bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory studies on the life‐histories of four enchytraeid worms (Oligochaeta) which inhabit sewage percolating filters
Authors: LEARNER M. A. 
Published: February 2008

SUMMARYThe life‐histories of four enchytraeid worms, Lumbricillus rivalis, Enchy‐traeus coronatus, E. buchholzi, and E. albidus which occur in sewage percolating filters, were studied under laboratory conditions at 8, 15 and 20°C.The number of ova per cocoon varied from 0 to 50 (L. rivalis), 0 to 33 (E. coronatus), 1 to 9 (E. buchholzi) and 0 to 22 (E. albidus). The mean number of ova per cocoon was highest at 15°C for all species except E. coronatus which had a highest mean value at 8°C. The number of ova in cocoons was correlated with cocoon length (P < 0.001) for all species.Cocoon production usually increased with temperature ranging from 0.8 cocoons per adult per week at 8°C to 2.0 at 20°C for L. rivalis, and from 1–4 to about 2.6 for E. coronatus and E. buchholzi.The total number of ova produced by each E. coronatus (350 at 8°C to 550 at 20°C) was similar to that produced by each L. rivalis (600 at 8°C to 350 at 20°C) and was about five times greater than the total numbers produced by the other two species. Cocoon and ova production and the number of ova per cocoon varied with the age of the adult, usually reaching a peak soon after maturity.Hatching success was low and generally 40–50 % of ova failed to develop; subsequent mortality among immature worms was about 10–20%.Growth was more rapid at the higher temperatures; L. rivalis matured in about 26 days at 20°C, the clitellum forming when the worm was 13–14 mm long; data for the other species are 13 days and 5–6 mm (E. coronatus); 16 days and 3–4 mm (E. buchholzi); 28 days and 13–14 mm (E. albidus). The maturation period at 8°C was at least twice that at 20°C.The generation period (cocoon to cocoon) was about a month at 20°C for all species except E. albidus (2 months), but as some species had longer reproductive periods than others the actual number of generations per year was highest in E. buchholzi, 7.0 per year, and lowest in E. albidus, about 3.3 per year, At 8°C all four species had between 1.4 and 2.8 generations a year.A comparison of expected and observed population densities of L. rivalis and E. coronatus in a sewage percolating filter showed that neither achieved values approaching their potential summer densities although ample food was apparently available.Of the four species studied only E. buchholzi produced viable ova without pairing.
The biology of Peronospora viciae on pea: the development of local and systemic infections and their effect on vining yield
Authors: PEGG G. F. , MENCE M. J. 
Published: February 2008

SUMMARYThe development of infection by Peronospora viciae (Berk.) Casp. was studied in field and plot experiments during 1967, 1968 and 1969. Numbers of primary systemically infected plants appeared shortly after emergence and reached a maximum by the end of May. Such plants acted as primary infectors and did not survive more than 3 weeks.Maximal sporangial release occurred between 06.00 and 08.00 h BST with a peak at 07.00 h, after 1–2 h insolation. Inoculation of leaves at 10.30 h resulted in greater infection than inoculation at 20.00 h. The result suggested a possible maturation requirement of sporangia following release from the sporangiophore.Initially the spread of foliar (local lesion) infection in the crop was sporadic and localized in cvs. Jade, Gregory, Dark Skinned Perfection (D.S.P.) and Frühe Kleine Pfälzerin (F.K.P.) during the 3 years. The number of plants of all cvs. with foliar infection reached 100% by mid‐June. Lesions rarely exceeded 15% of the leaf and stipular area of the mature plant. No effect of foliar lesions, at the highest level of infection, in haulm or seed fresh weight could be detected in cvs. F.K.P., Jade and D.S.P.Secondary systemic infection occurred sporadically in field crops usually with dense haulm growth. Plants of Jade with systemic infection were rated according to the number of nodes affected. There was a small but significant increase in haulm and seed fresh weight in plants with up to two nodes affected. But plants with three to five nodes showed a progressive reduction in the yield of green seed (resulting from a reduction in the number of podding nodes) and in pod size and haulm fresh weight. Total losses in Jade during 1968 and 1969 with all grades of infection did not exceed 4 % of the green seed crop. Systemic infection in some plants resulted in the death of the apex and the production of healthy, normally podding tillers. Such plants had no commercial value due to delayed maturation. Pod infection in Jade occurred largely independently of systemic symptoms: the overall level during 1969 did not exceed 16 % and only 2 % were severely infected.Total losses (from both systemic and pod infection) in Jade during 1968 and 1969 represented only a negligible part of the crop.
The effect of soil fumigation with D‐D on the yields of sugar beet and other crops
Authors: COOKE D. A. , HULL R. 
Published: February 2008

SUMMARYAn experiment in a field where sugar beet in 1965 had suffered from Docking disorder caused by Longidorus attenuatus tested the effect of fumigating the soil with 3741/ha D‐D and two amounts of nitrogen fertilizer on different crop sequences between 1966 and 1969. Although severe Docking disorder did not recur in sugar beet, fumigation increased yield in each of the three following years. Yield of barley was increased for 4 yr and of wheat, potatoes and ryegrass for 1 or 2 yr after treatment. All plant parasitic nematodes were controlled by the first fumigation and the numbers of those in unfumigated plots 3 yr after treatment. Fumigation also largely prevented infection of sugar beet by the fungus Helicobasidium purpureum.
Transmission of raspberry ringspot virus by Longidorus caespiticola, L. leptocephalus and Xiphinema diversicaudatum and of arabis mosaic virus by L. Caespiticola and X. diversicaudatum*
Authors: Valdez R. B. 
Published: February 2008

SUMMARYUsing a micro‐container inoculation technique, an English strain of raspberry ringspot virus (RRV) was transmitted by Longidorus caespiticola Hooper, L. leptocephalus Hooper and Xiphinema diversicaudatum (Micol.) to petunia test plants. RRV persisted in starved X. diversicaudatum for at least 10 days. From a mixed infection of RRV and a typical strain of arabis mosaic virus (AMV), batches of fifty X. diversicaudatum transmitted both viruses, but AMV the more readily, whereas batches of twenty‐five L. caespiticola transmitted both viruses with equal facility.
Effects of Pyrenochaeta lycopersici infection on nutrient uptake by tomato plants
Authors: GOODENOUGH P. W. , MAW G. A. 
Published: February 2008

SUMMARYThe growth of young tomato plants in nutrient solution or in soil and infected with Pyrenochaeta lycopersici Schneider & Gerlach, the cause of tomato brown root rot, was decreased relative to that of uninfected plants. The roots of plants grown in nutrient solution and infected with a mycelial mat of the pathogen contained lower concentrations of potassium and higher concentrations of calcium than roots of uninfected plants. These changes occurred largely in the visibly affected tissue, as opposed to the root system as a whole. The concentrations of magnesium, total nitrogen and phosphorus in the roots of infected plants were not significantly different from those of control plants.Magnesium, nitrogen and phosphorus concentrations in the tops of infected plants were also not significantly different from those of healthy plants, but no consistent changes were found in the concentrations of calcium and potassium.Young tomato plants grown in soil infested with P. lycopersici contained lower concentrations of phosphorus and potassium in the tops than plants grown in sterilized soil. It was not possible to separate intact damaged root systems of infected plants from soil.The changes in composition found in infected plants are discussed in relation to possible methods of manipulating the nutrition of the plant to offset the effects of the disease on crop yield.
Storage losses of taro corms in the British Solomon Islands Protectorate
Authors: GOLLIFER D. E. , BOOTH R. H. 
Published: February 2008

SUMMARYIn two storage trials, corms of taro (Colocasia esculenta) decayed and became unfit for human consumption after 1 to 2 weeks. There were three fairly distinct types of rot: A dry rot caused by Fusarium solani, a spongy black rot caused by Botryodiplodia theobromae, and a Sclerotium rot caused by S. rolfsii. Although it was found that, under humid conditions, all three fungi could penetrate and rot undamaged corms most natural infection is thought to occur through wounds. None of the pathogens rotted corms at low humidity.
Histology of Hevea roots infected by Forties lignosus
Authors: PERIES O. S. , IRUGALBANDARA Z. E. 
Published: February 2008

SUMMARYInspection of naturally or artificially infected Hevea roots showed that Forms lignosus can penetrate undamaged roots directly, but does so more readily through wounds or natural openings like lenticels, or through the bases of lateral roots and bark scales. Therefore, Pomes‐infected trees should be identified by leaf symptoms rather than by uncovering and inspecting roots, as this generally leads to root injury, which facilitates fungal penetration.Initial fungal entry into host tissue appears to be by mechanical pressure alone, but deeper penetration is through the action of extracellular enzymes. The fungus remains intercellular in the cortex but is intracellular in the woody tissue. Ray cell walls are penetrated mechanically, but the xylem through pits. The time taken for various stages of infection to occur is assessed.The amount of damage done by the fungus to roots and the blocking of xylem vessels by tyloses suggest that yellowing, curling and buckling of leaves on infected trees are drought symptoms and not a reaction to fungal toxins. The host reacts to the invasion of the cortex by forming a cork cambium and to the invasion of the woody tissue by blocking individual cells with phenols and resins, which could be important when breeding disease resistant Hevea root stocks.
The elimination of viruses from Narcissus tazetta cv. Grand Soleil d'Or, and rapid multiplication of virus‐free clones
Authors: STONE OLWEN M. 
Published: February 2008

SUMMARYArabis mosaic virus and narcissus degeneration virus were eliminated from Narcissus tazetta L. cv. Grand Soleil d'Or by meristem‐tip culture. Cultures grew equally well in two liquid nutrient media, but tubes 25times75 mm size and temperature c. 12 oC were optimal for growth and survival. Virus‐free bulbs grew more vigorously than infected bulbs, and gave more and larger flowers with a better colour. To increase the normal multiplication rate, either sector cuts were made in the basal plate, or bulbs were divided into chips (c. 1 g), before planting. Multiplication was greater by chip‐cutting. Five virus‐free bulbs were propagated to over 2000 in 8 years; theoretically, 20000000 bulbs should be produced in a further 5–6 years, sufficient to replant the Isles of Scilly with virus‐free stock.
Effects of growing resistant potatoes with gene H1 from Solarium tuberosum ssp. andigena on populations of Heterodera rostochiensis British pathotype A
Authors: TRUDGILL D. L. , PARROTT DIANA M. 
Published: February 2008

SUMMARYPure pathotype A populations of Heterodera rostochiensis produce a few females on ex andigena hybrids with the H1 gene for resistance. As the proportion of larvae able to become female on ex andigena hybrids was not increased by reproducing the nematodes on such hybrids for 3 years, these females seem not to be genetically different from the rest of the population. The proportion increased rapidly when the initial population contained a few pathotype (species) E nematodes but again no increase in the proportion of pathotype (species) A larvae able to become female on ex andigena was detected and pathotype E replaced pathotype A.
Causes and development of hollow heart in pea seed
Authors: PERRY D. A. , HARRISON J. G. 
Published: February 2008

SUMMARYPredisposition to hollow heart in pea seeds (Pisum sativum L.) is caused by high ambient temperatures during their maturation on the plant, and by drying them when immature. Symptoms develop during germination, and the proportion of seeds affected in any sample depends on the rate of water imbibition. It is suggested that predisposed cells die during rehydration.
Effects of hollow heart on growth of peas
Authors: HARRISON J. G. , PERRY D. A. 
Published: February 2008

SUMMARYHollow heart of pea seed (Pisum sativum L.) delayed germination and reduced seedling growth. Plants from seeds with the disorder were smaller and yielded less than those from normal seeds. Affected cells were dead, but immobilization of starch reserves within them could not wholly account for the reduced growth and evidence suggested the presence of a germination and growth inhibitor.
Yield compensation in gappy potato crops and methods to measure effects of fungi pathogenic on seed tubers
Authors: HIRST J. M. , HIDE G. A. , STEDMAN O. J. , GRIFFITH R. L. 
Published: February 2008

SUMMARYPathogens damage potatoes in so many ways and at so many stages of cropping, transport and storage that it is difficult to estimate their total effect. This paper describes methods used to measure how fungal pathogens affected crop health and yield, and experiments that measured how much the yield lost through gaps was compensated by extra growth of neighbouring plants.Some tubers in stocks were diseased, so healthy controls were not available and contrasts could be made only by selecting grades differing in symptom severity. The differences measured represented only part of the damage because many infections are symptomless, and vigorous plants compensate for the small yields of weak or absent neighbours.Plots gapped randomly to varying degrees at emergence or flowering showed that yields were decreased by 0–332 (± 0–129) %and“833 (± 0–094) % respectively, for every 1 % of plants removed. When up to 24 % of plants were removed the regression of percentage gaps on yield did not become significantly non‐linear.
Effects of skin spot (Oospora pustulans) on potatoes
Authors: HIDE G. A. , HIRST J. M. , STEDMAN O. J. 
Published: February 2008

SUMMARYKing Edward and Majestic seed potatoes selected as ‘clean’ (macroscopically symptomless), moderate and severe according to the extent of skin spot were planted in field experiments at Rothamsted between 1964 and 1968. Usually crops from ‘clean’ and moderately infected seed did not differ detectably in growth or yield. Plants from severely infected seed tubers emerged more slowly, had fewer stems and yielded less (King Edward 20 %, Majestic 13 %). Seed infection also affected tuber size distribution; severely infected seed of King Edward yielded almost 4 tons/acre less of 1 1/4‐2 1/4 in tubers and Majestic, 1 ton/acre less of these and 2 tons/acre less 2 1/4‐3 1/4 in tubers. However, the total yield from diseased seed stocks was only slightly less (King Edward, o‐6 ton/acre and Majestic o‐8 ton/acre) than the yields from the ‘clean’ tubers selected from them. Seed severely infected by Oospora pustulans often increased infection of the progeny tubers, and usually decreased their infection by Rhizoctonia solani and sometimes by Helmintho‐sporium solani.Another series of experiments compared King Edward seed tubers classified according to the number of live eyes showing in March. Seed with one, two, three and more live eyes yielded equally. About half the tubers without live eyes in March eventually produced plants, but late, with few stems and giving only half the yield of seed with three or more live eyes. Surprisingly, the progeny tubers from seed without live eyes were least infected by O. pustulans, R. solani and H. solani.Progenies of King Edward and Majestic seed from a common source grown on seven widely separated farms were infected more in 1963 than in 1964, but in each year infection differed widely between farms. Often where O. pustulans was common, R. solani was scarce and vice versa. By contrast, when King Edward stocks very differently infected by O. pustulans were grown at Rothamsted their progenies were almost uniformly infected by O. pustulans and R. solani.
The effect of time of harvest on the viability and pre‐emergence mortality in soil of pea (Pisutn sativum L.) seeds
Authors: MATTHEWS S. 
Published: February 2008

SUMMARYA series of harvests from field plots of peas showed that the younger seeds were at the time of harvest the lower was their percentage viability and the greater their percentage mortality in soil. Young seed also showed a high degree of solute leaching into steep water and had a high moisture content at harvest compared with older seeds. Heavy rainfall just prior to harvesting reduced the percentage viability of the dried seed and increased the moisture content of the seed at harvest as well as the leaching of solutes from the dried seed into steep water. Comparisons of moisture content at harvest and seed condition after drying suggested that cotyledons and embryo axes were only able to withstand enhanced drying after removal from the plant if the seed moisture content had already begun to decline whilst the seed was still on the plant.
The photosynthesis of ryegrass leaves grown in a simulated sward
Authors: WOLEDGE JANE 
Published: February 2008

SUMMARYPlants were taken from simulated swards of perennial ryegrass (Lolium perenne) grown in a controlled environment and the rates of photosynthesis of the youngest fully expanded leaves, and the second and third youngest leaves on the same tillers were measured. The youngest leaves had the highest rates and the third the lowest, with the second leaves intermediate.The rate of photosynthesis in bright light of successive youngest expanded leaves decreased as the swards increased in leaf area, but did not when plants were grown so that the main stem was not shaded. When plants were grown at different densities and the photosynthetic rates of leaves of a particular ontogenetic rank were measured, it was found that leaves on plants from higher densities had lower rates of photosynthesis. Also leaves on plants grown in bright light had higher photosynthetic rates than those on plants grown in dim light.It is concluded that the decline in the photosynthetic capacity of successive leaves in a rapidly growing simulated sward is due to the intense shading to which they are subjected during their expansion.
Distribution of cabbage root flies in brassica crops
Authors: FINCH By S. , SKINNER G. 
Published: February 2008

SUMMARYChanges in the distribution of adult cabbage root flies were determined in 0–05‐0‐4 ha brassica plots during 1970 and 1971 using yellow water‐traps.The three generations of flies occurred at similar times in both years and the numbers caught generally decreased from the first to the third generation. In resident populations, the numbers of males and females declined by 70 and 40% respectively, between the second and third generations. When there was no decline, immigration presumably compensated for flies trapped or otherwise lost. The results confirmed that male cabbage root fly movement is trivial, that wind has little effect on distribution at a brassica plot and that females move into the crop independently of males. They failed to confirm that females aggregate markedly at hedgerows or fences, that they spend little time in the crop or that they regularly return to hedgerows.Differences in the dispersal behaviour of the male and female flies were reflected in the numbers caught. Some males dispersed actively during the first 2 weeks after emergence but many were displaced slowly downwind. Once at a plot, wind appeared to have little effect on distribution of young males, but older males tended to shelter just downwind of the hedge. Relatively few males were caught near hedges but they tended to aggregate along the crop‐interfaces, particularly during the first generation. Plot size did not appear to influence the pattern of fly distribution greatly. Females dispersed more actively than males and were generally more uniformly distributed through the crops even during periods of immigration. Gravid females entered an isolated plot without accompanying males, inferring that they are migratory and mate near the site of emergence. Female distribution was not related to the stage of ovarial development except during maximum oviposition when those that had laid some eggs visited the hedgerow. Aged females became progressively easier to capture and usually died in the crop.
Effects of sublethal doses of pesticides on the oviposition behaviour of Encarsia formosa
Authors: IRVING By S. N. , WYATT I. J. 
Published: February 2008

SUMMARYFemale Encarsia formosa were enclosed in artificial arenas containing twenty‐five Trialeurodes vaporariorum scales on a Cellophane substrate. Either the substrate or the scales were previously treated with chemicals. The number of oviposition wound marks on the scales was used as a measure of effect on parasite behaviour. The insecticides, tetradifon and γ‐BHC, had their greatest effect when applied to scales. The fungicides, benomyl and dichlofluanid, were more active on the Cellophane. Pirimicarb applied to the scales decreased oviposition, but greatly increased it when applied to the substrate. It is concluded that even sublethal amounts of pesticides may seriously impair the effectiveness of this parasite in commercial biological control.
The toxicity to foraging honeybees, Apis mellifera, of endosulfan, malathion and azinphos‐methyl applied to flowering oil seed rape, Brassica napus
Authors: NEEDHAM P. H. , STEVENSON J. H. 
Published: February 2008

SUMMARYWettable powder and emulsifiable concentrate formulations of endosulfan and azinphos‐methyl and an emulsifiable concentrate of malathion were sprayed on oil seed rape in full flower to assess their relative toxicities to foraging honeybees. Endosulfan was very much safer to honeybees than the two organophosphate insecticides, but there was little difference between the two types of formulation.
The effect of fungicides on incidence of Sporobolomyces spp. and Cladosporium spp. on flag leaves of winter wheat
Authors: JENKYN J. F. , PREW R. D. 
Published: February 2008

SUMMARYSprays of benomyl, thiophanate methyl, NF 48 and captafol considerably decreased incidence of Sporobolomyces spp. and Cladosporium spp. on flag leaves of winter wheat. BAS 3170 F affected both genera but much less. Tridemorph and triforine had relatively little effect on Sporobolomyces spp. but tridemorph did decrease Cladosporium spp. Sandoz 52.133 affected only Cladosporium spp. and ethirimol affected neither genus.
Growth and wilting of radish seedlings, Raphanus sativus, infested with the aphid, Myzus persicae
Authors: FORREST J. M. S. , HUSSAIN A. , DIXON A. F. G. 
Published: February 2008

SUMMARYAfter 10 days of infestation by the aphid Myzus persicae growth of radish seedlings was reduced by 38 %, and the volume of sap bleeding from the stumps of cut stems of infested seedlings was 4% of that exuding from the stumps of uninfested seedlings of the same age. Diminished bleeding could not be accounted for by the 52 % reduction in the weight of the roots of infested seedlings. After 14 days of infestation, necrotic patches developed along the veins of the cotyledons which yellowed noticeably. If freed of aphids the seedlings subsequently resumed growth and their was an increase in the volume of bleeding sap produced by their cut stems. Symptoms associated with aphid infestation cannot be attributed either to virus disease or initially to exhaustion of the seedling's carbohydrate and nitrogen reserves. Possible causes of the symptoms described are discussed.