bluuebunny/crossref_metadata_2025_split huggingface dataset:
FACTORS AFFECTING THE BEHAVIOUR AND ACTIVITY OF THE CABBAGE ROOT FLY (ERIOISCHIA BRASSICAE BCHÉ)
Authors: MILES MARY 
Published: February 2008

The behaviour of cabbage root flies is governed by their need for food and shelter. Captive flies fed on sugar solution lived for periods up to 62 days, and a bred female laid 122 eggs.Weather conditions determine the activity and the length of life of the flies. Feeding and egg‐laying occur in warm sunny weather, and long periods of sunshine with temperatures of at least 60° F. in the latter half of April are associated with the onset of attack on the host plants. In cold or wet weather the flies shelter in soil or in thick herbage, and if they are immobilized for some time they die of starvation. In this way, the onset of cold weather checks the development of cabbage root fly attack. Details are given to show how the weather affected the activity of the flies in the springs of 1948–50 inclusive.Eggs are laid in batches of varying size at irregular intervals during approximately 4 weeks. The position of the eggs about the host plants is affected by weather conditions. They are usually laid in the soil, but when the pressure of sunshine and drought is removed they are laid freely on aerial parts of the plants.Knowledge of the influence of the weather on the activity of the flies enables attack to be anticipated with some degree of accuracy and control measures to be carefully timed.
THE REACTION OF VIRUS‐INFECTED POTATO PLANTS TO PHYTOPHTHORA INFESTANS
Authors: MÜLLER K. O. , MUNRO J. 
Published: February 2008

The growth of Phytophthora infestans was retarded on leaves of potato plants that had been artificially inoculated with virus X or with virus Y.Using different virus strains and potato varieties, the effect of virus infection on blight development was found to be greater, the more severe the systemic virus symptoms exhibited on the infected leaves before P. infestans inoculation.The development of the fungus was never increased by virus infection.The reduced blight development on virus‐infected leaves is partially caused by an increase of resistance to infection. It is also suggested that virus infection alters the nutritional status of leaves to one less favourable for the development of P. infestans.
VIRUS DISEASES OF CACAO IN WEST AFRICA VIII. THE SEARCH FOR VIRUS‐RESISTANT CACAO
Authors: POSNETTE A. F. , TODD J. McA. 
Published: February 2008

The methods used and the results of 10 years' search for cacao resistant to swollen‐shoot disease are described. Selection among the trees surviving in farms devastated by this virus disease led to the discovery of mild virus strains which can protect trees against virulent strains.When tested by graft inoculation with virulent virus, none of the selections showed any immunity or resistance save that conferred by previous mild‐strain infection. A low degree of tolerance was found in some selections.Local selections and a range of new introductions were tested by mealybug infection, and only types from the Upper Amazon region of Ecuador were consistently resistant to infection. This genetical resistance seems to be strongest in cacao from the Nanay peninsula, near Iquitos.
MUSTARD OILS AND CONTROL OF THE POTATO‐ROOT EELWORM, HETERODERA ROSTOCHIENSIS WOLLENWEBER: FURTHER FIELD AND LABORATORY EXPERIMENTS
Authors: ELLENBY C. 
Published: February 2008

Allyl isothiocyanate has already been shown to be effective against the potato‐root eelworm. Experiments are described in which this mustard oil, which occurs in the seed of black mustard, is compared with two similar substances; one, phenyl isothiocyanate, is synthetic, the other, phenethyl isothiocyanate, occurs in the roots of many crucifers, including black mustard.In hatching experiments, various concentrations of each of these oils in potato‐root excretions are used to stimulate eelworm cysts. The earlier results with allyl isothiocyanate are confirmed; it is also shown that the emergence of larvae decreases with increasing concentration of oil. An experiment in which different concentrations of oil are used in different strengths of root excretions showed that it is unlikely that there is any stoichiometric interaction between root excretions and mustard oil.Field experiments were carried out in different years and on different plots so that their comparison is difficult. But they appeared to show that talc is inferior to peat as a carrier for mustard oil. A comparison of the three oils on talc gave no significant improvement in yield, although plants treated with the allyl oil did best. In another trial with allyl isothiocyanate on talc, highly significant improvements in yield were obtained at dosages of 8 and 12 g. per row of ten plants, but the improvements were smaller than those reported previously for oil on peat. In a peat experiment on a plot giving the poor control yield of 4 oz. a plant, yield increased regularly with dosage and was almost trebled at 9 c.c. of oil per row of ten plants. On a plot with control yields of over 20 oz. a plant, 6 c.c. of oil per row increased yield by over 50%. It is shown that the increased yields are almost certainly due to a reduction in the severity of the attack, i.e. that the laboratory hatching trials ‘explain’ the field results. Although the cyst counts reported are by no means beyond criticism, they show conclusively that treated plants producing heavier crops of potatoes bear fewer cysts than control plants with lower yields.There is a suggestion that polyploidy may be induced by certain dosages of allyl isothiocyanate.
A SIMPLE METHOD FOR TESTING THE TOXICITY OF VOLATILE ANTISEPTICS TO WOOD‐ROTTING FUNGI
Authors: FINDLAY W. P. K. , VERNON J. W. 
Published: February 2008

Methods used for determining toxicity of volatile compounds to fungi are reviewed and a simple laboratory method for carrying out such tests is described.Results from this type of test may be applicable in practice where the mycelium of the fungus is freely exposed to the action of the vapour, but if it is desired to sterilize infected wood of any appreciable thickness, information about the penetration of the vapour across the grain of the wood and of its sorption by the wood must be obtained before any treating schedule can be drawn up.
THE BIOLOGY OF THE RICE WEEVIL, CALANDRA ORYZAE (L.)
Authors: HOWE R. W. 
Published: February 2008

The length of the developmental instars of Calandra oryzae has been estimated at relative humidities of 50, 60, 70 and 80% at 21° C., at 70% at 18, 25 and 30° C., and at 80% at 18° C., by the dissection daily of samples of infested wheat‐grains. The results are expressed as a median obtained by the method of probit analysis. Comparison of this method, with estimates of median and mean obtained by orthodox arithmetical methods from similar work on Rhizopertha, show that the probit method gives good estimates.About 90% of the eggs laid are fertile. Normally only one adult will develop in a grain, all other individuals being destroyed by cannibalism. The sex ratio is unity. It was not possible to cross C. oryzae and C. granaria.The daily oviposition rate of C. oryzae at 17, 21 and 25° C. increases with relative humidity. There is a critical point at about 60%r.h. below which egg laying declines rapidly, and mortality is high. At 100%r.h. the oviposition rates per female per day are approximately 1.3, 2.5 and 3.4 at 17, 21 and 25° C. respectively.In experimental conditions most eggs per grain are obtained by giving isolated females one grain each, but more eggs are laid by females given more than one grain. Daily egg output is reduced by grouping females or including males. In culture, depths of grain up to 7 cm. do not discourage egg laying.
THE ECOLOGY OF ANISOPUS FENESTRALIS SCOP. (DIPTERA) IN SEWAGE BACTERIA BEDS
Authors: HAWKES H. A. 
Published: February 2008

The assessment of populations of Anisopus fenestrate (Scopoli, 1763) in sewage bacteria beds by the trapping of adults at the surface has been previously proved to be unsatisfactory. Methods were therefore developed for determining the numbers of egg masses, larvae and pupae as well as the total organic matter in a unit volume of bed. The relative larval populations of three areas under investigation were related to the loading of the beds as measured by the sewage strength and rate of application. In the upper 2 ft. 6 in. the numbers of larvae and pupae per unit volume of bed decreased with depth. There was no evidence of any vertical migration of the larvae before pupation. The horizontal distribution of larvae was found to be affected by the method of distribution. In beds served with fixed spray jets larvae are more abundant nearer the jets than at some distance away. In beds served with travelling distributors the larvae are more abundant in the zones below the jets than in the drier intermediate zones. In both cases relatively higher percentages of pupae in the drier zones might indicate a horizontal migration of larvae before pupating or of the pupae themselves.The incidence of the larvae throughout 1949 in all three beds showed recurring peaks. In the following year a more intensive investigation on one area showed that this was due to successive generations of the fly; the proximity of the peaks is determined mostly by temperature and their size by the amount of food available in the bed during the larval grazing phase.In the area not treated with insecticide intraspecific competition during a period when food was limiting, due to depletion by the previous generation, resulted in a natural reduction in the population. In the area treated with insecticide the food was retained and this natural control was thereby delayed.
DRY‐ROT DISEASE OF THE POTATO*
Authors: FOISTER C. E. , WILSON A. R. , BOYD A. E. W. 
Published: February 2008

A study has been made of the incidence of dry rot in seed potatoes in relation to commercial handling methods, and it has been shown that infection following grading by mechanical reciprocating riddles fitted with bare wire screens is more serious than that following normal handling at harvest or during transport. Hand picking, hand riddling and the use of rubber‐spool graders or rubber‐coated screens reduced infection by varying amounts. The higher incidence of the disease in ‘transported’ as against ‘home‐saved’ seed is regarded as being due to machine grading of such stocks some months prior to planting.Contamination of stores or boxes has not been found to play any material part in the spread of infection under commercial conditions unless tubers are roughly handled during storage. As contact infection has been found to be rare, it is considered that the practice of ‘picking over’ stocks during the winter to remove diseased tubers is unnecessary and may lead to further infection.In addition to wounds, lesions of both blight and powdery scab, but not common scab, have been found to be a means of infection.
DRY‐ROT DISEASE OF THE POTATO
Authors: McKEE R. K. 
Published: February 2008

Examination of 144 samples of seed potatoes affected with dry rot, comprising 1218 tubers, showed the presence of parasitic Fusaria in 91% of the lesions. The parasitic Fusaria consisted of 93%Fusarium caeruleum, 6%F. avenaceum and less than 1% each of F. arthrosporioides and F. tricinctum. F. tricinctum has not previously been recorded on potato in this country.A method is described whereby the presence of F. caeruleum can readily be detected in tubers affected with dry rot.
DRY‐ROT DISEASE OF THE POTATO
Authors: McKEE R. K. , BOYD A. E. W. 
Published: February 2008

Living tubers were inoculated by a standard method with small quantities of the soil to be tested and held under conditions suitable for infection. The number of dry‐rot lesions that developed was regarded as giving a measure of the soil infectivity; this number, expressed as a percentage of the total number of inoculations, was termed the ‘Infectivity Index’ of the soil.In these experiments, 91% of the lesions were caused either by Fusarium caeruleum or by a few other Fusarium species of which much the most common was F. avenaceum. In most instances it proved possible to distinguish the lesions caused by these two groups of fungi in tubers of the variety Doon Star by the colour of the rotted tissues as seen on cutting; isolations showed that 85% of the separations made in this way were correct.Data are given indicating the sensitivity and consistency which may be expected from the method.
STUDIES IN RUBUS VIRUS DISEASES
Authors: CADMAN C. H. 
Published: February 2008

A chlorotic veinbanding disease of raspberries is shown to be due to a virus transmissible by the aphid Amphorophora rubi Kalt. after infection feeding periods of 18 hr. or more.This virus causes leaf symptoms, masked in hot weather, on a wide range of European and North American varieties. Symptoms on the latter are analogous to those of the red raspberry mosaic of American authors.The names veinbanding disease and raspberry veinbanding virus are proposed.
THE COMPETITION BETWEEN BARLEY AND CERTAIN WEEDS UNDER CONTROLLED CONDITIONS
Authors: MANN HAROLD H. , BARNES T. W. 
Published: February 2008

One of the commonest agricultural practices in Britain is the undersowing of barley and other corn crops with clover as a preparation for a clover ley after the corn crop has been reaped. The effect of the clover growing among the corn, where manuring (especially with nitrogen) is made as favourable as possible for the corn crop, is not clear. If nitrogen is deficient, it is well known that clover can furnish nitrogen for the corn, but where the supply is ample, the clover may act as a competitive crop.When barley and clover were planted together, with abundance of water and nutrients for both, it was found that the presence of even a small number of barley plants reduced the growth of the clover by over 50%, but that an increase in the density of the barley did not increase the effect. The presence of the clover reduced the barley crop by an amount which tended to get less as the density of the barley was increased. In a sparse crop of barley, increase in clover density reduced the growth of barley very little, while that of the clover was again found to be little more than half what was obtained when this plant was grown alone.There is no evidence of any specific effect of the roots of the one plant on the other. In the circumstances of these experiments it would seem that, far from the clover supplying nitrogen to the barley, it tends to steal some of that which would otherwise be available to the latter, when they are grown together.
VARIATION WITHIN FRENCH BEAN VARIETIES
Authors: BATEMAN A. J. 
Published: February 2008

The internal variability of several varieties and strains of French bean is investigated, confining attention to the single character, seed weight. Out of eleven strains examined only two appeared to be homogeneous for seed weight, whilst two were obviously heterogeneous even by superficial examination of the seed.A comparison of the distribution of seed weights in five strains of Canadian Wonder showed that each strain contains at least two or three lines out of the minimal estimate of four shared between them.The natural out‐crossing of fourteen varieties, including those analysed for seed weight, is compared. There are indications that varieties vary in their out‐crossing propensities. No indication was found of the causes of the high frequencies of out‐crossing occasionally encountered.The possible sources of intra‐varietal variation are briefly surveyed.
DRY‐ROT DISEASE OF THE POTATO
Authors: BOYD A. E. W. 
Published: February 2008

The standard injection method of inoculation was used in conjunction with the riddle‐abrasion method, at three periods during the storage season, to determine the effect of storage of potatoes of three varieties at three temperatures or ranges of temperature upon their subsequent susceptibility to Fusarium caeruleum.Susceptibility was greatly increased by increase in storage temperature. Low‐temperature storage (39°F.) before inoculation decreased susceptibility. If, however, such storage immediately followed inoculation, although little or no signs of rotting were obvious after 6 weeks, when these tubers were replaced for a further 6 weeks at the normal temperature of incubation (60°F.) the amount of rotting was enhanced.Some practical consequences of these facts are discussed.
STUDIES OF FLUCTUATIONS IN INSECT POPULATIONS XIII. AN IMPROVED METHOD OF ASCERTAINING THE CORRECT DATE TO SAMPLE WHEN ASSESSING LARVAL INFESTATIONS OF THE WHEAT‐BLOSSOM MIDGES
Authors: BARNES H. F. 
Published: February 2008

Fully fed larvae of the wheat‐blossom midges need moist conditions in order to descend from the ears to the soil. A dry spell coinciding with the fully fed stage therefore causes an accumulation of larvae, which subsequently leave the ears in a body when rain comes. Conversely, in wet weather each larva leaves the wheat as soon as it finishes feeding, and, since all the eggs are not laid on the same day, the descent will then be a gradual process.A method is described of taking small samples of wheat ears at frequent intervals, thus facilitating the determination of the correct date on which to take the main sample for the assessment of infestation by the two wheat‐blossom midges.
FURTHER OBSERVATIONS ON THE BIOLOGY OF THE CABBAGE ROOT FLY, ERIOISCHIA BRASSJCAE BCHÉ
Authors: MILES MARY 
Published: February 2008

In 1951, eggs of Erioischia brassicae were first found in the field on 2 May, and the peak period of egg‐laying occurred 19–31 May. This was up to a month later than in the period 1948‐50.The periodic removal and examination of the surface soil showed that eggs of E. brassicae were continuously present on the host plants from mid‐June to early November. Plants under observation during this period showed an average of 285 eggs per plant and other plants exposed to attack from July to November showed an average of 162 eggs per plant. Peak periods of egg‐laying, as indicated by numbers of eggs per plant per day, occurred in late June and early July, in mid‐August and, to a less extent, in the first half of October. The plants showed no increase in the rate of infestation as the season advanced, although E. brassicae has a reproductive capacity of about 100 eggs per female and three to four generations a year.The difference between the observed egg populations and pupal populations indicated that E. brassicae had a heavy mortality rate in its immature stages. The condition of puparia showed that the species was subject to a high degree of natural control, a fact for consideration when direct control measures are formulated.Pupal diapause extending from October 1949 to May 1951 was observed in one specimen of E. brassicae and from October 1949 to August 1951 in one specimen of its Hymenopterous parasite, Trybliographa rapae Westw.Tests with tar‐oil winter wash showed that at a concentration of 1 1/4% it killed eggs of Erioischia brassicae and repelled gravid females for approximately a week. Laboratory tests with BHC indicated that it had no adverse effects on the eggs but was larvicidal.
STUDIES IN THE RELATIONSHIP OF EELWORMS AND BACTERIA TO CERTAIN PLANT DISEASES
Authors: CROSSE J. E. , PITCHER R. S. 
Published: February 2008

Two types of organism are known to be present in strawberry plants suffering from cauliflower disease, namely, eelworms, Aphelenchoides ritzema‐bosi and/or Aphelenchoides fragariae, and a bacterium, Corynebacterium fascians. Neither type, inoculated separately, has consistently reproduced the disease.An experimental investigation of a possible obligate etiological relationship between the eelworm and the bacterium is described, in which Aphelenchoides ritzema‐bosi and several strains of Corynebacterium fascians were inoculated together and separately.No abnormalities appeared in the absence of the eelworm. Typical cauliflower symptoms were reproduced only by a combination of the eelworm and strains of C. fascians originally isolated from cauliflower strawberries. Small alaminate leaves and enations appeared in all treatments where the eelworm was introduced, including those where no bacteria were co‐inoculated. Subsequent isolations, however, demonstrated the presence of contaminant strains of C. fascians in the latter plants. The severity of the enation symptom was related to the presence of a particular strain of C. fascians, but the alaminate leaves showed no such correlation. Evidence on the source of the contaminant strains found in the experimental plants is discussed.In parallel field investigations it was established that eelworm‐infested strawberries showing no cauliflower symptom frequently bore alaminate leaves, with which C. fascians was consistently associated. It is suggested therefore that cauliflower is simply the least frequent of a range of symptoms of a bacterial disease endemic in strawberry plants infested with Aphelenchoides spp.
ACUTE DIE‐BACK OF CLOVE TREES IN THE ZANZIBAR PROTECTORATE
Authors: NUTMAN F. J. , ROBERTS F. M. 
Published: February 2008

The most widespread die‐back of clove trees (Eugenia aromatica) in the Zanzibar Protectorate is caused by Cryptosporella eugeniae sp.nov. The most noticeable symptom is the death of a branch or a portion of a branch, or, in young saplings, of the entire tree; in mature trees infection eventually leads to the semi‐moribund trees now common in almost every clove plantation. The fungus invariably enters through a wound, most often one resulting from harvest damage. Pycnidia, and later perithecia, develop near the point of entry. Internally the infected wood is clearly distinguishable from the healthy by a dark red‐brown stain.Experimental infections that reproduce typical symptoms can rarely be caused in plants aged 18 to 36 months, and not at all in young seedlings. Experimental infection of older plants becomes more certain with increasing age, and with saplings of 7–10 years old failure is rare.The prevalence of Cryptosporella die‐back is almost entirely attributable to the destructive methods of harvesting now practised, combined with the presence of much infected material present in the plantations. Suggested control measures are based on the removal of old sources of infection and prevention of future damage, combined with remedial treatment where possible.
SOME EFFECTS OF TEMPERATURE AND NITROGEN SUPPLY ON WHEAT POWDERY MILDEW
Authors: LAST F. T. 
Published: February 2008

The wheat variety Red Standard was more susceptible to infection by Erysiphe graminis at 14–20° C. than at c. 7° C. Conidia were produced per unit area of pustule more than ten times as rapidly at 14° C. as at 7° C.The increased susceptibility of wheat to mildew after applying nitrogenous fertilizer (N) was associated with changes in its growth rate. Both growth rate and susceptibility increased to a maximum and then declined; the curves for the two were parallel, with a lag of some days between effect on growth rate and effect on susceptibility. Plants that had passed through the susceptible phase and became resistant to mildew, again became susceptible when supplied with more N. Nitrogen‐deficient plants continuously resisted infection.The higher the average growth rate during an experiment the greater was the total amount of infection. Increasing the average growth rate was soon followed by a sharp increase in the amount of infection. When plants of two size groups received the same amount of N the initially smaller plants became more heavily infected than the larger plants.