bluuebunny/crossref_metadata_2025 huggingface dataset:
Long term water stress inactivates Rubisco in subterranean clover
Authors: MEDRANO H. , PARRY M A J , SOCIAS X. , LAWLOR D W
Published: February 2008

In long‐term field experiments, during consecutive years, microswards of subterranean clover were irrigated to minimise water deficits or subjected to progressively increasing drought over 30 days. Both leaf water potential and relative water content steadily decreased during the experiments. Plants affected by drought grew more slowly and photosynthesis was decreased. Photosynthetic rate (A) and Rubisco were analysed in relation to midday water potentials and relative water contents. The difference in A between draughted and irrigated plants increased progressively, in part as a result of decreased stomatal conductance and CO2 concentration within leaf (Ci). However, A‐Ci curves suggest that the photosynthetic capacity in plants experiencing long‐term stress was reduced by 50% when compared with irrigated plants. Drought decreased both the initial and the total Rubisco activity per unit area in a similar way but did not reduce the amount of Rubisco protein per unit leaf area. Thus, the specific activity of Rubisco, rather than its activation state, decreased suggesting that under water stress the active sites were blocked by inhibitors.
Attachment microbes antagonistic against Botrytis cinerea—biological control and scanning electron microscope studies in vivo
Authors: COOK DARRYL W M , LONG PETER G , GANESH SIVA , CHEAH L‐H
Published: February 2008

Bacteria and yeasts, selected by an attachment assay for their ability to adhere to Botrytis cinerea hyphae or conidia, were evaluated for biocontrol potential against B. cinerea on excised tomato stems. Eight of the 12 bacteria and seven of the eight yeast isolates conferred 90% to 100% biocontrol activity when antagonist populations were applied at three to 80 times the pathogen inoculum density. Biocontrol was maintained at similar levels when biocontrol agent (BCA) application was delayed up to 48 h after pathogen challenge. Scanning electron microscopy showed extensive colonisation of B. cinerea mycelium or conidia by many of these isolates and also evidence of pathogen degradation.

The biocontrol efficacy and potential for the assay are discussed with respect to cell‐to‐cell adhesion as a vehicle to deliver antagonistic mechanisms to highly specific pathogen sites.
The phenology of Lygus rugulipennis, the European tarnished plant bug, on late‐season strawberries, and control with insecticides
Authors: EASTERBROOK M A.
Published: February 2008

The phenology of Lygus rugulipennis, the European tarnished plant bug, was studied in fields of strawberries producing late‐season (July to September) crops. Adults invaded fields in small numbers, mainly in July. Large numbers of nymphs were found in late July and early August; these matured into adults from late August. Adults formed the overwintering population; some remained in strawberry fields but left in spring to feed on other host plants. All the insecticides tested, i.e. malathion, chlorpyrifos, heptenophos, cypermethrin, bifenthrin and trichlorfon, gave good short‐term control of nymphs.
Biological control of the black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) with entomopathogenic nematodes (Nematoda: Rhabditida)
Authors: KAKOULI‐DUARTE T. , LABUSCHAGNE L. , HAGUE N G M.
Published: February 2008

Trials conducted under glasshouse conditions showed that control of Otiorhynchus sulcatus larvae in strawberry plants can be effective using Steinernema carpocapsae and Heterorhabditis megidis, given that temperature and moisture extremes are avoided. In field experiments, the double line T‐Tape® drip irrigation system performed better than the single line T‐Tape® system, effectively distributing the nematodes along and across strawberry raised beds, and placing them close to the root zone where O. sulcatus larvae feed. As soil temperatures are satisfactory for nematode infectivity from late spring to early autumn, nematode applications were aimed at late instar larvae during spring, and early instar larvae during summer. Late summer field treatment with S. carpocapsae induced 49.5% reduction of the early instar larvae, and field application of the same nematode species in late spring resulted in 65% control of late instar larvae. In the same trial, spring application of H. megidis caused 26% mortality of late instar larvae of O. sulcatus.
The use of chemicals, antagonists, repellents and physical barriers for the control of Lycoriella auripila (Diptera: Sciaridae), a pest of the cultivated mushroom Agaricus bisporus
Authors: WHITE P F.
Published: February 2008

The sciarid, Lycoriella auripila, is a serious pest of commercial mushroom production. A series of trials demonstrated that the use of early, specifically‐targeted, treatments of insecticides and/or antagonists and repellents, which distance treatment time from crop harvest, have the potential to play a useful part in the control of initial and subsequent generations of this pest. Of the treatments examined, those involving a drench treatment of the compost at filling (before pasteurisation) proved to be the most effective. Cyromazine and diflubenzuron were the most active insecticides tested, with cyromazine achieving a superior level of control of the initial infestation. Repellents and antifeedants were also effective, with calcium oxalate and sinapic acid both achieving about 50% control when applied at filling. Treatments applied later during the production cycle, unless in combination with a treatment at filling, were progressively less effective at controlling both the initial sciarid infestation and later generations of larvae. Multiple treatments caused greater reductions in fly populations than did the single treatments and continued to do so throughout the cropping cycle, the greatest reduction in the initial generation (79%) occurring with a triple treatment of cyromazine. With the exception of some diflubenzuron treatments, those that were effective resulted in increases in yield. The use of a physical paper barrier caused significant increases in both fly numbers and total yield.
Black Sigatoka disease of banana: spatial and temporal variability in disease development
Authors: SMITH M C. , RUTTER J. , BURT P J A. , RAMIREZ F. , GONZALEZO E H
Published: February 2008

Field observations of black Sigatoka disease symptom development were made on banana plants from four sites (30 m apart) within an unsprayed plantation of dimensions 100 m × 200 m in Costa Rica during two field visits: October 1993‐February 1994 (wet to dry season) and April‐September 1995 (dry to wet season). From these observations, estimates of the symptom‐free period and the average rate of symptom development (during the symptomatic phase) were made for each leaf. No significant differences were found between sites in rates of symptom development in either 1993/94 or 1995, or in symptom‐free period for 1993/94 (data were not suitable to test for between‐site differences in symptom‐free period for 1995). This suggests that forecasts would not have to take into account differences in location within this small plantation. Symptom‐free time decreased over the 1995 observation period, was less than in 1993/94 and correlated with increases in hours per day at a relative humidity (r.h.) of 100%. Because plantations may be sprayed many times per year, forecasts have to be sensitive to short‐term changes in disease severity. Seasonal trends in some more rapidly‐and easily‐assessed characters (number of disease‐free leaves, disease scores of specific leaves and average disease scores of entire plants) accurately reflected trends in the more detailed observations of symptom severity, hours per day at 100% r.h. and numbers of leaves unfurling per unit time. This suggests that these could be used as indicators of changes in disease severity in a forecasting scheme.
Studies on population dynamics and spatial distribution of leafhoppers in vineyards (Homoptera: Cicadellidae)
Authors: BOSCO D. , ALMA A. , ARZONE A.
Published: February 2008

Thirty‐two species of Cicadellidae, including the Macropsinae, Agalliinae, Penthimiinae, Aphrodinae, Cicadellinae, Typhlocybinae and Deltocephalinae, 10 of which were already known as phytoplasma vectors, were captured in vineyards using yellow sticky traps. Adult population dynamics of the most abundant species of Penthimiinae and Deltocephalinae were studied over the whole growing season. Penthimia nigra was captured in May and June, Anoplotettix fuscovenosus in June‐August, Fieberiella florii in August‐October, Macrosteles sexnotatus in May and October, Scaphoideus titanus in July‐September, Thamnotettix spp. (Th. confinis, Th. dilutior, Th. exemtus, Th. zelleri) in April‐June, while Euscelidius variegatus, Neoaliturus fenestratus, Platymetopius major and Psammotettix spp. (P. alienus, P. confinis) were trapped throughout the growing season. The aggregation level of the above species was investigated by means of Taylor's power law. A. fuscovenosus showed a nearly random distribution in vineyards (0.95 < b < 1.11), while N. fenestratus, P. major and S. titanus were strongly aggregated (1.32 < b < 1.81). The other species showed intermediate levels of aggregation (1.12 > b < 1.32). The results indicate that at least six Deltocephalinae species, A. fuscovenosus, E. variegatus, F. florii, M. sexnotatus, N. fenestratus and S. titanus, known as phytoplasma vectors and commonly found in vineyards, could play a role in Grapevine Yellows (GY) epidemiology. GY transmission trials with these species are needed.
Transmission characteristics of Spiroplasma citri and its effect on leafhopper vectors from the Circulifer tenellus complex
Authors: ALMEIDA LYNETTE DE , RACCAH B. , KLEIN M.
Published: February 2008

Several leafhopper variants of the Circulifer tenellus complex were collected in “citrus stubborn” affected areas in Israel. Two of these variants transmitted the Spiroplasma citri to Matthiola incana after being injected with the disease agent. The variant from Atriplex halimus was designated Circulifer tenellus‐A (CTA) and the variant from Portulaca oleracea was designated Circulifer tenellus‐? (CTP). Transmission characteristics were determined for both leafhoppers. A high rate of transmission (43.3%) was obtained by single CTA leafhoppers that were injected with the Amiad S. citri isolate from the Upper Galilee, compared with 7% transmission obtained with the CTP leafhoppers. The Gilgal S. citri isolate from the Jordan Valley, was not transmitted by either. Injection was more effective than acquisition access feeding to render the leafhopper infective for both CTA and CTP. The minimum acquisition access period needed for the CTA variant to transmit the Amiad isolate was 1 h. Longer AAPs did not necessarily result in a higher rate of transmission. The minimum incubation period was 6 days and the maximum was 32 days. The LP50 calculated from the logarithmic curve y = 45.74Ln(x)–53.68 was 9.64 days. The minimum inoculation access period (IAP) was lh. The same transmission parameters for the CTP variant could not be determined, as no transmission was obtained even when groups of five‐six insects were placed on a single plant.
Rhabdovirus‐like and closterovirus‐like particles in ultrathin sections of Ribes species with symptoms of blackcurrant reversion and gooseberry veinbanding diseases
Authors: ROBERTS I M , JONES A T
Published: February 2008

In attempts to determine the causal agents of blackcurrant reversion (BCRD) and gooseberry veinbanding (GVBD) diseases of Ribes species, details of the ultrastructure of different kinds of tissue from plants affected with these different diseases were studied. In three of 12 blackcurrant plants affected with BCRD, leaves and flowers of plants showing symptoms typical of the severe (R) form of the disease, contained rhabdovirus‐like particles c. 65–80 nm × 215–485 nm. They were seen most often in the nucleus of cells as single particles but were also found in clusters or rafts. In leaves, these virus‐like particles (VLPs) were present only in cells associated with the xylem parenchyma where they occurred as membrane‐bound clusters within the nucleus. In flowers, they were also found in phloem parenchyma cells in the peripheral cytoplasm and very occasionally in the cytoplasm of epidermal cells. All non‐nuclear VLPs were membrane‐bound, either singly or in groups and the membrane seemed to be part of the endoplasmic reticulum. The proportion of vascular cells containing these VLPs was very low (< 1%). In a few cells, smaller bacilliform particles, c. 40–50 nm × 200–250 nm, were found in the nucleus together with the larger particles. Double‐membrane bodies, detected in fig leaves affected with fig mosaic (the agent of which is also mite‐transmitted), were not detected in any BCRD‐affected plants. In leaf tissue of one of three gooseberry and one of two blackcurrant plants affected with GVBD, two kinds of VLPs were found. Rhabdovirus‐like particles, similar to those in BCRD‐affected material, were present in the nuclei, perinuclear space and cytoplasm of xylem parenchyma cells. They were c. 60–72 nm × 155–230 nm but there was no evidence of the smaller rhabdovirus‐like particles detected in a few cells of BCRD‐affected tissues. The second kind of VLP was found in noncrystalline masses, with a mean centre‐centre spacing of c. 10 nm, in the cytoplasm of phloem cells. These particles, together with other ultrastructural changes, were typical of those reported for aphid‐transmitted closteroviruses. No badnavirus‐like particles, reported previously from GVBD‐affected plants, were observed in any of the plants studied. The significance of these findings in relation to these two important diseases of commercial Ribes species is discussed.
The effect of temperature on viability of imbibed weed seeds
Authors: THOMPSON A J , JONES N E , BLAIR A M
Published: February 2008

Imbibed seed of 10 common arable weeds were placed in trays in initially moist soil and, after imbibing for 2h, heated in ovens/incubators set to 31oC, 42oC, 56oC, 75oC or 100oC for 0.5, 1, 2, 4, 8 or 16 days or at 102oC, 155oC, 204oC or 262oC for 0.5, 1, 2, 5, 7.5 or 10 min. After heating, seeds were incubated for 28 days at 10/20oC or 20/30oC on a 12 h dark/light regime, depending on species, and germination recorded. At the lower temperatures, germination of all species was prevented by temperatures of 75oC or higher for periods of 0.5 days or more. Germination was lower after treatment at 56oC than at 31oC or 42oC for all species except Rumex obtusifolius. The maximum temperature required to prevent germination varied among species and was of greater importance than the duration of heating. Germination was variable with duration of heating. At the higher temperatures, there was very little germination of any species after heating at 204oC for 7.5 min or 262oC for 5 min or more. Seeds were greatly buffered from the air temperature by 3 mm of soil, throughout the shorter duration of heating. The average temperature of the soil, over the 10 min heating required to prevent over 90% germination, varied among species and ranged from 48oC for Avena fatua to 65oC for R. obtusifolius. This work implies that composting systems maintained at 65oC are unlikely to provide an efficient method of weed control. Recommendations for improvement of the laboratory technique are suggested.
Natural resistance to cucumber mosaic virus in lupin species
Authors: JONES R A C , LATHAM L J
Published: February 2008

Ten species of lupins (Lupinus spp.) were tested for resistance to cucumber mosaic cucumovirus (CMV) in field experiments where inoculation was by naturally‐occurring aphid vectors, and in the glasshouse by sap or graft‐inoculation. L. albus and six species of ‘rough‐seeded’ lupins did not become infected with CMV either under intense inoculum pressure in the field or when graft‐inoculated. Two L. hispanicus, 17 L. luteus and four L. mutabilis genotypes became infected with CMV in the field, but no infection was detected in L. hispanicus P26858 or seven L. luteus genotypes. CMV was detected at seed transmission rates of 0.2–16% in seedlings of infected L. luteus, differences in levels of seed transmission between genotypes being significant and relatively stable from year to year. Graft‐inoculation of CMV to plants of six genotypes of L. luteus in which no infection was found in the field induced a systemic necrotic reaction suggesting that the resistance they carry is due to hypersensitivity.

In L. hispanicus accessions P26849, P26853 and P26858, CMV sub‐group II isolate SN caused necrotic spots in inoculated leaves without systemic movement, while sub‐group I isolate SL infected them systemically without necrosis. Another sub‐group I and two other sub‐group II isolates behaved like SL in P26849 and P26853 but infected only inoculated leaves of P26858. This suggests that two strain specific hypersensitive resistance specificities are operating against CMV in L. hispanicus. When plants of L. luteus genotypes that gave hypersensitive reactions on graft‐inoculation were inoculated with infective sap containing two sub‐group I and seven sub‐group II isolates, they all responded like L. hispanicus P26858. A strain group concept is proposed for CMV in lupins based on the two hypersensitive specificities found: strain group 1 represented by isolate SN which induces hypersensitivity with both specificities, strain group 2 represented by the three isolates which induced hypersensitivity only with the specificity present in L. luteus and L. hispanicus P26858, strain group 3 by as yet hypothetical isolates that induce hypersensitivity only in presence of the specificity in L. hispanicus P26849 and P26853 that responded just to isolate SN, and strain group 4 by isolate SL which overcomes both specificities. When F2 progeny plants from crosses between hypersensitive and susceptible L. luteus parents were inoculated with isolate SN, the resistance segregated with a 3:1 ratio (hypersensitive:susceptible), suggesting that a single dominant hypersensitivity gene, Ncm‐1, is responsible. As gene Ncm‐1 had broad specificity and was not overcome by any of the five CMV isolates from lupins tested, it is valuable for use in breeding CMV resistant L. luteus cultivars.
Occurrence of Acremonium endophytes in wild populations of Lolium spp. in European countries and a relationship between level of infection and climate in France
Authors: LEWIS G C , RAVEL C. , NAFFAA W. , ASTIER C. , CHARMET G.
Published: February 2008

Infection with endophytic fungi (Acremonium spp.) was detected in wild populations of Lolium spp. from 15 of 20 European countries. Of 523 populations examined, 38% contained no infection, 48% contained 1–50% infection and 14% contained 51–100% infection. Level of infection was slightly but significantly associated with abundance of Lolium in the sward.

For data from France, significant correlations were obtained between level of infection and five climate variables; the highest correlations were with evapotranspiration (0.66, P < 0.001) and water supply deficit (‐0.66, P < 0.001). A model established using multiple regression analysis and incorporating five climatic variables, accounted for 56% of total variation; water supply deficit alone accounted for 43%. These climatic variables were shown by geostatistical analysis to account for a spatial structure in infection level. Groups of Lolium populations with a high level of infection were located mostly in Mediterranean regions, where stress from summer drought is common.
Positive and negative sense coat protein gene‐mediated protection against poplar mosaic carlavirus in Nicotiana benthamiana
Authors: EDWARDS M L , LIU Y Y , HAWES W S , HENDERSON J. , COOPER J I
Published: February 2008

Plants of Nicotiana benthamiana were transformed with four constructs based on the coat protein gene of a poplar mosaic carlavirus (PMV) isolate from the UK. The four constructs were: the capsid protein coding sequence plus a portion of the adjacent sequence encoding a protein with a molecular mass of 14 kDa (CP14k); the capsid protein coding sequence in the positive sense (CPP); a mutated capsid protein coding sequence (CPM) and the capsid protein coding sequence in the negative sense (CPN). Forty‐one regenerated plants, after selection for their kanamycin resistance, were confirmed by PCR to contain the appropriate sequences. Virus coat protein was detected in small amounts in 50% of the plants transformed with the CP14k or CPP constructs. Primary transformants showed a range of reactions to challenge with two isolates of PMV. These varied from apparently no infection in inoculated or in later‐formed young leaves, as assessed by ELISA, to typical systemic symptoms associated with large amounts of serologically detected virus. There was no correlation between the level of protection against virus infection and the observed accumulation of transgene protein product. Plants were protected whether transformed with the coat protein coding sequence in the positive or negative sense.
Effects of simulated insect damage and weed interference on cotton growth and reproduction
Authors: SADRAS V O
Published: February 2008

Early‐season insect pests of cotton (Gossypium hirsutum L.) crops, including Lepidoptera larvae and mirids, feed on vegetative buds. The loss of vegetative buds transiently delays the plant's development and growth and has the potential to reduce its competitive ability. Yield reductions due to weed interference and insect damage, therefore, could be greater than expected from the additive effects of weeds and damage acting separately. Three varieties, two levels of weed infestation, and two levels of simulated damage were combined in a factorial experiment designed to assess the responses of cotton plants to the combined effects of damage and weeds. Weed treatments were: with (+W) and without weeds (‐W), and damage treatments included: undamaged control (‐D) and damaged plants (+D) which had their active vegetative buds removed at 30 and 49 days after sowing.

Variety and interactions between variety and other factors were normally nonsignificant for all the response variables measured in this experiment. Cotton height, width, production of flowerbuds and production of fruit were all affected by both damage and weeds. While the effects of damage on these growth variables were transient, the effects of weeds normally increased with time throughout the season. Non‐additive effects of weeds and damage were minor for plant height and width, and large for flowerbud and fruit production.

At maturity, weed dry matter ranged from about 20 g m‐2 (‐W treatments) to 300 gm‐2 (+W), cotton dry matter from 144 gm (+W+D) to 945 gm‐2 (‐W‐D), and seed cotton production from 54gm‐2 (+W+D) to 417 gnT‐2 (‐W+D). Damage did not affect vegetative dry matter and marginally increased seed production in ‐W plots. Non‐additive effects of weeds and damage were negligible for vegetative dry matter but highly significant for seed production (P < 0.0001). These contrasting responses of vegetative and reproductive growth are in agreement with neighbouring models of plant competitive interactions that emphasise the effects of neighbour interference on the fecundity of target plants that are not mediated by changes in target‐plant size.
Efficacy of bracken (Pteridium aquilinum (L.) Kuhn) control treatments across a range of climatic zones in Great Britain
Authors: PATERSON S. , MARRS R H , PAKEMAN R J
Published: February 2008

Bracken control field experiments were conducted at six locations across Great Britain. The effects of various cutting and herbicide management regimes upon the seasonal dynamics of bracken fronds and rhizomes were examined over a three year period. This enabled a national overview towards bracken control to be constructed. Initially, spraying with asulam was the most effective treatment in reducing frond biomass and density but was least effective in reducing rhizome biomass. Differential reductions in rhizome biomass were observed in relation to cutting frequency, with cutting twice yearly giving superior control. The national trends confirmed a number of previous observations from independent single‐site studies; however, others were contradicted. Comparable management options were ranked consistently between the current and former investigation, however, the initial importance of differences in cutting frequencies did not agree between studies. This multiple‐site study improves understanding of the consequences of a national bracken control programme by reducing the influence of confounding site‐specific factors, and recommendations for the most appropriate bracken control techniques are made. The extent to which individual sites reflect a national trend in response to bracken control is considered and sites are compared. The hierarchy of treatments identified at the national scale was found to apply generally within individual sites. However, several responses which proved significant at the countrywide level were not so clearly defined at the site scale. Cutting once yearly was the only management regime which appeared to give different bracken control between sites. All other treatments gave similar responses between sites. This result was found in the Scottish Borders, during the second year of control, when frond biomass and density (relative to untreated plots) were greater than that recorded at other sites. This contrast was not found in subsequent monitoring. In terms of rhizome biomass depletion, poorer control was achieved following cutting once yearly at the northern sites (Mull, Scottish Borders, Lake District) compared with the southern sites (Clwyd, Breckland, Devon). The implications of experimental results are discussed in relation to increased cost effectiveness of national bracken control programmes.
Linkage between Frl (Fusarium oxysporum f.sp. radicis‐lycopersici resistance) and Tm‐2 (tobacco mosaic virus resistance‐2) loci in tomato (Lycopersicon esculentum)
Authors: VAKALOUNAKIS D J , LATERROT H. , MORETTI A. , LIGOXIGAKIS E K , SMARDAS K.
Published: February 2008

A study was carried out on the linkage relationship between the Frl locus carrying resistance to Fusarium oxysporum f.sp. radicis‐lycopersici and the Tm‐2 locus carrying resistance to several races of tobacco mosaic virus in the tomato inbred line IRB‐301‐31. The inbred line Motelle (Frl+/Frl+, Tm‐2+/Tm‐2+) was crossed with the inbred line IRB‐301‐31 (Frl/Frl, Tm‐2/Tm‐l). The resulting 222 F2 plants were selfed, and from each F3 family groups of 15–60 seedlings were tested for resistance to either F. oxysporum f.sp. radicis‐lycopersici or tobacco mosaic virus race 0. Segregation data indicated a very tight linkage between Frl and Tm‐2, equal to 5.1 ± 1.07 map units.
Factors affecting winter survival of the florally determinate white lupin cv. Lucyane
Authors: BATEMAN G L , FERGUSON A W , SHIELD I.
Published: February 2008

In a series of three field experiments with factorial design, on sites that had not grown lupins previously, sowing date was the main factor affecting over‐winter survival of autumn‐sown white lupin. In 1993, the sowing dates (23 September and 20 October) were too late to prevent much plant death in autumn and early winter, with the onset of frosts. In 1994, the sowing dates (30 August and 22 September) were early enough to prevent severe frost damage, but infestations of bean seed fly (Delia platura) occurred, more in the later than in the earlier sown crops, causing wilting and plant death. Losses were decreased where furothiocarb seed treatment was applied. In 1995, losses were greater in early‐sown (12 September) than in later sown (28 September) crops; plant death was gradual, occurring into the spring, and was apparently associated with over‐development of young shoots before an unusually long, cold winter. A chlorpyrifos spray (13 or 29 September for early or late sown plots, respectively) slightly increased survival, possibly by controlling Thrips angusticeps. Fungicides applied to seed or as sprays in late autumn had little or no effect in these experiments. In another series of experiments to test fungicides, in 1992‐93 and 1993‐94, survival was poor following late sowing (in October), but was increased by application of prochloraz in December or January, or, in 1994, by seed treatment with thiram.
Preferences and apparent digestibilities of sugars by fruit damaging birds in Japan
Authors: LANE SIMON J
Published: February 2008

Gray starlings Sturnus cineraceus, azure‐winged magpies Cyanopica cyana and brown‐eared bulbuls Hypsipetes amaurotis are among the main bird pests in commercial fruit orchards in central Japan. Recently Brugger & Nelms (1991) suggested that developing high‐sucrose fruit cultivars could reduce crop damage, because some pest birds lack the enzyme sucrase and can develop an aversion to sucrose. Preferences for, and digestibilities of, the monosaccharides glucose and fructose and the disaccharide sucrose by these pests species were therefore studied to assess whether this idea would be applicable in central Japan. Gray starlings and brown‐eared bulbuls were able to detect glucose, fructose, a mixture of glucose and fructose, and sucrose at a concentration of 12% w/v. Azure‐winged magpies also detected glucose and fructose, but failed to detect sucrose at the same concentration. In pairwise preference trials gray starlings and azure‐winged magpies selected the monosaccharides over sucrose, but brown‐eared bulbuls did not. To estimate the digestibility of the sugars the apparent assimilated mass coefficient, AMC*, was calculated for each species eating each sugar by measuring intake and faecal output. Monosaccharides had mean AMC*s of 0.77, 0.96 and 0.92 when consumed by gray starlings, azure‐winged magpies and brown‐earned bulbuls respectively. AMC* values for sucrose were 0.82 and 0.49 for brown‐eared bulbuls and azure‐winged magpies respectively, but gray starlings were shown to be unable to digest sucrose. As AMC* values varied from 0.75 to 0.97, consumption rates of sugars increased as digestibility decreased. Although increasing sucrose contents of commercial fruits may deter sucrase‐deficient birds such as gray starlings from depredating fruits, it may also lead to increased crop damage by species such as the azure‐winged magpie and brown‐eared bulbul which may have to consume more of the less digestible fruit in order to meet their energy requirements.
Assessment of the efficiency of a hand‐held suction device for sampling spiders: improved density estimation or oversampling?
Authors: SAMU FERENC , NÉMETH JÓZSEF , KISS BALÁZS
Published: February 2008

In the study a comparison is made between the results of two sampling procedures, both based on the application of the same hand‐held suction apparatus. Sampling was aimed at spiders, and was carried out on two alfalfa fields. In the first method suction sampling was applied to an enclosure of 0.48 m2. The enclosed area was sampled intensively, which was facilitated by the removal of the vegetation. The second method was a transect sampling procedure during which the suction apparatus with a 0.01 m2 nozzle was applied to single unenclosed sampling points 1 m apart. A linear series of 48 such subsamples comprised a transect, thus the total area covered in a transect equalled the area of the enclosure. In the transect samples three times more spiders were caught than in the enclosures. This result was consistent on different occasions and at both fields. This basic trend was found in all spider families that were present in significant numbers in the samples. Species composition in the samples collected by the two methods was similar, and species abundance ranks were highly correlated across dates. We propose that an “edge effect” can explain higher catches in transect samples. This edge effect is caused by lateral suction at the edges, which inflated the number of animals caught in the transect application.
The effect of hydoroxamic acid concentration at late growth stages of wheat on the performance of the aphid Sitobion avenae
Authors: NICOL D. , WRATTEN S D
Published: February 2008

From a previous worldwide screen of wheat cultivars as seedings, five were selected to encompass a wide concentraiton range of the hydroxaminc acid DIMBOA (0.99‐8.07 mmol Kg ‐1 fr. wt). Compared with those in seedings, the concentrations of DIMBOA in flag leaves of the same cultivars were relatively low (0.06‐0.87 mmol kg‐1 fr. wt). Concentraions of hydroxamic acids in whole ears at anthesis and the early milk stage were even lower, ranging from undetectable to 0.05 mmol kg‐1 fr. wt. The three‐day mean relaive growth rate (MRGR) was determined for nymphs of Sitobion avenace on the flag leaf (GS 39) and on the ear (GS 60‐60) of the five cultivars. No significant differences in MRGR were found between cultivatrs at the same growth stage, although MRGR was higher on ears on than on flag leaces. The results are discussed in realtion to the potential of hydroxamic acids in programmses aimed at breeding mature‐plant aphid resistance into wheat cultivars.
Effect of imidacloprid on the sivlerleaf whitefly, Bemisia argentifolii Bellows and Perrring (Homoptera: Aleyrodidae), and whitefly parasitism
Authors: BETHKE JAMES A. , REDAK RICHARD A.
Published: February 2008

Bioassays were conducted under greenhouse conditions to determine the effect of imidacloprid on adult and nymphal stages of the silverleaf whitefly, Bemisia argentifolii Bellows and Perring, and parasitism by Encarsia formosa (Gahan). A flowable formulation (24Oglitre‐1) of imidacloprid at six rates (0.09, 0.04 and 0.02 g a.i. litre‐1 pot volume for experiments 1 and 2; 0.009, 0.004, and 0.002 g a.i. litre‐1 pot volume for experiment 3) was evaluated. After a 48 h exposure to treated plants, high mortality of adult whitefly (>94%) was observed. Adults exposed to poinsettias treated 150 days earlier also had significantly greater mortality (>79%) than the adults on control plants. When exposed to treated plants for only 6 h, >65% of adults were killed. All three rates of imidacloprid caused >97% mortality of immature whiteflies by day 19. When treated plants were continually exposed to adult whiteflies, immature mortality was 100% for the three higher rates of imidacloprid up to and including 88 days after treatment. During the same time, emerging adults were reduced significantly. Immatures reinfested on plants treated 161 days earlier, incurred 80% mortality at the higher rate 0.09 g a.i. litre‐1 pot volume and 38% mortality at 0.02 g a.i. litre‐1 pot volume. At lower treatment rates, results varied. At 0.009 g a.i. litre‐1 of pot volume, mean percentage whitefly mortality (65%) 25 days after treatment was significantly higher than the controls; however, whitefly mortality at 0.004 and 0.002 g a.i. litre‐1 pot volume was not significantly different from controls or plants treated with the higher rate. Parasitoids could develop to the adult stage on whiteflies infesting imidacloprid treated plants. Parasitism occurred at low levels (< 10%), doe to high levels of whitefly mortality on treated plants. No phytotoxicity was observed for any treatment throughout the length of the trials that lasted through flowering.
An investigation inot the use of multiple site characteristics to predict the presence and infestation level of wireworms (Agriotes sup., Coleoptera: Elateridae) in individual grass fields
Authors: PARKER W E , SEENEY F M
Published: February 2008

Sixty‐two grass fields were sampled in England and Wales over a three year period to assess the level of wireworm population present. Data on site‐specific variables including soil physical characteristics, grass duration, grass genera diversity and other abiotic factors such as field aspect, altitude, and meteorological parameters were abiotic factors such as field aspect, altitude, and meteorological parameters were collected at each site. Only grass duration and soil bulk density showed any association with wireworm infestation stauts when considered as single variates. Data from a sub‐set of 41 fields were used to develop a series of multi‐variate discriminant rules to predit wireworm presence/absece in individual fields. These were vaildated using data from the remaining 21 fields. In general, the rules tended to over‐estimate the number of wireworm‐infested fields by misclassifying uninfested fields as infestes. Multivariate models to predict wireworm populaiton levels in infested fields were also developed using multiple and generalised linear regression. The predictive accuracy of these was poor. Neither the population prediciton models nor the presence/absence rulses accounted fully for the large inte‐field variation in wireworm infestation status.
Development of a dot immunobinding assay to detect Phytophthora spp. in naturally dark‐rooted woody plants
Authors: HAHN RENATE , WERRES SABINE
Published: February 2008

An indirect dot immunobinding assay (DIBA) with a PAb raised against an isolate of P. cinnumomi was evaluated to detect Phytophthora spp. in naturally dark‐rooted woody plants. Screening of different modifications of the procedure were done with root samples of Chamaecyparis lawsoniana non‐infected and infected with P. cinnamomi. With the optimised DIBA procedure, root infection could be diagnosed by a clearly defined halo around the spot and by a colour change in the spot using Fast Red or Fast Blue substrate. Detection of different Phytophthora species in Chamaecyparis plants from commercial nurseries was successful with the optimised procedure.
The effects of cassava mosaic virus disease on yield and compensation in mixed stands of healthy and infected cassava
Authors: OTIM‐NAPE G W , THRESH J M , SHAW M W
Published: February 2008

The effects of cassava mosaic virus disease (CMD) on yield in fully and partly infected stands of cassava were investigated in field trials in Uganda in 1990‐91 and 1991‐92. Three cultivars (Ebwanateraka, Bao and Bukalasa 1 l), each at three levels of cutting infection (O%, 50% and 100%) and harvested 510 and 15 months after planting (MAP) were used in a randomised block design with split‐split plots and four replicates. Moreover, yield and growth data for individual infected and uninfected plants were considered in relation to the health status of their nearest neighbours. In each experiment, fresh tuberous root yields of plants from 100% infected plots gave sigdicantly lower yields than those from 0% or 50% infected plots at each harvest date and the losses were greatest in cv. Bao. Yields of plants from 0% and 50% plots for each of the three cultivars were not significantly different, 10 and 15 MAP. The loss in yield differed between cultivars and harvest dates. Fresh stem, leaf and root yields and the number of tuberous roots were influenced by the health status of the plants harvested and that of their nearest neighbours. Uninfected plants surrounded by infected ones had more roots and heavier total fresh root, stem and leaf weights than those surrounded by uninfected ones. Overall, 26% and 42% compensation was recorded in 1990‐91 and 1991‐92, respectively. The effects of CMD on cassava production and of compensation in mixed stands of infected and uninfected plants are discussed, especially in relation to control strategies such as roguing.
Competitive ability and tolerance of organically grown wheat cultivars to natural weed infestations
Authors: COSSER N D , GOODING M J , THOMPSON A J , FROUD‐WILLiAM R J
Published: February 2008

Competitive ability of a traditional winter wheat cultivar (Maris Widgeon) was compared with two modem cultivars (Hereward and Genesis) when grown organically in each of four seasons in Gloucestershire, UK. In two seasons, cultivars were compared at two sowing dates (September and October or November). Cv. Maris Widgeon was the tallest cultivar and intercepted most photosynthetically active radiation (PAR), particularly if sown early. Cv. Hereward was taller than cv. Genesis when sown early. Cv. Maris Widgeon accumulated most nitrogen and dry matter early in the season (until the end of March) when sown early, but not when sown late. Relative nitrogen and dry matter accumulation by cultivars later in the season depended on season and sowing date. In one season cv. Maris Widgeon had significantly more early season ground cover. Cultivars did not differ significantly in early tiller production. Although most of these indirect measures of competitive ability were greater for the older variety cv. Maris Widgeon, infestation of Veronica spp. was greater in plots of this cultivar than in plots of either one or both of the shorter cultivars in two successive seasons. In the 1993/94 season, the soil seedbank from plots previously cropped with cv. Maris Widgeon produced more seedlings of Sinapis awensis. In the 1994 / 95 season, cv. Maris Widgeon plots contained less weed in terms of ground cover, numbers, dry matter and nitrogen than the other cultivars, and soil sampled from plots previously cropped with cv. Hereward sown late gave rise to larger numbers of weeds than cv. Maris Widgeon. Sowing date affected weed burdens and emergence to a much greater extent than wheat cultivar. In years and sowing date treatments with relatively low weed presence the shorter cultivars tended to yield more than cv. Maris Widgeon. When weed burdens were severe cv. Maris Widgeon yields were equal to or greater than those of either cvs Hereward or Genesis. The results suggest that the traditional tall cv. Maris Widgeon could be used beneficially to tolerate weeds in organic systems when high weed infestations were anticipated, but could not be relied upon to suppress weed development, and in some circumstances could actually encourage certain species.
Identification of the determinants of host resistantce and pathogenicity in interactions between Alternaria linicola Groves & Skolko and Linum Usitatissiumum L. accessions using multivariate analyses
Authors: EVANS N. , MCROBERTS N. , HITCHCOCK D. , MARSHALL M.
Published: February 2008

Multivariate analysis of variance (MANOVA) and canonical variates analysis (CVA) were used to examine differences in host plant resistance and pathogen behaviour in interactions between Altemaria linicola and three genotypes of Linum usitatissimum, previously identified as susceptible, moderately resistant and resistant to the pathogen. Significant differences in pathogen development were found among the Linum accessions at 18, 24, and 40 h after inoculation. At 18 h after inoculation attempted penetration by the pathogen was relatively rare on all three accessions and canonical variates analysis revealed that overall differences among accessions resulted from large differences with respect to a small number of variables associated with successful penetration on the most susceptible accession. At later times after inoculation, when attempted penetration was more common, overall differences among accessions were found to result from smaller absolute differences among a group of variables which characterised the early colonisation of the host tissue. The results from these investigations are discussed in relation to recent research on the ecology of the pathogen and the importance of the timing of host responses to infection in determining host plant resistance.
Emergence of temperate pasture grases from different sowing depths: importance of seed weight, coleoptiele plus mesocotyl length and shoot strength
Authors: ANDREWS M. , DOUGLAS A. , JONES A V , MILBURN C E , PORTER D. , McKENZIE B A
Published: February 2008

Inter‐specific relationships between mean seed weight, coleoptile + mesocotyl (sub‐coleoptile internode) length and width, shoot strength and emergence from different sowing depths were examined for timothy (Phleum pratense L., mean seed weight 0.33‐0.48 mg depending on seed line), cocksfoot (Dactylis glomerata L., 0.65‐0.78 mg), perennial ryegrass (Lolium perenne L., 1.71‐2.19 mg), tall fescue (Festuca arundinucea Schreb., 1.73–2.60 mg), annual ryegrass (Lolium multiflorum Lam., 5.10‐5.20 mg) and prairie grass (Bromus willdenowü Kunth., 10.5–12.2 mg). Across species at 10,30 and 60 mm sowing depths in the field and 10, 15 and 30 mm sowing depths under controlled environment conditions, there was a significant (P < 0.05) positive correlation between emergence % and mean seed weight. Across species at 10–30 mm sowing depth under controlled environment conditions, emergence % was not significantly correlated with coleoptile + mesocotyl length but there were significant positive correlations between emergence % and coleoptile and mesocotyl width: shoot strength increased with increased coleoptile width across species. For seed lines of timothy of different mean seed weight (0.21‐0.81 mg), emergence %, coleoptile + mesocotyl length and coleoptile and mesocotyl width increased with increased seed weight at 10 and 15 mm sowing depth. Shoot strength increased with increased coleoptile width for timothy. For emerged and non‐emerged cocksfoot and timothy seedlings regardless of seed weight, mean coleoptile + mesocotyl length was > 10 mm at 10 mm sowing depth. It is concluded that at 10–30 mm sowing depth, increased emergence % with increased seed weight across species is not due to increased coleoptile + mesocotyl length. It is proposed that increased emergence % with increased seed weight across species at 10–30 mm sowing depths and across seed lines of timothy at 10 mm sowing depth is primarily due to increased coleoptile and mesocotyl width resulting in increased shoot strength and hence an increased ability to penetrate the substrate.
Seasonal variation in the response of Hagberg falling and liquefaciton numbers to propiconazole fungicide in wheat
Authors: KETTLEWELL P S
Published: February 2008

The hypothesis was tested that seasonal differences in the response to propiconazole fungicide of hagberg failling and liquefaction numbers are related to grain drying rate, as indicated by potential evaportranspiration. The response of Hagberg failling and liquefaciton numbers to late‐season applicaitions of propiconazole was calculated using data from a field experiments in each of the years 1981 to 1990 on winter wheat (Triticum aestivum) cv. Agalong grown with similar husbandry at one site. Cumulative potential evapotranspiration was calculated over seven different periods during grain ripening.

No visible sprouting occurred in any experiment and Hagberg falling number was above 250 s in nine of the 10 years. Disease severity on the flag leaf was less than 7% in nine of the 10 years, and diseases were generally controlled well by propiconazole. There were no significant relationships between the response of Hagberg falling number and any of the potential evapotranspiration variables. The response of liquefaction number was exponentially related to each of three cumulative potential evapotranspiration variables which covered periods before the estimated date of 40% moisture content. Years with lower cumulative potential evapotranspiration gave the greater responses, but the relationships were considerably influenced by the two lowest potential evapotranspiration years. It was concluded that these data provide indirect evidence that the response of Hagberg falling number (when transformed to liquefaction number) to fungicide is mediated through grain drying rate, and furthermore that the results are compatible with the hypothesis that pre‐maturity alpha‐amylase activity is stimulated by slow grain drying.
A chance field observation and pilor laboratory studies of predation of the New Zealand flatworm by the larvae and adults of carabid and staphylinid beetles
Authors: GIBSON P H , COSENS D. , BUCHANAN K.
Published: February 2008

A chance finding in an Edinburgh allotment was made of a stained carabid beetle larva that had eaten Artioposthiu triungulata previously stained red and released into the allotment during a dispersal experiment. In a pilot laboratory study the flatworm was eaten by larval and adult carabid and staphylinid beetles whereas seven other carnivorous species from five arthropod families did not. In another feeding experiment a carabid and a staphylinid larva each ate several specimens of the flatworm and gained tissue weight over 14 days. The conclusion drawn from these preliminary studies and the field observation is that certain carabid and staphylinid beetles are potential predators of A. triangulata.