bluuebunny/crossref_metadata_2025 huggingface dataset:
Population studies on pea cyst‐nematode Heterodera goettingiana Liebs.
Authors: JONES F. G. W. , MEATON V. H. , PARROTT D. M. , SHEPHERD A. M. , KING J. M.
Published: February 2008

Changes in populations of Heterodera goettingiana Liebs. were studied in microplots containing three kinds of soil. Starting with an artificially uniform population, varieties of pea which matured quickly induced smaller numbers of cysts and eggs than later‐maturing varieties although there was ample time for completion of the life cycle on the former. Field bean was comparable with the late‐, and broad bean with the early‐maturing pea varieties.

When one variety of pea was grown on all plots of a group, yield decreased in proportion to the density of the population before planting. The relationship between yield and initial population over a narrow population range was expressed equally well by the simple equations Y=a+bx or Y=a+blogx, where Y= yield, x= the number of eggs, a= the Y intercept and b the regression coefficient. For plots with a wide range of initial populations (4–359 eggs/g. soil), neither equation was adequate and the relationship was best fitted by a sigmoid curve.

In two sets of plots, the influence of two population levels, nitrogen versus no nitrogen, and light versus heavy soil, was tested. Soils and populations affected yield significantly; nitrogen was ineffective on light soil but increased yield on the heavy soil. Only soil type affected the final population, that in the heavy soil which gave the greater yield being twice as large.

When peas were grown, the final population rose to a ceiling level independent of the initial population size. In the plots with widest initial population range, the ceiling level was determined by the number of females (new cysts) formed. Their number was almost constant over the whole initial population range and they produced on average 129 eggs/cyst which was the maximum theoretically possible rate of increase under the conditions of the experiment. At small initial egg densities (4 eggs/g.) about 50% of the eggs became female and at great densities (359 eggs/g.) only 1% or less.

Final populations in the microplots bore no relationship to yield of peas. It is suggested that the size and form of the central part of the root system determines how many females the roots can support and that root size is one of the factors that determines ceiling levels.

Nematicides used to decrease numbers of cyst‐nematode eggs or larvae in soil tend to remove only those surplus to the carrying capacity of root systems. Nematicides or enemies able to kill established females before they produce eggs would control reproduction more effectively.
Tomato fruit bronzing
Authors: JENKINS J. E. E. , WIGGELL D. , FLETCHER J. T.
Published: February 2008

Tomato fruit bronzing occurs in green fruits and produces variable symptoms in ripe fruits. The bronzing is caused by brown necrosis of the fruit wall, mainly at the calyx end of the fruit, which is also the most severely affected part. Field observations and experiments showed that bronzing is closely associated with infection of the plant with tobacco mosaic virus (TMV) and some other factors, notably rank or ‘soft’ growth. Symptoms occur within a short time of infection with TMV and affected fruits are produced over a relatively short period on any one plant. The symptoms in a particular fruit remain constant and do not get progressively worse. Plants systemically infected with TMV do not subsequently produce bronzed fruits. This disease can be distinguished from some other tomato fruit disorders such as blotchy ripening and appears to be similar to a disorder in the U.S.A. called internal browning.

A second type of bronzing in green fruits is less common but symptoms are more severe. In this case the necrosis of the fruit wall is not particularly associated with the calyx end and it gets progressively worse so that the fruit is often unsaleable; a characteristic symptom is a series of dark lines radiating from the stylar end of the fruit. Affected fruits are produced on a particular plant over a long period of time and are not associated with infection of plants with TMV.

A histological examination of both types of bronzing is reported.
Seed bacterization and biological activity of bulbiformin
Authors: SINGH PRITAM , VASUDEVA R. S. , BAJAJ B. S.
Published: February 2008

The production of bulbiformin by Bacillus subtilis has been observed on the seed coats, spermatosphere and rhizosphere of bacterized pigeon‐pea seeds sown in sterile and unsterile soils. The importance of different nutrients as a base for bacterization in enhancing the antibiotic production has been established. Maximum antibiotic activity was observed in the treatments where bacterization had been made in molasses solution supplemented with groundnut cake. The rate of antibiotic production reached a peak after 15–18 days. Relatively less antibiotic was synthesized under natural unsterile soil conditions.

It is shown that the antibiotic produced as a result of bacterization becomes systemic in plant tissue and provides a protective zone around the roots of pigeon‐pea seedlings. Appreciable reduction in the incidence of pigeon‐pea wilt has been obtained through seed bacterization.
Effects of daylength and temperature on ear size in S. 24 perennial ryegrass
Authors: RYLE G. J. A.
Published: February 2008

The size of the inflorescence of plants of S. 24 perennial ryegrass (Lolium perenne L.) grown in the glasshouse increased as daylength or temperature decreased. The larger ears had more spikelets and more florets in each spikelet. An increase in the number of axillary primordia accumulated at the shoot apex before spikelet initiation, together with the development of more spikelets after spikelet initiation, accounted for the larger number of spike‐lets. The number of florets per spikelet appeared to be determined by the balance between factors which controlled the rate of spike development and those which controlled the availability of metabolites during the same period.
Spraying arabica coffee for the control of coffee berry disease
Authors: WALLIS J. A. N. , FIRMAN I. D.
Published: February 2008

Three sprayers were used in each of three field trials to apply 8.4 g. of Perenox† per tree in a range of spray volumes from 0.2 to 1.7 1.

Copper deposits and conidial inoculum potential were determined on sample branches. The critical sampling zone was between the fifth and eighth node proximal to the youngest node flowering in the current season.

The low‐volume treatments were as effective as the highest (standard) volume in terms of copper deposit, reduction in inoculum potential and the number of diseased fruit, and in increasing the yield of coffee in the first year of the trials.
Studies on plant growth‐regulating substances XIX. Stability of 2,3,6‐trichlorobenzoic acid in wheat plants and in the rabbit and mouse
Authors: BALAYANNIS P. G. , SMITH M. S. , WAIN R. L.
Published: February 2008

Gas chromatography has been used in an investigation of the uptake and persistence of the herbicide 2,3,6‐trichlorobenzoic acid (TBA) in wheat plants. In addition, the capacity of the compound to pass through the alimentary tract of the rabbit and the mouse has been studied. The chemical was found to be present at harvest both in seeds and straw following its uptake by the roots or when applied as a spray at the stage of growth normally recommended for selective weed control. Some 17.6% of the acid fed to the rabbits and 2.7% of that fed to mice was recovered in the acidified extracts of the excreta.
Pea seed infection by Mycosphaerella pinodes and Ascochyta pisi and its control by seed soaks in thiram and captan suspensions
Authors: MAUDE R. B.
Published: February 2008

Apparently normal pea seeds from pods bearing lesions of Mycosphaerella pinodes were often internally infected with the fungus. When infected seeds were sown in sterile grit almost all the seedlings showed disease lesions, at or below soil level, 4–6 weeks after sowing.

Seed infected with Ascochyta pisi gave only 40% infection of seedlings: these showed lesions on the stem and first two leaves within 4 weeks of sowing.

Infection of seeds by both pathogens could be eradicated by soaking the seeds for 24 hr. in 0.2% suspensions of thiram or captan at 30d̀C. In laboratory or greenhouse tests these treatments did not check germination, but in the field the captan treatment reduced emergence.

The treated seeds became fully imbibed but could be dried and stored: the thiram treatment was used for semi‐commercial treatment of quantities of seed up to 3 cwt.
Fungicidal activity and chemical constitution: XIII.* Active components of commercial formulations containing dinocap
Authors: BYRDE R. J. W. , CLIFFORD D. R. , WOODCOCK D.
Published: February 2008

Six isomers, isolated from the mixture of dinitrophenols obtained by the hydrolysis of commercial formulations containing dinocap, were tested in the greenhouse against apple mildew caused by Podosphaera leucotricha.

The two most active compounds were 4‐(Ié‐ethylhexyl)‐ and 4‐(Ié‐propylpentyl)‐2,6‐dinitrophenols, which appear to account for most of the antimildew activity of the mixture. The crotonate of the latter phenol was considerably more effective than dinocap itself, but both crotonates were less effective than the corresponding free phenols.

Little evidence of synergism between two ethylhexyldinitrophenols was obtained.
The action of nabam, metham‐sodium and other sulphur compounds on Heterodera schachtii cysts
Authors: CLARKE A. J. , SHEPHERD AUDREY M.
Published: February 2008

When used in tests against eggs of Heterodera schachtii, sodium ethylenebisdithiocarbamate (nabam) solutions break down to give a number of compounds, some being hatch‐inhibiting and others hatch‐stimulating. The compound mainly responsible for the hatch‐stimulating activity of nabam solutions is ethylenethiuram monosulphide. Stored solutions of sodium ethylenebisdithiocarbamate lose activity because the ethylenethiuram monosulphide disappears.

Zinc and manganese ethylenebisdithiocarbamates were more active hatching agents than equimolar mixtures of zinc or manganese sulphates with nabam. Hatch stimulation was least with a zinc sulphate/nabam mixture of mole ratio 1.5:1, in which the dithiocarbamate ion became largely replaced by the sparingly soluble zinc dithiocarbamate. Increasing the zinc concentration in the mixture increased hatching because of the hatching activity of the zinc ion.

Nabam solutions containing manganese sulphate were inactivated because the manganese ion catalysed decomposition to the hatch‐inhibiting carbon disulphide.

Sodium N‐methyldithiocarbamate (metham‐sodium, Vapam), which readily decomposed in aqueous solution, was toxic to, and prevented the hatching of, H. schachtii. Methylisothiocyanate, the major decomposition product, was toxic to H. schachtii at concentrations greater than 0.1 mM.
Effects of photoperiod in growth cabinets on the growth of leaves and tillers in three perennial grasses
Authors: RYLE G. J. A.
Published: February 2008

Long photoperiods provided in growth cabinets and consisting of a conventional extended photoperiod or of a ‘light‐break’ in the middle of a long, dark period, generally increased leaf length and sometimes leaf width and consequently the rate of expansion of leaf surface, but decreased rate of leaf production and tillering in vegetative plants of S.37 cocksfoot (Dactylis glomerata L.), S.215 meadow fescue (Festuca pratensis Huds.) and S.24 perennial rye‐grass (Lolium perenne L.) compared with short photoperiods. All plants received the same total amount of light each day. These effects were observed both in single plants and in plants grown close together to simulate sward conditions. The total dry weight of plant material was greater in long than in short photoperiods.
Aphids from mangold clamps and their importance as vectors of beet viruses
Authors: HEATHCOTE G. D. , COCKBAIN A. J.
Published: February 2008

Mangold clamps are over‐wintering sources of the aphid‐transmitted beet mosaic, beet yellows and beet mild yellowing viruses, and of several species of aphid, three of the most common in clamps being Myzus persicae, Rhopalosiphoninus staphyleae tulipaellus and R. latysiphon. This study attempted to assess the relative importance of the different species in spreading viruses from clamps.

Compared with M. persicae, R. s. tulipaellus and R. latysiphon are seldom trapped in flight, except near large infestations. Alatae of M. persicae and R. s. tulipaellus become common in clamps in April, but few fly below 15d̀ C., a temperature seldom reached in eastern England in early spring. Flight muscle autolysis, which occurs later in R. s. tulipaellus and R. latysiphon than in some aphid species, also probably prevents many alatae in clamps from flying. We confirmed the importance of clamps as sources of beet viruses, the percentage of infected plants decreasing with increasing distance from infested clamps.

M. persicae is shown to be a better vector of beet viruses than the other clamp aphids, and is probably responsible for most virus spread from clamps. R. s. tulipaellus did not transmit beet mosaic virus, but it is a fairly efficient vector of beet yellows and beet mild yellowing viruses, and, although we did not find this species on sugar beet in the field, it probably spreads these viruses from clamps. R. latysiphon did not transmit any of the viruses, and the role of Macrosiphum euphorbiae, Aulacorthum solani and Myxus ascalonicus is probably small.
The relation between damage caused by insect pests and boll rot associated with Glomerella cingulata (Stonem.) Spauld. & von Schrenk (Colletotrichum gossypii Southw.) on Upland cotton in Uganda
Authors: LEAKEY C. L. A. , PERRY D. A.
Published: February 2008

The conidial form of Glomerella cingulata found on cotton bolls in Uganda was avirulent on undamaged bolls at normal humidity but formed a latent infection which became aggressive when the bolls were put in a saturated atmosphere. Mechanical damage and injury caused by insects feeding were associated with extensive rotting by the fungus at normal humidity.

The taxonomy of the fungus is discussed.
Varietal response in wheat to water supply in the field, and male sterility caused by a period of drought in a glasshouse experiment
Authors: BINGHAM J.
Published: February 2008

Field experiments in 1961 and 1962 with four winter wheat varieties (Professeur Marchal, Cappelle‐Desprez, Hybrid 46 and Holdfast) compared three water regimes: irrigation to prevent the soil water deficit exceeding 2 in.; shielding from rain; and normal rainfall. The experiments were done on soils selected for their liability to drought. Grain yield was decreased by water deficit; the effects differed between varieties, but the varietal differences were not consistent in the 2 years.

In glasshouse experiments, plants of Cappell‐Desprez were subjected to drought for 3–4 days during ear development and subsequently watered normally. When this treatment preceded pollen meiosis by a few days many of the lower florets of each spikelet were male‐sterile but female‐fertile. Also there was often proliferation, within the spikelet, of normally fertile florets above the male‐sterile ones, showing that the number of florets formed may increase until a late stage in ear development.

The results of the field experiment suggested that grain yield was restricted by the capacity of the grains as sinks for photosynthates. If so, a genetic improvement in grain yield could be obtained by breeding for an increase in number of florets per spikelet.
The antifungal activity of thiosemicarbazides in vitro and their systemic activity against cucumber scab Cladosporium cucumerinum
Authors: PLUIJGERS C. W. , SIJPESTEINN A. KAARS
Published: February 2008

The antifungal activity of a number of thiosemicarbazides was studies. The position and nature of substituents in thiosemicarbazide seem to be of great influence on growth‐inhibition. High activity was found for 1‐aryl substituted thiosemicarbazides, particularly derivatives, In systemic tests against cucumber scab, PTS and a number of its substitution products showed considerable activity.
The fungitoxicities of cuticular and cellular components of citrus lime leaves
Authors: MARTIN J. T. , BAKER E. A. , BYRDE R. J. W.
Published: February 2008

Cuticular and cellular components of leaves of Citrus aurantifolia Swingle were tested for toxicity to Gloeosporium limetticola Clausen, responsible for the withertip disease. Cuticular waxes isolated from mature, resistant leaves showed little activity. A dimethoxy furocoumarin, isopimpinellin, isolated from the cellular components, was highly toxic, and ester and acidic fractions obtained from both young susceptible and mature resistant leaves showed some activity. The contents in the leaves and the toxicitiesin vitroof the active constituents suggest that they may contribute, to an important degree, to the defence of the leaf against G. limetticola.
The distribution of diosgenin in Dioscorea spp
Authors: BAKER E. A. , MARTIN J. T. , WILSON APHRA P.
Published: February 2008

The distribution of diosgenin in Dioscorea deltoidea Wallich and D. sylvatica Ecklon at successive stages of growth is described. Diosgenin occurs in the cotyledon‐endosperm of the dormant seeds, and in the tubers, roots, stems and leaves of plants from the seedling stage onwards. It accumulates in the tubers of seedlings grown in daylight, but not in those of seedlings grown in darkness. Actively growing aerial tissues such as leader shoots appear to be the sites of formation from which the diosgenin is translocated to the tubers. The diosgenin is evenly distributed throughout the tubers.
Studies on the aphid, Cavariella aegopodii Scop: On secondary hosts other than carrot
Authors: DUNN J. A. , KIRKLEY JEAN
Published: February 2008

Of the eleven cultivated species of Umbelliferae heavily attacked in the field by Cavariella aegopodii Scop., chervil (Anthriscus cerefolium) attracted so many alates that it was killed before a population of alienicolae developed. Carrot was next in order of alate preference and coriander (Coriandrum sativum) and caraway (Carum carvi) were last. Despite its lack of attraction, caraway proved more lastingly suitable as a host and eventually supported the largest population of alienicolae.

Of the wild umbellifers tested, wild carrot, Daucus carota ssp. carota, was the species most preferred by the incoming alates and hemlock (Conium maculatum) the least. On hemlock, also, there was little colonization.

Although a sequence of wild umbellifers supported C. aegopodii through most of the year, few were suitable winter hosts; the apterae hibernated largely on carrot crops.

In spring, cow parsley (Anthriscus sylvestris) was one of the hosts first colonized by immigrant C. aegopodii and carried winged alienicolae before the end of June. The main development of winged alienicolae on Anthriscus and other wild Umbelliferae, however, was in July.

The possible role of the wild umbelliferous hosts of C. aegopodii in the spread of motley dwarf virus to carrots is discussed.
Verticillium wilt of the hop: the survival of V. albo‐atrum in soil
Authors: SEWELL G. W. F. , WILSON J. F.
Published: February 2008

Verticillium albo‐atrum was apparently eradicated from soil in which dicotyledonous plants were suppressed. In one field experiment V. albo‐atrum was not recovered after 4 years of weed‐free grass cover; in the same period soil infectivity reduced to very low levels under two bare fallow treatments. Where weeds developed after single annual cultivations soil infectivity declined from the initially high level but finally increased. In three observation trials in which hop plants were used to detect V. albo‐atrum after grass‐cover treatments, soil infectivity was very low after 2 years and apparently nil after 3–5 years.

Grass cover effectively stabilizes infested soil; it may be used for limiting spread from primary disease outbreaks, and also as a short‐term treatment to reduce the infectivity of soil to be re‐planted with resistant varieties.

The frequent incidence of V. dahliae hop infections in one trial indicated that this fungus was not amenable to control by grass cover treatment and hence may be ecologically distinct from V. albo‐atrum.
Host/parasite relationships between tomato and pathogenic isolates of Verticillium
Authors: GRIFFITHS D. A. , ISAAC IVOR
Published: February 2008

A close relationship was established between the virulence in the field of six isolates of Verticillium and their ability to penetrate and colonize sterile tomato seedlings grown in culture. The highly pathogenic species V. albo‐atrum and V. tricorpus rapidly colonized host tissue in culture, host reactions being absent or only slight. V. nigrescens and V. nubilum, mild pathogens, penetrated sterile roots more slowly and caused host reactions. The variation in pathogenicity in the field between two isolates of V. dahliae suggests that they are different physiological strains, but they induced no difference during the first stages of invasion‐reaction of sterile seedlings. Hyaline variants of all these isolates were less pathogenic than the original parent types.

Variations in temperature from 25° C. (near optimum for the growth of both tomato plants and the fungi) caused changes in host reactions. Ability to penetrate was not affected within the pH range 4.0–8.0, but at extreme values (3.2, 9.4 and 10.0) all isolates entered without any host reaction. Variations in nitrogen supply to the pathogens induced modifications in their ability to penetrate, whereas changes in supply of nitrogen to the seedlings had no apparent effect upon host/parasite relations.

The effects of simultaneous contact of non‐pathogenic and pathogenic isolates with seedling roots suggested that resistance of host tissue was controlled by the growing tip.
The survival on chrysanthemum roots of epiphytic mycelium of Mycosphaerella ligulicola
Authors: CHESTERS C. G. C. , BLAKEMAN J. P.
Published: February 2008

Mycosphaerella ligulicola has been shown to survive as epiphytic mycelium on the root surface of chrysanthemum cuttings: such survival could continue throughout the life of the glasshouse crop. Symptomless surface colonization of roots of cuttings could be induced in non‐sterile soil from an inoculum of (a) mycelium and sclerotia or (b) conidia (Ascochyta state); the colonization could spread upwards over the root surface.

After 12 weeks survival as an epiphyte on chrysanthemum roots the fungus was still pathogenic to unrooted cuttings.

Although the root surfaces of twelve other plants could be colonized by M. ligulicola the fungus survived on these roots for not more than 8 weeks.
Studies on sharp eyespot disease of cereals: Effects of the disease on the wheat host and the incidence of disease in the field
Authors: PITT D.
Published: February 2008

Greenhouse and field experiments showed that sharp eyespot disease can reduce establishment in wheat seedlings. Increasing disease severity caused a decrease in height and dry weight of surviving seedlings. Infection by the pathogen caused a reduction in tillering. Experiments also showed that a high incidence of disease can cause a reduction in the yield of grain of mature plants, but the disease level necessary for such effects is far higher than that usually encountered in the field.

Survey work in the East of Scotland in 1963‐65 showed a high percentage of crops infected with the disease. But even in 1964, a year of comparatively high disease incidence, there were few crops with a level of infection as high as that shown to affect yield.
Resistance to powdery mildew in rose
Authors: MENCE MARGARET J. , HILDEBRANDT A. C.
Published: February 2008

Resistance 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

Germination 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

The 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

Stem 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

Of 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

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

The 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

Germination 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

Conidia 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

The 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

In 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

Of 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

Purified 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

Healthy 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

In 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

Red 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

Transmission 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

Minimum 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

Studies 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

A 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.