bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies upon the copper fungicides
Authors: Wain R. L. , Wilkinson E. H. 
Published: February 2008

The soluble copper in freshly prepared 4:4:50 Bordeaux mixture was of the order of 7 p.p.m. but on standing in absence of air this fell to 0.7 p.p.m. after 10 days. The dried deposit on glass plates yielded about 0.5 p.p.m. of copper to water. With increasing alkalinity, the soluble copper in freshly prepared Burgundy mixtures decreased to a minimum of about 3 p.p.m. and then rose again. This effect was not observed using dried deposits which yielded consistently less copper to water. The amounts of copper dissolved by water from dried 4:4:50 Bordeaux deposit on runner bean leaves were slightly greater than from the same deposit on glass plates. The results cannot be taken as positive evidence that leaf excretions are involved in the liberation of soluble copper since detached leaves were used and the influence of bacteria could not be eliminated.Suspensions of Neurospora sitophila spores and the nitrates therefrom dissolved copper from dried 4:4:50 Bordeaux deposit in excess of the amount dissolved by water, though these quantities, as well as the amounts of soluble solids in spore filtrates, were appreciably less than were found by other workers in a similar investigation. Steam sterilization of spore filtrates had little effect on their capacity to dissolve copper from dried 4:4:50 Bordeaux. The temperature at which spores were suspended in water was a factor, though the substances capable of dissolving copper were rapidly yielded to water. The nutrient agar on which the fungus was grown influenced the amount of soluble solids in the spore filtrate and the capacity of these nitrates to dissolve copper from dried Bordeaux deposit.Study of the solvent properties of solutions of pure chemical substances of many types showed that copper could only dissolve from dried 4:4:50 Bordeaux deposit by a mechanism involving complex formation. Active substances included amino‐, hydroxy‐, and certain dicarboxylic acids and their salts, all possible constituents of spore exudate. The results obtained with carbohydrates indicated that such substances are not involved in the liberation of soluble copper from this fungicide.A hypothesis on the mechanism of the fungicidal action of copper, based on the results obtained, is presented. This assumes that copper dissolves from the deposit under the influence of excretions from the fungus spore and that the cupri‐complexes produced are the means by which soluble copper is transported to the spore wall. Dissociation of these complexes then make it possible for the active toxicant to be removed by the spore, thus enabling any reversible reactions involved to continue.
Serological studies on sugar‐beet yellows virus
Authors: Kleczkowski A. , Watson M. A. 
Published: February 2008

Specific antisera have been prepared against the sap expressed from beet plants infected with beet yellows virus.The antigen is unstable. In the sap it is destroyed by keeping for 2‐3 days at room temperature or by heating for 10 min. at 52d̀C. It is unaffected by pH changes between 5 and 9. In detached leaves at room temperature it remains unchanged for at least 6 days, whereas the ability of aphides to transmit from these leaves fell considerably in 4 days.The antigen can be reversibly precipitated by ammonium sulphate or sedimented by high‐speed centrifugation. However, all the attempts to isolate it from other sap constituents or concentrate it have failed.The precipitin reaction is of value for diagnosis, and works successfully with crude sap.
Soil conditions and the take‐all disease of wheat: VIII. Further experiments on the survival of Ophiobolus graminis in infected wheat stubble
Authors: Garrett S. D. 
Published: February 2008

Assimilable nitrogen in various forms prolonged the life of Ophiobolus graminis in infected wheat straw, whether added directly to the straw or to the surrounding soil. When the infected straws were buried in washed quartz sand, 0.5 g. nitrogen per 100 g. air‐dry straw was the optimum dressing for longevity of Ophiobolus. Addition of sodium phosphate did not significantly increase longevity.Nitrogen is considered to prolong the life of Ophiobolus by enabling the mycelium to form new branch hyphae, which can explore unexhausted parts of the substrate; it is suggested that aged mycelium dies from carbohydrate starvation, through exhaustion of the zones of enzymic erosion around the hyphae. This hypothesis is supported by the extended life of the fungus in infected straws that were shaken twice weekly in 3 % dextrose solution. Ophiobolus was found to survive longer in infected straws buried in a fallow soil than in the same soil under oats, mustard or trefoil; this finding suggests the use of catch crops as competitors with Ophiobolus for soil nitrogen.
Observations on the biology and physiology of wireworms of the genus Agriotes Esch
Authors: Evans A. C. 
Published: February 2008

Detailed studies of the growth of wireworms kept at a constant temperature of 15d̀ C. for 3 years and at natural soil temperatures for 2 years are presented. It is shown that small wireworms grow rapidly and moult frequently, but large wireworms grow slowly or remain constant in weight and moult infrequently. A basic pattern to account for the decreasing frequency of moulting during the life cycle is presented.The feeding activity and moulting frequency of a population of wireworms has been studied in detail throughout the season. Definite peaks in feeding activity and moulting frequency occur during the season. A suitable method for the analysis of such activity in a population has been found by dividing the population into groups on a basis of the number of annual moults.It is shown that increase in dry weight is a more valid estimate of growth than increase in fresh weight. The rate of growth of wireworms is strongly influenced by the food on which they feed: some plants (wheat and carrots) permit rapid growth; other plants (grass and clover) permit slower growth; while certain other plants (mustard and potatoes) allow the wireworm to maintain its weight. Wireworms reared on flax actually decrease in dry weight.In a field experiment it was found that the type of crop grown after breaking up old pasture had a distinct effect on the wireworm damage done to the following cereal crop. Beans had the effect of reducing the population to a level at which a very successful crop was grown. Better yields were obtained after wheat and grass than after the other crops, excepting beans, at similar levels of population.The cuticle of wireworms is permeable to water, and it is shown that in its relations to soil moisture the wireworm may be regarded as an osmotic system. The pF scale of soil moisture is shown to be of value in expressing the soil‐moisture relations of wireworms. Wireworms feed more actively in moist soil than in dry or wet soil.
The prevention of seed‐borne diseases of flax by seed disinfection II. Comparison of the dusting, short wet and fixation methods of treatment
Authors: Muskett A. E. , Colhoun J. 
Published: February 2008

Suitable organo‐mercury preparations applied by the short wet method of seed treatment and organo‐mercury powders, of the type used for treating cereal seeds, fixed to the seed with water by the fixation method of treatment, gave as satisfactory control of seedling blight and better control of stem break and browning than a proprietary dry fungicide containing tetra‐methyl thiuram disulphide (Nomersan) applied at the rate of 12 oz./cwt. of seed.Treatment of seed heavily infected with Polyspora Lint using an efficient fungicide resulted in highly significant increases in crop and fibre yields, while in the case of seed heavily infected with Colletotrichum Lini similar treatments significantly increased the yield of fibre but not the crop yield. Some treatments significantly increased the crop and fibre yields even when the seed used was only slightly contaminated with P. Lini and C. Lini. The results presented support the suggestion that effective treatment of the seed may produce an increase of fibre not directly attributable to the prevention of seedling blight or stem break and browning but which may be explained by a general beneficial effect due to seed disinfection.The results obtained suggest that no treatment consistently affected crop establishment in the field.
A two years' survey of the potato aphides in the Northern Agricultural Advisory Province
Authors: Jacob F. H. 
Published: February 2008

The role of aphis vectors in the deterioration of potato stocks is well known, and any effort to maintain healthy (virus‐free) stocks of potatoes depends on the degree of their isolation from these vectors. In practice this isolation depends on geographical, climatic, and biological factors; of these the biological factors are fundamental, as it is only from their study that the significant geographical and climatic factors can be determined.The present work consists of a survey made during 1942 and 1943, in the Northern Agricultural Advisory Province. Special attention is paid to overwintering, and the prevailing weather conditions at the time of the spring migration.
Beet eelworm (Heterodera schachtii Schm.) in East Anglia, 1934‐1943
Authors: Petherbridge F. R. , Jones F. G. W. 
Published: February 2008

Observations made on the beet eelworm (Heterodera schachtii Schm.) between 1934 and 1943 are described. This eelworm confines its attacks to crop plants of the families Chenopodiaceae and Cruciferae. Cysts similar to those of the beet eelworm have been recorded on many weeds. Records of beet eelworm on weeds of the above families are probably authentic, but those of other families require confirmation. In the field, the four so‐called strains of Heterodera schachtii (viz. the beet, oat, pea and potato strains) behave as distinct species. Some evidence is given for the possible existence of a cruciferous strain.Attempts were made to ascertain the distribution of beet eelworm in East Anglia. A general search was conducted throughout the area and special attention paid to beet‐sugar factories, beet‐loading sites, sewage farms, and to certain important beet‐growing areas located in the Isle of Ely and neighbouring counties. Throughout the search, diagnosis was based on the finding of lemon‐shaped cysts on the roots of sugar beet, red beet or mangolds. Details of our present knowledge of the distribution of beet eelworm are given. It appears to have been present in Britain for a considerable time but is not yet widely disseminated.The spread of beet eelworm is considered in detail, and it is concluded that the establishment of the beet‐sugar industry has led to a considerable increase in the rate of spread.Measures for the control of beet eelworm are described. In the early days of the industry, beet was grown without regard to rotation, thus providing conditions similar to those existing in Germany before 1870 when 'beet‐sickness was becoming a serious problem. The first control measure was the introduction of a clause into contracts forbidding the growing of beet after beet or mangolds. More effective measures, which were adopted in 1939, are described. In 1943, the Sugar‐Beet Eelworm Order was issued enforcing these measures over a wide area and extending them to cover all susceptible crops.Effective control measures may result in a reduced rate of spread of the beet eelworm but cannot eliminate it.
Gliotoxin, a fungistatic metabolic product of Trichoderma viride
Authors: Brian P. W. , Hemming H. G. 
Published: February 2008

Gliotoxin is shown to be a metabolic product of Trichoderma viride, and a semi‐continuous apparatus for its production is described. Ammonia nitrogen is preferable to nitrate nitrogen, but a wide range of carbon sources, and organic or inorganic sulphur sources, are suitable for gliotoxin production. No organic supplements to a glucose‐mineral medium have been found to affect gliotoxin production beneficially.Data are presented showing gliotoxin to be moderately toxic to a wide range of bacteria, actinomycetes and fungi. T. viride itself is resistant to its toxic effects. It shows fungicidal activity when applied as a dust to cereal seeds bearing various seed‐borne diseases, but is inferior to organomercury compounds for this purpose. Its value as a fungicide for control of plant or animal infections is reduced by the instability of aqueous solutions, except at low pH.
The use of abrasives in the transmission of plant viruses
Authors: Kalmus H. 
Published: February 2008

The effect of different abrasives on the transmissibility of several plant viruses was tested. Celite and animal charcoal were as effective as carborundum in increasing the number of lesions produced by a given inoculum: 400‐mesh carborundum was the most effective among the different sizes which were tested; this gave a result equivalent to increasing the virus content a hundred times. Some preparations of carborundum and charcoal reduced infectivity.Uninjured plants resisted infectivity when virus solutions were sprayed over them. Leaves previously nibbed without abrasives developed only few lesions whereas leaves rubbed with abrasives developed large numbers. Three hours after rubbing with abrasives leaves had regained their resistance to sprayed virus solutions.The effects of rubbing leaves with abrasives are described and their significance discussed.
Studies upon the copper fungicides: VII. The solution of copper from dressings on the pea seed
Authors: Wain Br R. L. , Wilkinson E. H. 
Published: February 2008

During the process of swelling pea seeds yielded substances to water which were capable of dissolving the insoluble copper dressings normally applied to the seed to prevent ‘pre‐emergence damping off’. This occurred under conditions in which soil factors were eliminated and irrespective of whether the dressing was on the surface of the seed or treated separately. Copper was readily taken into solution from dried 4:4:50 Bordeaux Mixture by water in which peas had been soaked, a circumstance which proved that the formation of soluble complex forms of copper was involved.A chemical investigation on the solution obtained by soaking peas in water showed that volatile acids or their salts were present together with a protein‐like material in colloidal solution. The occurrence of amino derivatives and other nitrogenous materials as well as carbohydrates was indicated and evidence of the presence of asparagine and citrate was also obtained.The suggestion is made that both the fungicidal and phytocidal actions of insoluble copper dressings on pea seed depend largely on the effect of the pea seed exudates, notably colloidal protein‐like material and certain amino derivatives, in bringing copper into solution.
Studies upon the copper fungicides: VIII. The penetration of copper into germinating peas
Authors: Wain R. L. , Wilkinson E. H. 
Published: February 2008

Three varieties of pea seed showed less damage when treated with solutions of simple cupric salts than with solutions of equivalent strength in which the copper could occur in complex form. On adding supplementary pea exudate to copper sulphate solution, thereby converting some cupric to complex copper, greater damage was caused. In spite of the greater phytotoxicity of complex forms of copper, the copper intake by the seeds was less. Sealing of the micropyle had little effect on the water and copper intake of peas.Colorimetric tissue tests on treated peas indicated a high concentration of copper in the testa and the embryonic radical with only small amounts in the cotyledonary tissues. These observations were largely confirmed by chemical analyses‐on the test as, cotyledons and embryos of copper treated peas.The results suggest that when copper dissolves from dressings on pea seeds much becomes fixed on the testa, so providing fungicidal protection. The soluble complex forms of copper produced by pea exudate are markedly phytotoxic and injury to the embryonic radical is regarded as the main cause of damage to peas.
The mode of action of sheep dips
Authors: Ph.D. E. T. Burtt, M.A., 
Published: February 2008

A study was made of the action on the tick (Ixodes ricinus L.) of some toxic substances used in dips. Methods are described of attaching ticks to limited areas on the sheep and of suspending ticks for individual tests.Chemical potentials rather than concentrations should be used in comparing the toxicity of different solutions. Phenol is less soluble in P31 paraffin oil than in water, and a solution of phenol in P31 paralyses the tick more rapidly than the same concentration in water. Solutions of phenol in paraffin and water which are in equilibrium show the same effect on the tick. The potentials are the same, but the concentrations are different.Each toxic substance tested acts more rapidly at a given concentration in a medium in which it is less soluble. Acid solutions of arsenious acid act more rapidly than alkaline. Solid arsenious oxide as crystals or as a deposit on wool acts more slowly than sodium arsenite under the same conditions, owing probably to its slow rate of solution. Sodium arsenite and arsenious oxide readily penetrate the tips of the feet, and sodium arsenite readily penetrates the dorsal surface of the tick.Previous work on arsenical dips and the contact toxicity of wool dipped in sodium arsenite indicate that arsenic is a contact and not a stomach poison to ticks.Phenols are toxic at low concentrations in water, but their greater solubility in wool fat and rapid evaporation from thin films explain their ineffectiveness as dips.DDT (2, 2 bis‐p‐chlor phenyl 1, 1, 1, trichlorethane) penetrates the feet of the tick more readily than the rest of the body surface. DDT acts more rapidly at 1% in paraffin oil (solubility 1‐3%) than in sesame oil (solubility 10%). Saturated solutions have the same effect. Similarly, vaseline solutions are more effective than solutions in lanoline.Rotenone penetrates the feet of ticks more rapidly than the back. Larval ticks are more rapidly intoxicated by 01% solutions in olive oil (solubility 0.2 %) than 0.1% solutions in castor oil (solubility 1‐2%). Saturated solutions have the same effect.The importance of a knowledge of the site of entry of insecticides into the organism is stressed.The less soluble the substance in the medium, the less is needed to give a high chemical potential and the more rapid will be the penetration of the organism. With low solubility, however, a small loss by diffusion causes a large fall in potential. Solubility is analogous to capacity. In practice, media will be needed in which the toxic substance is neither so soluble that a wasteful amount is needed to produce a high potential nor so insoluble that losses by diffusion cause large falls in potential.The carrier activity of different oil bases for insecticides and the synergistic action of insecticides applied together may in part be due to changes in solubility and hence chemical potential.
The influence of periodic fallowing on the prevalence of viable weed seeds in arable soil
Authors: Brenchley Winifred E. , Warington Katherine 
Published: February 2008

In view of the favourable reduction in the weed‐seed population on Broadbalk wheat field (Rothamsted Experimental Station) by the 2‐year fallows between 1925 and 1929 a cyclic fallowing of one section out of five per year was adopted to maintain control over the weeds. Annual samples for determining the weed seeds were taken from plots receiving farmyard manure, minerals and sulphate of ammonia together, and minerals and sulphate of ammonia in alternate years.The numbers of seedlings obtained were grouped to show the reduction in weed‐seed population during fallow and the behaviour of various species in succeeding years. By this grouping the effect of the variable seasonal and cultivation factors is greatly reduced, as several years are included in each figure.Most species are reduced by fallow, rise more or less rapidly during succeeding years, and are again reduced by a later fallow, usually to a lower level than by the first. Alopecurus agrestis showed the greatest variation from year to year. Papaver rhoeas was the outstanding exception to the general rule, as, once reduced by fallow, it failed to reassert itself except in a few cases, and was further reduced by the later fallow. These two species, with Alchemilla arvensis, Veronica arvensis and Medicago lupulina, contributed about 90% of the total seeds.Alternate manuring with minerals and sulphate of ammonia greatly influenced the production of weed seeds. With most species nitrogen induced heavier seed production, as was shown by the average number per section compared with those produced with minerals. Alopecurus agrestis, Alchemilla arvensis, and usually Papaver rhoeas responded thus, Veronica arvensis was the only one of the main species to behave irregularly, whereas Medicago lupulina showed a reverse response, being more benefited by minerals than nitrogen.In the first year after fallowing the crop and weeds alike were usually able to benefit by the stored fertility and did not appear to interfere with one another except where farmyard manure was used, when the competition of the crop at first prevented the weed‐seed population from rising. In the later years the crop tended to decrease, and the weeds to increase, until the balance was restored by another fallow.Field observations, as well as laboratory samples, have shown a steady improvement in the cleanness of Broadbalk field, the most noticeable reduction being in poppies. The various weed species fall into definite groups, in two of which the reduction or increase in numbers induced by fallowing is maintained, while in the third there is an irregular increase and decrease in numbers over a period of years.The general conclusion is that the fallowing of one section per year has fully justified itself, as the total weed‐seed population has not only been kept in check, but has also been gradually decreased during the 15 years the system has been applied.
A comparison of Fusarium avenaceum and Fusarium caeruleum as causes of wastage in stored potato tubers
Authors: Moore F. Joan 
Published: February 2008

Fusarium avenaceum is reported for the first time as a cause of rotting of potato tubers in Britain. The progress of rotting in tubers infected with F. avenaceum has been compared with dry rot due to F. caeruleum in the laboratory, clamp and potato store. Of the four varieties, Majestic, King Edward, Doon Star and Arran Pilot, tested for susceptibility, King Edward was the most susceptible to F. avenaceum and Doon Star to F. caeruleum.Optimum temperatures for growth on potato‐dextrose agar were 20‐25d̀ C. for F. avenaceum and 20d̀ C. for F. caeruleum; maximum temperatures were > 30 and 30d̀ C. respectively. For infection of wounded potato tubers, cardinal temperatures for F. avenaceum were similar to those on agar, but for F. caeruleum the optimum was 15d̀ C. and the maximum 25d̀ C. The optimum temperature for rotting tended, with both species, to be higher in the more susceptible potato varieties. At low temperatures F. caeruleum caused quicker rotting than did F. avenaceum, even though its rate of growth on agar was scarcely more than half that of the latter.High humidity favoured rotting especially by F. avenaceum; F. caeruleum was more tolerant of relatively low humidity. Both species caused quicker rotting in the clamp than in store, even though there was no appreciable difference in mean temperature between the clamp and the store. This was attributed to the higher atmospheric humidity in the clamp.