bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on the occurrence, pathogenicity and control of Pratylenchus vulnus, P. thornei and Xiphinema diversicaudatum associated with glasshouse roses
Authors: WINFIELD A. L. 
Published: February 2008

SUMMARYAbout half the nurseries and glasshouses in the Lea Valley of Hertfordshire were found to be infested with either or both Pratylenchus vulnus and Xiphinema diversicaudatum. The latter nematode probably occurred naturally in the soil on which the glasshouses were built but P. vulnus is thought to have been imported with rose rootstocks and is not known to occur outdoors in Britain. Both nematode species can cause decline of roses and even small numbers seem harmful. Numbers of P. vulnus can increase greatly, especially on rootstocks of Rosa canina, although numbers were often smaller when roses were severely damaged than on healthier crops. Numbers of X. diversicaudatum increased more slowly and R. canina was a better host for it than R. chinensis. X. diversicaudatum seemed to respond less quickly than P. vulnus to reduced host‐plant vigour. The two rootstocks exhibited different host‐status for the two species of nematode and cuttings of various rose cultivars showed different host‐status to P. thornei, another species of lesion nematode which is not known to be pathogenic to roses. Two applications of dibromochloropropane liquid at the rate of 70 l/ha in a large volume of water maintained nematode densities at an acceptably low level, and growers who adopted this treatment as a supplement to pre‐planting steam sterilisation and/or DD (dichloro‐propane: dichloropropene) prolonged the productive life of their crops for several years.
Intraspecific variation of Myzus persicae on sugar beet (Beta vulgaris)
Authors: LOWE H. J. B. 
Published: February 2008

SUMMARYDifferences in inherited resistance among seven sugar‐beet stocks had similar effects on Myzus persicae clones representing the range of variation in aphid response to resistant and susceptible sugar beet observed in fifty‐eight clones collected between 1969 and 1971. Three sugar‐beet stocks were consistently resistant. Statistically significant interactions between beet stocks and aphid clones did not indicate the existence of biotypes with specific abilities to overcome resistance. M. persicae clones differed in their vigour of colonizing sugar beet, irrespective of the differences between beet stocks. The readiness of adult aphids to settle determined the size of aphid population produced and included a component related to the response of the aphid clone to sugar beet as a host, and a component related to the resistance ranking of the beet stock. Breeding sugar beet with resistance to aphids will be simplified, as the results indicate that, at present, differences between aphid biotypes need not be considered a problem.
Investigations on fungicides.
Authors: BURDEN R. S. , ROGERS PAMELA M. , WAIN R. L. 
Published: February 2008

SUMMARYUninoculated roots of pea (Pisum sativum) and French bean (Phaseolus vulgaris) have been shown to exude a number of antifungal compounds when grown in a non‐sterile aqueous aerated medium. These have been identified and their possible importance in relation to disease resistance is discussed.
A model for the mechanism of stimulation of latex flow in Hevea brasiliensis by ethylene
Authors: OSBORNE DAPHNE J. , SARGENT J. A. 
Published: February 2008

SUMMARYA model is proposed for ethylene stimulation of latex flow from tapping cuts of Hevea brasiliensis, based on the predicted effects of ethylene on the plasticity and structure of cell walls of the latex vessels. Evidence for the model comes from the effects of ethylene on etiolated shoots of Pisum sativum.
Tolerance to ryegrass mosaic virus and its inheritance
Authors: WILKINS P. W. 
Published: February 2008

SUMMARYPlant yield within and between four cultivars of perennial ryegrass infected with ryegrass mosaic virus (RMV) was closely related to symptom severity.Distribution of symptom severity was continuous in four perennial ryegrass and four Italian ryegrass cultivars infected with a severe RMV isolate, and also in another perennial ryegrass cultivar infected with a severe isolate of the virus, a mild one and one of intermediate severity. Symptom expression was polygenically inherited in both Italian (cv. RvP) and perennial (cv. S.24) ryegrass. Both additive and non‐additive genetic variation was present in RvP, but the variation in S.24 was additive only. No significant maternal inheritance was present in either species.
Some effects of freezing temperatures on overwintering larvae of the large elm bark beetle (Scolytus scolytus)
Authors: BARSON G. 
Published: February 2008

SUMMARYOverwintering final instar larvae of Scolytus scolytus were tested for coldhardiness by exposure to a range of sub‐zero temperatures (–7°Cto –31 °C) in a frost‐gradient apparatus for 7 days. The Lt50 for larvae removed from the bark (– 20.5 °C) was significantly different (P < 0.01) from the Lt50 (–18.3 °C) for larvae insulated by the bark (thickness of 7 mm ± 2 mm). Larvae with food in their digestive tract were more susceptible to freezing than the overwintering final instars which had voided their stomach contents. Duration and intensity of cold did not cause any adverse long‐term effects. Most of the larvae which survived the sub‐zero treatments were able to pupate or reach the adult stage. The mean supercooling point of the overwintering larvae (–30.85 °C) confirmed their cold‐hardiness.
The effect on gangrene incidence of dusting seed potatoes with benomyl at time of planting
Authors: LOGAN C. 
Published: February 2008

SUMMARYIn 1 out of 2 years' field trials benomyl applied as a dust treatment at time of planting seed potatoes resulted in an increase in potato gangrene in the progeny of both gangrene‐free tubers planted in land contaminated with Phoma exigua var. foveata and gangrene‐diseased tubers planted in clean land. Gangrene‐infected seed tubers treated with benomyl also produced more stems infected with var. foveata than untreated tubers. Two hypotheses are presented to account for this increase in gangrene which does not occur in seed potatoes treated shortly after lifting.In all cultivars tested an organo‐mercury dip‐treatment increased total numbers of tubers in the seed and chat‐size grades without increasing total weight whereas benomyl dust increased the numbers in these grades in Majestic only. The treatment of gangrene‐diseased seed with benomyl dust affected neither total weight nor total number of tubers.
Effects of eyespot on the yield of winter wheat
Authors: SCOTT P. R. , HOLLINS T. W. 
Published: February 2008

SUMMARYFor 4 successive years, cultivars of winter wheat differing in resistance to eyespot (Cercosporella herpotrichoides) and to lodging were grown in plots in which different levels of eyespot were induced by inoculating at different times. Lodging was either allowed, or prevented by growing the plants through nets. Yield losses were greatest in the most severely infected plots in which lodging was allowed; losses were reduced where infection was less severe or where lodging was prevented. In the year in which eyespot was most severe, there was a significant regression of yield on disease severity, even for the plots in which lodging was prevented; where lodging was allowed, regression lines were steeper for the lodging susceptible cultivars, but did not differ for the lodging resistant cultivars. Eyespot reduced the number of tillers, measured in spring, but later there was partial compensation for these losses. Grain number per ear and 1000 grain weight of individual tillers were reduced by severe eyespot infection; moderate infection reduced only 1000 grain weight; slight infection caused no reduction. Tillers without severe infection produced extra grains in severely diseased plots, so that there was no overall effect of eyespot on grain number per ear. The results are discussed in relation to the breeding of dwarf cultivars, which may be highly resistant to lodging but can nevertheless suffer severe losses from eyespot.
Effects of mildew on the growth and yield of spring barley: 1969‐72
Authors: JENKYN J. F. 
Published: February 2008

SUMMARYMildew decreased grain yield by decreasing ear number and grain size (but not grain number/ear), the damage depending on the earliness and severity of mildew. In 1971 when mildew was early and severe, ethirimol seed dressings at 0.22 kg a.i./ha, which gave only early protection, increased yield more than did ethirimol sprays applied to protect the flag leaf and ear. In 1972 sprays were better than seed dressings at this rate because mildew was less severe during the seedling stages.
Growth inhibitors in roots of light‐ and dark‐grown seedlings of Zea mays
Authors: WILKINS H. , BURDEN R. S. , WAIN R. L. 
Published: February 2008

SUMMARYAbscisic acid and 6‐methoxy‐2‐benzoxazolinone have been identified as growth‐inhibitory compounds in the primary roots of Zea mays.
Damage caused by the Green Spruce Aphid to Norway and Sitka spruce needles
Authors: PARRY W. H. 
Published: February 2008

SUMMARYThree‐month‐old needles of Sitka spruce were less susceptible to Elatobium abietinutn than 15‐month‐old needles. Symptoms appeared after longer aphid feeding times but only a proportion of damaged needles fell. After short feeding periods symptoms appeared in more Norway spruce needles than in Sitka spruce, whereas longer feeding periods resulted in more needles producing symptoms in the Sitka spruce. The symptoms took 4—6 days longer to appear in Norway spruce, and needle fall followed a longer feeding period than on Sitka spruce. Following 72 h feeding, needle fall occurred more quickly on Sitka spruce than on Norway spruce. The time taken for needle fall to occur was inversely related to the feeding time in Sitka spruce but such a response was not evident in Norway spruce. The results are discussed in relation to the differences exhibited in the probing behaviour of the aphid on the two spruces.
Breeding for resistance to the white potato cyst‐nematode, Heterodera pallida
Authors: FULLER J. M. , HOWARD H. W. 
Published: February 2008

SUMMARYProgenies bred from material derived from the wild potato, Solanum vernei and from the cultivated potato, S. tuberosum ssp. andigena, clone CPC 2775, were compared for their resistance to Heterodera pallida, pathotype E. The influence of additional resistance derived from the wild species, S. multidissectum, was also investigated.Both S. vernei and CPC 2775 gave progenies with variable levels of resistance and there was often no clear segregation into resistant and susceptible categories. Incorporation of gene H2 derived from S. multidissectum increased resistance to pathotype E of H. pallida for resistant material bred from both S. vernei and clone CPC 2775. The results indicate that adequate resistance to all British populations of potato cyst‐nematodes can best be obtained by combining the factors for resistance from the two Andigena clones, CPC 1673 (gene H1) and CPC 2775 (gene H3), and from S. multidissectum (gene H2).
Tests for resistance to Aphis fabae in field beans (Viciafaba)
Authors: BOND D. A. , LOWE H. J. B. 
Published: February 2008

SUMMARYTwo lines of Viciafaba were as resistant to Aphis fabae as Rastatt, one of their progenitors, when compared with susceptible control varieties in glasshouse experiments. In short experiments, fewer adult aphids settled on plants of resistant varieties, which subsequently bore smaller total numbers of aphids. In a longer experiment, the aphids multiplied more slowly on the resistant varieties, which survived after susceptible beans had been killed.The bean varieties did not vary in numbers of aphids on the stem or growing point but resistant varieties had markedly smaller proportions of the total on the abaxial surface of the leaves; in particular the smaller veins supported fewer aphids. V. narbonensis was very resistant to A. fabae but was susceptible to Myzus persicae, indicating that its resistance mechanism is distinct from that within V. faba.In infested field trials most of the variation in yield of bean varieties was attributable to the size of A. fabae colonies, and resistant varieties outyielded susceptible varieties. Yields of resistant varieties in the presence of large numbers of aphids were, however, less than those from trials without aphids. In uninfested trials susceptible varieties usually gave the largest yields.The significance of these observations is discussed in relation to policies and methods for breeding for resistance to A. fabae in V. faba.
Control of Verticillium wilt transmission in strawberry runners with systemic benzimidazole‐type fungicides
Authors: JORDAN V. W. L. 
Published: February 2008

SUMMARYPre‐planting root dips and soil drenches with benomyl, carbendazim (MBC), thiabendazole and thiophanate‐methyl were used to reduce disease severity in mother plants. Transmission of the pathogen Verticillium dahliae through stolons and into young runners was prevented by two applications of benomyl or thiophanate‐methyl at o‐i% active ingredient applied at stolon appearance and 1 month later. Sufficient concentrations of fungistatic residues were detected in all plant tissues to suppress the internal spread of the pathogen.
The significance of ethylene in the ripening of stored apples
Authors: Knee M. 
Published: February 2008

ABSTRACTEthylene is ignored in commercial apple storage on the assumption that it does not cause ripening below 7 oC. If substantiated, this would affect ideas of ethylene action, but further investigation shows that ethylene hastens cell wall changes associated with softening in apples stored at 3–5 oC. Modified atmospheres influence these processes through effects on ethylene synthesis and action. Pigment changes are less affected by ethylene and may be more directly influenced by atmospheric composition.
Ethylene as a factor limiting the legume‐Rhizobium symbiosis in tube culture
Authors: Day J. , Dart P. , Roughley R. 
Published: February 2008

ABSTRACTGrowth and nitrogen fixation by Trifolium subterraneum plants at 15 and 10 oC root temperatures is much less in test tubes plugged with cotton wool than in open pots of sand. Removing the ethylene produced by plants growing in cotton wool plugged flasks by adsorption onto activated charcoal, or by aerating with sterile air, increased nitrogenase activity and growth over the first 25 days, to levels approaching that of plants grown in open pots of sand.
Insect pollination of sugar‐beet (Beta vulgaris) seed crops
Authors: FREE J. B. , WILLIAMS INGRID H. , LONGDEN P. C. , JOHNSON M. G. 
Published: February 2008

SUMMARYThe flowers of sugar‐beet crops grown to produce hybrid seed were visited by many species of insects which often carried much sugar‐beet pollen on their bodies and could have contributed to pollination.
Observations and experiments on the use of an avirulent mutant strain of tobacco mosaic virus as a means of controlling tomato mosaic
Authors: FLETCHER J. T. , ROWE J. M. 
Published: February 2008

SUMMARYIn 1973 tobacco mosaic virus (TMV) strain M II‐16 was successfully used by growers in the United Kingdom to protect commercial tomato crops against the severe effects of naturally occurring strains of TMV. However, plants in many crops had mosaic leaf symptoms which were occasionally severe, so possible reasons for symptom appearance were examined. The concentration of the mutant strain in commercially produced inocula (assessed by infectivity and spectrophotometry) ranged from 28 to 1220 μg virus/ml; nevertheless all samples contained sufficient virus to infect a high percentage of inoculated tomato seedlings. Increasing the distance between the plants and the spray gun used for inoculation from 5 to 15 cm resulted in a significant decrease in the number of tomato seedlings infected. When M II‐16 infected tomato plants were subsequently inoculated with each of fifty‐three different isolates of TMV, none showed severe symptoms of the challenging isolates within 4 wk, although some isolates of strain o induced atypically mild leaf symptoms. In a further experiment, M II‐16 infected plants showed conspicuous leaf symptoms only 7 wk after inoculation with a virulent TMV isolate. M II‐16 multiplied more slowly in tomato plants and had a lower specific infectivity than a naturally occurring strain of TMV. More than 50% of plants in crops inoculated with strain M II‐16 which subsequently showed conspicuous leaf mosaic contained TMV strain 1 or a form intermediate between strains o and 1. It is suggested that the production of TMV symptoms in commercial crops previously inoculated with strain M II‐16 may result from an initially low level of infection, due to inefficient inoculation, which allows subsequent infection of unprotected plants by virulent strains. Incomplete protection by strain M II‐16 against all naturally occurring strains may also be an important factor.
The distribution of pathotypes of the cereal cyst‐eelworm Heterodera avenae in England and Wales
Authors: SAYNOR M. 
Published: February 2008

SUMMARYTwo pathotypes of the cereal cyst‐eelworm (Heterodera avenae), occurred commonly in England and Wales and a third pathotype was apparently present in low numbers in a few areas. Pathotype 1, which can breed on most cultivars of wheat, barley and oats, but not on Drost barley nor barley cultivars containing the gene for resistance from barley No. 191, was most common in the south west of England. Pathotype 2, which can breed on most cereals, including Drost barley but not No. 191, was common throughout England and Wales and mixtures of these pathotypes occurred in many places. Pathotype 3, which can breed on barley No. 191 and probably on Drost and most cultivars of cereals, was rare and was found only in low numbers together with either or both Pathotypes 1 and 2. In the initial tests it was present or suspected in only nine fields (6%), but when these soils were retested in more detail the following year, Pathotype 3 was confirmed at only one site.
Effects of chloromequat chloride on related tall and dwarf rice varieties
Authors: GANASHAN P. , WHITTINGTON W. J. 
Published: February 2008

SUMMARYThe effects in growth room experiments of three levels of 2‐chloroethyltrimethylammonium chloride (chloromequat chloride; CCC) at two nitrogen levels were studied on a tall rice variety and a mutant dwarf derivative. CCC was found to reduce plant height in both varieties, to increase tiller number and spikelet number on the main panicle or in total but to delay flowering. Chemical dwarfing cannot be regarded as an alternative to genetic dwarfing since mutants may be shorter than chemically treated tall genotypes and may themselves respond favourably to further treatment.
Effect of pre‐harvest fungicides on the spoilage of soft fruit after harvest
Authors: DENNIS C. 
Published: February 2008

SUMMARYIn the 1972 season, Elvaron and Benlate reduced the count of Botrytis cinerea, Cladosporium spp., Penicillium spp. and Aureobasidiutn pullulans on strawberry and raspberry fruits during the first 2 wk of the season, but not subsequently. No such reduction was recorded for Hainesia lythri (strawberries only), Phoma state of Didymella applanata (raspberries only), Mucor spp., and Rhizopus spp. Similar results were obtained in 1973.In the first half of either season, both fungicides decreased the rate of fungal spoilage of stored fruit (except for Benlate in the 1973 season), although in the latter part of the season, there was little difference in the incidence of fungal spoilage between sprayed and unsprayed fruit. Both fungicides, however, reduced the development of B. cinerea (and Cladosporium spp. on raspberries) on stored fruit irrespective of season or harvest date except for Benlate in the 1973 season where Benlate‐resistant strains of the fungi developed on the fruit. The failure of either fungicide to reduce fungal spoilage in the latter part of the harvesting season was due to the development of Phycomycetes, particularly Mucor mucedo and to a lesser extent Rhizopus stolonifer and R. sexualis, except where Benlate‐resistant strains of B. cinerea and Cladosporium spp. were present.
Future virus problems?
Authors: Plumb R. T. 
Published: February 2008

SUMMARYOf seventeen viruses that infect British grasses several have been reported only recently; others that occur in Europe have hosts and vectors in Britain and could become a problem. Ryegrass bacilliform virus and ryegrass spherical virus are described and maize dwarf mosaic virus, maize rough dwarf virus and brome mosaic virus are considered as possible pathogens.
Resistance of red and white clover cultivars to clover rot (Sclerotinla trifoliorum)
Authors: Dixon G. R. 
Published: February 2008

SUMMARYVarious techniques for assessing the resistance of clover cultivars to clover rot have been investigated, including counting sclerotia around infected plants, measuring lengths of healthy and diseased rows and the use of a key to assess symptom expression on individual plants. The latter was found to be the most suitable under field conditions. Of fifty‐one red clover cultivars tested, nineteen were found to possess some level of resistance. Clover rot appears to be an increasing problem with white clover crops but tests have indicated that resistant cultivars are available.
The distribution and analysis of cabbage root fly egg populations
Authors: FINCH S. , SKINNER G. , FREEMAN G. H. 
Published: February 2008

SUMMARYThe distribution of the egg stage of the cabbage root fly around brassica plants was studied at Wellesbourne on 0.05–0.4 ha plots during 1970 and 1971.The three generations of flies occurred at similar times in both years and the numbers of eggs collected generally decreased from the first to the third generation. Differences between generations demonstrated that each generation should be treated separately. The number of plant samples required for a given level of precision increased from the first to the third generation, indicating that experiments relying on egg counts should be planned to coincide with the first generation whenever possible. A sampling plan for the range of oviposition normally encountered during the three generations is illustrated for both one‐ and five‐plant samples. For the same level of precision, estimates of the populations from five‐plant samples required only 50% to 80% of the time of those from one‐plant samples. When aestivation occurs the peak of oviposition in the second generation is difficult to determine, and designed experiments should not be undertaken. The negative binomial distribution failed to describe the clumping of the eggs for a complete generation, since a common k could not be fitted to the data. The distribution of the eggs was best described by Taylor's power law which showed that although sampling factors changed with generation, the value of the power did not. A value of 1.4 appears to be the index of aggregation characteristic of the egg stage of this species.