bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on periodicity of hatching of eggs of the potato cyst nematode, Heterodera rostochiensis Woll.
Authors: SHEPHERD AUDREY M. , COX PATRICIA M.
Published: February 2008

Soil containing new‐generation cysts of Heterodera rostochiensis was taken from the field at monthly intervals during late summer and autumn and kept in various conditions for up to a year. The number of eggs that hatched in the stored cysts was compared each month with the number that hatched in cysts taken directly from the field. Eggs did not hatch readily when stimulated during the late autumn and early winter, although more did so in cysts taken from the field before August than after. A few more eggs hatched in cysts stored in air‐dried soil than in cysts stored in moist soil. Some cysts were kept at 15 or 20 °C continuously and others at 5, 15 or 30 °C for 6 weeks followed by 20 °C continuously. Storage at 30 °C caused eggs to hatch sooner, but otherwise the temperature of storage had little effect on hatch at any time of the year. Warmth also increased the hatch of H. cruciferae sooner, and some synthetic hatching agents did so with both of these species. When freed from new cysts, more eggs of H. rostochiensis hatched than in intact cysts and hatch was further increased when the fragments of tanned cyst‐wall were left with the freed eggs. Puncturing the cyst‐wall of new brown cysts had little effect on the hatch in potato root diffusate. Like eggs in new cysts, those in 1‐year‐old cysts stored out of doors ceased to hatch during the autumn and winter. The term ‘dormancy’ is inadequate to describe the inability of eggs of H. rostochiensis and other Heterodera spp. to hatch in the appropriate stimulant and the term ‘facultative diapause’, as applied to insects, better fits the phenomenon.
The action of some systemic aphicides on the eggs of Anthocoris nemorum (L.) and A. confusus Reut
Authors: ELLIOTT W. M. , WAY M. J.
Published: February 2008

Comparisons were made of the systemic action of phorate, menazon and dimethoate on Aphis fabae Scop, and on the eggs of the aphidophagous Anthocoridae Anthocoris nemorum (L.) and A. confusus Reut., which are laid within plant tissue.

Against 4th‐instar apterous A. fabae the order of toxicity of the insecticides taken up by roots of the field bean Vicia faba L. was: menazon > dimethoate > phorate. Phorate concentrations needed to kill all A. fabae (10–15 ppm of wet weight of plant) killed most A. nemorum eggs but did not harm A. confusus eggs. Few A. nemorum eggs were killed by 15 ppm of menazon or 5 ppm of dimethoate.

In the field a commercial in‐row treatment of 1·5 lb/acre of phorate applied as granules in the seed drill of field beans sown in late April killed 86 % of eggs laid in June by overwintered A. nemorum and 30% of those laid in late July by second‐generation females. Plants initially treated with 6 lb of in‐row phorate per acre killed 74% of A. nemorum eggs in late July but did not harm A. confusus eggs. A. nemorum eggs laid in early June were unharmed by 1·5 lb/acre of in‐row menazon.

Of the A. nemorum eggs, 92–96% were inserted into the stipules and leaf margins of young bean plants, i.e. in the region (peripheral and distal part of the leaf) where most 32P from labelled phorate accumulates after root uptake. The egg‐laying sites of A. nemorum in potatoes and brussels sprouts (edges of the leaves) and in oats (the leaf tips) are also where most of the 32P accumulates. In contrast, 98% of A. confusus eggs were laid in the stems, petioles and leaf midribs of field beans, where there was generally much less 32P from labelled phorate.
Effects of feeding by larvae of Phaedon cochleariae (F.) and Plutella maculipennis (Curt.) on the yield of radish and turnip plants
Authors: TAYLOR W. E. , Bardner R.
Published: February 2008

Different numbers of larvae of the beetle Phaedon cochleariae (F.) and the moth Plutella maculipennis (Curt.) were fed on the leaves of turnip plants (variety Early Milan White) and radish (variety French Breakfast) growing in a constant‐environment room.

Turnips grew more slowly than radish, were less affected by insect feeding and were affected more by Phaedon than by Plutella. Phaedon larvae severed leaf veins and rasped the leaf surface, thus killing more leaf tissue by desiccation than they ate. They remained on and greatly damaged the older leaves and their feeding reduced yield. Plutella larvae fed on leaves of all ages, which they ate cleanly, leaving the veins. They pupated sooner than Phaedon and did less damage to older leaves, which grew larger and lived longer than corresponding leaves on intact plants. This compensatory growth by turnip prevented loss of yield and may have increased it, as indicated by dry weight of the roots.

Both species of insect decreased the yield of radish similarly. Loss of yield of turnip caused by Phaedon or of radish caused by both species of insects was negatively and linearly proportional to the number of larvae that fed on the leaves.
Field experiments on the chemical control of blackcurrant reversion virus and its gall‐mite vector (Phytoptus ribis Nal.)
Authors: THRESH J. M.
Published: February 2008

Healthy blackcurrant bushes and others infected with reversion virus were exposed equally to infestation by the gall‐mite vector (Phytoptus ribis Nal.) spreading from unsprayed sources planted nearby. Four applications of 1·0% lime sulphur at fortnightly intervals during the dispersal period were less effective than 0·05% endosulfan in preventing the infestation of healthy bushes, whereas endrin at 0·04% gave almost complete control. All spray treatments were much less effective when applied to the virus‐infected bushes, although endosulfan remained superior to lime sulphur and inferior to endrin. Infected bushes sprayed with lime sulphur developed more galls than unsprayed healthy bushes.

In another experiment, four applications of endrin or lime sulphur decreased the spread of mites and reversion virus from infested bushes to adjacent sprayed and unsprayed bushes. Lime sulphur was much less effective than endrin in preventing infestation with mites, but more effective in decreasing the incidence of virus.

These results are discussed in relation to commercial spray programmes and to the design of experiments on the effectiveness and mode of action of spray materials against mites and virus.
Field and laboratory studies of the effect of urea on ascospore production of Venturia inaequalis (Cke.) Wint
Authors: BURCHILL R. T.
Published: February 2008

Applications of urea after harvest but before leaf‐fall restricted perithecial production by Venturia inaequalis. Immersion of detached leaves in urea appeared to be the most effective method of preventing perithecial formation, although spraying attached leaves was equally effective when leaf abscission occurred within a week of treatment.

A high nitrogen content within the leaf was one of the major factors contributing to suppression. Urea‐treated leaves decomposed rapidly, thus destroying the overwintering substrate for the fungus.

When apple plants (clone M. 111) were sprayed in autumn with 5 % urea, followed by a second (pre‐bud‐burst) application at 2 %, ascospore production in the spring was suppressed. The second treatment appeared to prevent the release of ascospores from mature perithecia.
Factors affecting the occurrence of gangrene (Phoma exigua) in potatoes
Authors: MALCOLMSON JEAN F. , GRAY ELIZABETH G.
Published: February 2008

The presence in soil from Scotland and England of Phoma exigua f. sp. exigua and P. exigua f.sp. foveata, which cause gangrene, is confirmed by isolation, and it is established that infection of tubers occurs before lifting, and after lifting from soil adhering to tubers. The distribution of the disease is related to soil moisture, gangrene being most prevalent in tubers from the north‐eastern counties of Scotland where the moisture content of arable soils remains high throughout the growing season. The incidence of the disease may be affected by the haulm, either as a source of infection—though not an important source—or by its effect on the maturity of the tubers. The incidence of gangrene is less where haulm destruction is rapid.

The incidence of gangrene in a crop is not related to its incidence in the seed tubers planted and, unless infection is severe, the effect on yield is not serious.

Symptoms of skin necrosis were associated with tubers from acid soils, infected with P. exigua f.sp. foveata and stored at low temperature.
The incidence of gangrene of potatoes caused by Photna exigua in relation to handling and storage
Authors: MALCOLMSON JEAN F. , GRAY ELIZABETH G.
Published: February 2008

Damage to potatoes during harvesting and grading increases the incidence of gangrene. Among the factors involved, the condition of the soil and the type of damage caused by the implements may be of importance. Gangrene is most evident in tubers which have been stored cold or moved when cold; warmer storage at some stage usually reduces its incidence and severity.

Seasonal incidence is not directly related to rainfall but is determined by factors affecting ripening and destruction of haulm, moisture status of soils at harvest, susceptibility to damage, and exposure during storage and in transit.
The effect of species of Allium on soil bacteria in relation to germination of sclerotia of Sclerotium cepivorum Berk
Authors: COLEY‐SMITH J. R. , DICKINSON D. J. , KING J. E. , HOLT R. W.
Published: February 2008

Extracts made from Allium species were shown to exhibit marked antibiotic properties in a variety of tests. However, no evidence was obtained to suggest that intact Allium seedlings exude antibiotic compounds in sufficient quantity to cause inhibition of bacteria in the soil or in assay tests in the laboratory. Germination of sclerotia of Sclerotium cepivorum was induced by Allium extracts which were too dilute to cause antibiotic responses in laboratory tests using a number of bacteria. Synthetic methyl‐methanethiolsulphinate had little effect on germination of sclerotia. The specific reversal, by Allium species and their extracts, of the mycostatic effect of unsterile soil on sclerotia of S. cepivorum does not appear to be due to antibiotic effects.
The use of menazon seed dressing to decrease spread of virus yellows in sugar‐beet root crops
Authors: HEATHCOTE G. D.
Published: February 2008

Menazon, an organophosphorus insecticide (only slightly toxic to mammals), applied to sugar‐beet seed, decreased the proportion of seedlings infested with aphids during May and early June and the number of aphids per plant during June and early July to one‐third of that in the control plots. It also checked the spread of virus yellows.

Of eight field trials in 1965, 1966 and 1967 in which more than 10% of the plants in plots not treated with insecticide had yellows, menazon seed dressing increased sugar yield by about 8 cwt per acre. Spraying with demeton‐methyl when ‘a spray warning’ was issued in the area gave a similar increase, and had no further effect on plots sown with menazon‐treated seed.

Menazon‐dressed sugar‐beet seed is recommended in regions where yellows is usually prevalent, or where there is reason to expect a large aphid infestation.
Purification, properties and transmission of parsnip yellow fleck, a semi‐persistent, aphid‐borne virus
Authors: MURANT A. F. , GOOLD R. A.
Published: February 2008

Parsnip yellow fleck virus (PYFV) is the commonest cause of virus‐like symptoms in parsnip plants in Britain: it is sap‐transmissible but systemically infects few species outside the Umbelliferae. It has isometric particles 29–31 mμ in diameter, a sedimentation coefficient of 167s, and loses infectivity in sap after dilution to 10‐3‐10‐4, heating for 10 min at 57·5–65°C, or storage at room temperature for 4–7 days. Two isolates, from parsnip and Anthriscus sylvestris respectively, are only distantly serologically related.

The aphid Cavariella aegopodii transmits PYFV in a semi‐persistent manner from A. sylvestris but not from parsnip. Transmission by aphids apparently depends on the presence in A. sylvestris or other source plants of a second virus, anthriscus yellows (AYV), which is persistent in the vector and not manually transmissible. PYFV was therefore not transmitted by aphids from manually inoculated plants or from parsnip or other plants immune to AYV. In controlled experiments, C. aegopodii transmitted PYFV (both A. sylvestris and parsnip isolates) from chervil plants inoculated separately with PYFV and AYV, but not from plants inoculated only with PYFV.
The secretion of the systemic insecticides dimethoate and phorate into nectar
Authors: LORD K. A. , MAY MARGARET A. , STEVENSON J. H.
Published: February 2008

In pot experiments, root applications of dimethoate and phorate were made to plants of fuchsia, nasturtium and bean. Twenty‐five mg dimethoate applied to a 5‐in pot made nectar from fuchsia and nasturtium and nectaries of beans toxic to bees and Drosophila melanogaster. Similar amounts of phorate and disulfoton did not cause toxicity.

Gas chromatography showed that 4 days after treatment there was at least 100 times more dimethoate than phorate in the nectar of fuchsia and nasturtium.

The dimethoate in nectaries taken from bean plants treated at rates between 0·5 and 50 mg dimethoate per pot was assayed by gas chromatography. The concentration of dimethoate in the nectaries depended on the applied dose: it was greatest 4 days after treatment. Loss was more rapid with larger doses than with smaller doses.
Influence of direct‐drilling of winter wheat on incidence of take‐all and eyespot
Authors: BROOKS D. H. , DAWSON M. G.
Published: February 2008

Winter wheat drilled directly into stubble or pasture treated with paraquat to kill the vegetation has been found to be less severely attacked by take‐all (Ophiobolus graminis (Sacc.) Sacc.) and eyespot (Cercosporella herpotrichoides Fron) than wheat drilled after cultivation. The reduction of take‐all is associated, not with a direct effect of the chemical, but with factors, resulting from the technique, which limit the rate of spread of the fungus in the undisturbed soil.
The effect of 6‐benzylaminopurine (benzyladenine) on senescence and chocolate spot (Botrytis fabae) of winter beans (Viciafaba)
Authors: MOORE K. G. , LEACH R.
Published: February 2008

In laboratory trials on detached bean leaves, benzyladenine delayed both senescence and aggressive attack of chocolate spot disease.

In field plots, over 80% of the aggressive spots were on senescent leaves and the distribution of aggressively attacked leaves was predictable from the distribution of senescent leaves. The total frequency of aggressively attacked leaves per shoot was apparently related to the frequency of senescent spotted leaves.

Although benzyladenine significantly reduced leaf senescence in field plots sprayed in May, the senescent leaves were more frequently attacked aggressively. Wider plant spacing (14 in instead of 8 in) similarly increased the ratio of aggressive attack to senescence, and the individual fields retained until June the differences in infection earlier established by frost damage.
Studies on the influence of leaf washings on infection by Mycosphaerella ligulicola
Authors: BLAKEMAN J. P.
Published: February 2008

Infection of chrysanthemum leaf discs by spores of Mycosphaerella ligulicola was increased in the presence of concentrated leaf washings obtained from five plant species tested. On separation of leaf washings by dialysis the residue stimulated infection and caused aggregation of hyphae on leaf and cellophane surfaces. In the presence of the diffusible fraction an extensive branching network of hyphae developed but there was no increase in infection except in the presence of the chrysanthemum diffusate.

Infection of leaf discs of certain plants normally resistant to M. ligulicola occurred in the presence of concentrated leaf washings.

Leaf washings from a resistant variety of chrysanthemum had the same effects as those from a susceptible variety. An extract of chrysanthemum leaves was less effective in stimulating infection than was a leaf washing.

Defined nutrient media and potato extract stimulated infection but caused the development of different growth habits on leaf surfaces.

The active components of the dialysis residue of chrysanthemum leaf washings were heat‐stable but apparently volatile. Eluates from strips of certain regions of paper chromatographs of leaf washings and potato extract caused increased infection together with development of characteristic growth habits of the fungus on the leaf.
Studies on plant growth‐regulating substances XXV. The plant growth‐regulating activity of cinnamic acids
Authors: UGOCHUKWU E. N. , WAIN R. L.
Published: February 2008

Effects of ring substitution on the plant growth‐regulating activities of trans‐ and cis‐cinnamic acids have been investigated in the wheat cylinder, pea segment and pea curvature tests. Most of the cis‐ acids were shown to be active. Substitution of fluorine, chlorine or bromine into the ring of cis‐cinnamic acid in most cases increased the activity. The results are discussed in relation to mode of action and chemical structure/biological activity relationships: 4‐chlorobenzoic acid is shown to act as a competitive antagonist towards 4‐chloro‐cis‐cinnamic acid.
Resistance to the potato cyst‐nematode, Heterodera rostochiensis, in the plant genus Lycopersicon
Authors: ELLIS P. R.
Published: February 2008

Forty‐eight lines of Lycopersicon and four lines of Solanum were screened for resistance to twelve Heterodera rostochiensis populations of known patho‐type(s). Plant lines were assessed for resistance first by examining the outside of the root ball for cysts and later by washing the root ball to extract all cysts. Possible resistant plant selections were re‐tested against three eelworm populations, including the one to which they were first shown resistant. Resistance was discovered in two lines of Lycopersicon pimpinelli‐folium, two L. esculentum L. pimpinellifolium crosses, L. esculentum var. cerasiforme, six lines of L. peruvianum, in L. peruvianum var. humifusum, L. hirsutum var. glabratum, and in Solanum indicum. Because resistance was found most commonly in L. peruvianum and because it has already been used as a resistant parent in breeding programmes to incorporate resistance to root‐knot nematode (Meloidogyne spp.) in tomato, L. peruvianum seems to be the best source of resistance among plants tested so far.

The host‐parasite relationships of resistant L. hirsutum var. glabratum (B 6013) were compared with those of a commercial, susceptible tomato, L. esculentum‘Ailsa Craig’. Plants were inoculated with three eelworm isolates; the extent of eelworm invasion, plant reaction and eelworm development were studied. Larvae invaded and penetrated roots of the resistant plant as freely and in as large numbers as they penetrated roots of the susceptible tomato. In the latter, numerous larvae matured while, in contrast, few larvae matured in the roots of L. hirsutum var. glabratum. L. hirsutum var. glabratum was shown to possess a root diffusate as active in hatching larvae of Heterodera rostochiensis as that of L. esculentum‘Ailsa Craig’.

The existence of pathotypes of H. rostochiensis, identifiable by their differing abilities to increase on resistant tomato lines, was not clearly revealed in the experiments.
Some effects of the nematodes Ditylenchus myceliophagus and Aphelenchoides composticola on the yield of the cultivated mushroom
Authors: ARROLD N. P. , BLAKE C. D.
Published: February 2008

The addition of one, ten and fifty Aphelenchoides composticola per ioo g compost at spawning reduced the total yield of sporophores by 26%, 30% and 42% respectively (P= 0·01), demonstrating a significant regression (P= 0·05) of yield on inoculum concentration.

In pots inoculated at spawning with ten and fifty A. composticola per 100 g compost, cropping ceased after 12 weeks. The addition of twenty, 100 and 300 Ditylenchus myceliophagus at casing reduced the total yield of sporophores by 50%, 68% and 75 % respectively (P= 0·01). Cropping did not occur in pots inoculated at spawning, but continued for 9 weeks in pots inoculated at casing. The yield from pots inoculated at casing with either nematode was significantly greater (P= 0·05) than that from pots inoculated at spawning.

When inoculated at spawning, peak populations of D. myceliophagus and A. composticola were reached 7 and 13 weeks, respectively, after spawning. Then the numbers present were unrelated to the number in the inocula.
Properties, relationships and transmission of a strain of raspberry ringspot virus infecting raspberry cultivars immune to the common Scottish strain*
Authors: MURANT A. F. , TAYLOR C. E. , CHAMBERS J.
Published: February 2008

Plants of Lloyd George and Seedling M raspberry (Rubus idaeus L.) were found in eastern Scotland infected with raspberry ringspot (RRV), a virus to which these varieties were previously considered immune. Most RRV isolates from affected plants caused milder symptoms in herbaceous test plants than did the type isolates of the common Scottish and English strains. In graft‐transmission tests the Lloyd George strain of RRV infected all the raspberry cultivars tested, including those immune to the common Scottish strain. No consistent differences were found between isolates of the two strains in in vitro properties or serological behaviour. Both strains were transmitted in seed of Stellaria media and in soil containing Longidorus elongatus. Possible reasons why the new strain is uncommon in Scotland are discussed.
A biochemical difference between healthy bean leaves resistant and susceptible to the halo‐blight disease caused by Pseudomonas phaseolicola
Authors: EPTON H. A. S. , DEVERALL B. J.
Published: February 2008

Substrate for an endogenous oxidation in homogenates of leaves of bean (Phaseolus vulgaris) was traced to two fractions of lipids, each representing less than 2% of the dry weight of leaves. The substrate lipids, tentatively identified as galactosyl diglycerides, yielded linolenic and linoleic acids on acid hydrolysis. Amounts of linolenic acid in total lipids in resistant and susceptible leaves were similar. Amounts of free linolenic acid in resistant leaves increased eightfold to 408.6 μg and in susceptible leaves fourfold to 130.6 μg/g fresh leaf after homogenization and incubation for 16 min at 4 °C. These quantities are sufficient to account during their lipoxidation for the previously reported oxygen uptakes in homogenates. Differences between resistant and susceptible leaves were traced to the activities of lipase systems which liberate linolenic acid from substrate lipids.
Effects of infestation with fruit tree red spider mite, Panonychus ulmi (Koch), on the growth and cropping of young fruit trees
Authors: BRIGGS J. B. , AVERY D. J.
Published: February 2008

When Brompton plum, and M. IV and Crab C apple rootstocks grown in pots were inoculated with fruit tree red spider mites (Panonychus ulmi (Koch)), shoot extension was decreased by 7–17%, the dry weight of the new shoot by 21–32%, and the dry weight increments of old stem and roots by 12–30%, and 7–50%, respectively, compared with control plants sprayed with the acaricide tetradifon. Some of these effects were found in a field experiment with Brompton plum, but not with potted M. I apple rootstocks. Infestation of fruiting Lord Lambourne apple trees, also in pots, had little effect on vegetative growth but in one experiment modified fruit setting, and decreased the dry‐matter content, but increased the seed content of harvested fruit. Lighter inoculation caused no damage to Brompton plum. Spraying inoculated Brompton plum rootstocks with tetradifon + TEPP in mid‐June and mid‐July prevented damage, and though August sprays did not prevent damage to the new shoot, the decreases in dry weight increments of old stem and roots were only 9–13% and 11–19%, respectively, compared with 21–25% and 45–50% in infested, unsprayed plants.
The aetiology and development of damage in young fruit trees infested with fruit tree red spider mite, Panonychus ulmi (Koch)
Authors: AVERY D. J. , BRIGGS J. B.
Published: February 2008

Infestations of fruit tree red spider mite, Panonychus ulmi (Koch) altered the growth of young plants of plum and apple. At first, damage to the leaves from mite feeding did not affect their photosynthetic rates. The effects on other processes depended on the density of the infestation. Densities of 1–2 mites/cm2 of leaf decreased the rate of shoot extension of Brompton plum, but about 0.5 mite/cm2 increased it. Less dense infestations apparently caused no damage. The rate of growth of the leaf area of a plant relative to that of the mite population on it determined changes in the mite density, and therefore the effects of infestation. The growth of the root system was decreased before that of the shoots.

Later, when some leaves were severely damaged photosynthesis was decreased. The onset and severity of this phase probably depended on the number of mites and days of feeding on individual leaves. The later‐formed leaves were smaller, and sometimes fewer on infested plants. Some plants were infested with too low a density of mites to decrease shoot extension, but grew less in dry weight because of decreased photosynthesis later in the season.

The initial effects are ascribed to an imbalance in the growth controlling substances caused by feeding. Radioactivity was detected in the growing regions of plants remote from mature leaves on which 14C‐labelled mites were confined.
The effect of plant spacing on the numbers of aphids trapped over the groundnut crop
Authors: A'BROOK JOHN
Published: February 2008

Aphis craccivora, Aphis gossypii and Longiunguis sacchari were trapped at 3 ft above ground more often over widely‐spaced than over close‐spaced groundnuts. At crop height A. craccivora and A. gossypii showed a similar but greater response to plant spacing. Numbers of Rhopalosiphum maidis and Tetraneura nigriabdominalis caught were not affected by groundnut spacing differences. All aphid species studied except T. nigriabdominalis responded to yellow, but their sensitivity to colour was less during the dry season. It is suggested that the effect of plant spacing on numbers caught was not due to colour alone, but perhaps also to the contrast of plants and soil in widely spaced groundnuts. At crop height, an alighting response was shown only by those species that feed on groundnuts. The control of rosette disease of groundnuts by early planting and close spacing appears to be due to the inhibition of the landing response in A. craccivora by the continuous ground cover resulting from these treatments.
The incidence of virus diseases in English sweet‐cherry orchards and their effect on yield
Authors: POSNETTE A. F. , CROPLEY R. , SWAIT A. A. J.
Published: February 2008

Two thousand sweet‐cherry trees (Prunus avium) in English orchards were tested for virus infection by using Lambert and Mazzard F 12/1 as indicators. Most trees of varieties commonly grown before 1920 were infected with more than one virus, usually little cherry (69%) and necrotic ringspot/prune dwarf (56%). Other infection was less prevalent, 35% of these trees having European rusty mottle, 30% ring mottle and 3% necrotic rusty mottle. Most trees of varieties introduced since 1920 were virus‐free (61%) but some had become infected with each of these viruses except necrotic rusty mottle.

In a field trial of 12 years duration the yield of three varieties was diminished by infection with necrotic ringspot/prune dwarf, rugose mosaic, rusty mottle, ring mottle and necrotic line pattern. The effect of rusty mottle was due to growth suppression resulting in smaller trees, but that of other viruses was also due to impaired fertility. The yield of one variety (Merton Heart) was greatly enhanced by infection with rugose mosaic, rusty mottle and necrotic ringspot/prune dwarf viruses.

The high incidence of virus infection and consequent yield depression has probably diminished the potential yield by at least 30% and contributed to the decline in acreage of sweet cherries in England.
Virus diseases of garden lupin in Great Britain
Authors: HULL R.
Published: February 2008

Two viruses occur widely in lupins in Britain. Alfalfa mosaic virus (AMV), of which two strains were isolated, was found mainly in named Russell varieties. Lupin mottle virus (LMV), a previously undescribed strain of the bean yellow mosaic virus (BYMV) common pea mosaic virus (CPMV) complex, was found more commonly in seedling lupins. Cucumber mosaic virus (CMV) was isolated once.

The AMV strains were differentiated by their reaction in Phaseolus vulgaris; they were serologically closely related. Both AMV and LMV were aphid transmitted but not transmitted in lupin seed. LMV was distantly serologically related to both BYMV and CPMV. It cross‐protected against BYMV but not against CPMV and it differed from both these viruses in some host reactions. The CMV isolate from lupins was similar to type CMV. It was transmitted both mechanically and by aphid, easily from cucumber to cucumber, but with difficulty from cucumber to lupin.
Effects of volatile products of Allium species and their extracts on germination of sclerotia of Sclerotiutn cepivorum Berk.
Authors: KING J. E. , COLEY‐SMITH J. R.
Published: February 2008

It was shown that sclerotia of Sclerotium cepivorum, normally subject to the mycostatic influence of unsterile soil, germinated in response to a volatile principle evolved from growing onion and leek seedlings. Air, which was bubbled through diluted onion and garlic juices, contained vapours which stimulated sclerotia! germination. The vapours evolved at room temperature by garlic juice were collected as a condensate which also induced germination. Stimulatory activity was found in both distillates and distillands of garlic as well as in air bubbled through such a distillate.
Comparative toxicity of the two anti‐coagulants, coumatetralyl and warfarin, to wild house‐mice (Mus musculus L.)
Authors: ROWE F. P. , REDFERN R.
Published: February 2008

In comparative tests using individually caged wild house‐mice (Mus musculus L.) coumatetralyl at 0·05 % in an oatmeal bait‐base was found to be as acceptable as plain bait and as acceptable and as toxic as warfarin at 0·025% (the standard dosage). It was less readily accepted at 0·1 or 0·2% in the same bait‐base or at 0·05% in a proprietary bait formulation.

In further tests with suspected warfarin‐resistant mice, coumatetralyl at either 0·05, 0·1 or 0·2% proved more toxic than warfarin at either 0·025, 0·1 or 0·2% respectively. However, some individuals survived 21 days feeding on each of these concentrations of coumatetralyl and, in field and laboratory trials, 0·05 and 0·1% coumatetralyl baits failed to control warfarin‐resistant mouse populations after 3–5 weeks.

It is concluded that coumatetralyl is a suitable alternative poison to warfarin for use against mice that are susceptible to anti‐coagulants but that it is unlikely to control warfarin‐resistant populations effectively.
Micro‐meteorological studies of coffee berry disease A field investigation into the incidence of the physical conditions favourable for spore germination
Authors: WOODHEAD T.
Published: February 2008

In an investigation in a coffee plantation, the frequency and duration of the micro‐meteorological conditions necessary for the germination of conidia of Colletotrichum coffeanum were evaluated on coffee twigs of different ages, aspects and exposures. No consistent relationships between aspect and disease incidence were established, but there were indications that east‐facing branches might be slightly more disease‐prone than west‐facing ones because of more rapid warming of the surface water films by morning insolation.

The macro‐climate of the plantation was measured by conventional meteorological instruments. Daytime air temperatures, measured inside a Stevenson screen between the rows of trees, were, on average, about 1 C° and 2·5 C° lower than those recorded on twig surfaces under wet and dry conditions, respectively.
Some factors affecting germination of Peronospora farinosa conidia in water
Authors: RUSSELL G. E. , EVANS GWENLLIAN M.
Published: February 2008

The germination of conidia of Peronospora farinosa f. sp. betae, collected from sugar beet and suspended in deionized water, was inhibited by dilution with 10% solutions of glycerol, glucose or sucrose and with sap from sugar‐beet leaves. Germination was stimulated by diluting with deionized water but not with tap water or biological saline. Substances that diffused from excised buds of sugar‐beet plants into deionized water also stimulated germination of conidia but diffusates from leaves did not. This may partly explain why buds are more susceptible to downy mildew than leaves in sugar beet. Germination of conidia was apparently stimulated more by diffusates from buds of seedlings than by those from buds of older plants; this may help to explain why sugar‐beet seedlings are more susceptible to downy mildew than older plants. Diffusates from plants of four sugar‐beet stocks, that differed from each other in susceptibility to downy mildew, had very similar effects on germination of P. farinosa conidia. Stimulation of spore germination on the surfaces of buds and leaves did not seem, therefore, to be an important factor in determining resistance or susceptibility to downy mildew in these stocks.
The effect of inbreeding on potato cyst‐nematode, Heterodera rostochiensis
Authors: HOWARD H. W.
Published: February 2008

Two populations, Duddingston and Feltwell, of potato cyst‐nematode were inbred for seven and six generations respectively. The Duddingston population maintained a high fecundity in some lines for three generations, but in subsequent generations the fecundity as measured by cyst production declined in spite of selection for high fecundity. By selecting for fecundity, some lines of the Feltwell population still produced many cysts after five generations of inbreeding. In the Duddingston population it was possible to increase the number of cysts produced by an inbred line of poor fecundity by using paired cysts plus selection for fecundity. A similar change may have been obtained for unprolific lines of the Feltwell population. Selection for production of few cysts quickly produced lines with poor fecundity. One cause of poor fecundity was the small number of larvae in cysts used for inoculations. Yellow eggs were found in large numbers in some cysts but these were not a cause of loss of fecundity following repeated inbreeding.
Effects of sucrose sprays and darkness on aphid colonization of sugar beet and on aphid transmission of yellowing viruses
Authors: Russell G. E.
Published: February 2008

In the glasshouse, adult, apterous Myzus persicae (Sulz.) and Aphis fabae Scop, settled better and deposited more larvae on sucrose‐sprayed sugar‐beet plants than on water‐sprayed plants. M. persicae settled badly and deposited few larvae on plants that were kept in the dark before or after infestation. The effects of darkness on aphids were reduced by spraying the host plants with 10% solutions of sucrose before infestation.

Viruliferous M. persicae transmitted beet yellows virus (BYV) and beet mild yellowing virus (BMYV) less efficiently to dark‐treated plants than to those grown in normal daylight. Spraying sugar beet with sucrose before inoculation with viruliferous M. persicae increased the proportion of successful BYV transmissions but only when the plants were dark‐treated. The effects of sucrose and darkness on settling and larviposition of aphids and on virus transmission may be related to changes in the concentration of carbohydrates, particularly sugars, in the leaves.
Studies on the bacterial diseases of Sudan crops
Authors: SABET K. A. , ISHAG FARIDA , KHALIL OSMAN
Published: February 2008

New records are presented of bacterial diseases affecting the following weed plants: Heliotropium sudanicum, Rhynchosia memnonia, Vigna radiata, V. pubigera, Euphorbia acalyphoides and Phyllanthus niruri. Bacterial leaf blight of pigeon pea (Cajanus cajan) caused by Xanthomonas phaseoli f. cajani is reported for the first time from the Sudan. The causal bacteria, all of which belong to the genus Xanthomonas, are compared with related pathogens. The differences between these bacteria are considered of little diagnostic value. Pathogenically, they can be separated into three groups: (i) the Heliotropium pathogen; (ii) the bacteria affecting leguminous plants; and (iii) the bacteria affecting species of the family Euphorbiaceae. Because of the diversity in opinion on speciation in the genus Xanthomonas, two alternative proposals are put forward. In the first, Xanthomonas is considered a monotypic genus with X. campestris as the sole species. The pathogens reported in this work from previously unrecorded hosts, which proved to differ in pathogenicity from established ones, are considered to be new formae speciales. These are X. campestris f.sp. heliotropii from H. sudanicum, X. campestris f.sp. rhynchosiae from R. memnonia, X. campestris f.sp. vigna‐radiatae from V. radiata, X. campestris f.sp. euphorbiae from E. acalyphoides and X. campestris f.sp. phyllanthii from P. niruri. The organism from V. pubigera is accordingly identified as X. campestris f.sp. vignicola. Other bacteria used for comparison are also reduced to ff.sp. of X. campestris.

The other proposal is to lump together pathogens with overlapping host ranges in a single species that comprises a number of ff.sp. differing in pathogenicity. Thus the bacteria from leguminous plants are all considered to belong to X. phaseoli as previously suggested by Sabet. New ff.sp. are created for the pathogens from R. memnonia (X. phaseoli f.sp. rhynchosiae), and V. radiata (X. phaseoli f.sp. vigna‐radiatae). The organism from V. pubigera is identified in this case as X. phaseoli f.sp. vignicola. The bacteria from members of the Euphorbiaceae are considered to belong to X. ricini on priority grounds. X. cassavae and X. poinsettiaecola which have been used for comparison are reduced to the ff.sp. X. ricini f.sp. cassavae and f.sp. poinsettiaecola respectively. Two new ff.sp. are created: for E. acalyphoides pathogen, X. ricini f.sp. euphorbiae and for P. niruri pathogen, X. ricini f.sp. phyllanthii.

The creation of a new species (X. heliotropii sp.nov.) is proposed for the Heliotropium pathogen.

The present study shows that many weed plants may be affected with new bacterial strains that can also infect cultivated crops.
Studies on Claviceps purpurea (Fr.) Tul. parasitic on Phragmites communis Trin
Authors: Mantle P. G.
Published: February 2008

Isolates from C. purpurea sclerotia occurring naturally on Phragmites communis usually sporulated vigorously on the culture medium employed, and their failure to produce alkaloid in vitro was associated with a thin white growth form. Such isolates also failed to produce sclerotia on the host plants tested. A variant having a plectenchymatic morphology in vitro and producing a thick pigmented non‐sporulating growth form yielded alkaloid (up to approximately 300μg/ml mainly δ8–9 and δ9–10 lysergic acids and chanoclavine) in surface or submerged culture and developed typical ergot sclerotia (containing 0·2‐0·4% alkaloid, mainly ergotoxine and ergotamine) in vivo.

Improved alkaloid yield in vitro was obtained from a strain reselected after passing through a parasitic phase.

Aetiological aspects of the P. communis ergot are discussed.
Experiments on integration of chemical and biological control of aphids on brussels sprouts
Authors: WAY M. J. , MURDIE G. , GALLEY D. J.
Published: February 2008

Two field experiments were made to test whether natural enemies would take over control of brussels sprouts aphids at the time when protection from a selectively acting, soil‐applied systemic insecticide, menazon, began to fail.

The natural enemies, notably Syrphidae, proved ineffective against Brevicoryne brassicae L. despite advantages given by the insecticide and by close planting, which greatly increased the ratio of numbers of syrphid eggs and larvae to aphids. Thus, development of the aphid population was little altered when infested plants were kept free of most natural enemies by hand removal.

I lb/acre (1–12 kg/ha) of menazon applied as spot treatments to the soil at planting‐out time decreased the number of overwintering parasite mummies by 70 % but such ‘mortality’ was compensated for by decreased mortality from hyperparasites and other causes, so the numbers of adults of the primary parasite Diaretiella rapae (McIntosh) which emerged in the spring were similar to those from untreated plots. Soil cultivation in winter drastically decreased the numbers of emerging adult primary parasites, hyperparasites and syrphids.

The menazon treatment designed for integrated control (1 lb/acre) seemed too unpredictable in action, e.g. less effective in dry than in damp conditions, to provide the hoped‐for chemical control needed until natural enemies became abundant. Menazon at 4 lb/acre (4·48 kg/ha) protected the crop throughout the growing season and bioassays showed that menazon or its toxic derivatives continued to occur in leaves during cool periods in winter and also in the following April‐May nearly 1 year after application. The same amount of menazon per unit area of crop was less effective on 1 ft 6 in (45·6 cm) spaced than on 3 ft (91·2 cm) spaced brussels sprouts plants.
The potentiation between thanite and arprocarb in their action on houseflies
Authors: HEWLETT P. S.
Published: February 2008

There was considerable potentiation between thanite and arprocarb in their actions on an insecticide‐susceptible strain of houseflies. The isobole at the LD 50 level was asymmetric, which was to be expected, since thanite probably potentiates arprocarb but not vice versa. The joint action ratio, i.e. the maximum actual potency of the jointly acting insecticides relative to what their joint potency would be if they showed additive action, was about 4·6 (apart from in one aberrant experiment). Thanite appears to potentiate arprocarb less than it potentiates isolan or m‐iso‐propylphenyl N‐methylcarbamate.
The multiplication and spread of sacbrood virus of bees
Authors: BAILEY L.
Published: February 2008

Sacbrood virus multiplied without causing symptoms in adult bees when it was injected into them or when it was fed to young individuals. More virus accumulated in heads of infected bees than elsewhere in their bodies, and much was in their hypopharyngeal glands. The extract of each infected head contained about 102medial lethal doses (LD 50s) of sacbrood virus for larvae when given in their food. The infective dose of sacbrood virus by injection for adults was about 10‐4of the LD 50 in food for larvae. The infective dose by mouth for adults was about 102LD 50s for larvae, but bees older than 4–8 days could not be infected this way. Infection did not spread between adults but is probably transmitted in nature from infected adults to larvae and back to young adults that ingest remains of larvae killed by sacbrood. The youngest adult bees infected with sacbrood ate little pollen and lived only about 3 weeks in the laboratory, as did bees receiving no pollen, whereas bees fed with ample pollen lived 9 weeks.
The control of Aphis fabae Scop, on spring‐sown field beans (Vicia faba L.)
Authors: GOULD H. J. , GRAHAM C. W.
Published: February 2008

Disulfoton or phorate granules or demeton‐S‐methyl, menazon and vamidothion sprays, applied once in early June as preventive treatments before heavy aphid colonies developed, gave good control of Aphis fabae Scop, on field beans. Phosalone gave relatively poor results and DDT was ineffective. Applications in June to crops sown in February and early March were made with minimal wheel damage to the crop and are known to be less harmful to bees than sprays at flowering time. Eradicant treatments with demeton‐S‐methyl and dimethoate sprays or with disulfoton or phorate granules on heavily infested plants during flowering were also effective, but menazon was less satisfactory. These eradicant sprays are likely to be harmful to bees, and wheel damage in late June reduced yield by 1–2 cwt/acre (125–250 kg/ha).

Peak populations of 3000 aphids/plant in early July reduced yield by 6 cwt/acre (750 kg/ha) in one trial.
The insect faunas of pear and apple orchards and the effect of windbreaks on their distribution
Authors: LEWIS T. , SMITH B. D.
Published: February 2008

Two coir netting windbreaks, each 7 m tall and 46 m long, were erected in a pear and an apple orchard, to try to increase the number of insect pollinators present at blossom time. The flying insects were sampled with suction traps and insects visiting trees were sampled by examining marked clusters of blossom.

The mean aerial density was calculated for each of the forty‐two taxa, mainly families, identified from the aerial population. There were about 50% more insects flying in the pear than in the apple orchard. The distribution of flying insects was greatly affected by the windbreaks, and the sheltered zone contained three times as many of most species, and more than three times as many Chironomidae, Psychodidae and Bibionidae as elsewhere.

Small flies were the most abundant insects in the air, in both orchards. In the pear orchard large insects comprised only about 7 % of the total aerial population, of which honeybees constituted 0–7% and wild bees 0–3%.

By contrast, large insects accounted for a greater proportion of the population on blossom. The reasons for this are discussed. On apple blossom Syrphidae and honeybees were the insects most often seen, and on pear blossom Bibionidae and Mycetophilidae.
Laboratory and field tests in 1966‐67 on chemical control of wireworms (Agriotes spp.)
Authors: GRIFFITHS D. C. , SCOTT G. C. , LOFTY J. R. , ROBERTS P. F.
Published: February 2008

Of sixteen compounds applied to soil in laboratory tests, azinphos‐ethyl, P2188 (O,O‐diethyl S‐chloromethyl phosphorothiolothionate), ‘Dursban’ (O,O‐diethyl O‐3,5,6‐trichloro‐2‐pyridyl phosphorothioate), P1973 (S‐(N‐methoxycarbonyl‐N‐methylcarbamoylmethyl) dimethyl phosphorothiolothionate), B77488 (O,O‐diethylphosphorothioate O‐esterwith phenylglyoxylonitrile oxime) and R42211 (O,O‐diethyl O‐(2‐diethylamino‐6‐methyl‐pyrimidin‐4‐yl) phosphorothioate) killed wireworms when first tested, but in second tests with the same soils only ‘Dursban’, P2188 and B77488 did so. Treating seeds with ‘Dyfonate’ (O‐ethyl S‐phenyl ethyl phosphonodithioate) or with ethion/γ‐BHC mixtures killed few wireworms.

Three field trials compared the organophosphorus insecticides ‘Dursban’, ‘Dyfonate’ and phorate with organochlorine standards. In trials with barley and potatoes the standard was 3 lb a.i./acre (3·36 kg/ha) of aldrin. The organophosphorus compounds increased plant stands of barley almost as much as aldrin, although they killed fewer wireworms; and they protected fewer potato tubers from wireworm damage. The third trial compared the organophosphorus compounds with 0·5 lb a.i./acre (0·56 kg/ha) γ‐BHC sprayed on a site drilled with sugar beet seed dressed with dieldrin. The γ‐BHC increased plant stands almost as much as did 3 lb a.i./acre of the organophosphorus insecticides, and killed as many wireworms.
Changes in a Heterodera rostochiensis population through the growing season
Authors: EVANS K.
Published: February 2008

Changes in the numbers of all stages of Heterodera rostochiensis in plants and soil were studied in a potato crop growing on infected land. Hatching and invasion occurred early in the season, when plants were very young and temperatures were below those considered necessary for hatching and invasion in Long Island, U.S.A. More larvae hatched from cysts nearer than away from potato roots. Males were abundant during June and July, when fertilization probably occurs. Many new cysts appeared during late June and early July. In May/June, there were many larvae in the roots of young plants but later there were few; a slight increase during August probably indicated a small second generation. The larvae for this second invasion may have come from the most recently formed cysts, which may have been stimulated to hatch either by root exudates or by substances from other soil organisms.