bluuebunny/crossref_metadata_2025_split huggingface dataset:
BACTERIAL CANKER OF STONE‐FRUITS: IV. INVESTIGATION OF A METHOD FOR MEASURING THE INOCULUM POTENTIAL OF CHERRY TREES
Authors: CROSSE J. E. 
Published: February 2008

Pseudomonas mors‐prunorum Wormald, the organism causing bacterial canker of stone‐fruits, was present on healthy cherry leaves during the autumn in numbers sufficient to suggest that they were the main source of inoculum for the infection of stems and branches. Quantitative estimates of the pathogen could be obtained by shaking leaves in water and plating out the washings. This method was examined in detail as a possible means of comparing the inoculum potentials on different cherry varieties.The numbers of the pathogen varied considerably between leaves and between branches, but not between trees of the same variety. It was estimated that a sample of 192 leaves, eight from each of twenty‐four different branches would be adequate to show differences between varieties if sufficiently replicated in time. The accuracy of a twenty‐four branch sample was tested by comparing parallel samples from two separate groups of trees of the same variety. There was a highly significant correlation between the numbers of bacteria obtained from the two series of samples. From the error variance in an analysis of variance, it was calculated that five successive samples would show a significant difference between two such groups of trees if one exceeded the other by 54%.It was necessary to wash leaves for 4 hr. or more, depending on temperature, to recover all the bacteria from the leaf surfaces. At temperatures lower than 27° C. however, bacterial growth intervened before this stage was reached. At laboratory temperatures a period of 4 hr. washing was found to be most suitable for comparing varieties and gave 80–90% recovery of bacteria without errors due to growth.A characteristic flora of non‐parasitic bacteria was observed on cherry trees, coexisting with the pathogen on the leaf surfaces. The fungus Pullaria pullulans was also extremely abundant.
LEAF INFECTION OF COTTON BY XANTHOMONAS MALVACEARUM (E.F.SM.) DOWSON
Authors: LAST F. T. 
Published: February 2008

Xanthomonas malvacearum spread more rapidly along vascular tissue than into mesophyll when inoculated to the main veins of susceptible cotton leaves. The extent of spread varied with the concentrations of inocula, tissue age and cotton variety.Increasing concentrations of inocula accelerated the initial spread of disease.Bacteria spread more rapidly in young leaves than in old—increasing age greatly decreased disease in the mesophyll. The initial invasion was quicker in young leaves of young plants than in young leaves of old plants.Three types of behaviour, according to the host's reaction, distinguish Knight's resistance factors: (a) where X. malvacearum spread extensively along veins and into mesophyll of plants containing factors B3 and B5; (b) where it was restricted to the point of inoculation in plants containing B4, B9 and combinations with B6m; and (c) where it spread along veins but not appreciably into mesophyll in varieties containing B2 and B2B3.From this and four other different types of tests, factors B2 and B3 seem to increase mesophyll resistance but only B2 gives appreciable vascular resistance. Further, the vascular bundles in varieties with B2 seem to be surrounded by an additional ‘barrier’ which resists X. malvacearum.
THE SURVIVAL IN SOIL OF APTERAE OF THE LETTUCE ROOT APHID, PEMPHIGUS BURSARIUS (L.)
Authors: DUNN J. A. 
Published: February 2008

Some aphids in a population of Pemphigus bursarius on the roots of a summer host do not form wings and fly back to poplar. The fate of these apterae has been investigated and it was found that they could successfully overwinter even though their original host plant had died. Having overwintered without their host, they were then able to colonize the roots of a spring‐planted lettuce crop. Whether the soil was cultivated before or after winter seemed to have little effect on the numbers of apterae that survived.The influence of temperature on the survival of apterae was studied, and from the findings it appears to be well within the capacity of P. bursarius, in the Midlands, to hibernate in the soil without a host from October to April.
EXPERIMENTS ON THE MODE OF ACTION OF INSECTICIDAL SEED‐DRESSINGS, ESPECIALLY AGAINST LEPTOHYLEMYIA COARCTATA FALL., MUSCIDAE, THE WHEAT BULB FLY
Authors: WAY M. J. 
Published: February 2008

Certain chlorinated hydrocarbon insecticides applied as seed‐dressings to wheat can kill wheat bulb fly larvae either by contact or by systemic action.Newly hatched larvae may be killed by contact action when they pass close to the treated seed on their way to attack the shoot. Such kill depends on the behaviour of the larvae and on the depth the seed is sown. Larvae move upwards after hatching and probably reach the surface soil where they search for the host plant, entering the shoot at a depth of between 1/4 and 1 in. This behaviour explains results of experiments in which about half of the larvae were killed by contact action of dieldrin on seeds sown 1/4 in. deep and few or none by similarly treated seeds sown at 3 in. It is not known whether the larvae are killed directly by contact action or whether they die of starvation after being deterred.Larvae not killed by contact may be killed by systemic action. The systemic action of dieldrin and aldrin, unlike their contact action, does not protect the plant from damage by wheat bulb fly larvae, which tunnel within the shoot and destroy the growing point before they are killed. γ‐BHC applied as a seed‐dressing apparently remains systemically active for less time than dieldrin or aldrin, but while active usually kills, or perhaps deters, the larva before it significantly damages the plant.The uptake of dieldrin and aldrin by the wheat seedling depends on contact between the insecticide and the seed or roots, close contact with the seed seeming especially important. Systemic action is also favoured by late sowing, by sowing the seed very shallowly and by increasing the dose of insecticide adhering to the seed. Dieldrin applied as a seed‐dressing at 4.5 mg./seed was not phytotoxic to Cappelle wheat sown within 10 days of treatment, whereas γ‐BHC, even at 0.022 mg./seed, delayed the germination of some seeds.Preliminary experiments with dieldrin seed‐dressings against onion fly larvae showed that newly hatched larvae mostly enter the young onion plant at the base of the bulb close to the position of the treated seed and thus are likely to be killed by contact with the insecticide on the seed. There was no evidence that dieldrin seed‐dressings act systemically against onion fly larvae.
HOST FINDING BY APHIDS IN THE FIELD: GYNOPARAE OF MYZUS PERSICAE (SULZER)
Authors: KENNEDY J. S. , BOOTH C. O. , KERSHAW W. J. S. 
Published: February 2008

Attempts to test experimentally the theory of olfactory attraction to host plants gave negative results, and more conclusive evidence was sought by recording the behaviour of host‐finding migrants in the field. The first of three occasions when the natural alighting rate was high enough for comparative purposes was an autumn migration dominated by Myzus persicae returning to its specific overwintering host, the peach tree.The proportion of M. persicae gynoparae among all aphids caught alighting on a spindle tree, where persicae does not overwinter, was as high as on peach. The much heavier accumulation of migrants on the peach was evidently due, not to their differential alightment, but to their differential rate of departure, with a longer average stay on the peach. The proportion of persicae gynoparae was smaller in catches on transparent sticky traps than among alighters on the trees, and they avoided alighting on brussels sprout plants more often than on peach. Only a fraction of those that approached the plants alighted, even on peach; and only a small fraction of those that did alight, stayed, even on peach.There was appreciable colonization of spindle and sprouts by the M. persicae gynoparae and some ‘wasted’ oviposition by their progeny on spindle. After the migration was over the peach leaves entered the last stages of senescence before the spindle leaves, and persicae gynoparae (no longer able to fly) that were given access to both at that time, settled preferentially on spindle. The distribution of males created the impression that they were less host‐specific than gynoparae.
HOST FINDING BY APHIDS IN THE FIELD: APHIS FABAE SCOP. (GYNOPARAE) AND BREVICORYNE BRASSICAE L.; WITH A RE‐APPRAISAL OF THE ROLE OF HOST‐FINDING BEHAVIOUR IN VIRUS SPREAD
Authors: KENNEDY J. S. , BOOTH C. O. , KERSHAW W. J. S. 
Published: February 2008

Aphis fabae gynoparae occurred in the same large proportion in simultaneous collections of all aphids alighting and probing on, and taking off from, a host plant (spindle) and a non‐host (peach), and behaved similarly when approaching and leaving them in the same conditions. Most alighters took off again from leaves of both kinds within a few minutes, staying longer and probing more times on the host. In atmospheric conditions favouring local ‘hovering’ instead of dispersal, flying and alighting aphids became concentrated around host plants, not through any specific attraction to them, but apparently because more aphids had accumulated upon them and were now taking off. Brevicoryne brassicae occurred in the same large proportion in simultaneous collections of aphids alighting on a host plant (cabbage) and a non‐host (sugar beet). No satisfactory evidence was found of preferential alightment on cabbage and there were indications of preferential alightment on the non‐host. A very small minority of the A. fabae and B. brassicae that alighted on their hosts stayed there long enough to larviposit. This minority was rather larger among alighters late in the day, but in the absolute sense, more colonization occurred during earlier periods when more aphids arrived.The intensely dispersive type of host‐finding behaviour in Myzus persicae, A. fabae and B. brassicae may be common among Aphididae. It seems ideal for the dissemination of non‐persistent plant viruses, more particularly among the less‐favoured host plants of each aphid. The tendency to commensal association between virus and vector provides an ecological framework which may govern the incidence of virus‐vector specificity and symbiosis.
STUMP PROTECTION AGAINST FOMES ANNOSUS: TREATMENT WITH CREOSOTE
Authors: RISHBETH J. 
Published: February 2008

Creosoting of pine stumps immediately after felling commonly prevents the entry of Fomes annosus and other primary basidiomycete colonizers through the cut surface. Ceratocystis spp. and Ophionectria cylindrospora frequently enter creosoted stumps, but growth tends to be slow.Light applications of creosote often fail to exclude basidiomycetes. Failure to achieve protection may also result from delay in application, especially when resin flow from the cut surface is rapid; this flow impedes creosote penetration.In one experiment creosoting also controlled air‐borne Fomes annosus infection of larch stumps. Various protectants were tested in the forest, a preliminary indication of their efficiency being obtainable after 2 months. A gasworks creosote (b.p. 190–300° C.) was promising, whilst a tar/creosote mixture was unsatisfactory.Disadvantages of creosote as a stump protectant arise mainly from its retarding effect on stump colonization. Creosoted stumps tend to remain alive longer than untreated ones and the risk of F. annosus attaining dominance in stumps already having root infection is correspondingly greater.
BACTERIAL ROTTING OF APPLE FRUIT
Authors: COLE MARTIN 
Published: February 2008

Three bacterial isolates obtained from a rotten apple were found to produce actively spreading firm brown rots when stab‐inoculated into Bramley's Seedling apples, but bacteria were not found at the front of the rot.One isolate was a capsulated, non‐motile, non‐fluorescent, Gram‐negative rod apparently not described previously. The name proposed for the isolate is Pseudomonas pomi. The other two isolates were the same and were non‐capsulated, non‐fluorescent, Gram‐negative motile rods, usually with two polar flagella, and were considered to be identical with Ps. melophthora Allen & Riker (Allen & Riker, 1932).The three isolates grew on media at pH 5.0 and in apples with juice of pH 3.5. For each isolate the square of the distance of the front of the rot from the point of inoculation of apples, was found to be directly proportional to the time after inoculation. The isolates were able to invade fruit at the stalk and eye ends and where the skin had been pricked. No apparent infection followed spraying leafy shoots or flowers of Bramley's Seedling trees with bacterial suspensions and there was no visible reaction after hypodermic inoculation of bacterial suspensions into apple shoots.
THE INCIDENCE OF CERTAIN SEED‐BORNE DISEASES IN COMMERCIAL SEED SAMPLES
Authors: MARSHALL GILLIAN M. 
Published: February 2008

Samples of commercial wheat seed submitted to the Official Seed Testing Station, Cambridge, have been examined from 1918 to 1957 for the presence of bunt balls (Tilletia caries (DC.) Tul.) and earcockles (Anguina tritici (Stein.) Filipjev) and the incidence of these organisms is reported.The highest proportion of contaminated samples was found in 1921 (33% with bunt balls and 9% with earcockles). Since then incidence has decreased rapidly and is now steady at less than 1% with bunt balls and nil or less than 0.1% with earcockles. Low bunt‐contamination was confirmed by finding no bunt spores in 122 samples in 1957.The survey illustrates the effective control and almost complete elimination of a seed‐borne disease and pest in the United Kingdom.No seasonal effect on the incidence of either pathogen was found nor was any varietal susceptibility to bunt detected.
THE DETERMINATION OF THE REACTION OF BARLEY VARIETIES TO LOOSE SMUT
Authors: MALIK M. M. S. , BATTS C. C. V. 
Published: February 2008

The inoculation of barley with loose smut (Ustilago nuda) using various techniques has given results which do not reflect the known behaviour of varieties under natural conditions. No consistent results have been obtained, but all the varieties thus inoculated could become infected. No variety therefore possessed true physiological resistance and in the field some must escape infection. The inoculation techniques obviously overcame this escape.A method has been devised which, with the varieties used, has reflected their behaviour in the field. Drops of coloured water or spore suspension are allowed to fall from a height on to ears at anthesis. Grains on the ears of varieties which do not become infected in the field do not become coloured or infected (depending on the drops used), while grains of varieties susceptible in the field do become coloured or infected. This is due to the glumes of the former group of varieties remaining closed, and so preventing access of smut spores under natural conditions.
THE TOXICITY OF ZINC SULPHATE TO RAINBOW TROUT
Authors: LLOYD R. 
Published: February 2008

The toxicity of zinc sulphate to rainbow trout (Salmo gairdnerii Richardson) has been investigated in waters of different chemical and physical properties.Zinc sulphate was less toxic to rainbow trout in hard water than in soft water; when the log concentration of zinc was plotted against log median period of survival of the fish the dose response curve was linear in a very soft water, and curvilinear in a hard water, approaching an apparent threshold concentration. Solutions of zinc sulphate containing calcium chloride were less toxic than those containing an equivalent concentration of calcium as bicarbonate.An increase in temperature decreased the survival time of rainbow trout in solutions of zinc sulphate in a hard water, but the threshold concentration was not appreciably affected by changes in temperature.A reduction in the dissolved oxygen concentration of the water increased the toxicity of zinc sulphate, but the effect was reduced when the fish were previously acclimatized to the lower oxygen concentration of the test.The cause of death of fish in solutions of zinc sulphate was not by the precipitation of mucus on the gills but probably by damage to the gill epithelium.
SOME FIELD HABITATS OF MITES OF STORED FOOD PRODUCTS
Authors: GRIFFITHS D. A. 
Published: February 2008

Forty‐seven samples were collected from stacks of hay, corn and straw and from permanent grassland in the East Midland counties of England. The living mites were extracted and all except the Oribatei were identified. Records were kept of the occurrence of those mites associated with stored food products, of the mites Forcellinia fungivora Oud. and Alliphis halleri Can., and of the beetle Enicmus minutus L.Fifty‐two species of mites were identified of which twenty‐two were associated with stored food and food stores. Twenty‐one stored‐product species were collected from hay‐ and strawstacks and five from grassland. Acarus siro L., a major pest of stored cereals and cereal products, was the dominant mite in stacks and was also found in grassland samples. Tyrophagus longior Gerv. was similarly distributed and occurred almost as frequently. The motile hypopial stage of Acarus siro was found in 43% of the stack samples; it was attached to mites, beetles and other invertebrates. Its distribution pattern resembled that of the fungus beetle Enicmus minutus. Tyrophagus palmarum Oud., an uncommon stored‐product mite, was the dominant species collected from grassland samples.It is concluded that: (a) all the mites commonly associated with foodstuffs stored indoors are present in the outdoor habitat afforded by stacks; (b) Acarus siro and Tyrophagus longior are dominant in stacks and both appear to be field dwellers; (c) T. palmarum appears to be a successful field dweller and its occasional association with stored food may be accidental; (d) the dominant warehouse partnership of Acarus siro and Glycyphagus destructor does not occur outdoors; here Tyrophagus longior replaces Glycyphagus destructor; (e) species of the family Glycyphagidae appear to live mainly in haystacks sited in stackyards; and (f) considering how the mites were acquired, grainstacks standing in the open field have a peculiar combination of dominants, namely: Acarus siro, Tyrophagus longior, T. palmarum and Alliphis halleri.
OSCINELLA FRIT L. IN SOUTH WALES. THE RELATIONSHIP BETWEEN SOWING DATE, PLANT DEVELOPMENT AND PROGRESS OF ATTACK IN SPRING OATS
Authors: FIDLER J. H. , WEBLEY D. 
Published: February 2008

The degree of lateness of sowing of spring oats in south Wales is reflected in a proportional increase of frit‐fly damage to the shoots. Late‐sown crops are also more subject to heavy attacks on grain than those sown earlier.Equations are given relating the development of frit‐fly attack both to the growth of the plant and to the date of sowing.
DIDYMELLA STEM‐ROT OF OUTDOOR TOMATOES
Authors: KNIGHT DOROTHY E. , KEYWORTH W. G. 
Published: February 2008

Experiments were made during 1954‐7 on the control of Didymella stem‐rot of tomatoes, by applications of various fungicides. The toxicity of a wide range of compounds to the fungus and to tomato plants was determined in the laboratory and promising compounds were then tested in the field. There were two main test methods, in both of which the plants were infected artificially at varying periods before or after treatment with the fungicides. In one method the inoculum was applied to leaf scars and in the other to the stem bases, the fungicides being sprayed on to the same sites.Of the compounds tested, maneb was the most successful, showing both eradicant and protectant properties at 1 and 2%. Captan (0.25 and 0.5%) was a good protectant but was less effective as an eradicant. Attempts were made to test the compounds under conditions of natural spread of the disease but this was so slight that the results were not conclusive.
FIELD SPRAY TRIALS AGAINST WILDFIRE AND ANGULAR LEAF SPOT OF TOBACCO IN RHODESIA*
Authors: COLE J. S. 
Published: February 2008

Field tests in Southern Rhodesia compared several antibiotics with copper fungicides for the control of wildfire and angular leaf spot of tobacco.When streptomycin‐sensitive strains of the pathogen were used, streptomycin gave the best control. During one test, strains of Pseudomonas tabaci developed which were resistant to streptomycin: this was followed by a rapid breakdown of control. In another test, which compared streptomycin, oxytetracycline, neomycin, chlortetracycline and copper, streptomycin was the only effective spray. Cultures, isolated at the end of this test, showed resistance to all the antibiotics except chlortetracycline, but they lost their pathogenicity during laboratory tests. Oxytetracycline was generally no better than the lower rate of copper, and in one test it was ineffective. When variants resistant to streptomycin were used, a mixture containing oxytetracycline and streptomycin at quarter‐strength and copper at half‐strength was slightly better than full‐strength copper or a mixture of half‐strength copper and oxytetracycline.Half‐strength streptomycin and copper was slightly better than full‐strength copper or half‐strength streptomycin and oxytetracycline, against a mixture of streptomycin‐resistant and sensitive variants of P. tabaci.
THE USE OF ENDRIN AND OTHER INSECTICIDES AGAINST LETTUCE ROOT APHID, PEMPHIGUS BURSARIUS L
Authors: DUNN J. A. 
Published: February 2008

Several insecticides have been used as protectants against lettuce root aphid, including, in 1955, lindane, schradan, aldrin and endrin; the last‐named giving the most promising results. With a dressing of an equal weight of 50% endrin dust added to lettuce seed, 86% reduction in aphid numbers was obtained. In 1957, a seed dressing with endrin also gave a good control, which was superior to that obtained with thimet 44D. However, in 1956 and 1958 endrin seed dressing failed to control the aphid. When a seed dressing with endrin was supplemented by an endrin spray applied to the seedlings a consistently good control resulted.A high level of aphid control was obtained in 1958 with two sprays of diazinon applied along the lettuce rows, the first applied after singling and the other at the early rosette stage. Diazinon or endrin, applied to the soil at 4 lb. actual insecticide/acre and rotavated into the top 3 in. before sowing, also gave high levels of control.No recommendations for the use of endrin on lettuce can be made until levels and persistence of residues are known.
STUDIES ON THE PHOTOLYSIS OF PYRETHRUM
Authors: JONES G. D. GLYNNE 
Published: February 2008

The rates of photolysis of films of pyrethrum were studied to determine the factors which could contribute to their increased stability.The claims that the green colouring matter (referred to as chlorophyll) present in crude oleoresin contributed to the rapid photolysis of pyrethrum films were verified. Evidence was accumulated to show that light of a wide range of wavelengths could effect photolysis.The action of para‐aminoazobenzene as a stabilizer was studied in detail and the experimental evidence obtained strongly suggested that this compound did not exert its action by virtue of its light‐absorbing properties but as a direct or indirect inhibitor of a chemical reaction. Assays of the four active principles in extract before and after irradiation showed that the PAAB protected primarily the cinerin II and pyrethrin II.Sudan IV and p‐methoxyazobenzene and Spirit Red were shown to have similar stabilizing properties to PAAB.