bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycoplasma‐like bodies associated with Rubus stunt disease
Authors: MURANT A. F. , ROBERTS I. M. 
Published: February 2008

SUMMARYMycoplasma‐like bodies were found by electron microscopy in the sieve tubes of blackberry, loganberry and raspberry plants showing symptoms of Rubus stunt disease, but not in those of normal plants. Watering diseased blackberry plants with aureomycin caused remission of the symptoms and greatly decreased the number of mycoplasma‐like bodies.
Studies on plant growth‐regulating substances
Authors: HARPER D. B. , WAIN R. L. 
Published: February 2008

SUMMARYThe metabolism of certain 2,6‐disubstituted phenols that possess high auxin activity in the pea segment, pea curvature and tomato‐leaf epinasty tests, but are much less active in the wheat cylinder test, has been investigated in wheat, pea and tomato tissue. Metabolites were identified by thin‐layer chromatography and a semi‐quantitative assay method was developed.The low activity of 2,6‐dihalogenophenols and inactivity of 2‐halogeno‐6‐nitro‐phenols and 3‐halogeno‐2‐hydroxybenzonitriles in the wheat cylinder test was caused by rapid metabolic conversion of the compounds in this tissue to inactive compounds by a process involving hydroxylation of the aromatic ring in the para‐ position. No such inactivation occurred in pea and tomato tissues.Evidence for a novel detoxification of nitrophenols within both pea and wheat tissue was obtained; 2‐bromo–6‐nitrophenol was converted via 2‐bromo‐6‐aminophenol to N‐acetyl‐2‐bromo‐6‐aminophenol.Certain 3‐halogeno‐2‐hydroxybenzaldehydes and corresponding aceto‐phenones, although fulfilling the necessary structural and electronic criteria for auxin activity, are inactive. Metabolic studies indicate that this is because they are metabolized in wheat, pea and tomato tissues to compounds not possessing the structural requirements for auxin activity.
The effect of sowing date on adult plant resistance to Erysiphe graminis f.sp. avenae in oats
Authors: JONES I. T. , HAYES J. D. 
Published: February 2008

SUMMARYA technique developed for detecting small differences in mildew infection under glasshouse/laboratory conditions is described. A satisfactory correlation was found between results obtained by this method and infections in the field.Detailed examination of the levels of infection in cultivars Maldwyn and Milford showed that the upper and more recently developed leaves of Maldwyn had a significantly smaller area infected than those of Milford, although seedling leaves of both genotypes were very susceptible. This was most marked when plants were in the 6‐ to 7‐leaf stage.Comparison of host plants sown on successive dates during the spring and early summer showed that with the acceleration of the rate of growth occurring in later‐sown plants, resistance was expressed progressively earlier in the life of the plant.Newly expanded leaves which show very low level of infection at the 6‐ to 7‐leaf stage become susceptible as they age, resistance being then expressed in the younger leaves.
Observations on blight (Phytophthora infestans) and resistant potatoes at Toluca, Mexico
Authors: LAPWOOD D. H. 
Published: February 2008

SUMMARYA late blight epidemic studied at Toluca, Mexico, in 1962 may have started from stems infected at soil level by soil‐borne Phytophthora infestans. Its severity was demonstrated by the large differences in the rate foliage was destroyed and in yield of tubers between fungicide‐sprayed and unsprayed susceptible and resistant cultivars. The foliage resistances of some Mexican and European cultivars were compared using conventional blight keys and recording the destruction of marked leaves. Cultivars reacted in four ways: (1) Up‐to‐Date and Alpha leaves were infected and killed soon after plants emerged; (2) Bertita, Conchita and Florita abscissed many infected lower‐canopy leaves, and many infections on upper leaves aborted; (3) Elenita leaves had a few lesions in which the fungus grew slowly but remained alive; (4) Greta showed no infection until the potato plants met between rows but then infections developed rapidly and the foliage soon died. Mexican cultivars, except for Elenita, had few blighted tubers; susceptible European cultivars were killed before many tubers formed.Most spores were released during the morning, as in Europe, and leaf infection seemed associated with days with rain when much of the night remained humid. Cool nights lengthened incubation and generation times.
Properties of cherry ring mottle, a distinctive strain of prune dwarf virus*
Authors: RAMASWAMY S. , POSNETTE A. F. 
Published: February 2008

SUMMARYA virus was transmitted from sweet cherry trees with cherry ring mottle disease to cucurbitaceous plants with the aid of liquid nitrogen, caffeine or polyethylene glycol, which were more effective than sodium diethyldithiocarbamate, polyvinylpyrrolidone and other materials used in sap‐transmission studies. The virus was transmitted from dormant buds, petals, young leaves, anthers and pollen. Of 172 herbaceous species and varieties tested, twenty‐five (thirteen spp.) became infected with virus. Ribes nigrum and peach seedlings were also infected. Of the systems produced in woody plants, those in Italian Prune resembled the symptoms caused by prune dwarf virus, but those in other Prunus spp. did not. In cucumber extracts the thermal inactivation point was between 40 and 44 d̀C; dilution end‐point was 1/16 to 1/32 and longevity in vitro 8–16 h. Formaldehyde (4%) fixed the particles and preserved their shape for electron microscopy; they were spherical, with a mean diameter of 24 nm. The virus reacted with prune dwarf virus antiserum but differed in several ways from other isolates
Effects on Myzus persicae (Sulz.) and transmission of beet yellows virus of applying certain trace elements to sugar beet
Authors: RUSSELL G. E. 
Published: February 2008

SUMMARYApplications of lithium chloride (LiCl), zinc sulphate (ZnSO4) or nickel sulphate (NiSO4) to the roots of sugar‐beet plants in the glasshouse encouraged settling on the leaves of adult apterae from a clone of Myzus persicae (Sulz.); conversely, treatment with boric acid (H2B2O7) inhibited aphid settling. Larviposition of M. persicae was increased by NiSO4 and tin chloride (SnCl2). Viruliferous M. persicae transmitted beet yellows virus (BYV) more efficiently to plants treated with LiCl or H2B2O7 than to those treated with copper sulphate (CuSO4), ZnSO4 or SnCl2. The sulphate and chloride anions of the applied chemicals appeared to have little effect on M. persicae and virus transmission.It is suggested that applications of trace elements to sugar beet affected M. persicae and virus transmission by changing the concentrations of trace elements in the aphids' diet and by altering the metabolism of the leaf tissues in the host plant.
Studies on plant growth‐regulating substances: XXXII. Chlorosubstituted α‐hydroxy‐and α‐methoxy‐phenylacetic acids
Authors: CHAMBERLAIN VALERIE K. , WAIN R. L. 
Published: February 2008

SUMMARYThe plant growth‐regulating activities of all the mono‐ and di‐chloro‐substituted α‐hydroxy‐phenylacetic (mandelic) acids and their methoxy derivatives have been determined in the wheat coleoptile cylinder, pea segment and pea curvature tests. In general, chloro‐substituted α‐hydroxy acids were less active in all three tests than the corresponding α‐methoxy acids. The α‐methoxy compounds and the dichloromandelic acids were more active in pea than in wheat tissues.These results are discussed in relation to the plant growth‐regulating activities of the corresponding phenylacetic and phenoxyacetic acids.
Apple stem‐grooving virus: propagating hosts and purification
Authors: UYEMOTO J. K. , GILMER R. M. 
Published: February 2008

SUMMARYIsolates C431 and DGEV of apple stem‐grooving virus infected Zucchini squash (Cucurbita maxima) and pumpkin (C. pepo) systemically; these hosts were superior to Chenopodium quinoa for propagating the virus. Virus concentrations were assayed by counts of local lesions on cowpea (Vigna sinenis). Good yields of virus were concentrated from Zucchini squash sap clarified with bentonite or chloroform‐bentonite and purified by densitygradient centrifugation and zone electrophoresis. Filamentous virus particles 615 nm (C431) and 640 nm (DGEV), virtually free of host constituents and only slightly aggregated, were observed in electronmicrographs.
An analysis of the effects of nutrient supply on the growth of potato crops
Authors: DYSON P. W. , WATSON D. J. 
Published: February 2008

SUMMARYFertilizer nitrogen did not delay tuber initiation by the potato variety King Edward in the field, but slowed the early growth of tubers. Later, N hastened tuber growth and the largest amounts prolonged it. Leaf and stem growth were increased by N from an early stage. Leaf area index (L) reached maxima of 2.5 to 3.0 with the largest amounts of N, and 1.0 with no nitrogen: L decreased after late July, faster with increased N, and only the largest amount prolonged the life of the haulm. N increased leaf area duration (D) by up to 125% in both years. D was 21% greater in 1964 than 1963, and net assimilation rate in August and September was larger; consequently mean yield was 50% more in 1964. Uptake of nitrogen and N % of dry matter were increased by increasing nitrogen. The N % of tuber dry weight remained constant or increased slightly from about 2 weeks after tuber formation, while N % of the leaves and stems decreased rapidly, and much N was transferred from tops to tubers. The 1964 results suggest that tuber growth depends on continued nitrogen uptake by the plant.P and K had small effects compared with those of N. K increased leaf area duration by 9% in 1963 and 3% in 1964, and yield by 11 and 8% respectively. P increased leaf area duration by 17% and yield by 9% in 1964. K had very small effects until the end of the season, when it prolonged the period of growth. P increased growth rates of all parts of the plant up to 4 weeks from emergence, and the differences in dry weight at that time persisted to maturity but did not increase.
Studies on plant growth‐regulating substances: XXXIV. The effects of 3,5‐dichlorophenoxyacetic acid on plant growth
Authors: FIRD R. D. , WAIN R. L. 
Published: February 2008

SUMMARYThe effect of 3,5‐dichlorophenoxyacetic acid (3,5‐D) in reducing the shoot growth of tomoato plants has been investigated and evidence is presented which suggests that the inhibition of shoot growth which occurs is not the result of a competitive antagonism between 3,5‐D and endogenous auxin or gibberellins. A reinvestigation of the effect of 3,5‐D on certain auxin‐induced responses failed to reveal evidence which would support the previous classification of 3,5‐D as an ‘anti‐auxin’.
The seasonal release of spores of Nectria galligena from apple cankers in Northern Ireland
Authors: SWINBURNE T. R. 
Published: February 2008

SUMMARYTrapping of ascospores and conidia of Nectria galligena Bres. released from cankers on Bramley's Seedling apple trees over a period of three years showed that ascospores were most prevalent in the spring and early summer, and conidia from early summer to late autumn. Few ascospores were released in late summer or mid‐winter but a minor period of discharge occurred in autumn.The distribution of cankers within trees in various orchards was also examined, and most were found to occur at the junctions of different seasons' growth. Possible reasons for this are discussed.
Lesion and epidemic development of Alternaria longipes (Ell. & Ev.) Mason on tobacco
Authors: NORSE D. 
Published: February 2008

SUMMARYLesion development of A. longipes was studied in the glasshouse and in the field. The incubation period on glasshouse plants varied from 3 to 8 days. Some pinpoint lesions failed to develop, and lesion development on the upper leaves of pot plants was less than on the lower ones. The maximum estimated lesion multiplication rate was 2.1 daughter lesions/mother lesion/day, but was generally ≤ 0.6.Epidemic development was studied in four seasons (1966 to 1969) by weekly assessment of infection levels on alternate leaves. Leaf area, airborne inoculum concentrations, air, leaf and soil temperature, soil moisture, saturation deficit, rainfall, duration of leaf wetness, and wind speed were also measured. Relative infection rates varied from 0.17‐0.26 units/day. Slow disease development in 1968 (r = 0.17 units/day) could be related to the adverse effects of climate on host development and on infection processes. The relative rate of infection varied widely at different stalk position (0.16‐0.29 units/day in 1966) and at different times at the same stalk position (0.17=0.48 units/day at position 25 in 1969). There was no consistent relationship between the stalk position of leaves and the rate at which they were infected. Similarly there was no consistent relationship between the rate of infection of whole plants or of leaves at a particular stalk position and climatic or inoculum factors, although during limited periods, changes in one or other of these factors did coincide with an alteration in the relative rate of infection.The interpretation of rates of infection and the theoretical results of greater field hygiene are discussed.
Bait shyness of two gerbils, Tatera indica indica Hardwicke and Meriones hurrianae Jerdon
Authors: PRAKASH ISHWAR , JAIN A. P. 
Published: February 2008

SUMMARYTwo rodents, Tatera indica indica Hardwicke and Meriones hurrianae Jerdon, developed aversion to zinc phosphide after one day's exposure to a sublethal dose. The poison shyness persisted for at least 115 and 35 days, respectively.
Verticillium wilt of cacao in Uganda: symptoms and establishment of pathogenicity
Authors: EMECHEBE A. M. , LEAKEY C. L. A. , BANAGE W. B. 
Published: February 2008

SUMMARYPathogenicity tests have shown that Verticillium dahliae Kleb. causes a vascular wilt disease of cacao (Theobroma cacao L.) in Uganda. Isolates of V. dahliae from cacao, okra (Abelmoschus esculentus Medik.), and cotton (Gossypium hirsutum L.) induced similiar symptoms on artificially inoculated cacao seedlings.External symptoms of the disease include acute wilting, foliar chlorosis and abscission, stunting of roots and shoots, and production of suckers at lower nodes of severely affected plants. The internal symptoms are vascular discoloration, tylosis, and presence of gum deposits and mycelium of V. dahliae in xylem vessels.
Pepper veinal mottle virus‐a new member of the potato virus Y group from peppers (Capsicum annuum L. and C. frutescens L.) in Ghana
Authors: BRUNT A. A. , KENTEN R. H. 
Published: February 2008

SUMMARYPepper veinal mottle virus (PVMV), a previously undescribed virus widespread in Capsicum annuum and C. frutescens in the Eastern Region of Ghana, is acquired and inoculated in 2 min feeding periods by aphids (Myzus persicae and Aphis gossypii); it is transmissible by inoculation of sap to eleven of fifteen Solanaceae and to five of forty‐six other species within three of seventeen other families. The virus was propagated in Nicotiana clevelandii and Petunia hybrida, and assayed in Chenopodium quinoa, C. amaranticolor and C. murale. Sap from Capsicum annuum was infective after dilution to 10‐3 but not 10‐4, after 10 min at 55 but not 60oC, and after 7 but not 8 days at 25oC. Lyophilized sap from P. hybrida was infective after 6 years in vacuo.Yields of 10–25 mg of virus per kg of leaf tissue were consistently obtained from P. hybrida or N. clevelandii by extracting systemically infected leaves in 0.5 M borate (pH 7.8) containing 0.2% mercaptoethanol and chloroform, followed by repeated precipitation with 50 g polyethylene glycol (M.W. 6000) per l, several cycles of differential centrifugation and centrifugation in sucrose density‐gradient columns.Virus preparations had ultraviolet absorption spectra typical of a nucleoprotein containing c. 6% nuclei acid (A 260/280 = 1.25; A 260/246 = 1.27) and contained numerous unaggregated and unbroken filamentous particles c. 770 times 12 nm which sedimented as a single component with a sedimentation coefficient (so20,w) of 155 S. PVMV contained RNA (moles %: G = 24, A = 23, C = 27, U = 26), and a single protein species with a molecular weight of 32000–33000 daltons. PVMV was not serologically related to potato virus Y (three strains), or to twelve other morphologically similar viruses, and seems to be a distinct member of the potato virus Y group.The cryptogram of PVMV is R/(I):*/(6):E/E:S/Ap.
Organo‐mercury fungicide treatment of sugar‐beet seed
Authors: BYFORD W. J. 
Published: February 2008

SUMMARYSugar‐beet seed treated with I% (v/w) of 1.2% ethyl mercuric phosphate (EMP) solution applied as a mist gave seedling emergence in the field and final plant stand comparable to those of seed treated by 40 ppm EMP steep. However, when the mist‐treated seed was stored after treatment, phytotoxic effects sometimes developed; consequently the treatment is not considered a suitable replacement for the EMP steep, now given to all sugar‐beet seed in Britain.
The life‐cycle and host preferences of the bird cherry‐oat aphid, Rhopalosiphum padi L., and their bearing on the theories of host alternation in aphids
Authors: DIXON A. F. G. 
Published: February 2008

SUMMARYEmigrants of the host‐alternating bird cherry‐oat aphid fly from the primary host to various grasses before the end of June, even in the absence of natural enemies on bird cherry. They fly before the leaves of bird cherry mature and at a time when numbers of insect predators are rapidly increasing. In the autumn gynoparae and males return to bird cherry whose senescing leaves again provide the aphids with a rich source of food. The growth efficiency of R. padi on bird cherry and oats indicates that the quality of the available food on the two hosts is markedly different.Apterous exules prefer oats to young bird cherry leaves and survive best on oats. Gynoparae prefer bird cherry leaves and only successfully produce offspring on the primary host. This, and other work published on R. padi, support the premise that a change in the aphid's preferences causes the change of host.The dual‐discrimination theory of host alternation in aphids is examined in the light of this and other published work.
The role of the apple spray programme in the protection of fruit buds from powdery mildew
Authors: BUTT D. J. 
Published: February 2008

SUMMARYComparisons of programmes, which differed in the dates on which high‐volume sprays of dinocap (0.019 %) were omitted, indicated that applications in the period from green cluster to early fruitlet protected the bourse buds of apple cv. Cox's Orange Pippin from infection, and so controlled the number of mildewed blossom trusses in the following year. This role of the sprays in preventing primary mildew declined after the early fruitlet stage. The existence of two phases of the disease was confirmed, and although dinocap at late blossom and early fruitlet contributed to the control of preliminary infections of secondary mildew on vegetative shoots, the latter phase did not become severe until after the peak invasion of bourse buds. Fewer than 20% of the fruit buds which produced primary‐mildewed blossom in 1968 were succeeded by healthy fruit buds in the next year; this poor recovery was not improved by dinocap applied during the flowering period in 1968.Fruit‐set and crop of James Grieve and Cox's Orange Pippin were reduced in 1968 by dinocap applied at green cluster and pink bud, or at full blossom and petal‐fall, but no deleterious effects were produced by equivalent sprays in 1969. The need for mildew control during flowering is discussed in relation to phytotoxic sensitivity.
A study of seed lots of peas (Pisum sativum L.) differing in predisposition to pre‐emergence mortality in soil
Authors: MATTHEWS S. 
Published: February 2008

SUMMARYIn three seed lots the condition of the cotyledons was found to be important in denning seeds predisposed to pre‐emergence mortality. Such seeds readily exuded materials into seed‐steep water, were rapidly infected by Pythium spp. and showed intensely stained cotyledons after being in solutions of tetrazolium chloride. In soil, infection of the cotyledons was found to occur before infection of the seedling axis and occurred in normal seed if disks of cotyledon material were placed in the soil next to the seed.It is suggested that cotyledons influence predisposition by either increasing exudation around the seed and stimulating the fungal pathogen or by acting as a food base for the fungal hyphae which infect and kill the seedling axis.
Grain yield and quality of wheat as affected by chlormequat (2‐chloroethyl‐trimethyl ammonium chloride)
Authors: LOWE L. B. , CARTER O. G. 
Published: February 2008

SUMMARYThree field experiments studying the effect of chlormequat (CCC) on the grain yield of spring wheat and the quality of the grain for baking purposes were made. In the first, CCC applied as a spray during the stage of rapid internode elongation proved more successful than application as a mixture with superphosphate drilled with the seed at sowing. Both methods prevented lodging and the depression of yield which occurred in the control plots. In the other two experiments the sole method of CCC application was by spraying.In all three experiments CCC‐treated plots had more ears per unit area and grains per ear than control plots; the one exception being at the lowest plant density derived from a seeding rate of 24 kg/ha. CCC helped prevent weather damage to the grain and as a result baking performance of the flour from treated plots was superior to that from the untreated plots.
Cereal aphids, their parasites and predators caught in cages over oat and winter wheat crops
Authors: JONES MARGARET G. 
Published: February 2008

SUMMARYThe trapping of alate aphids in emergence cages each 1 yd2 (0–83 m2) over cereal crops from mid‐June to the end of July, 1964 to 1971, always revealed colonies of cereal aphids within the crop.Four species, Sitobion avenae, S. fragariae, Metopolophium dirhodum and Rhopalosiphum padi occurred every year in different proportions. Alate aphids from winter wheat were most numerous in 1968 and fewest in 1967. Alatae developed slightly earlier in cages than in the field and peak catches were a few days earlier than in a nearby 12‐2 m suction trap.Cereal aphid colonies were adversely affected by bad weather in May, e.g. in 1969, and by predators. Coccinellidae (chiefly Propylea 14‐punctata) were the dominant predators in 1971 and 1968, Syrphidae in 1966, 1971 and 1968 and Chrysopidae in 1970. Parasites belonging mainly to the genus Aphidius were numerous every year. When hyperparasites such as Asaphes vulgaris, Lygocerus sp., Conostigmus sp. and Phaenoglyphis sp. were abundant as in 1967, they affected numbers of aphids in the current year and increased them in the following year (1968), possibly by hindering early, heavy parasitism. Hyperparasites could have an important influence in fluctuations of cereal aphid populations from year to year. Aphids of one species or another are always present in cereal crops in sufficient numbers during the summer months to provide copious quantities of honey dew, and this is unlikely to be a limiting factor in the biology of the wheat bulb fly, Leptohylemyia coarctata.
Effect of numbers of fungicidal sprays and dates of application on control of celery leaf spot (Septoria apiicola) and on chemical residues
Authors: RYAN E. W. , GORMLEY T. R. , KAVANAGH T. 
Published: February 2008

SUMMARYExperiments at two sites in each of three seasons showed that successful control of celery leaf spot depended more on the choice of fungicide than on the number of sprays and the dates of application. Organotin fungicides gave best control of celery leaf spot and with one exception residues were not detected even when the last application was given 4 weeks before harvest rather than 6 weeks.