

Under laboratory conditions, isolate TH–203 ofTrichoderma harzianumwas found to be tolerant of up to 20 000 ppm methyl bromide (MB) (v/v), whereas the plant pathogenRhizoctonia solaniwas susceptible to a dose of less than 9000 ppm (v/v). Exposure to sub–lethal concentrations of MB had no effect on thein vitroantagonistic ability ofT. harzianum. Soil fumigation with MB at the equivalent of a commercial dose of 500 kg/ha did not reduce the population ofTrichodermain soil and allowed rapid colonization ofTrichodermato develop in the soil.

Under greenhouse conditions a combination ofT. harzianumand a reduced dose of MB (equivalent to 200 kg/ha) completely controlled disease incidence ofR. solaniin bean seedlings compared with controls in untreated soils. Similar disease control was achieved with the recommended dose of MB. Under field conditions, the combination of 200 kg/ha MB andT. harzianumgave a significant synergistic effect on damping–off of carrot seedlings caused byR. solani, and had a similar effect on growth, yield and disease control to that of the recommended dose.

T. harzianumwas also able to prevent reinfestation byR. solaniin fumigated soils.
A selective survey of potato cyst‐nematode pathotypes in Great Britain
Authors: STONE A. R. , HOLLIDAY J. M. , MATHIAS P. L. , PARROTT D. M.
Published: April 2007

One hundred and forty‐four samples of potato cyst‐nematodes, the majority chosen to contain G. pallida, from England, Wales and Scotland were identified to pathotype. Where G. rostochiensis was present it proved to be pathotype Rol, there being no indication of other pathotypes of this species. Of G. pallida, a minority of samples incorporated pathotype Pa 1; many were pathotype Pa3 but distinction between Pa2 and Pa3 was unsatisfactory in many more. It is concluded that recognition of these latter two pathotypes is of little value. The proposed pathotype New Leake could not be recognized.
Glasshouse and field evaluation of benomyl and triadimefon applied at seeding to control take‐all in wheat
Authors: BALLINGER D. J. , KOLLMORGEN J. F.
Published: April 2007

The effects of two fungicides, benomyl and triadimefon, applied at seeding, on the incidence and severity of take‐all (Gaeumannomyces graminis var. tritici) of wheat were investigated in the glasshouse and in the field. In glasshouse studies with an artificially inoculated and naturally infested sandy loam, both fungicides caused significantly less disease, whereas in a field study with a clay soil and artificial inoculum, triadimefon caused significantly less disease. In the field, both fungicides were more effective when placed near the seed as granules or as pellets than when applied as seed treatments.
Some characteristics of Botrytis cinerea isolates tolerant to procymidone
Authors: FRAILE AURORA , ALONSO ANGELA , SAGASTA E. M.
Published: April 2007

Of 104 isolates of Botrytis cinerea collected from greenhouses in south‐east Spain, 70 (67%) were tolerant to procymidone. The tolerant isolates appeared as often in greenhouses treated with dicarboximides for only 1 year as in those treated for several years, indicating a rapid development of tolerance under greenhouse conditions. Although the tolerant isolates grew more slowly on PDA than the sensitive ones, their sporulation per unit area was similar. The sporulation and the viability of conidia of tolerant isolates collected in greenhouses where dicarboximides were used for 3 years were enhanced by the presence of procymidone in the growth medium, features that may have important epidemiological implications.
The relative resistance of wheat, rye and triticale to take‐all caused by Gaeumannomyces graminis
Authors: HOLLINS T. W. , SCOTT P. R. , GREGORY R. S.
Published: April 2007

In seven field experiments conducted over 6 years with a wide range of disease severities, triticale was intermediate in resistance to Gaeumannomyces graminis between wheat (susceptible) and rye (resistant). Use of triticale is suggested as an immediately available means of introducing take‐all resistance into cereal cultivation.

Octoploid triticale was slightly more susceptible than hexaploid triticale. There was little evidence of consistent variation in resistance among wheat or rye cultivars but a few hexaploid triticale cultivars varied in resistance. The resistance of triticale was not reliably expressed in the glasshouse tests used, so selection for resistance to take‐all in a breeding programme would need to be conducted in the field. Individual pairs of rye chromosomes added to wheat did not significantly reduce its susceptibility. The feasibility of transferring the resistance of rye to wheat is considered.
The susceptibility of Brassica oleracea cultivars to Plasmodiophora brassicae (clubroot)
Authors: DIXON G. R. , ROBINSON D. L.
Published: April 2007

An evaluation of 404 Brassica oleracea cultivars for susceptibility to Plasmodiophora brassicae (clubroot) at one field site in northern Scotland over the four years 1979‐82 is reported. The population of P. brassicae at this site possessed a high degree of virulence to B. oleracea as determined by seedling tests in a glasshouse environment, using the European Clubroot Differential series. No statistically significant differences in susceptibility were consistently identified between cultivars when tested under field conditions. Data over years and over crops were analysed by the residual maximum likelihood technique. Differences between cultivars were small compared with cultivar x year interactions. No obvious differences were identified in susceptibility between the crop types Brussels sprout, cabbage, calabrese and cauliflower. Disease levels as analysed over all field trials increased markedly in years three and four of this experiment compared with the first two years.
Attempted somatic hybridization of Puccinia striiformis f. sp. tritici and P. striiformis f. sp. hordei
Authors: NEWTON A. C. , JOHNSON R. , CATEN C. E.
Published: April 2007

Attempts were made to produce somatic hybrids between isolates of Puccinia striiformis f. sp. tritici and f. sp. hordei. A mixed infection was produced on a common susceptible barley host, Fong Tien, using white‐spored isolates of P. striiformis f. sp. tritici and yellow‐spored isolates off. sp. hordei. Selection was made for non‐parental spore colour on selective wheat and barley hosts, and variants thus isolated were analysed for virulence markers, and for isozyme and double‐stranded RNA (dsRNA) markers, all of which clearly differentiated the parental isolates. Two white‐spored (non‐parental) isolates were found on the selective barley host which otherwise resembled the parental f. sp. hordei isolate in virulence, isozyme and dsRNA markers. The most likely explanation of the origin of these isolates is mutation to white spore colour in the f. sp. hordei isolate.
Control of lettuce drop disease, caused by Sclerotinia sclerotiorum, with metham‐sodium soil treatment and foliar application of benomyl
Authors: BEN‐YEPHET Y. , BITTON S. , GREENBERGER A.
Published: April 2007

The effects of metham‐sodium (MES) soil treatment, a varying number of benomyl foliar sprays (two, three and six) and combined treatments on control of lettuce drop disease were studied at two sites in Israel naturally infested with the pathogen Sclerotinia sclerotiorum. MES killed 85% of the S. sclerotiorum sclerotia in the top 10 cm of soil where initial populations were 0.6 and 1.6 viable sclerotia per kg soil at the two sites. Of the remaining viable sclerotia. only 30% produced apothecia. MES treatment alone reduced numbers of apothecia to 5% of those counted in the unsprayed control treatment. Numbers of ascospores deposited on the crop in the MES‐treated plots were 7‐20% of those deposited on control plots. Lettuce drop decreased the total yield by 30% in unsprayed control plots; MES application reduced the loss to 4% and also increased the number of marketable plants. Benomyl sprays alone also significantly reduced numbers of apothecia and disease development and consequently increased yield, although not to the extent observed with the MES treatment alone. Combined treatments produced the best disease control, but this improvement was not accompanied by any major increase in yield compared to that with MES treatment alone.
Interference between potyviruses during aphid transmission
Authors: KATIS N. , CARPENTER J. M. , GIBSON R. W.
Published: April 2007

Single aphids (Myzus persicae) were allowed sequential access to two leaves which were either free from infection or infected with potato virus Y° (PVY°). PVYN. beet mosaic virus (BMV), or tobacco mosaic virus (TMV). Aphids given prior or subsequent access to PVYN‐infected leaves transmitted PVY° and BMV less frequently than aphids given prior or subsequent access to virus‐free leaves; those given prior or subsequent access to BMV also transmitted PVY° less frequently. However, prior or subsequent access to PVY° did not decrease transmission of either BMV or PVYN, and access to BMV did not decrease transmission of PVYN. Access to the non‐aphid‐transmissible TMV did not affect transmission of either PVY° or PVYN. PVYN had the greatest electrophoretic mobility. BMV was least mobile and PVY° was intermediate, so ability to decrease transmission was not directly related to the total anionic charge on the virus particles.
Synthesis of DNA complementary to the polyadenylated genomic RNA of potato virus Y and its molecular cloning
Authors: ROSNER A. , RACCAH B. , MAYORAL M. L. , BAR‐JOSEPH M. , GINZBURG I.
Published: April 2007

The naturally polyadenylated genomic RNA of PYV served as a template for the synthesis of complementary DNA (cDNA) strand‐primed with oligo‐dT using the enzyme avian myeloblastosis virus reverse transcriptase. A second cDNA strand was made with DNA polymerase I and the double‐stranded product (about 10 kbp) was cleaved with a Hind III restriction endonuclease. The resulting five main fragments of 800,950, 1250,2400 and 2600 bp were subsequently cloned into the Hind III site of the pBR322 plasmid of Escherichia coli. Three types of cDNA inserts (800, 950 and 2400 bp) were detected among the isolated recombinant plasmid clones. Intact untreated virus particles and phenolized virus samples hybridized with the cloned cDNA sequences. These clones hybridized with a major virus RNA band of about 10 kbp and a minor band of higher molecular weight in blots of RNA extracted from purified virus particles and fractionated in a denaturing agarose gel. The prospects of using cloned PVY sequences for the analysis of the virus genome and for virus detection are discussed.
Fungal pathogens in rotted basal leaves of lettuce in Humberside and Lancashire with particular reference to Rhizoctonia solani
Authors: WAREING P. W , WANG ZU‐NAN , COLEY‐SMITH J. R. , JEVES T. M.
Published: April 2007

Rhizoctonia solani was an important though erratically occurring pathogen of protected lettuce but was unimportant in outdoor crops. The most common fungal pathogen in rotted basal leaves of both protected and outdoor lettuce in Humberside and Lancashire was Botrytis cinerea. Sclerotinia sclerotiorum was common in leaves of outdoor lettuce in Lancashire but was encountered infrequently in protected crops in Humberside, Of 27 isoJates of R. solani which were tested for anastomosis group. 11 were AG‐L 13 were AG‐2 type I. two were AG‐2 and one was AG‐4. The AG‐4 isolate had a Thanatephorus praticola teleomorph whereas representatives from the other groups were Thanatephorus cucumeris.
Infection of Australian and New Zealand Rubus subgenera Dalibarda and Lampohatus by the European blackberry rust fungus Phragmidium violaceum
Authors: BRUZZESE E. , HASAN S.
Published: April 2007

Laboratory inoculations of native Australian and New Zealand Rubus spp. showed that R. gunnianus (subgenus Dalibarda) from Tasmania and R. schmidelioides and R. cissoides (subgenus Lampobatus) from New Zealand were moderately susceptible to the European blackberry rust fungus Phragmidium violaceum. Although the rust infected all species of subgenus Lampobatus tested. R. australis. R. parvus. R. squarrosus and R. moorei were more resistant and unlikely to be adversely affected when the rust reaches their area of distribution.
Epidemics of apple powdery mildew (Podosphaera leucotricha) in a mixed cultivar orchard
Authors: JEGER M. J. , BUTT D. J.
Published: April 2007

Epidemics of apple powdery mildew were monitored on leaves of vegetative extension shoots in a mixed‐cultivar orchard in 1979. 1980 and 1981. Cultivars Cox's Orange Pippin. Golden Delicious. Ida Red and Suntan were very susceptible but little mildew developed on cv. Discovery in any year. Results with cvs Crispin and Spartan were less consistent due, in part, to differing patterns of vegetative growth. The rankings of cultivars for disease incidence (proportion of leaves with mildew), number of colonies and mildewed area were similar, and were also consistent on fungicide‐sprayed and unsprayed trees in 1981. Less disease occurred on fungicide‐treated Golden Delicious than on Cox's Orange Pippin. Most infections occurred on the rolled leaves at the shoot tip. Spore production was greatest on leaves at positions ‐1 to ‐4 where leaf 0 was the youngest and leaf ‐ 1 the adjacent and older unrolled leaf.
A method for inducing apothecia from sclerotia of Sclerotinia sclerotiorum
Authors: MYLCHREEST SUSAN J. , WHEELER B. E. J.
Published: April 2007

An isolate of Sclerotinia sclerotiorum from oilseed rape was grown on sterilized wheat grain for 3 weeks at 20 C, followed by 4 weeks at 4oC. Harvested sclerotia were buried 1 cm deep in compost in plastic containers and kept at 10oC until apothecial stipes appeared (c. 6 weeks). When these dishes were placed under near‐UV light (14 h/day) at 22oC, apothecia matured in 5 days. The method also induced apothecia from sclerotia of 35 other isolates of S. sclerotiorum obtained from 17 different hosts.