bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies upon the copper fungicides: XII. Absorption of complexes by leaves
Authors: ARMAN P. , WAIN R. L. 
Published: February 2008

SUMMARYMeasurements were made of the amount of copper absorbed by leaves from solutions containing 10 p.p.m. of copper as copper sulphate, with and without the addition of various amounts of complexing agents.A tentative explanation of the results is given. It is suggested that leaves can absorb both cupric ion and many copper complexes, this absorption being subject to interference from other substances in solution.The significance of these findings is discussed in relation to absorption of copper from spray deposits.
Studies on plant growth‐regulating substances: XVII. Chloromethylphenoxyacetic acids and chloromethylphenylglycines
Authors: CLARKE G. G. , WAIN R. L. 
Published: February 2008

SUMMARYAll ten isomeric chloromethylphenoxyacetic acids together with the corresponding ten chloromethylphenylglycines have been synthesized and their plant growth‐regulating activity has been assessed in three different tests. The biological results are discussed in relation to chemical structure.
The translaminar effect of Kelthane on three strains of glasshouse red spider mite Tetranychus urticae Koch (T. telarius L.) on cucumbers
Authors: COOKE V. A. 
Published: February 2008

SUMMARYKelthane was applied at several concentrations to the upper surfaces only of cucumber leaves. Strains of mites confined to the lower surfaces of the leaves, and therefore feeding on residues penetrating into the leaf, were assessed for mortality after 5 days. Differences were found between strains reported to be resistant and one known to be susceptible to Kelthane, although previous dipping tests had failed to differentiate between them.
Control of seed‐borne lucerne stem eelworm with phorate
Authors: GOSTICK K. G. 
Published: February 2008

SUMMARYLucerne stem eelworm (Ditylenchus dispaci) has been controlled with 0·25% phorate dust and liquid dressings in pots, and 1·0% dust dressings in outdoor plots. Little phytotoxicity was found with dosages of 4% phorate. The possible advantages of nematicidal seed dressings are discussed.
Greenhouse evaluation of chemicals for control of powdery mildews
Authors: KIRBY A. H. M. , FRICK E. L. 
Published: February 2008

SUMMARYExperiments in the greenhouse with surface‐active agents for control of apple and barley powdery mildews indicated that cationic compounds were of particular interest. On barley, significant protective disease control was given only by agents providing good wetting; on apple, even good wetting was not necessarily followed by good protection. Didecyldimethylammonium bromide (DDAB) and domiphen bromide were among the most effective agents, giving a high degree of protection at 0·05%; curative action on apple was extremely good even at 0·025%, especially by DDAB. The latter was outstanding among many fungicides for protection of strawberry foliage against powdery mildew in the greenhouse, but more prolonged protection was given by lime sulphur or dinocap in a late‐season field trial.DDAB caused no damage on foliage of any of these three host species, except on strawberry where a non‐ionic agent was also included in the formulation. But disease control was reduced when certain cationic agents, including DDAB, were used to formulate several pure fungitoxicants, e.g. captan or dodine acetate.
Induction of Verticillium wilt disease symptoms in detached shoots of resistant and of susceptible tomato plants
Authors: BLACKHURST FRANCES M. 
Published: February 2008

SUMMARYInduction of disease symptoms and water loss from detached shoots placed in cell‐free filtrates from cultures of Verticillium albo‐atrum and dilute solutions of substances of high molecular weight have been studied. There was no difference between the effect of these solutions on resistant and on susceptible plants. Freezing and heating decreased the effect of culture filtrates in reducing water loss and causing wilt. Solutions of pectic substances as dilute as 30 p.p.m. induced wilting and were 30 times as effective as solutions of certain polysaccharides in reducing water loss. Filtrates from pectate cultures had a very high polygalacturonase activity and when diluted up to 250 times induced typical disease symptoms in leaves of cut shoots in 70 hr.; this property was lost on autoclaving.No difference was found in the composition of xylem exudates from resistant and susceptible plants. Filtrates from cultures on a synthetic plant‐sap medium to which insoluble plant material from resistant and from susceptible plants had been added were found to have different effects on cut shoots; this may depend on the different polygalacturonase activities of these filtrates.Studies on water loss from shoot‐inoculated resistant and susceptible plants showed that the water loss/fresh weight was reduced to almost the same extent in resistant and susceptible shoots, despite the fact that resistant plants developed only mild symptoms of disease. Resistant plants were found to be more drought‐resistant than susceptible plants.
A physiological difference between bean leaves (Phaseolus vulgaris), resistant and susceptible to halo blight, caused by Pseudomonas phaseolicola
Authors: DEVERALL B. J. , WALKER J. C. 
Published: February 2008

SUMMARYLines of bean (Phaseolus vulgaris), which were resistant or susceptible to the halo‐blight disease incited by Pseudomonas phaseolicola, were derived from a cross between the resistant variety Red Mexican U.I. No. 3 and the susceptible variety Kinghorn Wax.Homogenates of the leaves absorbed oxygen rapidly when placed in an oxygen electrode or a Warburg flask. Preparations of healtlyj resistant leaves had a higher uptake than those of healthy susceptible leaves, grown to the same stage at the same time. This was checked on the parental varieties and with 24 F 3 progenies of the cross. Only one line, a resistant, was difficult to distinguish by oxygen uptake on some occasions.Attempts were made, using the crude homogenates, to reveal the nature of the oxidation as a guide to more precise analysis. Maximum uptake occurred between pH 3–4 and 5, homogenate derived from 0.5 g. fresh weight of leaf absorbing about 100 μl. of oxygen in the 1st hr. at 25° C. R.Q.'S were low, 0·06 to 0·3. Several inhibitors of metal oxidases had no effect, but hydroxylamine, azide and cyanide inhibited by 20, 30 and 40%, respectively, at 10‐3M. Krebs cycle acids and malonic acid had no effect, but glycolic and dihydroxymaleic acids were readily oxidized. Preparations from young resistant leaves oxidized dihydroxymaleic acid more rapidly than did those of young susceptible leaves, and the rate could be greatly influenced by different phenols.The oxygen uptake was not thought to be due to respiration, nor was there any evidence that it was associated with copper oxidases. The tentative suggestion is made that the uptake was caused by an oxidative peroxidation, comparable with indoleacetic acid oxidation.
The reaction of different cacao types to infection with swollen‐shoot virus
Authors: LONGWORTH J. F. , THRESH J. M. 
Published: February 2008

SUMMARYGraft tests were used to investigate the reaction of different cacao types to infection with swollen‐shoot virus. Budlings of all the clones in Nigeria were infected with virulent isolates so that the sequence of symptom expression could be followed.All the Amelonado and Morona clones and most of the Trinitarios were affected severely. They showed extensive, conspicuous leaf symptoms and large stem swellings. The Upper Amazon cacaos reacted less uniformly. The Scavina clones developed conspicuous symptoms, whereas those produced in the Nanay and Iquitos types were often slight and sometimes transient. Many Parinari clones and hybrids of Parinari parentage showed an extreme reaction: a veinal necrosis which often caused complete collapse of affected leaves and sometimes extended to the stem and growing point. Tests on progenies derived from crosses of sensitive with tolerant parents suggested that the sensitive reaction was dominant.These results are discussed in relation to the present plant breeding programme and to the possibility of releasing high‐yielding hybrid progenies for replanting the extensive and heavily infected areas of Nigeria, within which control measures have been stopped.
The effect of sowing date and spacing on rosette disease of groundnut in Northern Nigeria, with observations on the vector, Aphis craccivora
Authors: BOOKER R. H. 
Published: February 2008

SUMMARYIn Northern Nigeria, groundnuts planted in June outyielded those planted in July, and, in rows I yard apart, plants spaced at 9 in. gave a heavier total crop than those at 18 in. In two experiments, early sowing reduced the number of rosetted plants per acre; close spacing merely reduced the percentage of plants infected. There was a correlation between the total of aphid‐infested plants during the growing period and the number of diseased plants. Late‐sown crops support more Aphis maccivora, both apterae and alatae. The principal host of the vector during the 6 months dry season is Euphorbia hirta, whereas in East Africa groundnut is the principal host throughout the year. A list of predators is given, with observations on relative numbers of syrphid larvae and aphids.
A method for the detection of dahlia mosaic virus in Dahlia
Authors: ROBB SHEILA M. 
Published: February 2008

SUMMARYInclusion bodies in the cells of the leaf epidermis of dahlia plants infected with dahlia mosaic virus are spherical and highly refractive. They stain with trypan blue or phloxine, and this staining provides a quick and simple test for the detection of dahlia mosaic virus in dahlia plants, which is particularly useful for varieties that do not show external symptoms.
An attempt to increase total yield per acre by growing kale and swedes together
Authors: HAMMERTON JOHN L. 
Published: February 2008

SUMMARYKale and swedes were grown together either in alternate drill rows, or as alternate singled plants within the row. In 2 years' experiments neither of these spatial arrangements gave an increase in total dry‐matter yield over that of either kale or swedes in pure stand. The yield of both kale and swedes when grown together was generally adversely affected by the presence of the other species. It is tentatively concluded that there was competition for light, for nitrogen and possibly for water.
Field trials on the effect of a Nigerian swollen‐shoot virus on the growth of different cacao types
Authors: LONGWORTH J. F. , THRESH J. M. 
Published: February 2008

SUMMARYTwo brief field trials in Western Nigeria compared the effects of infection by a virulent strain of swollen‐shoot virus on growth of West African Amelonado cacao with those on other types. These included hybrid progenies from crosses with Upper Amazon cacao. Within each progeny, severity of leaf symptoms was correlated with growth rate, but the Amelonado showed more severe symptoms than the Amazon progenies, although infection decreased its growth rate proportionally less. However, most of the Amazon progenies are so much more vigorous that some infected ones grew more rapidly than the uninfected Amelonado. Three progenies were exceptionally tolerant and their growth rate was little affected by infection: such types may prove valuable in areas where attempts to eradicate swollen‐shoot disease have been abandoned.
The epidemiology of tomato mosaic
Authors: BROADBENT L. , FLETCHER J. T. 
Published: February 2008

SUMMARYTomato plants were easily infected with tomato mosaic virus (TMV) by contact with infective clothing. TMV persisted for over 3 years on clothing stored in a dark enclosed space, but was inactivated within a few weeks in daylight. Dry‐cleaning, or washing clothing with detergents in hot water, decreased its content of TMV to a low level. A survey of clothes worn by workers on tomato‐growing nurseries showed that men's outer clothing is seldom cleaned and is often worn from one season to the next.Tests of TMV persistence on painted, heated, wooden glasshouses and on cool structures, and on glass and metalwork in them, were done by wiping tomato leaf sap or brushing tomato leaves over them, and then trying to recover TMV by wiping the structures with damp cotton swabs. Virus was rapidly inactivated in daylight, often being undetectable after a month, but sometimes persisting at low concentrations for over 2 months. A survey of commercial glasshouse structures showed that TMV seldom overwintered on them but sometimes TMV persisted in dry tomato leaf debris. Such debris should be removed from structures by washing.
The reaction of monogenic resistant and susceptible varieties of tomato to inoculation with Fusarium oxysporum f. Zycopersici into stems or through Bonny Best rootstocks
Authors: KEYWORTH W. G. 
Published: February 2008

SUMMARYThe aerial parts of tomato varieties showing low and high (monogenic) resistance to Fusarium wilt were inoculated, either directly into stems or through the roots of low resistance Bonny Best rootstocks on to which they had been grafted. Symptom development was recorded and the distribution of the fungus within the plants was determined by isolation.From stem inoculations the fungus invaded Bonny Best stems and leaves (although much less readily than from root inoculations) and caused mild symptoms. Little or no invasion of Jefferson (high resistance) stems occurred and there were no symptoms. It was concluded that the stems of the two varieties differed in resistance to invasion.When invaded from infected Bonny Best rootstocks, scions of five varieties of low resistance showed normal wilt development with considerable leaf flaccidity. Vascular browning in the leaves was often associated with the presence of the fungus. Scions of six monogenic high‐resistance varieties invaded from Bonny Best rootstocks showed symptoms more quickly and of a different type (severe yellowing and necrosis with less leaf flaccidity). Vascular browning was extensive in the leaves but was produced far in advance of fungal invasion, which was normally restricted to the lower part of the stem. It appeared that the scions were highly sensitive to toxins produced in the lower part of the plant. These differences were apparent when scions of the two types were invaded from a common rootstock.The results confirm the observations of other workers that the stems as well as the roots of monogenic resistant varieties of tomato show greater resistance to invasion by Fusarium than corresponding organs of tomato varieties of low resistance. They also provide an explanation for the apparently conflicting results of previous grafting experiments.
Toxicological studies on a beetle, Alphitobius Zaevigatus (F.)
Authors: HEWLETT P. S. 
Published: February 2008

SUMMARYA series of joint action experiments was done using 4,6‐dinitro‐2‐n‐butylphenol and 4,6‐dinitro‐2‐sec‐butylphenol in solution in Risella 17 oil. The following were tested: (1) the joint action of doses of the n‐butyl compound on two sites of application on the beetle, the mesoscutellum and the hind coxae; (2) the joint action of doses of the sec‐butyl compound on the two sites; (3) the joint action of the two compounds applied to the mesoscutellum; and (4) the joint action of the two compounds applied to the hind coxae.The data obtained were interpretable on the assumption that the joint action of the doses (whether of one compound on the two sites, or of the two on one site) was simply similar, with complete positive correlation of tolerances, and that the amount of toxicant reaching the site of action was proportional to the dose (volume of solution) raised to the power of η, where η < 1. This meant that the joint applications were more toxic than was predicted by an equation for similar joint action given by Finney (1952), which in effect makes the assumption that η= 1. In the portion of the present work in which the results can be so expressed, the joint applications ranged from 1·11 to 1·51 times as toxic as the predictions by Finney's equation. The estimates of 7 ranged from 0·62 to 0·87, with a mean of 0·755 ± 0·037. The finding that the joint toxicities were higher than predicted by Finney's equation agrees with predictions made by Plackett & Hewlett (1952) and by Hewlett & Plackett (1959, 1961). Experiments with the see‐butyl compound indicated that values of η < 1 were not interpretable on the hypothesis that the coefficient of regression of probits on log‐concentration was greater than that on log‐volume, for estimates of the two coefficients were not significantly different.
Studies on the fungitoxicity of captan
Authors: RICHMOND D. V. , SOMERS E. 
Published: February 2008

SUMMARYDeterminations have been made by amperometric titration with silver nitrate of the total sulphydryl (SH) content of intact spores of Alternuria tenuis, Aspergillus niger, Botrytis allii, B. fabae, Coleosporium senecionis, Neurospora crassa, Penicillium expansum, P. italicum, Podosphaera leucotricha, and Rhizopus nigricans, and of yeast cells. When titrated in alcohol‐ammonia buffer the cells were generally first denatured by heating with sodium dodecylsulphate; for confirmatory titrations in tris buffer on A. niger and N. crassa this pre‐treatment was essential. The fungistatic activity of captan to eight of these species and the captan uptake, on an equivalent fresh weight basis, by all the fungi has also been determined: conidia of Venturia inaequalis were included in these tests. The spore dimensions, fresh and dry weights of all the fungal species are given.There was no evidence of a relationship between captan uptake and toxicity, captan uptake and spore surface area, or captan toxicity and SH content. However, captan uptake has been found to be broadly related to cell SH content; increasing SH content giving increased captan uptake. This is in agreement with our previous hypothesis that most of the captan uptake required to completely inhibit spore germination is decomposed by cell thiols before it reaches vital receptor sites. When toxic doses of captan were taken up by N. crassa spores the SH content was reduced by 35% and the molar proportions for the captan: thiol reaction were approximately 1:1.
Toxicological studies on a beetle, Alphitobius laevigatus (F.)
Authors: HEWLETT P. S. 
Published: February 2008

SUMMARYThe joint actions of pairs of like and unlike toxicants have been investigated. Four pairs of like toxicants were selected, 4,6‐dinitro‐2‐sec‐butylphenol and 4,6‐dinitro‐2‐n‐butylphenol, 2‐n‐valeryl‐I,3‐indandione (n‐valone) and 2‐n‐butyryl‐I,3‐indan‐dione, DDT and 2,2′‐bis(p‐fluoropheny1)‐I,I,I‐trichloroethane, and dieldrin and endrin. Six pairs of unlike toxicants were formed by taking the first‐mentioned of each like pair and using them in all possible combinations of two. Beetles were dosed topically with the toxicants dissolved in non‐volatile oil, and each pair of toxicants was used in a series of experiments, with the proportions of the toxicants varied in respective tests.Broadly speaking the results were clear, though quantitatively they were less regular than had been hoped. The toxicants of the mixtures relative to their components were measured primarily by a quantity J derived in theoretical investigations (Hewlett & Plackett, 1959). Values of η estimated in preceding work were used with the relation J=λ/η to calculate estimates of a parameter λ, measuring the similarity of the actions (λ= o for complete dissimilarity, λ∼ I for complete similarity). For the pairs of like toxicants it was found that λ∼ I. For combinations of sec‐butyl‐dinitrophenol or n‐valone with DDT or dieldrin, λ ranged from 0·18 to 0·30. For DDT with dieldrin λ∼ 0·81. For sec‐butyl‐dinitrophenol with n‐valone λ∼ 1·00.Generally λ was greater the greater the chemical resemblance between the members of the pairs of toxicants. The high value of λ for sec‐butyl‐dinitrophenol with n‐valone is explained by the probability that the latter exists as an enol, implying a considerable resemblance to the former. However, the dinitrophenol stimulates the oxygen consumption of the beetle whereas n‐valone does not (Gostick, 1961), suggesting that the stimulation of oxygen consumption by the former is irrelevant to its lethal action.
The relationships between cacao viruses and their vectors: the feeding behaviowr of three mealybug (Hornoptera: Pseudococcidae) species
Authors: ENTWISTLE P. F. , LONGWORTH J. F. 
Published: February 2008

SUMMARYIn transverse sections of cacao stems, 164 of 345 stylets of Planococcoides (=Pseudo‐coccus) njalensis were seen to end in the phloem. Passage through the cortex was intra‐cellular and the stylets entered the phloem by avoiding the peripheral blocks of sclerenchyma. Stylets of Ferrisiana virgata, which transmits cacao viruses less readily than P. njalensis, were also seen in the phloem, but less often. Phenococcus madeiriensis, which is not a vector of cacao viruses, fed differently; of the few stylets seen in sections of stems none ended in the phloem, and, though its stylets are long enough to reach this tissue, they did not extrude for the full length when the mealybugs were fed on agar.
Some factors affecting the relative incidence, distribution and importance of beet yellows virus and sugar‐beet mild yellowing virus in eastern England, 1955‐62
Authors: RUSSELL G. E. 
Published: February 2008

SUMMARYSugar‐beet mild yellowing virus (SBMYV) was much more common than beet yellows virus (SBYV) in beet in south‐eastern England during 1961 and 1962. SBYV strains and strain‐mixtures, typical of those in East Anglia between 1958 and 1961, decreased sugar yield of a commercial sugar‐beet variety inoculated in the field slightly more than did SBMYV isolates. Simultaneous inoculation with SBYV and SBMYV decreased yield more than did either virus alone. SBMYV probably caused about three times as much sugar loss as SBYV in England during 1961 and about ten times as much during 1962. Aphis fabae Scop. did not transmit SBMYV from sugar beet to sugar beet or to Claytonia perfoliata and this aphid seems not to spread SBMYV in the field. The surveys of 1955‐62 showed that SBW is common in most years only in parts of Essex and Suffolk; it is suggested that the main overwintering sources of SBYV were confined to those areas, where Beta maritima is probably an important source of SBW. The sources of SBMYV were probably very much more widespread and numerous. The facts that SBMYV persists longer than SBYV in Myxus persicae Sulz. and is not lost during moulting apparently also favour the wider distribution of this virus.
The hatch of beet eelworm (Heterodera schachtii Schm.) larvae in rivanol, and its use for the estimation of field populations
Authors: MORIARTY F. 
Published: February 2008

SUMMARYThe hatch of beet eelworm (Heterodera schachtii Schm.) larvae from cysts in 0–1% aqueous solutions of rivanol (3,9‐diamino‐7‐ethoxyacridine lactate) was greatest and fastest in 1 % rivanol, which also inhibited the growth of micro‐organisms. The hatching effect of rivanol was specific to beet eelworm out of five Heterodera species tested. Larval hatch from cysts on nylon sieves at the surface of 1% rivanol was not lessened by a thin layer of debris, nor was hatch affected by soil storage and drying times except with new cysts.Measuring the density of beet eelworm infestations in fields by larval hatch in rivanol would avoid errors from inclusion of related species, observer bias, and difficulties of determining viability. The number of cysts used could easily be increased to help reduce sampling errors.