bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of Myzus persicae on year‐round chrysanthemums by introducing aphids parasitized by Aphidius matricariae into boxes of rooted cuttings
Authors: SCOPES N. E. A. 
Published: February 2008

SUMMARYComplete control of Myzus persicae on the chrysanthemum cultivar Tuneful was achieved within 2 months or less of planting using the parasite Aphidius matricariae. The success of the technique depends on introducing a small population of parasitized aphids into boxes of rooted cuttings, and the rapidity of control is determined by the ratio of aphids to parasites present at the time of introduction. The method is likely to be even more successful where cultivars less susceptible to aphids are grown. A. matricariae cannot be used to control M. persicae if the aphids are infected with the fungus Cephalosporium aphidicola.
Green mould of oranges caused by Penicillium digitatutn Sacc.; effect of additives on spore germination and infection
Authors: KAVANAGH J. A. , WOOD R. K. S. 
Published: February 2008

SUMMARYWater extracts of rind, essential oil and juice from oranges, also citrus pectin and citric acid promoted the formation of lesions when spores of Penicillium digitatum were placed in wounds 1·0 mm deep in flavedo of oranges; fructose, glucose and sucrose had little effect.Rind extracts were less effective in wounds 0·5 mm deep but orange juice and pectin still increased infection. None of the substances allowed the parasite to infect fruit through unwounded surfaces.Germination of spores in water increased as spore concentration decreased but was poor even at low concentrations. Almost all spores germinated in aqueous extracts of flavedo, albedo or whole rind, or in wounds on the surface of fruit. Fructose, glucose, sucrose and xylose were less effective but still caused over two‐thirds of spores to germinate but only in the presence of phosphate buffer. Without buffer, germination was little different from that in water. Arabinose and galactose stimulated germination to a lesser extent but with the same phosphate effect. Carboxymethylcellulose and pectin did not affect germination.A variety of substances containing nitrogen increased germination but to different degrees, decreasing in the order, casamino acids, yeast extract, ammonium salts, nitrate. Thiamin and to a lesser extent biotin were also effective.Volatile substances from rind infected with P. digitatum stimulated spore germination and growth of germ tubes.The significance of these results is discussed in relation to infection.
Rainfall and cropping patterns in relation to coffee berry disease*
Authors: GRIFFITHS ELLIS , WALLER J. M. 
Published: February 2008

SUMMARYBoth the increase in severity and extent of coffee berry disease (CBD) during the 1960s and the failure of early‐season sprays to control it have been attributed to changes in climatic conditions and cropping patterns. A critical analysis of rainfall data since 1951, when CBD first appeared in the East Rift coffee districts of Kenya, produces no evidence that conditions affecting CBD development were any different in the 1960s than in the 1950s, in either high‐or low‐altitude coffee‐growing areas. A marked increase in overlapping crops occurred during the late 1950s, and this was caused mainly by a change in pruning methods. The increased disease hazard from this change of cropping pattern cannot account for the failure of early season sprays, which were successful before 1962.An estimate of the time of main crop flowering shows that only in those years when flowering was early and the rainy season finished early did early‐season sprays achieve substantial benefits. It is concluded that their effect in these years was obtained by fungicidal protection of the crop throughout most of the rainy season, and that their failure in other years contributed to the worsening disease situation.
Chemical control of Didymascella thujina on Western red cedar in forest nurseries
Authors: BURDEKIN D. A. , PHILLIPS D. H. 
Published: February 2008

SUMMARY Didymascella thujina causes a serious needle blight in nursery stock of Western red cedar. It may be controlled by cycloheximide applied at a concentration of 85 ppm of active ingredient and at a rate of 100 gal/acre (1123 1/ha) at the end of March and again at the end of April. In south Wales and south‐west Scotland a third application may be needed in mid‐June.Other fungicides tested were not effective against this disease.
Characterization of the components of plant cuticles in relation to the penetration of 2,4‐D
Authors: BAKER E. A. , BUKOVAC M. J. 
Published: February 2008

SUMMARYQuantitative comparisons were made of the components of the cuticles of leaves of plantain, fat hen, dandelion, dock, chickweed and forget‐me‐not. Hydrocarbons and triterpenoids were prominent in the surface wax of plantain; esters and alcohols in the other surface waxes. Polar compounds predominated in the cuticular waxes. Cuticle development in plantain, dandelion and chickweed was similar, but the cutins differed in the relative proportions of hydroxy‐fatty and fatty acid components. Sorption of 2,4‐D by the cuticular membrane was inversely related to the amount of cuticular wax. Hydrocarbons and an aldehyde fraction isolated from surface wax most effectively reduced the penetration of water in a model system.
The reproductive behaviour of Metopolophium festucae (Theobald) at different temperatures and on different host plants
Authors: HILL A. R. 
Published: February 2008

SUMMARY Metopolophium festucae is a cold‐hardy species: on young oat seedlings nymphs are produced from apterae at temperatures below 6 °C. Alatae are less well adapted to low temperatures: in a laboratory experiment the average daily production of nymphs from apterae was 0·96 at 10·2 °C and 2·71 at 22·8 °C; the corresponding figures for alatae were 0·42 and 1·81.Aphids on oats, wheat and Italian ryegrass have a slightly higher progeny production than on barley, timothy and cocksfoot: the adults produced on the cereals are heavier than those on the grasses.It is postulated that the aphids require a perennial crop on which to overwinter as nymphs or parthenogenetic adults; consequently successful colonization of cereal crops is rare.
The biology of Peronospora viciae on pea: factors affecting the susceptibility of plants to local infection and systemic colonization
Authors: MENCE M. J. , PEGG G. F. 
Published: February 2008

SUMMARY Peronospora viciae (Berk.) Casp. penetrated leaf disks of Pisum sativum L. through the cuticle. Resistance of pea plants and of individual leaves to infection by P. viciae increased with age, but decreased again at senescence. Resistance was shown by a restriction in fungal growth and sporulation and by a chlorotic reaction in the leaves. Systemic invasion followed infection of meristematic tissue, and was induced by inoculation into the apical bud of young plants, or on to the epicotyl or hypocotyl, but not roots of germinating seedlings. Most plants whose growth was retarded showed an increased resistance to systemic infection. Pods were infected externally by sporangia, rather than by mycelial growth through the peduncle and pedicel. Oospores and mycelium were found in the testas of some seeds, but seeds from infected pods did not give rise to infected seedlings.
Control of raspberry stamen blight
Authors: MONTGOMERIE ISABEL G. 
Published: February 2008

SUMMARYEvidence from field observations suggests that where stamen blight (Hapalosphaeria deformans Syd.) is prevalent dissemination of spores by wind may account for the establishment of the disease in initially healthy plantations. Captan and dichlofluanid were equally effective in significantly decreasing the level of disease.
Pathogenicity of Fusarium oxysporum to Easter lily, narcissus and gladiolus
Authors: BALD J. G. , SUZUKI TERRY , DOYLE ANNA 
Published: February 2008

SUMMARYIsolates of Fusarium oxysporum from roots, bulbs and stems of Easter lilies (Lilium longiflorum) differed widely in pathogenicity and also, apparently, in tissue specificity. Virulent isolates caused a typical basal rot and root rot (but not a wilt) in which the mycelium advanced intercellularly through the scales and basal plates. Mildly pathogenic isolates became established in mature or senescent outer scales, at first producing only superficial effects, but further growth of mycelium occurred as the outer scales died and sometimes continued until the dead tissues were permeated and chlamydospores were formed. The underlying scales were then colonized.The modes of pathogenicity and survival in Easter lily were compared with those of the F. oxysporum formae causing bulb rots of gladiolus and narcissus.It is suggested that advance of hyphae by penetration between the cells of the vascular parenchyma, which is common in isolates causing rots in bulbs and corms, represents a stage in the evolution of the truly vascular habit among fusaria.
Some factors influencing the performance of spray programmes for the control of coffee berry disease*
Authors: GIBBS J. N. 
Published: February 2008

SUMMARYIn 1968 in a field trial at Kamundu, Kenya, early‐season (Jan.‐Mar.) sprays of copper, captafol and Tuzet failed to control coffee berry disease (CBD), in the late (main) crop of cultivars S.L.28 and S.L.34. Copper and captafol caused some delay in disease development but eventually infection reached over 50 % in all treatments and final yields of sprayed plots were below those from unsprayed plots.In a similar trial in 1969 at Yara on the cultivar French Mission a similar spray programme achieved significant benefits: copper and captafol kept the level of disease below 20% and gave improved yields compared with unsprayed plots. A continuation of the sprays until June increased yields still further.In a second trial in 1968 at Kiamara on the cultivar French Mission substantial quantities of early crop were present and disease in this was effectively controlled by early‐season sprays of captafol, although the late crop on the same trees became severely affected. Removal of this overlapping early crop in January caused only a limited delay in disease development in the late crop, despite the fact that with some treatments this stripping resulted in the removal of a large source of potential inoculum from the tree.The results are considered in relation to differences between seasons and fungicides and it is concluded that further evidence has been provided for the importance of the protective role of fungicides against CBD. It is considered that stripping of the early crop is never likely to be a necessary management practice.
The integration of chemical control of the melon aphid with predatory control of glasshouse red spider mite on cucumbers
Authors: BINNS E. S. , BOCION P. , GOULD H. J. 
Published: February 2008

SUMMARYThe suitabilities of eleven chemical aphicides were compared for application to plants on which biological control of Tetranychus urticae by Phytoseiulus persimilis was in progress. It was concluded that currently used aphicides offer insufficient selectivity to provide a basis for integrated control programmes, although some older insecticides may have value.
Morph determination in the bird cherry‐oat aphid, Rhopalosiphum padi L
Authors: DIXON A. F. G. , GLEN D. M. 
Published: February 2008

SUMMARYBoth crowding and poor nutrition induce the appearance of emigrants in Rhopalosiphum padi L. No emigrants developed when the aphid was reared in isolation for six successive generations on actively growing leaves of bird cherry. However, emigrants developed as soon as the leaves ceased to grow or when the aphids became crowded.Crowding of mothers and postnatal crowding of the nymphs of apterous exules both influenced the induction of alate exules. The highest proportion of alate exules developed when both mother and offspring were crowded.Short day‐length induced the appearance of gynoparae and males. For 50% production of gynoparae and males, over the range of temperature 10–18d̀C, a 1.75 h reduction in day‐length is required for every 4d̀ increase in temperature. At 18 d̀C, even at day‐lengths as short as 6 h, exposure for three generations is required before all offspring become gynoparae or males. Low temperature and short day‐length was ineffective in inducing the development of gynoparae or males in the first three generations developing from the fundatrix.
Interactions between Heterodera rostochiensis Woll. and Verticillium dahliae Kelb. on potatoes and the effect of CCC on both
Authors: CORBETT D. C. M. , HIDE G. A. 
Published: February 2008

SUMMARY H. rostochiensis (British pathotype A) increased the severity of the disease caused by Verticillium dahliae in potato plants grown in pots when there were more than ten eggs/g of soil and both pathogens parasitized the root system together. The growth‐suppressing chemical CCC, which severely stunted plants, prevented the disease and decreased H. rostochiensis reproduction. An estimate of foliage symptoms measured the effects of the disease more precisely than did tuber yields.
Analysis of growth and yield of inbred and crossbred maize
Authors: ALLISON J. C. S. 
Published: February 2008

SUMMARYIn experiments with young widely spaced plants grown in sand culture, net assimilation rate (E) of two single‐cross hybrids, N x S and W x M, was respectively > 20% and 13–19% greater than that of their parental inbreds, N and S, and W and M. Relative growth rate (R) of W x M exceeded that of W or M, and R of N x S exceeded that of S, but not that of N because leaf area ratio (F) of this inbred was greater than that of N x S. E of N x S was about 10% greater than that of an open‐pollinated variety, OP. When the size of plants of N x S was varied by sowing seeds of different sizes, E was little affected but R increased as plant size decreased, because F increased with decrease in plant size.In a field experiment total dry weights at final harvest of N, S and OP were respectively 66, 46 and 98% of that of N x S; their respective grain weights were 47, 20 and 70% of that of N x S. N, S and OP flowered later than N x S and accumulated respectively 56, 26 and 89% as much dry matter after flowering as N x S. Grain formed 71, 65, 83 and 65% of the dry matter accumulated after flowering in N, S, N x S and OP, respectively.Up to about the time of flowering, E and R of the relatively small N and S plants were greater than those of N x S plants, but later E of N and S was smaller than that of N x S. Before flowering, when leaf area of OP was less than that of N x S, E was greater in OP than in N x S. After flowering leaf area was greater, and E smaller, in OP than in N x S.
Effects of plant density and nitroǵen fertilizer on growth and yield of short varieties of wheat derived from Norin 10
Authors: THORNE GILLIAN N. , BLACKLOCK J. C. 
Published: February 2008

SUMMARYThe short varieties of spring wheat, Lerma Rojo 64 (R) and Mexico 120 (M), derived from Norin 10, had similar yields of grain to the taller European variety, Kloka (K), when the nitrogen applied ranged from 50 to 200 kg/ha. All varieties had their maximum yields, of about 500 g/m2 of grain, with 125 kg/ha of N. Yields of R and M were unaffected by change in plant population from 75 (M) or 105 (R) to 298 plants/m2. There were 213 plants of K per m2. When compared at similar plant populations, all varieties had a similar number of ears of similar weights. Ears of K had many small grains borne on many spikelets. Those of R had fewest spikelets and most grains per spikelet. With 213 plants/m2 about 60% of shoots of K and 70% of those of R and M survived to produce ears.The short variety of winter wheat Gaines (G), derived from Norin 10, had a similar yield of grain to the taller European variety Cappelle‐Desprez (C), when nitrogen ranged from 75 to 300 kg/ha and there were 240 plants/m2. The largest grain yields of both varieties, about 670 g/m2, were obtained with 150 kg/ha of N. Increasing the plant population of G to 400 plants/m2 decreased grain yield by 10%. G had more ears than C and the ears weighed less because the grains were smaller. The numbers of grains per ear were similar: ears of G had fewer spikelets than C, each bearing more grains. G always had more shoots than C and about 70% of the shoots produced by each variety survived to form ears.The dry weight per m2 of stem plus leaves of the short varieties was less than of the tall ones at flowering and at maturity. Hence harvest index (ratio of grain yield to total dry weight), and the proportion of total dry weight in the ears at flowering, were greater for the short than for the tall varieties.Grain leaf ratio, the apparent efficiency of the leaf area present after flowering in producing grain, estimated as grain dry weight divided by leaf area duration after flowering, was greatest for M and least for K in the spring experiment. No similar difference occurred between the winter varieties. When leaf area of either spring or winter varieties was increased by nitrogen fertilizer or denser sowing, grain yield did not increase proportionately and so grain leaf ratio decreased.
The resistance of three Solanum species to Myzus persicae, Macrosiphum euphorbiae and Aulacorthum solani (Aphididae: Homoptera)
Authors: GIBSON R. W. 
Published: February 2008

SUMMARYA study was made of the resistance of three wild potato species, Solanum chacoense, S. stoloniferum and S. demissum, to three aphid species, namely Myzus persicae (Sulz.), Aulacorthum solani (Kalt.) and Macrosiphum euphorbiae (Thomas), which all commonly infest the cultivated potato, S. tuberosum. The resistance of each Solanum species differed with the species of aphid, with the part of the plant and with the physiological condition of the leaf. As a result, it may be difficult to utilize such resistance, since it is ineffective against some of the pest aphid species and may break down as the physiological condition of the plant changes.
Methods of assessment celery leaf spot (Septoria apiicola) in relation to fungicide evaluation
Authors: KAVANAGH T. , RYAN E. W. 
Published: February 2008

SUMMARYSix criteria for evaluating fungicides for control of celery leaf spot (Septoria apiicola) were compared. Two of these criteria consisted of yield measurements, of which marketable yield gave better statistical separation of the fungicides than gross yield. Of the other four criteria, assessment of leaf spot on a whole‐plot basis was the most valuable. Overall disease rating on individual intact plants, rating of each petiole and numbers of diseased petioles per plant were less useful assessment criteria.
Some factors affecting the concentrations of sugars in leaves of inbred sugar‐beet lines
Authors: RUSSELL G. E. , BARFORD I. A. 
Published: February 2008

SUMMARYIn the glasshouse, large differences in concentrations of glucose and sucrose were observed between leaves of inbred sugar‐beet lines that are known to differ from each other in resistance to pests and diseases. Differences between these lines in concentrations of fructose, glucose and sucrose were more pronounced in the petiole than in the lamina.The concentrations of glucose and fructose were lower in the first two leaves (primary leaves) than in those produced subsequently (secondary leaves); both types of leaf contained similar concentrations of sucrose.Secondary leaves from plants that had been kept in darkness for 17 h contained less fructose, glucose and sucrose than those of plants kept in sunlight for 5 h. Longer period of darkness lowered the concentrations of monosaccharides in the leaves further but did not affect the sucrose content.Primary and secondary leaves from the same sugar‐beet plant often differ in non‐race‐specific resistance to pests and diseases; and darkness can affect suscetibility of beet to downy mildew and to the aphid Myzus persicae. The results of the sugar determinations therefore support the hypothesis that the concentrations of certain carbohydrates in sugar‐beet leaves are important in non‐race‐specific resistance to pests and diseases.
Tests of aryltin compounds as potato blight fungicides
Authors: McINTOSH A. H. 
Published: February 2008

SUMMARYTriphenyl(phenylthio)tin and triphenyl(p‐chlorophenylthio)tin were as effective as fentin acetate in controlling potato blight (Phytophthora infestans) in laboratory tests on detached leaflets. Diphenyltin dichloride and bis(triphenyltin)sulphide were moderately effective. Dibenzyltin and some diphenyltin compounds were ineffective.A small change in the bioassay conditions, bringing them slightly closer to field conditions, increased the relative effectiveness of bis(triphenyltin)‐sulphide, making it about one‐quarter as effective as fentin acetate; however, the change did not increase the relative effectiveness of triphenyl(phenylthio)tin or dibutyltin diacetate.
Studies on plant growth‐regulating substances: XXXIII. The influence of ring substituents on the plant growth‐regulating activity of phenylacetic acid
Authors: CHAMBERLAIN VALERIE K. , WAIN R. L. 
Published: February 2008

SUMMARYA comprehensive range of phenylacetic acids substituted with nitro, halogen, methyl, amino, hydroxyl and N‐acetylamino groups have been synthesized and their growth‐regulating activities assessed in the wheat cylinder, pea curvature and pea segment tests. The influence of substituents on molecular shape is shown to be more important in determining activity than their effects on electron distribution.Studies with 2,6‐disubstituted phenylacetic acids have indicated that the most active compounds can attain a certain spatial configuration in which one surface of the molecule, including the plane of the ring system, is flat and the carboxyl group is above with its axis of rotation perpendicular to this surface.Positional requirements for growth‐regulating activity in phenylacetic acids are shown to be less important than in the phenoxyacetic and benzoic acids.
Climatic factors restricting the distribution of the aphid Rhopalosiphoninus latysiphon to the subterranean parts of field potato plants
Authors: GIBSON R. W. 
Published: February 2008

SUMMARY Rhopalosiphoninus latysiphon (Davidson) infests the roots of field potato plants, but it is normally absent from the foliage. In cool conditions it is possible to rear this aphid on the foliage of potato plants. From experiments, it is suggested that R. latysiphon does not normally infest the foliage because it does not tolerate the high air temperatures and the radiant heat to which it would be exposed; a damp environment is also preferred. These are probably the main causal factors in the aphid's selection of a subterranean environment.