bluuebunny/crossref_metadata_2025 huggingface dataset:
Sugar, organic acid, phenolic acid and plant growth regulator content of extracts of honeydew of the aphid Myzus persicae and of its host plant, Raphanus sativus
Authors: HUSSAIN A. , FORREST J. M. S. , DIXON A. F. G.
Published: February 2008

The honeydew of Myzus persicae feeding on radish seedlings contains glucose, fructose, trehalose, melezitose and sucrose, of which glucose and fructose are present in radish seedlings. In addition, the honeydew contains eight organic acids, of which seven are present in uninfested seedlings and six are present in infested radish seedlings: of the eighteen phenolic acids in the honeydew, five are present in uninfested radish seedlings. Auxins, gibberellins, growth inhibitors and cytokinins are present in the honeydew. The presence of carbonate and bicarbonate previously recorded in honeydew of M. persicae could not be confirmed, but ammonia is present in fresh honeydew and accounts for its high pH.
The influence of expanding leaves and the reproductive stem apex on apical dominance in Lolium multiflorum
Authors: LAIDLAW A. SCOTT , BERRIE ALEX M. M.
Published: February 2008

In vegetative plants of Lolium multiflorum removal of the two youngest emerging leaves resulted in increased expansion of basal tiller buds. A similar release of inhibition of tiller buds took place if the floriferous apex was removed. The surgical procedures did not affect the response.

Under conditions of N‐deficiency total tiller number was reduced but on removal of the apex the deficient plants showed an increased initial rate of tiller bud expansion.

Apical dominance during the vegetative stage of growth in this grass was apparently due to the expanding leaves in the vegetative apex, but in the flowering plant the control was exerted by the inflorescence or the elongating stem.
Resistance to bacterial blight of cotton varieties homozygous for combinations of B resistance genes
Authors: INNES N. L.
Published: February 2008

In the Sudan, inoculation experiments were done on a wide range of Egyptian cotton lines homozygous for single genes and for digenic and trigenic combinations of Knight's B genes for resistance to bacterial blight. Although leaf inoculation was successful, stem inoculation was only partially so and boll inoculation, using two different techniques, failed to produce measurable disease symptoms. There was a good general relationship between leaf and stem resistance, and a close association between resistance to natural attack in the field and leaf resistance to artificial inoculation. Confirmation was obtained of the strong resistance conferred by B2 B9K, which was as effective as B2B6 or B2B3B6. No other combination was as effective when inoculated artificially. Nevertheless, in a natural field attack, only mild symptoms were found in lines homozygous for B1 B9K and for B4B6. Under the same conditions lines with B2B6 showed no symptoms but those with B2B3 were severely attacked. Reasons for continuing to use major genes in the breeding of blight‐resistant cotton in the Sudan are discussed.
The efficiency of spawning machines for mixing insecticides into mushroom compost
Authors: WYATT I. J. , GURNEY BARBARA
Published: February 2008

Insecticides incorporated into mushroom compost, using a spawning machine, are seldom mixed uniformly enough to achieve satisfactory pest control. The mixing efficiencies of various application methods and machines were investigated by mapping the distributions of fluorescent granules and emulsions under ultraviolet light. The pattern in which granules were applied to a compost block greatly affected the distribution after mixing but even uniformly peppering the surface resulted in acceptable concentrations in only 49% of the compost. Mixing twice increased this to 57%. With three times as many smaller granules, 89% of the compost was acceptably treated. Watering or spraying the compost with emulsions gave poor distributions except when the spray was directed into the spinner, which acceptably treated 83%. A machine which threw compost upwards into a hood beyond the spinner before it fell into a tray, gave better mixtures than conventional machines.

The granule distribution affected the control of Heteropeza pygmaea larvae. Virtually complete control was obtained by peppering diazinon granules on to compost at 50 ppm a.i. and then mixing twice through a spawning machine.
Studies on plant growth‐regulating substances.: The effects of light and hormone inhibitors on plant root growth
Authors: WILKINS H. , LARQUÉ‐SAAVEDRA A. , WAIN R. L.
Published: February 2008

Light inhibition of primary root elongation in Zea mays seedlings was found to be an almost instantaneous response and the inhibitory effect was shown to persist for at least six hours following a short exposure to white light. Removal of the root cap completely removed the inhibitory effect of light. The apical region of the root appeared to be mainly responsible for perceiving light and initiating the production of factors involved in the inhibition of elongation.

Extraction of the roots of light‐exposed Zea seedlings revealed the presence of the carotenoid pigments, violaxanthin, neoxanthin and lutein, together with an unidentified non‐acidic growth‐inhibitory compound. Xanthoxin, however, was not detected.
Post‐harvest physiology of tetraploid banana fruit: response to storage and ripening
Authors: NEW S. , MARRIOTT J.
Published: February 2008

Aspects of the post‐harvest physiology relating to storage and ripening of the fruit of tetraploid banana clones resistant to Sigatoka disease, have been compared with fruit of Valery, an important commercial triploid cultivar. Significant differences in susceptibility to low temperature injury, duration of the preclimacteric period, the texture of pulp and peel and ethylene evolution have been found between tetraploid and Valery fruit and also between tetraploid fruit of different clones.

Fruit of Valery and one tetraploid clone developed serious chilling injury during storage at 12 °C whereas that of five other tetraploid clones showed only slight damage. The preclimacteric period for fruit of two tetraploid clones was 30–45% less than for Valery fruit at an equivalent stage of physical development. Pulp firmness of preclimacteric tetraploid fruit was 20–30% less than that of Valery fruit and the differences persisted through ripening. The softening response to applied ethylene was up to 15 h earlier in fruit of tetraploid clones than of Valery but respiratory patterns, colour development and starch‐to‐sugar conversion were similar. Unlike Valery fruit, ripe tetraploid fruit did not develop senescent spotting, and shelf life was terminated by rapid deterioration of peel strength to a state of severe finger drop. Temporal and quantitative differences occurred between fruit of tetraploid clones and Valery in production of ethylene and these may relate to the observed differences in control of softening in both pulp and peel.
The development ofPuccinia hordeion barley cv. Zephyr
Authors: SIMKIN M. B. , WHEELER B. E. J.
Published: February 2008

Germination of uredospores ofPuccinia hordeiwas similar on cover‐slips and on the first leaves of barley seedlings (cv. Zephyr) at 100 % r.h. over the range 5–25 °C, being greatest at 20 °C. At 15, 20 and 25 °C maximum germination was attained in 6 h. No uredospores germinated on coverslips in humidities below saturation.

The numbers of pustules which subsequently developed on plants incubated at 5, 10, 15 or 18 °C and 100 % r.h. for varying periods up to 24 h, were directly related to rise in temperature and length of incubation.

The time from inoculation to eruption of pustules (generation time) was 6 days at 25 °C, 8 days at 20 °C, 10 days at 15 °C, 15 days at 10 °C and 60 days at 5 °C. Pustule production on inoculated plants which had been kept at 5 °C was rapidly accelerated when they were transferred to 20 °C. Data obtained at constant temperatures were used to predict generation times of the fungus in the field.

The productivity of pustules, determined as weight of uredospores, was examined at 10, 15 and 20 °C. Significantly more spores were produced at 15 than at 10 °C and most were produced at 20 °C.

The results are discussed in relation to those obtained by other workers and to the development of brown rust in the field.
The effect of soil‐ and tuber‐borne inoculum on the incidence of potato gangrene
Authors: LOGAN C.
Published: February 2008

Under optimum growing conditions neither tuber‐ nor soil‐borne Phoma exigua var. foveata inoculum appreciably affected stand or yield of the subsequent potato crop. Seed tubers with gangrene rots caused high levels of stem and tuber symptoms when planted in var. foveata contaminated or uncontaminated land; contaminated seed tubers with no rots also produced progeny with a high gangrene potential.

Sufficient soil‐borne inoculum was carried over in land that produced a gangrene affected crop in the previous year to override the effect of tuber disinfection. Effective gangrene control was achieved by a combination of tuber disinfection shortly after harvest over successive years with a 1 in 5 yr potato crop rotation.

Gangrene rots usually developed through injuries to the tuber periderm, rots in other tubers being associated with pustules of powdery scab (Spon‐gospora subterranea).
The invasion and development of the cereal cyst‐nematode, Heterodera avenae in the roots of autumn‐and spring‐sown cereals
Authors: KERRY B. R. , HAGUE N. G. M.
Published: February 2008

Observations were made at 2 or 4 wk intervals from December to harvest on all stages of Heterodera avenae in winter oats growing on infested land. Second‐stage larvae were present in all soil samples except on 5 and 20 July. Invasion and development of larvae was slow during winter. The nodal and seminal roots of winter oats were both heavily invaded by the nematode; larvae which invaded seminal roots tended to become male whereas those in nodal roots tended to become female. There was a small second invasion in August. Females were first observed on the roots of winter oats on 17 May, 214 days after the crop was sown and 62 days after the first fourth‐stage larva was observed.

The nodal roots of spring barley contained few H. avenae larvae whereas these roots were heavily invaded in winter wheat and oats. In spring barley the nodal roots were developing in June and July when few second‐stage larvae were in the soil whereas in winter oats and wheat the nodal roots were growing rapidly in April when larvae were most numerous, and so were heavily invaded.
Membrane‐associated particle aggregates in extracts of plant: infected with some viruses of the potato Y group
Authors: BRUNT A. A. , ATKEY P. T.
Published: February 2008

Membrane‐associated aggregates of filamentous virus particles were found occasionally in sap from plants infected with each of five distinct viruses of the potato Y group. The aggregates measured up to 960 × 700 nm and contained from four to twenty‐four virus particles. Their occurrence is apparently specifically associated with potato Y and allied viruses, observations suggesting that they may be either fragments of virus‐containing cytoplasmic strands or groups of particles enveloped during cellular disruption by pieces of tonoplast with which they are associated in vivo.
Root and shoot growth of semi‐dwarf and taller winter wheats
Authors: LUPTON F. G. H. , OLIVER R. H. , ELLIS F. B. , BARNES B. T. , HOWSE K. R. , WELBANK P. J. , TAYLOR P. J.
Published: February 2008

Investigations are reported of root and shoot growth in semi‐dwarf and taller winter wheat varieties grown in contrasting soils over three years. Comparisons were made of the distribution with depth of roots, estimated by injecting rubidium‐86 into stem bases and counting the content in soil cores. The relative ability to absorb phosphate from different zones was measured from the recovery in aerial parts of 32P injected into the soil at different depths. The distribution of dry matter in roots and aerial parts, and total root length, was measured using soil cores and samples of aerial parts taken during the growth of the crop. Relative growth rates of the aerial parts followed a sigmoid curve, but those of the roots showed little change between germination and anthesis. There was little evidence of varietal differences in root growth, though there was some indication that at depth the roots of the semi‐dwarf varieties were more extensive and absorbed more phosphate than those of the taller varieties.
Tracer studies with 32P on the distribution of functional roots of Arabica coffee in Kenya
Authors: HUXLEY P. A. , PATEL R. Z. , KABAARA A. M. , MITCHELL H. W.
Published: February 2008

Seven experiments were done over a period of 21 months at Ruiru, Kenya, using 4 mCi/tree of 32P tracer to study the distribution of functional roots of mature Arabica coffee trees. Tracer was placed at sixteen equally spaced sites around individual trees at one of five depths (to 180 cm) and three distances (to 135 cm = mid‐row). Thereafter, samples of three‐leaf shoot tips were collected at 14‐day intervals for up to seven occasions and the radioactivity assessed after drying and ashing.

There was negligible activity at any time at 180 cm depth but at other depths, and at all three distances, the relative level of activity changed markedly with season. After prolonged drought relatively high root activity was found at mid‐depth, near to the trunk; after the soil was re‐wetted by rain most root activity occurred in the topsoil at the quarter‐row distance; after the soil profile had been wet for some time there was a more general distribution of functional roots. Some departures from this general scheme are discussed as are practical implications and the need for further investigations.
Dispersal of the cabbage root fly
Authors: FINCH S. , SKINNER G.
Published: February 2008

The dispersal rates of wild and culture cabbage root flies Erioischia brassicae were determined in release‐recapture experiments at Wellesbourne in 1971–3. The experiments were concerned mainly with the first 7 days of adult life. The flies, released from nine locations in the area, were recaptured in yellow water‐traps.

Dispersal was affected by wind, rain and the terrain the flies were crossing. The flies least often recaptured were those released into the host crop when 6–12 days old. The results indicated the following pattern of behaviour.

Flies moved little during the first 2 days of adult life but by the third day both sexes had dispersed to c. 100 m from the release point. Flies are known to mate about the fourth day and after this the males continued to disperse at c. 100 m per day for the three subsequent days. ‘Wild’ females from field‐collected pupae carried out a ‘migratory’ flight, however, and dispersed at c. 1000 m per day during the fifth and sixth days, the days preceding the start of oviposition. Similar rates of dispersal were recorded from flies released across host crop and non‐host crop areas.

Some females did not stop at the first crop they encountered. The culture females from the laboratory‐reared pupae dispersed only c. one‐third of the distance of the wild females. There was considerable intermingling of local populations. The percentage recapture of young culture and wild flies released during the pre‐oviposition period of this species was 38 ± 4 and 19 ±4 for males, and 15 + 2 and 8+1 for females, respectively.

The dispersal range of the cabbage root fly is probably within a 2000–3000 m radius of the site of infestation.
Factors affecting the assessment of resistance of potatoes to gangrene (Phoma exigua var. foveata)
Authors: ROGERS W. G. , KILLICK R. J.
Published: February 2008

Three experiments designed to elucidate the effects and interactions of different inoculation methods, inoculation positions, strains of Phoma exigua var. foveata and clones of potato tubers inoculated were analysed using as data dimensions of the lesions and a more general surface score. The assessment of susceptibility was affected by all these factors. The ranking of varieties for resistance altered considerably depending upon whether the surface area or the depth of lesions was considered. Derivation of more complex scores combining these measurements reduced the relative genetic component and hence would be of no value to potato breeders.
Fungitoxicity of acetaldehyde vapour to some major post‐harvest pathogens of citrus and subtropical fruits
Authors: PRASAD KRISHNA
Published: February 2008

In laboratory trials, fumigation with acetaldehyde vapour at 0–75 to 20 % concentration (v/v) for 0–5 to 120 min at 21 oC killed six species of post‐harvest citrus pathogens grown on agar media. The fungicidal effect of acetaldehyde vapour at this temperature was a function of concentration and exposure. Penicillium digitatum and P. italicum were not as susceptible to inhibition of spore germination as Alternaria citri, A. tenuis, Colletotrichum gloeosporioides and Glomerella cingulata. A concentration of 10 % acetaldehyde vapour at 21 oC for 10 min was fungitoxic to all the pathogens tested.
Role of ethylene in the effects of sucrose and other sugars on detached Sinapsis cotyledons
Authors: Moore K. G.
Published: February 2008

Culture of excised cotyledons in 6 × 10‐2 M sucrose reduces petiolar chlorophyll protein and RNA, inhibits CO2 fixation and suppresses the development of root primordia. This syndrome is preceded by enhancement of ethylene production by sucrose, particularly in the light. Glucose also increases ethylene production and petiole senescence whereas 3‐O‐ethyl glucose does not.
Ethylene in the soil atmosphere, and its effects on root growth
Authors: Smith K. A.
Published: February 2008

Ethylene concentrations in the soil atmosphere can greatly exceed levels known to markedly influence plant growth. The ethylene is microbial in origin and the rate of production under anaerobic conditions is correlated with organic matter content. Under field conditions the highest concentrations occur when soil temperatures and moisture levels are high, resulting in development of anaerobic zones.

Crop species differ widely in the sensitivity of their roots to ethylene, this sensitivity being broadly correlated with known intolerance of waterlogged (anaerobic) environments.
Relationship between ethylene production and sensitivity to ethylene in roots of several species
Authors: Konings H.
Published: February 2008

Ethylene usually inhibited root elongation in various species, but there was some stimulation of growth at low concentrations of the gas. Evidence will be presented that the different growth responses of the roots to ethylene are related to the different levels of endogenous ethylene in these roots. These levels are probably not controlled by auxin in all roots.
Ethylene and abnormal developmental patterns in tulips
Authors: Munk W. J. DE
Published: February 2008

Under certain conditions ethylene has very serious effects on morphogenetic processes in tulip bulbs, which can lead to the disorder bud‐necrosis. Fusarium‐infected bulbs are the main source of ethylene.

Bud blasting in tulips can result from exposure of bulbs or growing plants to ethylene. There are immediate effects on growing plants and exposed bulbs produce plants that are vulnerable to unfavourable growing conditions. The occurrence of blasting can be counteracted by kinetin, GA3 and GA4+7.
Ethylene in relation to the coiled sprout disorder of potato
Authors: Hillman J. R. , Catchpole A. H.
Published: February 2008

Many of the features of the coiled sprout disorder of potato can be induced by applying ethylene to normal healthy sprouts. The conditions inducing this disorder have been examined and its development may be correlated with aberrant ethylene metabolism.
The potential uses of ethephon in apple growing
Authors: Childs R. D.
Published: February 2008

The effects of ethephon on growth, fruit bud formation and abscission in apple will be discussed in relation to the possible use of this chemical in orchards. It is possible, for example, to accelerate the ripening of fruit on trees and yet avoid abscission effects by combining ethephon with other growth regulators. In this way, the programmed harvesting of mature fruits is possible.
Physiology of ethylene production by Fusarium and possible consequences in the host‐parasite relation in tulip bulbs
Authors: Kamerbeek G. A.
Published: February 2008

Fusarium oxysporum f. tulipae produces at least 2000 times more ethylene than all other Fusarium species or formae specialis tested. Ethylene production is oxygen dependent but not correlated with the growth of mycelium.

Ethylene prevents the synthesis of the antifungal compound tulipaline (methylene butyro‐lactone) in host tissue. These observations support the hypothesis that ethylene may play an important or even essential role in host‐parasite relations.
Germination of Erysiphe gratninis f.sp. hordei conidia on barley leaves
Authors: RUSSELL G. E. , ANDREWS CHRISTINE R. , BISHOP C. D.
Published: February 2008

Germination of Erysiphe graminis f.sp. hordei conidia on leaves of several barley cultivars was studied in the laboratory. On both detached leaves and intact plants, within 48 h of inoculation a higher proportion of conidia had germinated on the basal and middle portions of the adaxial leaf surface than on the corresponding portions of the abaxial surface. Such differences between surfaces were not observed near the leaf tip. Similar results were obtained with all the cultivars and growth stages tested, and with five isolates of E. graminis, and are consistent with the observation that there is usually less powdery mildew on the abaxial than the adaxial surface of barley leaves.

With most of the barley genotype/mildew isolate combinations tested, within 48 h of inoculation higher proportions of conidia germinated on seedlings and juvenile plants than on older plants. Inherited characteristics which affect spore germination on the leaf surface may be important factors in the development of adult‐plant resistance of barley to powdery mildew, particularly in certain genotypes.
Observations on the relationship between morphological variation and host range in populations of cereal cyst‐nematode
Authors: COOK R.
Published: February 2008

British pathotype 3 of cereal cyst‐nematode differs morphologically from Heterodera avenae. Mature cysts have a distinct underbridge which is absent from pathotypes 1 and 2. A population of pathotype 3 produced cysts on cereal genotypes resistant to pathotypes 1 and 2. The relationship of this pathotype to other graminaceous cyst‐nematodes is discussed.
Glasshouse studies on the effect of low temperature on infection of perennial ryegrass seedlings by Fusarium nivale
Authors: HOLMES S. J. I. , CHANNON A. G.
Published: February 2008

In glasshouse experiments, isolates of Fusarium nivale, applied as mycelial macerates, caused marked reductions in the number and length of roots, and in the height and fresh weight of S. 321 perennial ryegrass seedlings. Spore inocula failed to cause infection.

Damage by F. nivale was increased when inoculation was immediately followed by four alternate 12 h periods in a growth cabinet at 0°C and in a warm glasshouse at c. 17°C, succeeded by a further 11 days in the same glasshouse.

Although inoculated seedlings receiving no cold treatments initially showed damage, regrowth of roots and some recovery of the shoots occurred in a fortnight. Exposure of the plants after that time to four intermittent 12 h periods at 0°C, however, arrested their recovery and caused further root damage.

The implication of these results in the importance of low temperature in the winterkill syndrome is discussed.
Herbicides and insecticides: their compatibility and effects on weeds, insects and earthworms in the minicauliflower crop*
Authors: FINLAYSON D. G. , CAMPBELL C. J. , ROBERTS H. A.
Published: February 2008

In field experiments on a sandy loam at Wellesbourne, England in 1972 and on a silt loam at Agassiz, British Columbia in 1973, combinations of herbicides and insecticides were applied at sowing to determine their effects on weeds and invertebrate populations and on the growth and yield of cauliflowers grown at high density

There was good agreement between the results from the two locations. The two combinations of herbicides, 0.6 kg trifluralin/ha incorporated pre‐drilling plus 2.2 kg propachlor/ha pre‐emergence and 2.2 kg nitrofen/ha plus 2.2 kg propachlor/ha both applied pre‐emergence, gave good weed control, their relative effectiveness depending on the species composition of the weed population. The insecticides isophenphos, carbofuran, chlorfenvinphos and fensulfothion were applied as bow‐wave treatments. None of them, whether in combination with herbicides or not, adversely affected crop stand or yield. Yield was reduced when either weeds or root‐fly maggots (Hylemya brassicae (Bouché)) were not controlled.

Only in one experiment was there any evidence of any herbicide‐insecticide interactions. Where trifluralin and carbofuran were applied together at Agassiz, the control of both weeds and maggots was less than that with the other combinations. None of the treatments affected the populations of predatory beetles, but the numbers of earthworms were greatly reduced by carbofuran and to a lesser extent by chlorfenvinphos. Except for carbofuran in one experiment, the treatments had no effects on the numbers of aphids, lepidopterous larvae or leaf miners present at harvest.
Effect of herbicides on bracken rhizome survival
Authors: WILLIAMS G. H. , FOLEY A.
Published: February 2008

Glyphosate sprayed at 1.1, 2.2, 4.5 or 6.7 kg/ha on to bracken decreased the total carbohydrate content of the storage rhizome 20 months after spraying, the decrease being greater when spraying was carried out at the beginning rather than at the end of August. Asulam, benazolin and metribuzin, although reducing frond numbers, showed no significant effect on the rhizomes over the same period.
Rose powdery mildew: field trials with systemic fungicides, 1970–2
Authors: WHEELER B. E. J.
Published: February 2008

Trials were carried out with benomyl and dodemorph in 1970, 1971 and 1972, with triarimol in 1971 and with MBC in 1972. In 1970 and 1971 there were some indications that dodemorph was a more effective eradicant but the differences between materials generally appeared less important than the timing of the spray application. An attempt in 1972 to obtain better control by applying sprays in relation to predictions of mildew growth, based on temperature and humidity, was only partially successful.

No significant effects of mildew on leaf area or number of flowers could be demonstrated. High levels (25 and 50%) of mildew were associated with small leaves but this may reflect only the abundance of such leaves at periods generally favourable for mildew. The rate of increase of mildew appeared to be directly related to rate of host growth. The significance of this is discussed.
Protein composition of unusual tobacco mosaic virus strains
Authors: DAWSON J. R. O. , REES M. W. , SHORT MARGARET N.
Published: February 2008

Amino acid analyses have been made of the proteins of single‐lesion isolates of five strains of tobacco mosaic virus (TMV) differentiated by Lycopersicon hosts. These hosts differed in their genetical control of resistance to TMV, and the virus strains had therefore survived specific selection pressures. Two of the five strains differed in their amino acid composition from type TMV and from all other tomato strains of TMV previously examined.

Symptoms induced by the five strains in four tomato lines and in Nicotiana tabacum cvs White Burley and Kawala are described.
Effect of European wheat striate mosaic, acquired by feeding on diseased plants, on the biology of its planthopper vector Javesella pellucida
Authors: AMMAR E.‐D.
Published: February 2008

Ten lines of Javesella pellucida transmitted European wheat striate mosaic (EWSM) from diseased plants with an average efficiency of 31% compared to 10% efficiency for eleven lines of J. dubia. The effect on J. pellucida of EWSM, acquired through feeding on diseased plants by first and second instar nymphs, was studied in two outbred lines of hoppers. Three categories were compared: hoppers that fed on diseased plants for 7 days and became infective, hoppers that fed similarly but did not become infective, and control hoppers never fed on diseased plants and which were non‐infective. No statistically significant variation was found between these three categories in survival of nymphs to adulthood, adult longevity of either sex, total, and rate of, egg production per female, or survival of eggs to eclosion. Transovarial transmission of EWSM occurred in 6 to 43% of the progenies of infective females of J. pellucida.
An improved method of marking cabbage root flies
Authors: FINCH S. , SKINNER G.
Published: February 2008

A new marking method has been developed to follow the movements and dispersal of cabbage root flies during their most active period, 2–7 days after emergence, using one of thirty‐four combinations of four head markings with fluorescent powders and six body markings with oil‐soluble dyes. The method permits simultaneous replication of dispersal experiments and rapid detection of marked flies. It requires no expensive equipment and provides a permanent record of the results.
Potato tuber lenticels: development and structure
Authors: ADAMS M. J.
Published: February 2008

Stomata on growing potato tubers are changed to lenticels by about the third internode from the apical bud (A‐3). In wet soil lenticels proliferate, while in dry soil the filling cells become suberized by about the fifth internode (A‐5).

Lenticels did not proliferate in the field after mid‐August, and laboratory experiments on freshly harvested and stored tubers showed that lenticels proliferated less readily as tubers aged. Proliferation occurred more readily on stored tubers induced to sprout than on tubers from which the eyes had been removed, but nevertheless proliferation is unlikely during winter storage.
Leafhopper transmission of a virus causing maize wallaby ear disease
Authors: GRYLLS N. E.
Published: February 2008

A virus causing maize wallaby ear disease was transmitted experimentally by Cicadulina bimaculata to fourteen species of monocotyledonous plants. It was also transmitted by Nesoclutha pallida, and by grafting. The symptoms obtained resemble closely those reported for maize leaf gall disease in the Philippines and maize rough dwarf virus in Italy and Israel.

About 85% of C. bimaculata caught in the field carried maize wallaby ear virus (MWEV), and many of their progeny were viruliferous even when not allowed access to infected plants. The proportion of infective individuals in clones bred for nine generations from selected non‐transmitting adults decreased from 85% in the first nymphs to less than 1%; such individuals were difficult to rear, as their fecundity and longevity decreased greatly. N. pallida transmitted MWEV after injection with partially purified extracts of infected plants.

Spherical particles c. 85 nm in diameter were found in the salivary glands of viruliferous C. bimaculata, but not in those of non‐transmitting individuals. The particles occurred in tubules in the cytoplasm and each had a densely stained core c. 50 nm in diameter. Particles similar in size to the core were found in extracts of infected but not uninfected maize, and in extracts of viruliferous but not in non‐viruliferous C. bimaculata and N. pallida.
The efficiency of two organomercury compounds in controllingg seed‐borne Septoria nodorutn on winter wheat
Authors: BATEMAN G. L.
Published: February 2008

The influence of various factors on the performance of organomercury seed treatments in controlling seed‐borne Septoria nodorum was studied in laboratory experiments. Control was least effective on the most heavily infected seed samples. On heavily infected seed ethyl mercuric chloride was more effective than phenyl mercuric acetate, although 5 wk storage of the treated seed before sowing increased the effectiveness of the latter compound. Effectiveness was not generally influenced by differences in soil moisture. Seedling vigour was significantly improved by levels of mercury below those applied commercially. The significance of seed treatment in the epidemiology of Septoria disease is discussed.
Photosynthetic and translocation pattern in contrasting winter wheat varieties
Authors: RUCKENBAUER P.
Published: February 2008

The rates of photosynthesis and patterns of translocation of 14C from the flag leaves of tall and semi‐dwarf wheat varieties, with and without awns, were compared in a field experiment. The rates of photosynthesis of the awnless varieties fell during the 14 days after anthesis but those of the awned varieties did not change. Wide differences in translocation pattern of 14C supplied at anthesis were also found between varieties, but the differences in distribution pattern of 14C supplied 14 days later were less. At anthesis, the high yielding semi‐dwarf selection translocated most carbohydrate to the ears and awned selections least. It is suggested that varietal differences in translocation pattern are determined by differences in the capacity of the grain to store carbohydrate.
The effect of early blight disease caused by Alternaria solani on shoot growth of young tomato plants
Authors: COFFEY M. D. , WHITBREAD R. , MARSHALL C.
Published: February 2008

The effect of increasing spore concentration of Alternaria solani (Early blight disease) on the shoot growth of young tomato plants was analysed. Changes in growth were related to the severity of infection which increased with increasing inoculum. Leaf production was not affected but dry weights and especially leaf expansion were decreased. The effective leaf areas of the five inoculated leaves (L1‐L5 numbered from the plant base) were drastically decreased by expanding necrotic lesions and, to a lesser extent, by premature leaf fall. Healthy leaves expanding soon after inoculation (L6, L7) were markedly affected by the disease on the lower leaves and had decreased specific leaf areas (ratio of leaf area to leaf dry weight) but later formed (from L8) leaves were less affected and had greater specific leaf areas than equivalent leaves on uninoculated plants.
Serological and immunoelectrophoretic relationships among viruses in the tombusvirus group
Authors: HOLLINGS M. , STONE OLWEN M.
Published: February 2008

Serological cross‐reactions among eighteen virus isolates of the tombusvirus group were compared in precipitin tube and immunodiffusion serological tests. The isolates were also compared by immunoelectrophoresis in agar gel.

Although precipitin tube tests showed considerable and reproducible differences between the various isolates, the results were too greatly affected by other factors to be of value in assessing strain relationships.

When pairs of isolates were compared for spur formation in gel‐diffusion tests, the results suggested that most isolates could be placed in one of two groups; one group comprised isolates from pelargonium (leaf curl), the other consisted of petunia asteroid mosaic virus and artichoke mottled crinkle virus isolates from Italy and tomato bushy stunt isolates from soil around this Institute and from cherry. Four isolates did not fall into either of these groups; they nearly always formed spurs when compared among themselves, or with viruses in either of the two groups. Pairs of isolates that could be distinguished from each other in spur‐formation tests using antiserum homologous to one of them could not always be differentiated when antiserum heterologous to both isolates was used.

Immunoelectrophoresis gave consistent results with several methods of virus preparation; it indicated grouping and separation of the isolates in general agreement with the results of gel‐diffusion tests: all pelargonium leaf curl isolates were grouped together with slow migration towards the cathode. The petunia asteroid mosaic isolate and the isolates from cherry and from soil from this Institute (GCRI) moved slowly towards the anode. Tomato bushy stunt virus type strain migrated rapidly to the cathode, differing greatly from all other isolates. The method offers a relatively simple means of typing isolates of the tombusvirus group.
Field experiments on the cereal cyst‐nematode (Heterodera avenae) in south‐east England, 1967‐72
Authors: GRAHAM C. W. , STONE L. E. W.
Published: February 2008

Field trials in south eastern counties of England over the period 1967‐72 have been carried out on sites infested by the cereal cyst‐nematode, Heterodera avenae. In the main, spring barley was the cereal used, since this is the dominant cereal grown, and during this period resistant cultivars became available. Behaviour of soil populations of this nematode was erratic, but resistant cultivars from the Welsh Plant Breeding Station, based on Rika/Proctor, consistently lowered the nematode population in the soil, and outyielded more modern susceptible cultivars on infested soils. Evidence was found, in 1972, of a reduction in viability of cysts, associated with disease.
Incorporating granular nematicides in soil to control potato cyst‐nematode, Heterodera rostochiensis
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E. , FRENCH EILEEN M. , SMITH J.
Published: February 2008

Incorporating either Du Pont 1410 or Nemacur P at 11‐2 kg a.i./ha in peaty loam topsoil in Spring, controlled potato cyst‐nematodes (Heterodera rostochiensis) to 20 cm deep as well as did 5.6 kg incorporated in Winter before ploughing followed by another dose of 5.6 kg incorporated in the seedbed in Spring. In pots Du Pont 1410 remained effective after several months incubation in soil at 5 or 10 oC. Dazomet at 440 kg/ha incorporated in the topsoil in Winter (220 kg before ploughing and 220 kg after ploughing) did not control the nematodes as consistently as 5.6 or 11.2 kg a.i./ha of Du Pont 141 o or Nemacur P, even when the dazomet‐treated plots were covered with Polythene sheeting to prolong fumigation. In large containers, aldicarb at 45 mg a.i./13 l soil increased the yield of Arran Banner potatoes as much when incorporated to 13 cm deep in moderately infested peaty loam as when incorporated to 25 or 38 cm deep, but not as much as when all the soil (to 51 cm deep) was treated. Treating the soil to 13 cm deep did not control the nematodes 13–25 cm deep even though some of the nematicide was probably leached into this layer. In field plots, the nematodes were better controlled when Du Pont 1410 or Dowco 275 was rotavated into the top 10 cm than into the top 20 cm of a peaty loam soil. Rotavating soil twice instead of once after applying aldicarb, Du Pont 1410 or Dowco 275 to the soil surface did not increase nematode control. Although small amounts of aldicarb incorporated into the topsoil in Spring controlled the nematodes, the same amounts concentrated in the seed furrows, just before susceptible potatoes were planted in them, did not.
Effects of a synthetic juvenile hormone and some analogues on Ephestia spp. (Lepidoptera: Phycitidae)
Authors: HONG BY TAN KENG
Published: February 2008

Depending on their stage of development, treatment of mature larvae of Ephestia kühniella with a synthetic juvenile hormone resulted in the production of super larvae (which invariably prolonged larval life) and larval‐pupal intermediates. When migrating last‐instar larvae were treated with the juvenile hormone analogues (JHA) ethyl‐3,7, n‐trimethyldodeca‐2,4‐dienoate (ZR512) and isopropyl ii‐methoxy‐3,7, ii‐trimethyldodeca‐2,4‐dienoate (ZR515), larval‐pupal intermediates and pupal mortality were induced. However, when applied topically, ZR515 appeared more effective than ZR512. Both analogues prevented adult emergence when topically applied to the migrating larvae at doses between 28–52 ng. One‐day‐old pupae were most susceptible while older individuals became less sensitive with age. When larvae pupated in corrugated cardboard rolls were treated with ZR512 those of both E. cautella and E. kiihniella failed to emerge. At an estimated dose of 179 ng cm‐2, ZR515 prevented 77‐6%E. cautella and 100%E. kühniella larvae from emerging as adults. The control of Ephestia by JHA treatment of the pupation sites is discussed.
Effect of leaf age and inoculum concentration on the symptoms produced by Gymnosporangiumjuniperi‐virginianae on apple
Authors: ALDWINCKLE H. S.
Published: February 2008

Gymnosporangium juniperi‐virginianae, the incitant of cedar apple rust, induced the greatest number of lesions (flecks, pycnial lesions, aecial lesions) on 6‐ and 8‐day‐old leaves of single‐shoot potted apple plants inoculated and incubated under controlled conditions. The largest pycnial lesions developed on 2‐ and 4‐day‐old leaves and the largest aecial lesions on 6‐day‐old leaves. The number of lesions was positively correlated with the concentration of basidiospores in the inoculum, but lesion size was constant at different inoculum levels. Elevated inoculum concentrations failed to induce pycnia on cv. McIntosh which normally bears only flecks; very low concentrations induced the development of pycnia but not aecia on cv. Rome Beauty, which normally bears aecia. An ‘infection rating’, log10 (10 nd2), where n is the highest number of pycnial lesions per leaf and d is the largest mean diameter of pycnial lesions on any leaf, calculated for four cultivars in greenhouse tests showed a positive correlation with a ‘susceptibility rating’ developed from observations of natural infection of these cultivars in the field.
Storage rots of taro (Colocasia esculenta) in the British Solomon Islands
Authors: JACKSON G. V. H. , GOLLIFER D. E.
Published: February 2008

Several fungicides chosen for their ability to control the pathogens previously isolated from stored corms of taro failed to prevent severe rotting. This result led to a reappraisal of the organisms involved in the initial stages of decay. Isolations made from stored corms during the first 5 days showed that Phytophthora colocasiae and Pythium splendens were the dominant fungi in the rots. Later Botryodiplodia theobromae rapidly colonized the corms to complete the decay.

Attempts to reduce losses by leaving petiole bases, cormels and roots attached only succeeded in delaying infection by a few days. Corms placed in soil in well‐drained pits stored relatively well up to 4 wk without impaired taste. Fungal rots were completely eliminated in corms stored in the soil but bacterial rots caused by Erwinia chrysanthemi were responsible for some decay.
Effects of mist irrigation on the physiology of sugar beet
Authors: MILFORD G. F. J.
Published: February 2008

High radiation and transpiration demand created low leaf water potentials in sugar beet even when adequate water, applied as irrigation to the soil, was apparently available to the roots. Applications of small quantities of water as a mist to the leaves under such conditions enabled the plant to maintain greater water potentials and to photosynthesize faster.
The behavioural basis of a pheromone monitoring system for pea moth, Cydia nigricana
Authors: LEWIS T. , WALL C. , MACAULAY E. D. M. , GREENWAY A. R.
Published: February 2008

The flight and mating behaviour of the pea moth(Cydia nigricana)was studied at overwintering sites and in pea fields to see whether it could be exploited to provide early warning of adult immigration into pea crops. The field threshold temperature for take‐off is 18CC. Most flight activity‐occurred in June and July between 16.00 and 18.00 B.S.T. with peak activity at 17.04 h. Moths were not caught in suction traps at heights above 0–4 m, but they can probably travel several km by fluttering above vegetation in winds of up to 10 km/h.

Female moths produce a sex pheromone(s) highly attractive to males; ‘calling’ by females and mating occur during the period of maximum flight activity.

Suction traps and egg counts detected the presence of moths in crops at about the same time. On average, sticky and water traps containing live virgin females as a lure caught respectively 17 and 130 times more males than suction traps and, on occasions, 25 and 300 times more; these attractive traps should detect the arrival of immigrants sooner than suction traps or egg counts.

Extracts of virgin females dispensed from filter paper at doses of one and five female‐equivalents (FE) attracted males rapidly but temporarily. Rubber dispensers with extracts of twenty FE remained attractive for 6 days. Several synthetic attractants were screened using doses of o‐i mg on rubber dispensers in sticky traps. CYs‐8‐dodecenyl acetate and erans‐8, frans‐io‐dodeca‐dienol at doses of o‐i mg were slightly attractive; the latter at doses of 1 ‐o mg was more attractive than twenty FE doses of extract and could be used for experimental monitoring of pea moth until its own synthetic sex pheromone(s) is available.
Effects of variation in temperature and light intensity at different times on growth and yield of spring wheat
Authors: FORD MARGARET A. , THORNE GILLIAN N.
Published: February 2008

Spring wheat grown in pots outdoors was transferred to growth rooms for various periods to study the effect of increasing the temperature from 14‐4 to 20‐3 oC (Expt 1) or from day/night values of 15‐0/15‐2 to 20‐0/15‐2 oC (Expt 2) and of increasing the amount of visible radiation in a 16 h day from 424 to 792 J cm‐2 (Expt 1) or 374 to 740 J cm‐2 (Expt 2). There were no interactions between temperature and radiation.

In Expt 1 neither the increase in temperature nor extra radiation, applied for 14 days immediately after the appearance of double ridges on the stem apex, or 14 days later, increased grain yield at maturity. Warmth early, but not late, increased dry weight, leaf area and the number of floret primordia immediately after treatment, but these effects had disappeared by anthesis, 30 days later. Dry weight but not leaf area was increased by extra radiation but the effects had disappeared 2 wk after treatment.

An increase in temperature imposed for 16 days starting 5 or 21 days after anthesis (Expt 2) increased dry weight of the ear and decreased that of the rest of the plant immediately after treatment, and decreased leaf area at all times. When plants from the two temperatures were put together in the same conditions, ear growth of plants that had been in the warm was slower than that of plants from the cold treatment, so that the difference in ear weight observed after 16 days of treatment reversed and grain yield was decreased by warmth applied in either period; the component of yield decreased by warmth was grain size. Additional radiation in either post‐anthesis period increased dry weight of all parts of the plant and had negligible effects on leaf area. Final grain yield was increased by c. 15% because the individual grains were larger. Early treatment also increased grain number slightly. The effects of treatment during the two post‐anthesis periods were similar in size, and additive.
The size and shape of plots in sugar‐beet experiments
Authors: JAGGARD K. W.
Published: February 2008

Uniformity of root yield and plant density of sugar beet was assessed on four areas each of 250 small plots‐two in each of the years 1969 and 1970. Plots from which 2–5‐100 m2 of crop was harvested from the centre rows were constructed and their coefficients of variation calculated. Coefficient of variation decreased as harvested area increased, but little additional accuracy was achieved by harvesting more than 40 m2. Plots drilled‐to‐a‐stand appeared no more variable in root yield or plant density than carefully hand‐singled plots.