bluuebunny/crossref_metadata_2025 huggingface dataset:
The behaviour of populations of potato‐root eelworm (Heterodera rostochiensis Woll.) towards some resistant tuberous and other Solanum species
Authors: JONES F. G. W. , PAWELSKA KRYSTYNA
Published: February 2008

Forty‐seven British populations of potato‐root eelworm (Heterodera rostochiensis) were tested for ability to form cysts on plants with resistance derived from Solanum tuberosum ssp. andigena, S. multidissectum, S. vernei, S. sanctae‐rosae, S. famatinae and S. × juzepczukii, and on S. nigrum, S. sarachoides and Nicotiana spp.

The potato variety Arran Banner was used as the standard susceptible host and the number of cysts formed on the resistant plants in pot tests was expressed as a percentage of those formed on Arran Banner or assessed visually from the cysts observed on the outside root mat. Cyst production on andigena hybrids ranged from less than 1% of those on Arran Banner to slightly over 100%. About half of the populations produced 10% or less, and populations of this type, against which andigena resistance would be effective, were especially common in south‐east England and Northern Ireland. Cyst production on famatinae hybrids, a race of S. nigrum from East Germany, S. miniatum and S. sarachoides, resembled that on andigena hybrids. Cyst production on multidissectum hybrids varied less and only a few populations produced less than 10% and none less than 3% of the number on Arran Banner. S. vernei was highly resistant to all but about 5% of populations and a race of S. nigrum from Rothamsted was resistant to all tested.

In selection experiments the proportion of females able to complete development increased when andigena hybrids, S. vernei or S. nigrum, were grown repeatedly in the same inoculum. Increase on S. vernei was slow, the pattern of increase on andigena hybrids suggested recessive inheritance but this could not be confirmed and increase on S. nigrum was more rapid, suggesting that the genetic mechanisms concerned in plant resistance and those concerned in the production of resistance‐breaking nematode biotypes differ for the three types of plant.

The tests revealed much variability between populations of potato‐root eelworm from different localities despite the fact that they have undergone much selection on one type of host plant, cultivated Solanum tuberosum ssp. tuberosum. No cysts were seen on Nicotiana spp. Nevertheless, H. tabacum may prove to be little more than a recognizable biotype of H. rostochiensis.
The effect of restricted air supply on some insects which infest grain
Authors: OXLEY T. A. , WICKENDEN GLORIA
Published: February 2008

If insect pests of grain develop in a strictly airtight container all are killed by exhaustion of oxygen when the concentration of this gas falls to approximately 2%. If the walls of the container permit limited access of oxygen from the atmosphere by diffusion, at a rate dependent on the difference between the internal and external concentrations, the insect population may also be killed, but this will depend on the amount of diffusion and on the level of the original population. A method for investigating this in the laboratory using polythene diaphragms to admit oxygen is described. A population of six adult Sitophilus granarius per pound of wheat in a container admitting 7·5 mg. of oxygen per litre per day at zero internal concentration will not be killed immediately but will be reduced to a very low level and may eventually die out after many months. In the same container a smaller number of insects may survive sufficiently long to increase in numbers to a level at which they also are killed. At a critical population level (about twelve adults per pound) there may occur sharp fluctuations in oxygen concentration, and presumably of insect activity, which may or may not lead to death. A population initially much greater than twelve adults per pound will certainly be killed although this may take a little longer than in an airtight container.

If the container is substantially full of wheat having a moisture content near 14% the apparent respiratory quotient of the insects is about 0·69 but if the proportion of the air space occupied by wheat is reduced, the apparent respiratory quotient is increased until it is approximately unity when the volume of wheat is about 5% of the volume of the container. It is concluded that carbon dioxide is adsorbed by wheat in proportion to the concentration of the gas.
A diffusion technique for assessing antifouling activity
Authors: CHRISTIE A. O. , CRISP D. J.
Published: February 2008

A diffusion method for measuring the antifouling effectiveness of chemicals is described. The chemicals under test are allowed to diffuse through a porous container which is suspended in the sea under natural fouling conditions. These tests showed both tri‐n‐butyltin oxide and atrazine to have considerable antifouling activity. The test method is discussed in relation to conventional laboratory tests against single organisms.
Assessments of the infection of guineacorn (Sorghum vulgare) by covered smut (Sphacelotheca sorghi (Link) Clint.) in Northern Nigeria in 1957 and 1958
Authors: HARRIS K. M.
Published: February 2008

A survey of the guineacorn (Sorghum vulgare) crop in Northern Nigeria in 1957 and 1958 indicated that, in both years, about 1% of all guineacorn spikelets were infected by covered smut (Sphacelotheca sorghi). This level of infection represents the annual loss of about £500,000 worth of grain or the unrewarded cultivation of at least 70,000 acres. There is evidence that the levels of infection are highest in those areas where temperatures at sowing time are relatively low.
Some graminicolous fungi associated with spotting of banana leaves in Jamaica
Authors: MEREDITH D. S.
Published: February 2008

A dense spotting of leaves of young Lacatan banana plants is reported; the diameter of individual lesions rarely exceeds 2 mm. The disease is common near grassland or sugar‐cane but rare in grass‐free areas removed from sugar‐cane. Although widespread throughout Jamaica, it appears to be of negligible economic importance. Direct microscopic examination of lesions, spore‐trapping, isolation work and pathogenicity tests show that Cochliobolus sp. (?C. heterostrophus), Curvularia lunata and C. geniculata, and several species of Helminthosporium are associated with the disease and that spores of these fungi are regular components of the air‐spora in the vicinity of spotted banana leaves. The evidence suggests that grasses and sugar‐cane are major sources of inoculum. Other spots are caused by Detghtoniella torulosa which sporulates abundantly on decaying banana leaves.
The control of Gloeosporium album rot of stored apples by orchard sprays which reduce sporulation of wood infections
Authors: BURCHILL R. T. , EDNEY K. L.
Published: February 2008

The number of conidia of Gloeosporium album released from infections on the wood of Cox's Orange Pippin apple trees has been measured over a period of 21 months. The application of phenyl mercuric chloride at 0·10 and 0·05% in March 1960 reduced the amount of inoculum dispersed in the period May‐July and there was less rotting of the fruit in store. A similar reduction in sporulation occurred following the application of sprays in autumn 1960 and spring 1961, but spore production was enhanced when the effect of the sprays had disappeared. After an initial application of dichlorophen (5,5‐dichloro‐2,2‐dihydroxy‐diphenyl‐methane) at 0·25% in June 1961, two subsequent sprays were applied, when the records of spores trapped indicated that the previous spray was no longer effective. This treatment also reduced losses from rotting in store.
Studies upon the copper fungicides: XII. Absorption of complexes by leaves
Authors: ARMAN P. , WAIN R. L.
Published: February 2008

Measurements 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

All 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

Kelthane 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

Lucerne 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

Experiments 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

Induction 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

Lines 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

Graft 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

In 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

Inclusion 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

Kale 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

Two 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

Tomato 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

The 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

A 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

Determinations 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

The 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

In 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

Sugar‐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

The 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.
Ecological characteristics of nematode ‐trapping Hyphomycetes
Authors: COOKE RODERIC C.
Published: February 2008

A study of thirteen species of nematode‐trapping Hyphomycetes demonstrated wide differences in their growth rate, competitive saprophytic ability, effect on free‐living nematode populations and ability to produce traps spontaneously.

The species producing adhesive reticulate traps tended to have the most rapid growth rates and the highest saprophytic ability ratings. In the soil they appeared to be pre‐daceously inefficient and did not form traps in pure culture. In contrast the ring‐formers had slow growth rates and lower saprophytic ability ratings. They tended to be predaceously efficient and two of the four species studied formed traps spontaneously. The adhesive branch or knob‐forming fungi resembled the ring‐formers in their growth rates, predaceous efficiency and spontaneous trap formation.

Thus it appears that the development of predaceous efficiency has been accompanied by a tendency to lose those characters associated with an efficient saprophytic existence in the soil; namely rapid growth rate and good competitive saprophytic ability.
Studies on the chemical control of Phytophthora palmivora (Butl.) Butl. on Theobroma cacao L. in Nigeria
Authors: HISLOP E. C.
Published: February 2008

In laboratory trials, phenyl mercury nitrate at 0·02 p.p.m. and fentin acetate at 0·2 p.p.m. severely retarded growth of four isolates of Phytophthora palmivora on cassava agar. These two chemicals, with captan, maneb and a dithiocarbamate‐copper chelate, were also highly toxic to encysted zoospores of a ‘rubber’ group isolate of P. palmivora.

Deposits of captan on pods were readily removed by artificial rain, but some improvement in tenacity was obtained by the addition of a sticker. In other laboratory trials, the deposit from low‐volume sprays of cuprous oxide dried more quickly on pods than that from high‐volume sprays but showed no advantage in subsequent resistance to weathering.

In a field trial in 1961, seven fungicide treatments were applied three‐weekly and compared with an unsprayed control. The lowest percentage black‐pod infection followed treatment with fentin acetate: Bordeaux mixture and carbide Bordeaux both gave good control. The captan treatments were completely ineffective. More black pods were harvested from close‐spaced trees than from those wide‐spaced.

Weekly applications of 0·15% fentin acetate to seedlings induced no significant damage.

In a field trial made in 1962 very heavy rainfall provided a severe test of the fungicides, the most effective being Bordeaux mixture and carbide Bordeaux mixture applied three‐weekly, carbide Bordeaux mixture applied four‐weekly and fentin acetate applied two‐weekly. Captan with added sticker was again no better than the control. There was no marked effect of spacing.

Comparisons of Bordeaux and carbide Bordeaux mixtures made at two other sites in 1962 showed no difference in disease control. It is suggested that carbide Bordeaux mixture could be replaced by the cheaper preparation made with lime.
Dressed cereal seed as a hazard to wood‐pigeons
Authors: MURTON R. K. , VIZOSO MONICA
Published: February 2008

The dynamics of a wood‐pigeon population in Cambridgeshire are described and the potential risk of dressed grain considered in relation to the feeding behaviour of the birds and the use of the dressings seasonally and annually. Wood‐pigeons use autumn sowings as a source of food only in the absence of better grain supplies on stubbles; it is unusual for more than 50% of the population to feed on them, and the conditions leading to high exploitation of autumn sowings are discussed. In contrast, spring sowings coincide with a period of poor alternative food supplies and are fed upon by over 80% of the population.

In the spring of 1961 about one‐quarter of the acreage of cereals planted in the study area had been treated with aldrin or heptachlor insecticides and most of the remainder with γ‐BHC or organo‐mercury dressings. In autumn 1961 only 3·3% of the total acreage was treated with heptachlor and no aldrin or dieldrin was used, while in spring 1962 only γ‐BHC or plain organo‐mercury dressings were used.

In 1961 there were no differences between the distribution of pigeons on fields containing grain treated with aldrin or heptachlor and that on fields planted with BHC‐treated grain; also there was no field evidence that pigeons found dressed grain unpalatable. Counts in 1962 showed no difference in the distribution of feeding wood‐pigeons in fields containing cereals treated with plain organo‐mercury dressings and in fields sown with grain treated with mercury plus γ‐BHC.

Many dead pigeons were found in the spring of 1961: population counts in one roost indicated that at least 8% of the birds had been killed. However, in the spring of 1962 wood‐pigeon mortality was too low to measure. It is concluded that the voluntary agreement from I January 1962, after which aldrin, dieldrin and heptachlor dressings were not to be used on spring‐sown cereals, virtually abolished direct wood‐pigeon mortality resulting from the consumption of treated grain. The general significance of such bird mortality on population size is briefly discussed.
The use of insecticides to find when leaf roll and Y viruses spread within potato crops
Authors: BURT P. E. , HEATHCOTE G. D. , BROADBENT L.
Published: February 2008

Attempts to find when leaf roll and Y viruses spread within Majestic potato crops, made during 4 years at Harpenden by spraying with aphicides to restrict virus spread during four different periods per season, succeeded with leaf roll but not with virus Y.

I n 1957, 1958 and 1961 leaf‐roll virus spread mostly before mid‐July, very little between mid‐ July and early August, but a little more from early August to the season's end. In 1959, when the summer was exceptionally fine, more virus spread during July. Four sprays with persistent aphicides: (I) when 50 yo of the crop has emerged from the ground; (2) 10 days later; and (3) and (4) at fortnightly intervals, will prevent leaf‐roll virus spreading within a potato crop until the end of July and in most seasons will therefore prevent almost all spread; the earliest sprays are usually the most important. Systemic soil insecticides applied to prevent leaf roll virus spreading should make the plants lethal to aphids as early as possible.

Little was learned about the time of spread of virus Y because in the experimental conditions the insecticides did not prevent its spread.

Further evidence was obtained that leaf roll virus is spread within crops mostly by alatae colonizing the potatoes in spring and early summer.
The epidemiology of tomato mosaic V. The effect on TMV‐infected plants of nutrient foliar sprays and of steaming the soil
Authors: BROADBENT L. , WINSOR G. W.
Published: February 2008

Spraying tomato plants infected with tomato mosaic virus (a strain of tobacco mosaic virus) and uninfected ones at weekly intervals with a 0·3% aqueous solution of urea, or this solution with 0·1% mono‐ammonium phosphate and 0·1% potassium sulphate, had little effect on the yield or quality of the fruits, although there was a slight increase in mean weight per fruit in sprayed, early‐infected plants. Steaming the soil did not affect total yield of fruits (weight) but increased fruit number by nearly 6% and also the proportion of good quality fruits. Some severe fruit‐quality disorders were prevalent only on late‐infected plants. A mild tobacco strain of mosaic virus failed to protect inoculated plants from late infection with the tomato strain of the virus.
Studies on parsnip canker
Authors: CHANNON A. G.
Published: February 2008

In field experiments at Wellesbourne, reductions in both black and orange‐brown canker of parsnips were obtained either by late sowing (in May or June), or by singling the plants to a narrow interval (3 in.), or by a combination of both treatments. The treatments reduced mean root size, and small roots had less canker than large ones.

It seemed that much of the disease reduction obtained was a consequence of the reduction in mean root weight caused by the treatments. There was evidence, however, that the reductions in black canker obtained by late sowing were also dependent to some extent upon the shorter period that the roots were in the ground.

Marketing assessments were made on four occasions in an experiment in which crops were grown from seed sown in March and May and were singled to 3 in. or 6 in. in rows 15 in. apart. They showed that the highest total and highest marketable yields were generally obtained from the earlier‐sown crop at the narrower spacing.
Hypersensitivity of monogenic resistant tomato scions to toxins produced in Bonny Best rootstocks invaded by Fusarium oxysporum f. lycopersici
Authors: KEYWORTH W. G.
Published: February 2008

Previous experiments made by the writer showed that scions of tomato varieties that were monogenically resistant to wilt caused by Fusarium oxysporum f. lycopersici were apparently hypersensitive to toxins produced in infected Bonny Best (susceptible) rootstocks on to which they were grafted. The experiments did not prove conclusively, however, that the toxins were generated in the rootstocks, since they might have arisen from an interaction between the invading fungus and the resistant scion or by the generation of toxic materials when non‐toxic metabolites from the invaded root‐stock entered the resistant scion.

In the present study it was demonstrated that the symptoms on the resistant scions arose when the fungus was still confined to the susceptible rootstocks. By double grafts, using resistant or susceptible intermediate stem pieces, it was also shown that the translocation of metabolites from invaded susceptible rootstocks through such stem pieces caused no change in their toxicity.

It was concluded that resistant scions were highly sensitive to the direct action of toxins formed in invaded susceptible rootstocks, at concentrations which had no apparent effect on susceptible scions.
Investigations on fungicides
Authors: CARTER G. A. , GARRAWAY J. L. , SPENCER D. M. , WAIN R. L.
Published: February 2008

A series of β‐(thiocarbamoylthio)‐aldehydes and ‐ketones, N‐methyl analogues and 2,3‐dihydro‐2‐thio‐1,3‐thiazines derived therefrom were examined in laboratory tests for fungitoxicity against seven fungi and in greenhouse tests against four plant diseases. The most active compounds were the phenyl‐ or trichloromethyl‐substituted β‐(N‐methylthiocarbamoylthio)‐ketones. The corresponding thiazines were less fungitoxic. Structure/fungitoxicity relationships are discussed with special reference to the influence of water solubility and water/oil partition coefficients.
Investigations on the use of dichlorvos in the control of the mushroom phorid, Megaselia halterata (Wood)
Authors: HUSSEY N. W. , HUGHES J. T.
Published: February 2008

Concentrations of dichlorvos (2,2‐dichlorovinyl dimethyl phosphate), lethal to mushroom flies, were produced in cropping houses by automatic aerosols, application of emulsion to the floors and by slow vaporization from a solid formulation in a plastic resin. Techniques used to measure these aerial concentrations and determine any residues in mushrooms are described.

A concentration–time product of 0·7 μg./1./hr. was found completely effective. No residues were found in mushrooms grown in houses treated with dichlorvos aerosols at rates up to 600 mg./100 cu.ft. but in laboratory tests residues of the order of 1 p.p.m. persisted for 24 hours when the mushrooms were directly exposed to the aerosol. The aerial concentrations of dichlorvos used were well below the mammalian safety level of 1·0 μg./1.
The life history and behaviour of the willow weevil Cryptorrhynchus lapathi L
Authors: SMITH B. D. , STOTT K. G.
Published: February 2008

Cryptorrhynchus lapathi L. is a serious pest of basket willows in Somerset, feeding as both larva and adult on the rods and stools. Adults reared in outdoor cages at Long Ashton completed their life history in 12 months in a cycle similar to that found in Southern France, Italy and North America. However, part of the population on reaching the adult stage in late summer did not emerge before the following May and so had a 2‐year life cycle. In contrast, willow bed sampling indicated that the population showed only the 2‐year cycle generally similar to that found in Northern and Eastern Europe. Maximum damage to rods occurred in May and June when adults emerged and in 1959, when there was a serious infestation, 62% of the rods were damaged. The maximum density recorded at one time was one adult per six stools or 138 shoots but surveys in which marked weevils were recaptured showed that only part of the total adult population was visible at any one time and hence over a 5‐day period a density of one adult per four stools was found. Soon after emergence adults showed a preference for evening activity. There appeared to be very little lateral movement of adults across the rows in willow beds and flight has been observed only in the laboratory. There was no evidence of alternate host plants being used at any stage in the life history or for the hypothesis of alternating light and heavy infestation years between 1958 and 1963.
Strawberry latent ringspot: a new nematode‐borne virus
Authors: LISTER R. M.
Published: February 2008

The properties and mode of transmission of strawberry latent ringspot virus (SLRV) are described. Natural infections have been found, in several widely separated localities, on cultivated and wild rosaceous species—strawberry, raspberry, cherry, plum, black currant—and on elder (Caprifoliaceae), but so far no diseases in these plants have definitely been associated with SLRV. Similarly, SLRV was transmitted mechanically to a wide range of hosts, many of which it infected symptom‐lessly. SLRV is transmitted by Xiphinema diversicaudatum (Micoletsky), has polyhedral‐shaped particles of about 26 mμ diameter, and has other features that suggest it should be classified along with a group of other similar soil‐borne viruses.
Studies on a strain of raspberry ringspot virus occurring in England
Authors: DEBROT E. A.
Published: February 2008

A strain of raspberry ringspot virus (RRV‐E) infecting blackberry in Essex was transmitted by inoculation of sap to twenty‐six herbaceous species, and caused symptoms in Nicandra physaloides, Datura metel and Gomphrena globosa that differentiated it from the Scottish strain of the virus (RRV‐S). In sap, with an infection end‐point of 10‐5, it was inactivated in 10 min. at 74° C, and in 5 weeks at 23° C. It was precipitated without inactivation by a 30% acetone or 30%‐saturated ammonium sulphate solution, but was inactivated when acidified to less than pH 4. Partially purified preparations of RRV‐E contained approximately equal amounts of three components with sedimentation rates of 50, 90 and 127S; electron micrographs of preparations mounted in neutral sodium phosphotungstate showed three kinds of particles with diameters about 30 mμ but with different internal structure. A preparation of RRV‐S contained a main component with a sedimentation rate of 129s, and a minor one with 50S.

Petunia hybrida, cucumber and French bean seemed equally susceptible to infection with RRV‐E when grown in soil containing the nematode vector Longidorus macrosoma, but inoculation of sap infected the roots of P. hybrida much more readily than roots of the other two species. Cucumber seedlings became infected when exposed for 1 day to infective L. macrosoma, and virus‐free L. macrosoma acquired the virus from plants in 4 days. Infective L. macrosoma transmitted readily at 20° C, occasionally at 25° C, and not at 30° C; feeding seems inhibited at 30° C. RRV‐E was transmitted to seedlings grown in soil containing L. macrosoma that had been kept free from plants for 34 days. Of sixty‐eight extracts of infective L. macrosoma inoculated to Chenopodium quinoa plants, only one caused infection.
Studies on the physiology of cocoa (Theobroma cacao L.)
Authors: ASOMANING E. J. A. , LOCKARD R. G.
Published: February 2008

Shading retarded the growth of cocoa seedlings infected with cocoa swollen‐shoot virus proportionately more than the growth of uninfected seedlings. Infected seedlings grown in bright light did not produce the swellings on stems and roots which were consistent symptoms of infection on plants grown under shade. The type of leaf symptoms also differed in shaded and unshaded seedlings.

Attention is drawn to the possible implications of shade in the severity of swollen‐shoot outbreaks in farmers' cocoa.
Factors influencing seedling infection of barley by Ustilago nuda (Jens.) Rostr
Authors: KAVANAGH T.
Published: February 2008

In the seedling method of inoculation of barley with Ustilago nuda, a chlamydospore suspension is introduced into decapitated coleoptiles held under partial vacuum. The optimum conditions for infection were provided by the use of a partial vacuum of 25 in. of mercury for 2 min. on coleoptiles 1‐1·5 cm. long: lower infection percentages resulted when the coleoptiles were over 1·5 cm. No benefit was obtained by suspending the spores in dextrose or peptone solutions.

The variety Jet remained immune to infection.