bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistance to powdery mildew in rose
Authors: MENCE MARGARET J. , HILDEBRANDT A. C. 
Published: February 2008

SUMMARYResistance and susceptibility of rose species and varieties to the powdery mildew fungus Sphaerotheca pannosa were tested on detached leaflets in Petri plates. Strains of the pathogen from greenhouse plants were maintained under aseptic conditions on rose shoots growing in agar medium in glass vials. Biological specialization in S. pannosa was confirmed; the strain on Rosa virginiana did not infect common rose varieties. Variation in susceptibility of commonly cultivated rose varieties to another strain of mildew was demonstrated, and resistance increased with age of leaf. Germination and prepenetration development of the fungus were not related to disease resistance. Fewer fungus haustoria developed normally in epidermal cells of resistant than of susceptible rose varieties. The relative importance of morphological barriers and internal resistance factors is discussed. Attempts failed to infect freshly isolated or long established callus tissue cultures of several rose varieties.
Powdery mildew of tobacco (Erysiphe cichoracearum DC.): Some effects of methods of inoculation and air humidity on germination of conidia and growth of hyphae on leaves*
Authors: COLE J. S. 
Published: February 2008

SUMMARYGermination of conidia of Erysiphe cichoracearum and hyphal growth in 3 days at 23° C. and 6 mb. saturation deficit was similar, whether conidia were applied dry or suspended for up to 1 hr. in glass‐distilled water before being sprayed on tobacco leaves.Growth of single conidial colonies whose hyphae were more than 333 μ long, was positively correlated with numbers per cm.2 of leaf (P < 0.01) on three of the eleven times tested, mostly when conidia were sparsely distributed; ten of the regressions were positive.A greater percentage of conidia germinated at 0–1.7 mb. saturation deficit than at 7–9 mb. Subsequent growth of hyphae was greater in the drier air.
Brown blight (Colletotrichum coffeanum Noack.) of arabica coffee in East Africa
Authors: HOCKING D. 
Published: February 2008

SUMMARYThe anthracnoses of coffee known in East Africa as ‘brown blight’ are denned with respect to coffee berry disease, both caused by strains of Colletotrichum coffeanum Noack(Ghmerella cingulata (Stonem.) Spauld. & von Schrenk). Pathogenicity of brown blight strains to twigs, leaves, blossoms and berries is investigated and discussed with the conclusion that consistent differences in pathogenicity are absent. Latent infections on green berries were observed to become active upon ripening. The general role of C. coffeanum (other than CBD strains) appears to be confined to colonization of necrotic and moribund tissue, with sporadic active parasitism under certain local conditions.Maximum apparent losses are blemishing of 4% of parchment coffee and possible total loss of 2 %, both avoidable by regular picking. Other possible losses are discussed.
Mycosphaerella stem rot of cucumbers in the Lea Valley
Authors: FLETCHER J. T. , PREECE T. F. 
Published: February 2008

SUMMARYStem rot of cucumbers, caused by Mycosphaerella melonis (Passer.) Chiu & Walk, was present in Butcher's Disease Resister in every glasshouse in the Lea Valley examined in 1963 and was sometimes noticed as early as April. No correlation was detected between the severity of the disease and the type of bed used (straw bale or traditional), type of training (arch or cordon), thermostat setting, ventilation practice, date of planting, or routine fungicidal spraying practice.The disease could be transmitted on a pruning knife to any node of the plant. Infection by air‐borne spores was induced experimentally. Leaves could not be infected artificially.The frequency of air‐borne ascospores of the fungus showed a conspicuous evening peak. Numbers of spores were highest in wet dull weather.Dithiocarbamates appear to be the most effective fungicides now available for control.
Inorganic ions and the hatching of Heterodera spp
Authors: CLARKE A. J. , SHEPHERD AUDREY M. 
Published: February 2008

SUMMARYOf various inorganic ions tested for their ability to stimulate hatching of eggs of the cyst nematodes of cereals (Heterodera avenae Woll), carrot (H. carotae Jones), cabbage (H. cruciferae Franklin), soybean (H. glycines Ichinohe), pea (H. goettingiana Liebs.), potato (H. rostochiensis Woll.), beet (H. schachtii Schm.), tobacco (H. tabacum Lownsbery & Lownsbery) and clover (H. trifolii Goffart), some were active. Zn2+ hatched many eggs of seven species and some of H. goettingiana, but inhibited hatch of H. avenae to below that in water. Zinc salts are the first recorded very active hatching stimulants for H. glycines in vitro. Many other metal ions stimulated hatching of H. schachtii eggs to varying extents; these also hatched some but not all of the other species. Vanadate ions were particularly effective for H. rostochiensis, more so than Zn2+. No ion increased the hatch of H. avenae to above that in water. The most active ions were not those most abundant in soil.The behaviour of different ions with different species did not suggest any obvious affinities between species, but the differences between the hatching of H. tabacum and H. rostochiensis add weight to the view that, despite morphological similarities and overlapping host ranges, they are distinct species rather than pathotypes of a single species.Ions and other hatching agents may be absorbed by materials within the egg or larva and alter the structure and function of these materials. The lack of correlation between the hatching of H. schachtii by ions and the known stability sequences of various biological metal‐binding systems suggests that there may be several sites of action that differ in their response.
Verticillium wilt of sage (Salvia officinalis L.)
Authors: RYAN C. L. J. 
Published: February 2008

SUMMARY Verticillium dahliae Kleb. was established as the cause of wilt in sage. The disease causes leaf yellowing and necrosis from the base of the plant upwards, followed by defoliation. Microsclerotia found in the bark and sometimes the pith of severely affected stems are regarded as a diagnostic feature. Surveys confirmed the widespread occurrence of the disease in the Vale of Evesham and showed that it was most severe on heavy clay soils and in poorly drained areas but was not related to soil pH, phosphate or potash content.The rate of disease spread and the distribution of affected plants suggested that infected debris was the main source of disease dispersal, particularly as microsclerotia were abundant in many fallen leaves. It was shown that the disease could be disseminated in propagating material, and field evidence suggested that the pathogen could survive in the field in the absence of sage for at least 10 years. Replanted sage in affected areas generally contracted the disease within 1 year.Control measures suggested include careful stock selection, weed control and improved general hygiene.
Interaction between Fusarium oxysporum F. vasinfectum and Cephalosporium maydis on cotton and maize
Authors: SABET K. A. , SAMRA A. S. , MANSOUR I. S. 
Published: February 2008

SUMMARYThe interaction between Fusarium oxysporum (cause of cotton wilt) and Cephalosporium maydis (cause of maize late‐wilt) on cotton roots is associated with an appreciable decrease in the severity of the cotton wilt disease. Reduction in infection is more pronounced when the latter fungus precedes the former in the soil than when they are inoculated simultaneously. C. maydis exerts little or no such effect when it follows F. oxysporum in the soil. C. maydis grows on the surface of cotton roots near growing points as a root‐surface inhabitant. Dark red lesions are produced but these disappear, as does the fungus, when the root becomes hardened either naturally or in response to the growth of the fungus on the surface. The presence of the fungus is associated with increased production of root laterals. Cotton plants, including those which may appear healthy, show only mild internal symptoms of Fusarium infection when grown in soil inoculated with the two fungi, suggesting that the decreased severity of wilt is largely due to increased tolerance of the plants to infection with the disease as a result of increased number of root laterals. It is also possible that cotton roots with C. maydis on their surface become less suitable for the progress of F. oxysporum. F. oxysporum produces in culture a metabolite inhibitory to C. maydis. This may partly account for the little effect that the latter fungus exerts on the severity of wilt when it follows F. oxysporum in the soil.It appears that the interaction between F. oxysporum and C. maydis does not affect the pathogenicity of the latter fungus to maize.
The toxicity of sulphur dioxide to Diplocarpon rosae Wolf causing blackspot of roses
Authors: SAUNDERS P. J. W. 
Published: February 2008

SUMMARYGermination of conidia of Diplocarpon rosae Wolf is inhibited in a solution made by dissolving 35 p.p.m. sulphur dioxide in water. Inhibition is permanent after exposure for 3 hr. Gaseous SO2 in air under controlled conditions at 100μg./m3 markedly reduces infection of rose leaves after exposure for 2 days. Blackspot of roses is checked or eliminated in areas where SO2 pollution of air exceeds 100/μ./m.3.
Epidemiological aspects of blackspot disease of roses caused by Diplocarpon rosae Wolf
Authors: SAUNDERS P. J. W. 
Published: February 2008

SUMMARYConidia of Diplocarpon rosae Wolf are dispersed mainly by water‐splash. Within a crop the spread of the disease can be traced from primary foci. Infection follows the ‘compound interest’ pattern, sensu van der Plank (1963), which is typical of most leafspot diseases. Accumulation of inoculum, together with certain conditions of rainfall and temperature in August, led to a characteristic, rapid development of the disease in September 1963 and 1964, after an incubation period of 2–4 weeks.
Coiled‐sprout in the potato: the effect of various storage and planting conditions
Authors: MOORBY J. , McGEE S. 
Published: February 2008

SUMMARYThe incidence of coiled‐sprout was determined in Scotch and local‐grown Arran Pilot and Duke of York seed tubers which had been stored at 10°, 4° and 15° C. and in a farm store with no temperature control. All four tuber types were planted in the field and, in addition, the two types of Duke of York were planted in Perlite at 7°, 10° and 15° C. In the field, and when maintained at 7° and 10° C, the percentage of sprouts coiling and the intensity of coiling was greater in tubers stored at 10° and 15° C. than at 4° C. There was no coiling when the Duke of York tubers were planted at 15° C.In a further experiment tubers were stored at 20° C. in the light and dark and samples were planted monthly for 3 months at temperatures of 7°, 10° and 15° C. During the following 3‐month period only light‐stored were planted because of the excessive amount of tip‐death in the tubers stored in the dark. There was very little coiling in the dark‐stored tubers. In the first two plantings of the light‐stored tubers there was virtually no coiling of those planted at 15° C. There was some, however, at 7° and 10° C. In subsequent plantings there was more coiling and no effect of planting temperature.Attempts to isolate Verticiculum nubilum from sprouts were successful in only a small percentage of attempts and it was not possible to demonstrate any difference between its distribution on coiled and normal sprouts. It was not possible to induce coiling by infection of sprouts with spores of V. nubilum.Over a wide range of sprout sizes the amount of coiling was a function of sprout size at planting. However, the parts which coiled were those in the apical bud of the sprout at the time of planting and hence contributed only a small amount to the total sprout size. It is likely, therefore, that the correlation between coiling and sprout size reflects the changing metabolism of the elongating regions of sprouts with their increase in length, these regions developing in such a way as to produce a greater tendency to coiling. The internal reactions concerned in these changes, however, are not known.
Spore dispersal in Alternaria porri (Ellis) Neerg. on onions in Nebraska
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYIn spore‐trapping studies in 1965, conidia of Alternaria porri (Ellis) Neerg. were detected in the atmosphere immediately above onions affected by purple blotch disease. On calm summer days, peak conidium concentration occurred between 08.00 and 14.00 hr., few conidia being trapped between 20.00 and 06.00 hr. On windy days, there were marked increases in concentration. Concentration tended to increase with increasing wind velocity. Increased conidium concentrations were also recorded after rainfall and irrigation, and during spraying operations.Laboratory observations indicate that in A. porri, the attachment of conidium to conidiophore is weakened, if not broken, by movements in the conidial apparatus which occur in response to a decrease in vapour pressure.Possible causes of fluctuations in atmospheric content of A. porri conidia are discussed.
Studies on the etiology of black rot, Stemphylium radicinum (Meier, Drechsl. & Eddy) Neerg., and leaf blight, Alternaria dauci (Kühn) Groves & Skolko, on carrot crops; and on fungicide control of their seed‐borne infection phases
Authors: MAUDE R. B. 
Published: February 2008

SUMMARYOf nineteen commercial samples of carrot seed in use at Wellesbourne in 1963, eight were found to be infected with both Stemphylium radicinum and Alternaria dauci and five with S. radicinum alone. Both fungi caused damping‐off of seedlings and when carrots were grown at high densities A. dauci caused severe foliar infection. Neither fungus gave rise to marked infection of ware crops at normal spacings but, when seed infected with S. radicinum was sown in the autumn, the resulting seed crop was heavily infected by the succeeding autumn.Spring‐sown carrots grown in soil that had borne infected crops or contained debris infected with either fungus showed little or no infection in the autumn or after storage for 3 1/2 months; autumn‐sown or spring‐planted (steckling) carrots put into ground infected with S. radicinum showed severe infection in the following autumn. This suggested that ware‐crop carrots were resistant to infection from the soil whereas the seed crop was not.Both fungi were eradicated from seed by a 24 hr. soak at 30d̀ C. in a 0.2% thiram suspension, but were not completely eliminated by seed dust treatments with a range of fungicides.
Arabis mosaic and Prunus necrotic ringspot viruses in hop (Humulus lupulus L.)
Authors: BOCK K. R. 
Published: February 2008

SUMMARYPurified virus preparations made from nettlehead‐diseased hop plants, or from Chenopodium quinoa, to which the virus was transmitted by inoculation of sap, contained polyhedral virus particles of 30 mμ diameter which were identified serologically as arabis mosaic virus (AMV). There were serological differences between AMV isolates from hop and from strawberry, and also differences in host range and in symptoms caused in C. quinoa and C. amaranticolor. AMV was always associated with nettlehead disease. The nematode Xiphinema diversicaudatum occurred in small numbers in most hop gardens, but was numerous where nettlehead disease was spreading rapidly.Preparations from nettlehead‐affected hops also contained a second virus, serologically related to Prunus necrotic ringspot virus (NRSV), in mild and virulent forms which infected the same range of test plants but showed some serological differences. Mild isolates did not protect C. quinoa plants against infection by virulent isolates. Hop seedlings inoculated with virulent isolates of NRSV developed symptoms indistinguishable from those of split leaf blotch disease. Latent infection with NRSV was prevalent in symptomless hop plants. Nettlehead disease is apparently associated with dual infection of AMV and virulent isolates of NRSV.An unnamed virus with rod‐shaped particles 650 mμ long was common in hop and was transmitted by inoculation of sap to herbaceous plants. Cucumber mosaic virus was obtained from a single plant of Humulus scandens Merr.
Influence of cocksfoot streak virus on the growth of single cocksfoot plants
Authors: CATHERALL P. L. , GRIFFITHS ELLIS 
Published: February 2008

SUMMARYHealthy and streak‐virus‐infected cocksfoot plants of a single genotype were examined over a 2‐year period. In the first year infection decreased tillering by about 40%, but in pot‐grown plants individual tiller weights were 30% higher so dry‐matter yield was decreased by only 10%. In the second year the larger tiller weights compensated completely for decreased tillering. No similar compensation was observed in field‐grown plants.The virus had the largest effects when soil fertility was highest, healthy plants producing significantly greater responses to nitrogen effects, but potassium, at certain times of the year, produced larger tiller weights in infected than in healthy plants. Infection decreased dry‐matter yield more in frequently than in infrequently cut plants.Infection greatly decreased the number of vegetative but not of fertile tillers. Infected plants tended to flower earlier and produced fewer, slightly smaller, viable seeds.
Comparison of tolerance to barley yellow dwarf virus in barley and oats
Authors: JENKINS G. 
Published: February 2008

SUMMARYIn a field trial, three varieties each of oats and barley were infected with barley yellow dwarf virus (BYDV) either at growth stage I or at growth stage 8 (Feekes scale), using a virulent isolate of BYDV transmitted by the ‘plum‐grain’ aphid (Rhopalosiphum padi L.). Early infection decreased yields of the susceptible varieties, Blenda oats and Proctor barley, by 97% and 93% those of the more tolerant oat varieties, Albion and CI 7488, b31% and 12%, but had no effect on the yield of the two tolerant Ethiopian barleys, CI 2325 and CI 7224. Late infection decreased grain yield only in Blenda. Mature straw height was decreased by early infection in all three oat varieties and by late infection in Blenda oats and in the barley variety CI 7224. The number of fertile tillers, number of grains per ear and Iooo‐grain weights were decreased in parallel with the decreases in yield, except that early infection increased the number of ear‐bearing tillers in CI 7488 and increased rooo‐grain weight in Albion. The lower yield resulting from late infection in Blenda was not accompanied by a decrease in number of grains per ear.
Preliminary studies on sap‐transmissible viruses of red clover (Trifolium pratense L.) in England and Wales
Authors: VARMA PRABHATI , GIBBS A. J. 
Published: February 2008

SUMMARYRed clover plants, collected from nine widely separated permanent pastures in England and Wales, were tested for sap‐transmissible viruses. Viruses were identified by the symptoms they caused in test plants, by electron microscopy, and by serological tests. Of the 265 plants tested 14% were infected. Only pea mosaic virus was common and widespread; it was found in 8% of the plants, and in seven of the fields. Other viruses isolated were arabis mosaic, bean yellow mosaic, red clover mottle, and red clover vein mosaic; only red clover mottle virus produced diagnostic symptoms in red clover. No viruses were detected in seedlings grown from seed from eighty‐nine commercial seed crops. Attempts to transmit red clover mottle virus by the Collembolan Sminthurus viridis L., which is common on red clover, failed.
Seed‐transmission of nematode‐borne viruses
Authors: LISTER R. M. , MURANT A. F. 
Published: February 2008

SUMMARYTransmission through seed of crop and weed plants seems to be characteristic of nematode‐borne viruses. It occurred with tomato black ring virus (TBRV) in nineteen species (thirteen botanical families), with arabis mosaic virus (AMV) in thirteen species (eleven families), with raspberry ringspot virus (RRV) in six species (five families), and also, in more limited tests, with tomato ringspot, cherry leaf roll and tobacco rattle viruses. A remarkable feature was that infected seedlings, except those containing tobacco rattle virus, often appeared healthy. The occurrence and extent of seed‐transmission depended on both the virus and the host plant. In many progenies more than 10%, and in some 100%, of seedlings were infected. The viruses were transmitted through at least two or three generations of seed of those host species tested. After 6 years' storage, TBRV‐ and RRV‐containing seed ofCapsella bursa‐pastorisandStellaria mediagerminated to give infected seedlings.In controlled crossing experiments with strawberry and raspberry, virus was transmitted to seed from both male and female parents but, at least in raspberry, the presence of competing virus‐free pollen much decreased the ability of pollen from infected plants to set seed. There was no evidence that healthy mother plants became infected when their flowers were pollinated with infected pollen.
Effects of shading and time of year on net assimilation rates of young glasshouse tomato plants
Authors: COOPER A. J. 
Published: February 2008

SUMMARYMinimum and maximum net assimilation rates were determined from calculated curves of closest fit to data for 2 years. The minimum (14 g./m.2/week) occurred in mid‐December, immediately before the shortest day, and the maximum (78 g./m.2/week) between 27 June and 8 July, just after the longest day. The northern limit at which the tomato cannot maintain vegetative growth under glass in mid‐winter is probably latitude 59–60° and is determined by a limiting daylength of approximately 6 hr. The proportional reduction in net assimilation rate by shading was independent of the time of the year. The photosynthetic system of glasshouse tomato plants is not light‐saturated in midsummer in southern England.
Phytotoxicity to blackcurrants of sprays containing sulphur
Authors: SMITH B. D. , CLARKE G. M. 
Published: February 2008

SUMMARYStudies in 1963–65 of the phytotoxic effects, on leaves, flowers and yields of blackcurrants, of sprays containing sulphur, particularly lime sulphur, showed that there was considerable variation in degree of effect between years and between experiments in the same year. It was difficult to damage flowers except at low temperatures, but if fruit set was affected then yield was depressed. Leaf scorching has to be very severe before yields are depressed. There was no evidence from preliminary experiments that sprays of seaweed extract reduced sulphur shock if used up to 3 days before lime sulphur application.The growth rate of shoots was reduced by 1/4–4% lime sulphur for short periods, dependent on concentration, but total bud numbers, flower/ vegetative bud ratios and yield were unaffected.It was found that no adverse effects of lime sulphur were carried over into the following year.
A comparison of fungicide spray volumes for the control of coffee berry disease
Authors: WALLIS J. A. N. , FIRMAN I. D. 
Published: February 2008

SUMMARYA continuation of previous trials in which three sprayers were used to apply 8.4 g. of Perenox in a range of spray volumes from 0.2 to 1.7 l. per tree confirmed that the volume of spray did not affect greatly the deposit retained on the branch surface. Branches were able to retain up to about 250 mg. Cu/m.2 and it is considered that a volume equivalent to 100 gal./acre would provide the greatest margin of safety to compensate for inaccuracies of application, while avoiding serious run‐off. Where coffee was well pruned, intensive copper spraying raised the annual yield by about 2 cwt. of clean coffee per acre. Copper spraying did not provide an adequate control of coffee berry disease and, under certain circumstances, increased incidence.