bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in the relative resistance of two carrot cultivars to carrot fly attack over five seasons
Authors: ELLIS P. R. , FREEMAN G. H. , HARDMAN J. A.
Published: February 2008

A comparison was made over five seasons of carrot fly (Psila rosae) damage on two carrot cultivars, Sytan and Danvers, which represented the extremes of resistance discovered in screening trials at Wellesbourne. Plants were harvested regularly during the seasons and at each harvest the number and weight of roots was recorded and carrot fly damage was assessed using various techniques; in 1979‐80 the numbers of carrot fly larvae and pupae in and around root samples were counted. The experiments confirmed repeatedly the relative resistance of cv. Sytan compared with Danvers. The estimated reduction in carrot fly larvae on Sytan relative to Danvers in early November in four seasons ranged from 40% to 67%. When tested against first generation carrot fly attack the reduction in larvae on Sytan was 54%. There were 45% fewer mines per root on Sytan resulting in less damage at each harvest in all seasons. Larvae took longer to develop on Sytan than Danvers and 18% more plants of Sytan survived carrot fly attack. Differences in seedstock, season, sowing time, generation of carrot fly, plant size and density did not account for observed differences in damage between the two cultivars. The studies indicated satisfactory practical techniques for assessing carrot fly damage in cultivar screening trials.
A glasshouse screening method to assess resistance in onions to damage by onion fly (Delia antiqua) larvae
Authors: SONI S. K. , FREEMAN G. H. , ELLIS P. R.
Published: February 2008

Factors influencing the resistance of onion (Allium cepa) cultivars to onion fly (Delia antiqua) damage were investigated. These included different environments, methods of plant raising and egg inoculation, and plant size. A glasshouse compartment maintained at 14 to 37 °C was as satisfactory for assessing the resistance as a controlled environment.

The basic test unit comprised 10 onion seedlings raised in a 400 × 50 × 50 mm deep plastic trough and inoculated with 50 onion fly eggs from a laboratory culture. Resistance was assessed by counting wilted plants every two or three days for 21 days after egg inoculation. The reciprocal of number of days for each plant to wilt (wilting rate) was an appropriate variate for statistical analysis, adjusted for the length of the longest leaf at the time of inoculation. The method enables cultivars or breeding lines of onion species to be reliably screened for resistance to larvae of this pest in a glasshouse so that only the most promising need be tested in the field.
Desiccation studies in relation to the storage of Araucaria seed
Authors: TOMPSETT P. B.
Published: February 2008

Relationships between seed moisture content (fresh weight basis) and germination were examined for nine Araucaria species by desiccation under mild environmental conditions. The lowest safe moisture content, below which germination percentage begins to decline, was estimated in each case. Seeds can be grouped into three moisture content categories: the first group (including A. araucana, A. angustifolia, A. hunsteinii and A. bidwillii) cannot be safely dried to below 25–40%; the second group (including A. columnaris, A. rulei, A. nemorosa and A. scopulorum) cannot be dried to below about 12% without damage; the third category contains A. cunninghamii, which can be dried to 2% without damage.

Seeds in the first group should be stored at 0–5 °C with moisture contents above the lowest‐safe value. Provided freezing damage does not exceed 10%, seeds in the second group should be kept at ‐ 18°C or lower with about 7% moisture content for long‐term storage and at 0–5 °C with about 12% moisture content in the short term. Seed of A. cunninghamii is best retained at near 5% moisture content and in ‐18°C or lower.

The lowest‐safe moisture content was found to be associated with seed size and weight, higher moisture content values coinciding with greater size and weight of seed. Food reserve materials also differed among the groups; seeds of the first group were mainly starchy, whilst those in the other categories possessed a high lipid content.
Effects of activated charcoal on attack by larvae of the wheat bulb fly, Delia coarctata
Authors: SCOTT G. C. , GREENWAY A. R.
Published: February 2008

Activated charcoal interferes with normal host‐seeking by larvae of the wheat bulb fly, Delia coarctata, by adsorbing arrestant compounds exuded from the plants. Thus, in laboratory tests, activated charcoal in soil surrounding one of two rows of wheat seedlings decreased larval attack on the treated row. Charcoal in soil above the level of the seeds decreased attack but had no effect when below the seeds. However, there was no decrease in attack when both rows were in charcoal. Attempts to develop a practical application of this effect in the field are described.
Intercontinental variation of Sclerospora graminicola
Authors: BALL S. L. , PIKE D. J.
Published: February 2008

Collections of S. graminicola were made from local pearl millet crops in West Africa and India. Asexual inoculum was derived from the collections in Polythene tunnels and used to infect pearl millet cultivars from both continents. Analysis of deviance of the incidence of disease was performed on the logit scale using GLIM. The host × pathogen interactions were interpreted by use of the Finlay‐Wilkinson regression technique widely used in the study of genotype × environment interactions. While the West African collections were consistently more pathogenic than the Indian ones, West African hosts were potentially more susceptible to Indian than to West African pathogen isolates; conversely some Indian hosts were more vulnerable to West African than to Indian isolates. There was a fairly stable relationship between incidence of disease and relative pathogenicity of West African isolates but the Indian isolates were more variable in their susceptibility to changing background levels of disease. These results could influence resistance breeding strategies in pearl millet improvement programmes. The methods of analysis could be valuable for application to other complex and ill‐defined pathosystems.
The epidemiology of anthracnose disease of mango: inoculum sources, spore production and dispersal
Authors: FITZELL R. D. , PEAK C. M.
Published: February 2008

Anthracnose disease spreads within mango trees by water‐borne conidia of Colletotrichum gloeosporioides var. minor. Conidia were produced in lesions on leaves, defoliated branch terminals, mummified inflorescences and flower bracts. Conidia were trapped from these sources in the orchard during periods when anthracnose disease was developing both in flush growth and in flowers. The majority of conidia were trapped from lesions in young leaves.

Conidia were produced in the laboratory from acervuli in leaf lesions over a wide temperature range (10–30°C) both in wet and humid (95–97% r.h.) conditions. Conidia would be present for dispersal within the tree throughout the entire season.

Large numbers of conidia were trapped during prolonged periods of rain, and when these occurred during active growth or flowering, severe outbreaks of disease were recorded. No conidia were trapped following dews.

Ascospores of Glomerella cingulata var. minor were not trapped while the disease was active in the orchard. These spores do not appear to contribute to the infection cycle of mango anthracnose.
Production and field evaluation of codling moth granulosis virus for control of Cydia pomonella in the United Kingdom
Authors: GLEN D. M. , PAYNE C. C.
Published: February 2008

Codling moth granulosis virus (Cp GV) was produced in larvae of Cydia pomonella reared on artificial diet. The average yield of virus (9 × 109capsules/larva) was increased by raising the larvae on diet containing methoprene, a juvenile hormone analogue.

In field trials in 1978 and 1979, one or two high‐volume applications of Cp GV at 7 × 1010 capsules/litre achieved reductions in numbers of mature larvae and damaged fruit that were little different from those obtained by two applications of azinphos‐methyl. A field trial in 1980 showed that at concentrations of Cp GV ≥ 6 × 108 capsules/litre, damaged diminished slowly with increasing virus concentration. Following virus application in 1980, Cp GV infectivity was reduced by half in 3 days, but some activity persisted at least 4–8 wk after spraying. The results indicate that codling moth GV is an effective control agent particularly in reducing numbers of larvae and the more severe forms of fruit damage.
Codling moth granulosis virus: effects of its use on some other orchard arthropods
Authors: GLEN D. M. , WILTSHIRE C. W. , MILSOM N. F. , BRAIN P.
Published: February 2008

In four field trials from 1978 to 1980, sprays of codling moth granulosis virus (CpGV) plus 1·0% skimmed milk powder did not significantly affect damage to fruit by leaf rollers (tortrix moths). In laboratory tests, survival of larvae of the leaf roller Archips podana fed on leaves sprayed with CpGV plus milk was unaffected and they grew faster than on unsprayed leaves, because of the milk deposits. This might increase damage by A. podana if CpGV plus milk were applied during the feeding period of this species. In one field trial an unusual infestation of fruit by larvae of pith moth Blastodacna atra was not affected by CpGV. Azinphos‐methyl significantly reduced damage by B. atru and, in one field trial where sprays were correctly timed, that by leaf rollers. CpGV had no consistently significant effects on numbers of fruit tree red spider mite Panonychus ulmi or its predators, whereas azinphos‐methyl induced outbreaks of P. ulmi by killing its predators.
Variation among British isolates of potato leafroll virus
Authors: TAMADA T. , HARRISON B. D. , ROBERTS I. M.
Published: February 2008

Twenty isolates of potato leafroll virus (PLRV) were readily transmitted by Myzus persicae from a wide range of potato cultivars to Physalis floridana. The isolates also infected Montia perfoliata but not turnip or broad bean, and all were readily detected by direct enzyme‐linked immunosorbent assay. Four isolates, selected to represent the range of differences in severity of symptoms in P. floridana, also induced symptoms of differing severity in M. perfoliata, but their virulence in one species did not necessarily parallel that in the other. In general, virus concentration increased with increasing symptom severity. None of these four isolates was transmitted readily by Macrosiphum euphorbiae and their particles were antigenically indistinguishable in gel‐diffusion precipitin tests.

Further tests on one PLRV‐infected potato plant from which virus was at first not transmitted by M. persicae showed that it contained a poorly‐transmissible isolate (isolate 15). The inefficient transmission of this isolate could not be attributed to inadequate uptake or retention by M. persicae of virus from P. floridana, and aphids failed to transmit isolate 15 when it was acquired from purified preparations in membrane‐feeding tests. Although the poor aphid transmissibility of isolate 15 is therefore an intrinsic property of its particles, these were antigenically indistinguishable from the particles of readily aphid‐transmissible isolates.

Immunoelectron microscopy tests showed that PLRV and beet mild yellowing virus are antigenically closely related.
Large scale production, storage and transport of the insect‐parasitic nematodes Neoaplectana spp. and Heterorhabditis spp.
Authors: BEDDING R. A.
Published: February 2008

A method for producing up to 2000 million infectives of Neoaplectana bibionis per container is described and is applicable to other species of Neoaplectana and Heterorhabditis spp. The nematodes were cultured within autoclavable plastic bags, on crumbed polyether polyurethane sponge coated with chicken offal homogenate that had been sterilised and inoculated with the primary form of the appropriate symbiotic bacterium (Xenorhabdus spp.). Procedures for extracting and cleaning the nematodes on a large scale are described. Nematodes were stored and transported on clean sponge in aerated polyethylene tubes. The techniques are suitable for industrial use with little further development.
The effect of fungal parasitism and predation on the population dynamics of nematodes in the activated sludge process
Authors: GRAY N. F.
Published: February 2008

Nematophagous fungi, both predators and endoparasites, were found to be common components of activated sludge. Although rotifers and ciliate protozoa (both potential prey) were also abundant, no fungi were parasitic on these organisms. Endoparasitic fungi, which were far more abundant than predators, were able to infect nematodes and complete their life cycles successfully. Neither of the predatory fungi observed were able to produce conidia: an unidentified net‐forming species lived saprophytically and failed to capture any prey, although it played a minor role in the formation of microbial flocs, and a single conidium of Dactylella mammillata was observed to capture a nematode by spontaneous trap formation. Several endoparasites were recorded although single species dominated each sludge examined; these were Meria coniospora and Catenaria anguillulae. Both endoparasites were related to the population dynamics of the nematodes with 100% of the nematode population becoming infected at certain times. Clear predator (parasitetprey (host) associations were discernible and these are discussed.
Sampling conditions for reliable routine detection by enzyme‐linked immunosorbent assay of three ilarviruses in fruit trees
Authors: TORRANCE L. , DOLBY C. A.
Published: February 2008

Enzyme‐linked immunosorbent assay (ELISA) was used to test plum trees for prune dwarf (PDV), Prunus necrotic ringspot (NRSV) and apple mosaic (ApMV) viruses, cherry trees for PDV and NRSV, and apple trees for ApMV. Optimum conditions were determined for sampling in large‐scale surveys for these viruses. All three viruses were detected throughout the growing season in individual samples of young leaves, or twigs with newly formed buds. However, when single infected leaves were combined with different numbers of healthy leaves, tests were most successful for all three viruses early in the growing season. PDV was detected in 1/40 (infected/total leaves) cherry leaves in April and May and 1/40 plum leaves until July, whereas NRSV was detected in 1/20 cherry leaves until July and 1/20 plum leaves until May. ApMV was detected in 1/20 apple or plum leaves until June but was detected less readily in mature leaves after June than either NRSV or PDV. There was no evidence of uneven distribution of virus infection in the trees. The viruses were detected in leaf samples kept for 8 wk at 3°C but freezing was less reliable for storage especially with ApMV. ApMV was detected in tests on plants held for several weeks at 25°C, and PDV and NRSV in plants held at 30°C.
Development and practice of a glasshouse screening technique for resistance of wheat to the aphid Sitobion avenae
Authors: LOWE H. J. B.
Published: February 2008

Differences in resistance to S. avenae were confirmed amongst eight spring wheat stocks in glasshouse tests. Taking these stocks as standards, a glasshouse screening technique was developed in which 15 plants of each entry were arranged randomly in one block and aphids were scattered over the whole at the stem‐extension phase. When the infestation of individual plants was scored about 2 wk later, resistant and susceptible stocks were well differentiated. Provided that scoring was completed before or at ear emergence, separation of resistant entries was more efficient with older plants. Ranking of the standard stocks was little influenced by other variations of technique or environment.

Twenty‐six out of 91 previously untested spring wheat breeding lines appeared to be moderately resistant to S. avenae, suggesting that progress in the selection of resistant cultivars will depend more on the further development of suitable techniques than on the availability of heritable resistance.
Resistance to halo‐blight in the Cambridge accessions V4604 and V4058 of Phaseolus beans
Authors: INNES N. L. , CONWAY JANET , TAYLOR J. D.
Published: February 2008

V4604, a Cambridge University accession of Phaseolus vulgaris, had a high degree of leaf resistance to race 1 of Pseudomonas phaseolicola and partial resistance to race 2. Genetic control of resistance to race 1 was by a major dominant gene which is also present in the cv. Red Mexican. The partial resistance of V4604 to race 2 was under polygenic control, as was the low level resistance to race 2 in V4058.
A method for assessing the field susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica)
Authors: LAPWOOD D. H. , GANS P. T.
Published: February 2008

In experiments to develop a method for assessing the field susceptibility of potato cultivars to blackleg (Erwinia carotovora subsp. atroseptica) seed tubers were stab‐inoculated near the stolon (attachment end), with a suspension of the bacterium, or with water, before planting. Disease symptoms were recorded in three years (1980–1982) and plant growth and yield in 1982. Estima and Maris Bard were the most susceptible cultivars with many plants failing to emerge and most of those that did showing disease symptoms. Pentland Crown was the most resistant: few plants failed to emerge and few showed blackleg. Nevertheless compared with water‐inoculated plants bacterial inoculation of the seed tubers of this cultivar caused loss of yield and differences in tuber size distribution. Cara, Wilja and King Edward showed intermediate reactions.
Genetics of resistance to bacterial speck of tomato caused by Pseudomonas syringae pv. tomato
Authors: FALLIK E. , BASHAN Y. , OKON Y. , KEDAR N.
Published: February 2008

Two tomato cultivars, Ontario 7710 and Rehovot 13, and their F1, F2, F3 and backcross progenies were screened for resistance to bacterial speck (Pseudomonas syringae pv. tomato) of tomato. The results support the hypothesis that the resistance factors contained in the two parents are non‐allelic and controlled by two different genes.
Patterns of aphid resistance in the genus Vicia
Authors: BIRCH N. , WRATTEN S. D.
Published: February 2008

The performance of three aphid species, Aphis fubae, Acyrthosiphon pisum and Megoura viciae, was quantified on 22 taxonomically‐selected host plant species from the genus Vicia (vetches), using intrinsic rate of increase (rm) k standard errors. A. pisum proved to be the most successful aphid species, both in terms of highest potential population increase and widest host range; M. viciae was least successful, with most restricted host range and low rm values on all but the closest relatives of Vicia faba. A wide range of antibiotic resistance was found within the genus, and host resistance to the three aphid species was found to be broadly related to classification patterns based on taxonomy and life‐form. Analysis of the components of rm revealed that nymphal survival rates were the most significant factor limiting host colonisation, not pre‐reproductive period which is the most important factor in cultivars of V. faba. The consequences of aphid polyphagy on performance are discussed.
Aspects of nitrogen uptake and distribution in maize
Authors: ALLISON J. C. S.
Published: February 2008

The amount of nitrogen (N) taken up after treatment decreased by nearly 50% when either the top five or middle four leaf laminae of maize (Zea mays) plants were removed shortly after flowering, and by 70% when both the middle four and bottom six laminae were removed, but the amount of N moving from the remaining parts of the shoot to the grain did not change much. When all the laminae were removed little N was taken up and only 35% as much N as in untreated plants moved from the shoot to the grain. Removal of all the laminae increased the N content per cent of dry weight of both grain and shoot at final harvest, but the other treatments did not have much effect on the N concentration of any of the parts of the shoot.

Plants bearing grain, whether intact or with alternate laminae removed (half‐defoliated) at the time of flowering, took up N approximately in proportion to their increase in dry weight during the 4 wk after flowering. The N taken up went to the ear (husks, core and grain) and so did N from the stem and leaves. Intact and half‐defoliated plants with no developing grains, because pollination had been prevented, took up no N during this period, though they accumulated about as much dry matter as did plants with grain; the N increment of the husks and core was supplied by the stem and leaves.

At final harvest total and grain N content of plants per unit area of land increased by 20 and nearly 30%, respectively, with increase in population between 2·3 and 6·1 plants/m2, but apparently fell slightly with further increase of population to 7·4 plants/m2. Until shortly after flowering N uptake was rapid enough to maintain similar N contents per cent of dry weight of the parts of the shoot in all populations. Uptake continued at a steady rate, though a slower one than before flowering, until near the time of final harvest in the most widely spaced population. In the denser populations uptake slowed down progressively after flowering, and in the densest population it apparently ceased a few weeks before final harvest. The N concentration of the grain of maturing plants fell with increase of population, but not that of the other parts of the shoot. At final harvest N content of the grain decreased from 1·6% in the most widely spaced to 1·2% in the densest population. That of the rest of the shoot varied between 0·70 and 0·79%. Between 6 and 18 wk after sowing, N content per unit area of green parts of the leaf laminae decreased only slightly, changing from about 20 to 18 mg/dm2 with 2·3 plants/m2, 18 to 16 mg/dm2 with 3·5 plants/m2, and 16 to 13 mg/dm2 in populations between 4·8‐7·4 plants/m2.
Visual assessment of grain yield and its components in single plants and ears of spring barley
Authors: ISMAIL A. B. , VALENTINE J.
Published: February 2008

Visual assessments of yield/plant and tillers/plant were more effective than unaided assessments of grains/ear and 1000‐grain weight on a per plant basis. Assessments of the latter yield components were generally improved by the use of specially developed keys described by Ismail & Valentine (1983). Gains in efficiency were associated with the amount of extra time spent on making these assessments.

Assessments of yield/ear were not more effective than assessments of yield/plant. This was attributed to the ease of assessment of tillers/plant which was strongly associated with yield/plant. Assessments of grains/ear and 1000‐grain weight in single ears were clearly more effective than corresponding assessments in single plants in which there is high variability between ears.

Apart from using keys, further improvements in the assessments of grains/ear and 1000‐grain weight are necessary in order to increase the effectiveness of single plant selection in the F2 generation which is the first opportunity of increasing yield in later generations.
Viability of onion (Allium cega) seed as influenced by temperature during seed growth
Authors: GRAY D. , STECKEL JOYCE R. A.
Published: February 2008

The yield and performance of seeds from crops of winter‐hardy, bolting‐resistant onion grown at temperatures of 15–16, 18–19 and 22–23°C in 1979, 1980 and 1982 were compared.

Yields of seed from crops grown at 22–23°C were lower than those from crops grown at lower temperatures but the seeds ripened between 11 and 32 days earlier. Seeds from crops grown at mean temperatures of above 18°C gave higher percentage germination when imbibed at 30°C than 20°C and they also gave higher percentage seedling emergence than those from crops grown at lower temperatures. Seedlings from seeds produced at mean temperatures above 18°C were heavier than those from seeds of a similar weight but produced at lower temperatures. None of these differences were associated with differences in seed weight, embryo weight or seed dormancy but were positively correlated with differences in seed N‐concentration. The differences were also associated with the rate of imbibition of water as high germination, high N‐content seeds had a slower rate of imbibition than low germination, low N‐content seeds of the same weight.
The effects of growth stage in wheat on yield reductions caused by the rose‐grain aphid Metopolophium dirhodum
Authors: WATT A. D. , WRATTEN S. D.
Published: February 2008

Field‐caged populations of the rose‐grain aphid Metopolophium dirhodum were established on winter wheat (cv. Bounty) during the summer of 1981. An early wheat growth stage (G.s.) (40 to 69) and a late (G.s. 65 to 73) aphid infestation treatment were compared; only the early infestation resulted in a significant reduction in grain weight (15%), although the infestation sizes were similar in the two treatments. Baking quality of the flour was unaffected by both treatments. Caged populations were also established on winter wheat (cv. Avalon) in 1982 but, in spite of aphid numbers as large as in 1981, no significant yield loss was recorded. An infection of take‐all fungus Gaeumannomyces graminis developed during the course of this experiment and may have masked the effect of the aphids.
Glasshouse tests and field selection for heritable resistance to Myzus persicae in sugar beet
Authors: LOWE H. J. B. , SINGH MOHAN
Published: February 2008

A technique is described to assess and select in the field for resistance to Myzus persicae in sugar beet. Lines developed by this method were aphid resistant when compared with commercial cultivars. The resistance was inherited by progeny lines. Variation between beet lines in glasshouse tests suggested segregation of a number of resistance genes with varying effects. Integration of selection for aphid‐resistance and agronomic performance during beet breeding is discussed.
The effect of growth retardant application on floret site utilisation and assimilate distribution in ears of perennial ryegrass cv. S.24
Authors: HAMPTON J. G. , HEBBLETHWAITE P. D.
Published: February 2008

Application of the growth retardant paclobutrazol (PP333), at 2 kg a.i. ha‐1 at spikelet initiation to plots of perennial ryegrass cv. S.24 in 1981 and 1982 significantly increased the number of seeds per spikelet present at final harvest by reducing the number of seeds aborted during seed development. Distribution of florets and seeds per spikelet was altered by PP333, as both basal and penultimate spikelets contained more florets and seeds than did those of untreated plants. Seed weight and germination were increased in florets of penultimate spikelets, although PP333 application delayed maturity by 3–5 days.

In untreated plants, assimilate recovery was significantly lower from the terminal section of the ear, whereas in PP333 treated plants, no differences were found between basal, intermediate or terminal sections of the ear. PP333 increased assimilate demand at all sections of the ear when the ear and leaves were fed. The implications of this are discussed.
Restricted multiplication of potato leafroll virus in resistant potato genotypes
Authors: BARKER H. , HARRISON B. D.
Published: February 2008

Plants of a range of potato genotypes differing in rating for field resistance to potato leafroll virus (PLRV) were inoculated with the virus by grafting or by aphids (Myzus persicae). Plants of all genotypes tested became infected by each inoculation method and PLRV was detected by ELISA in the upper leaves of all genotypes within 26 days after grafting. Most genotypes with high resistance ratings developed only mild primary and secondary symptoms whereas those with low resistance ratings developed more pronounced symptoms. However, one genotype (G7461(4)) with a high resistance rating was very severely affected. The concentrations attained by PLRV in genotypes with high resistance ratings were only 1–10% of those in genotypes with low resistance ratings. These differences in virus concentration were found in young leaves of plants with primary or secondary infection, whether inoculated by grafting or by aphids and whether grown in the glasshouse or the field. In older leaves, differences in virus concentration between genotypes were at least as pronounced as those in younger leaves. In contrast, PLRV concentration in vascular tissue at the heel end of tubers of plants with primary infection was similar for all the genotypes tested. Although low PLRV concentration was consistently associated with high resistance rating it is not the only form of resistance to PLRV occurring in potato.
Pre‐harvest retting of flax with glyphosate: effect of growth stage at application on uptake, translocation and efficacy of glyphosate
Authors: HARVEY B. M. R. , SPENCE L. , CROTHERS S. H.
Published: February 2008

Flax cv. Hera was grown in pots at a density of 2000 plants/m2. At various stages of maturity plants were either sprayed with glyphosate (Roundup, Monsanto plc) at a rate equivalent to 1.4 kg a.e./ha or the uppermost leaves of the main stem were treated with 14C‐glyphosate. Uniform desiccation to greater than 80% DM within 5 wk was obtained with sprays applied up to and at 2 wk after the mid‐point of flowering (MP) and also at 10 wk after MP, when all seed had been shed. Sprays at 4–6 wk after MP caused little or no desiccation of the lower stem.

Autoradiography demonstrated that 14C‐glyphosate applied to the 10 uppermost leaves of the main stem at MP, or to the upper stem at 10 wk after MP, was distributed throughout the plant within 48 h. However, no downward translocation was detected within 48 h of applications during seed filling, i.e. at 2 or 5 wk after MP.

Quantitative determinations of distribution of 14C‐glyphosate were made at 48 h after application either to the five uppermost leaves on the main stem or, after leaf drop, to the base of the inflorescence. Translocation out of the treated zone was 58–67% of applied 14C‐glyphosate with applications at 0, 2 or 6 wk after MP but only 13% with application to senescing leaves at 4 wk after MP. Little downward translocation occurred with any of these applications, 14C‐glyphosate accumulating mainly in the upper stem and inflorescence.

Thus failure of glyphosate to desiccate the lower stem may be related to poor downward translocation during seed development and to reduced uptake into, and export out of, senescing leaves.
A preliminary comparison of some management options for reducing grass losses caused by leatherjackets in Northern Ireland
Authors: BLACKSHAW R. P.
Published: February 2008

Leatherjackets can cause serious yield reductions in Northern Ireland grass. This paper considers the distribution of field population sizes derived from 19 years' data in conjuction with calculated damage functions to estimate average expected losses. Six management options were compared. These were ‘No action’, routine insecticide application in September or March, insecticide application in March in high risk years only and the use of monitoring and economic thresholds in September or March. The annual expected revenues for each of these options was calculated for herbage dry‐matter values of £0.01–0.07 kg‐1. It was concluded that action against leatherjackets in September would give better returns than action in March and that the use of monitoring and spraying of only those field populations above an economic threshold gave rise to greatest revenue. An annual loss to leatherjackets in Northern Ireland of over £15 million was calculated from an assumed herbage value of £0.035 kg‐1 dry matter.
Solar radiation interception by leafless, semi‐leafless and leafed peas (Pisum sativum) under contrasting field conditions
Authors: HEATH M. C. , HEBBLETHWAITE P. D.
Published: February 2008

Foliage composition, photosynthetic area index (PAI) and radiation interception were measured for crop canopies of leafless (var. Filby), semi‐leafless (var. BS3) and leafed (var. Birte) peas (Pisum sativum). Tendrils and petioles contributed more than 60% of total leaf area for leafless peas but less than 30% for semileafless and leafed pea canopies.

PAI was related to radiation interception by calculating attenuation coefficients which indicated that leafless peas intercepted more radiation per unit PAI than either semi‐leafless or leafed peas. Data interpretation, however, was complicated because of difficulties in estimating the tendril and petiole surface area contribution to PAI.

Radiation interception was related to dry matter accumulation by calculating photosynthetic efficiencies. Leafless and semi‐leafless peas converted intercepted radiation into dry matter as efficiently as leafed peas.

Under conditions of moisture stress, leafed and leafless peas both intercepted radiation more effectively but converted it into dry matter with reduced photosynthetic efficiency.
Photosynthesis and assimilate transport in potato with top‐roll disorder caused by the aphid Macrosiphum euphorbiae
Authors: VEEN B. W.
Published: February 2008

In pot experiments in a glasshouse, top‐roll symptoms were induced on potato plants after infestation with the aphid Macrosiphum euphorbiae. Leaves showing symptoms accumulated carbohydrates and tuber yields of affected plants were decreased by 44% compared with controls. Leaves grown after killing the aphids had a normal appearance and sugar contents. Infestation with aphids primarily inhibited carbohydrate transport in the stem and the accumulation of 14C‐labelled assimilate in the vascular bundles of the leaves. It is suggested that photosynthesis is inhibited by impaired phloem transport and subsequent accumulation of carbohydrates in the leaves and not by direct mechanical damage caused by the feeding aphid.
An analysis of leaf growth in sugar beet.
Authors: MILFORD G. F. J. , POCOCK T. O. , JAGGARD K. W. , BISCOE P. V. , ARMSTRONG M. J. , LAST P. J. , GOODMAN P. J.
Published: February 2008

The increase of leaf area index (L) was examined in a series of sugar‐beet crops grown on different sites (Broom's Barn, Suffolk and Trefloyne, Dyfed) or with different husbandry treatments (sowing dates and nitrogen rates) between 1978 and 1982. The development of L could be described as a function of thermal time using three parameters; DE, which was essentially an estimate of the thermal time required for crop establishment, and rHL and DL, the thermal rate and duration, respectively, of the increase of L. Variations in DE between seasons and with sowing date were small, but significant; they were attributed to factors affecting the condition of the seedbed. There were much larger variations in rHL, especially between seasons, sites and crops given different rates of nitrogen fertiliser, and there was a strong negative relationship between rHL and DL. Much of the variation in rHL was associated with differences in the concentrations of nitrogen in the lamina dry matter. Faster rates for rHL at Trefloyne than at Broom's Barn, and in the crop grown in 1982 as compared with other years, were also partly attributable to particularly warm conditions during the early development of some of the larger, faster‐growing leaves within the canopy. The wider application of the relationships established from these experiments was tested with data from a series of crops grown on other sites between 1960 and 1962. The relationships held particularly well for beet grown on soils with high water‐holding capacity but not for those on soils of low water‐holding capacity.
Stem‐boring Diptera in perennial ryegrass in relation to fertiliser.
Authors: MOORE D. , CLEMENTS R. O.
Published: February 2008

Two levels of fertiliser were applied to perennial ryegrass in four equal doses according to two different time schedules. Stem‐borer larvae were more frequent in plots treated with the higher rate and the relative incidence of the species varied according to fertiliser level. At the high fertiliser level the later applications resulted in an earlier increase in larval numbers and a higher larval population in the winter. At the low fertiliser level the total number of larvae was greater in the plots receiving earlier fertiliser applications due to an increase in the number of Oscinella vastator larvae. Populations of larvae were related to the tillering of the grass but not to the nitrogen content of the host plants.
The effects of post‐inoculation wet and dry periods, and inoculum concentration, on lesion numbers of Septoria nodorum in spring wheat seedlings
Authors: JEGER M. J. , GRIFFITHS ELLIS , JONES D. GARETH.
Published: February 2008

Lesion numbers in seedlings of spring wheat cvs Kolibri and Maris Butler, inoculated with Septoria nodorum in a growth cabinet, varied with the length of wet or dry period following inoculation. Increasing the length of dry period led to a curvilinear decrease in lesion numbers at 15° C (60% r.h.) and 20° C (40% r.h.), but some infection still occurred with a dry period of 72 h. Increasing the length of wet period gave a linear increase in lesion numbers in cv. Maris Butler, but lesion numbers levelled off at 12 h at 15° C (60% r.h.) in cv. Kolibri. Increasing the inoculum concentration gave an increase in lesion numbers in both cultivars irrespective of whether wet or dry periods followed inoculation. On occasion, Kolibri and Maris Butler differed significantly in lesion numbers, but differences were not consistent between experiments, and there were interactions with the length of wet period.
Tulip chlorotic blotch virus, a second potyvirus causing tulip flower break
Authors: MOWAT W. P.
Published: February 2008

Tulip chlorotic blotch virus (TCBV), an apparently undescribed potyvirus found in field grown tulips in Australia, causes symptoms in tulip leaves and flowers identical to those induced by tulip breaking virus (TBV). TCBV was transmitted mechanically to 14 of 34 species in four of 13 families. Nicotiana clevelandii is a suitable propagation host and Chenopodium amaranticolor a local‐lesion assay host. TCBV was transmitted from tulip to tulip and TV. clevelandii by the aphid Myzus persicae. Unlike TBV it was not transmitted to Lilium formosanum either by M. persicae or by manual inoculation.

Leaf extracts from TCBV‐containing TV. clevelandii were infective after dilution to l0‐3 but not 10‐4 and after heating for 10 min at 50°C but not 60°C; infectivity and particle recovery were adversely affected by freezing at ‐20°C. TCBV particles were purified (c. 1 mg/100g g N. clevelandii leaf) from tissue extracts in 0·3 M citrate buffer containing 10 mM EDTA and 0·2% (v/v) 2‐mercaptoethanol at pH 7·4 by clarification with 8·5% (v/v) n‐butanol followed by differential centrifugation and sucrose density gradient centrifugation. Purified particles measured c. 720 × 12 nm. Virus particle antigen was readily detected in leaf and tepal extracts of tulip by enzyme‐linked immunosorbent assay. A distant serological relationship was found between particles of TCBV and those of bean yellow mosaic virus but no serological relationship was found to TBV or four other potyviruses.
The occurrence and distribution of isolates of raspberry bushy dwarf virus in England
Authors: BARBARA D. J. , ASHBY S. C. , KNIGHT V. H.
Published: February 2008

The distribution of distinct isolates of raspberry bushy dwarf virus (RBDV) in Rubus in England was studied. Isolates similar in Rubus host range to the Scottish type isolate (D200) were largely confined to the old red raspberry (Rubus idaeus) cv. Norfolk Giant, but were also encountered in a single plant of an unidentified raspberry cultivar and in a clump of wild R. idaeus. Outside East Mailing Research Station (EMRS) RBDV isolates with wider Rubus host ranges than that of the type isolate were found only and exclusively in hybrid berries (Loganberry, clones LY59 and L654, and Tayberry) in which infection ranged from < 1% to 100%. The significance of these findings is discussed.
Inactivation of a nuclear polyhedrosis virus on cotton by the substances produced by the cotton leaf surface glands
Authors: ELLEMAN C. J. , ENTWISTLE P. F.
Published: February 2008

Loss of viability of a nuclear polyhedrosis virus (NPV) of Spodoptera littoralis was shown to occur on cotton leaves but not on cabbage leaves or on semi‐synthetic insect diet. The inactivation was rapid, occurred in the dark and required contact between the cotton leaf surface and the polyhedral inclusion bodies (PIBs). It was shown that the products of the cotton leaf glands, which exude a crystalline material onto the leaf surface, could account for the rapid inactivation observed. Inactivation did not involve loss of virus polyhedral inclusion bodies. The use of EDTA or a low pH buffer in the NPV suspension reduced the inactivation which suggested that the loss of activity was due to the presence of calcium and magnesium in the cotton gland exudate.
The effect of resistant cultivars of catch crops on the hatching of Heterodera schachtii
Authors: COOKE D. A.
Published: February 2008

In laboratory tests with Heterodera schachtii, root leachates of nematode‐resistant and susceptible cruciferous crops stimulated egg hatches of up to 77% and 95% respectively. In these tests very little hatch occurred at 5°C or 10°C, more at 15°C and most at 20°C. In field experiments in which these crops were sown in September 1982 and August 1983 into soil infested with H. schachtii, numbers of viable eggs had decreased only slightly under resistant crops 4–5 months later. This was possibly because the soil was too cold and dry to permit a large proportion to hatch.
DNA stability in the anabiotic fourth‐stage juveniles of Ditylenchus dipsaci (Nematoda)
Authors: BARRETT J. , WORTH PENELOPE E. BUTTER.
Published: February 2008

Water plays an important role in DNA structure and desiccation of microorganisms has been correlated with breaks in their DNA.

The fourth‐stage juveniles of the anabiotic nematode Ditylenchus dipsaci can lose up to 90% of their body water and survive in a dehydrated state for long periods of time; however, there was no increase in the frequency of breaks in DNA isolated from anabiotic as opposed to hydrated juveniles. Desiccation of the non‐anabiotic nematode Panagrellus redivivus similarly did not lead to an increased frequency of DNA breaks, nor did the polyol glycerol significantly effect DNA stability.

The stability of DNA during tissue desiccation, like the stability of proteins, seems to be a general feature of biological material and not a unique property of anabiotic organisms.
Seed survival and seasonal pattern of seedling emergence in some Leguminosae
Authors: ROBERTS H. A. , BODDRELL JUNE E.
Published: February 2008

Seeds of 11 species of Leguminosae were collected, usually in each of 3 years, and mixed with the top 7·5 cm of sterilised soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Emergence was recorded for at least 3 yr. Some seedlings of all species emerged soon after sowing but their numbers varied both within and between species, a probable reflection of the percentage of ‘hard’ seeds in the samples. Appreciable numbers of seedlings appeared in the following 3 yr but few seeds remained viable and dormant after 5 yr. The annual weed Vicia hirsuta was an exception, with an average of 11% of the seeds sown still viable at this time. Most seedlings of Lotus corniculatus, Medicago lupulina, Melilotus altissima, Trifolium repens and Vicia cracca emerged in spring, V. cracca rather later than the others. In contrast, maximum emergence of Trifolium arvense, T. campestre and T. dubium took place from June to September. Limited data indicated a similar pattern for T. striatum and Lathyrus pratensis. Seedlings of Vicia hirsuta emerged from October to May but scarcely at all in summer. Although variation in the percentage of hard seeds influenced the extent of immediate germination and seed persistence, the seasonal patterns in seedling emergence of most species were found to be very consistent.
The effects of pH during treatment of lettuce seeds with chlorine‐releasing compounds on germination and seedling development
Authors: DREW R. L. K. , BROCKLEHURST P. A.
Published: February 2008

Hypochlorite seed treatments have been reported in the literature as giving variable results. We report experiments on this topic in which lettuce seeds were used as a model biological system. Seeds were treated for 2 h with solutions of sodium hypochlorite diluted with buffers of pH 9·8, 10·8 and 11·8, or with the buffers alone. Only the seeds treated with hypochlorite diluted with pH 9·8 buffer showed increased numbers of abnormal seedlings when subsequently germinated. In an experiment in which lettuce seeds were treated with sodium dichloroisocyanurate (a chlorine‐releasing triazine compound) and related non‐chlorinated compounds, seedling abnormalities were related to chlorine in solution. Measurements of pH together with the known chemistry of hypochlorite suggest that the damaging agent in these experiments was the biocidal undissociated hypochlorous acid.
Relationship between the concentration of chlorogenic acid in carrot roots and the incidence of carrot fly larval damage
Authors: COLE R. A.
Published: February 2008

Chlorogenic acid (1·24‐3·36 mg/g) was identified as the main phenolic component in the peel of carrots by hplc analysis. The higher the concentration of chlorogenic acid in different cultivars the greater the susceptibility to carrot fly larval damage. Increases in concentration were found both after carrot fly damage and after carrots had overwintered in the field. The presence and location of chlorogenic acid was confirmed in sections of carrot tissues, mounted in 0·05 M ammonia solution by viewing them using a u.v.‐epifluorescent microscope. The importance of phenolic compounds and their function in the production of insect cuticle is discussed in relation to the different concentrations of chlorogenic acid and resistance to carrot fly in carrots.
Occurrence of Cryphonectria canker disease of Eucalyptus in Kerala, India*
Authors: SHARMA J. K. , MOHANAN C. , FLORENCE E. J. MARIA.
Published: February 2008

Cryphonectria cubensis, recorded for the first time in India, is responsible for causing severe stem cankers in Eucalyptus grandis in Kerala. Disease outbreaks are localised and vary in severity with host species, at times affecting up to 30% of the trees in a stand. Infection usually occurs on the main stem 1 to 1 ·5 m above ground and occasionally near ground level. There is evidence of tree to tree spread of the disease from the primary infection foci. The disease also affects coppicing by stumps after harvest. Details on the incidence and epidemiology of the disease are presented.