bluuebunny/crossref_metadata_2025 huggingface dataset:
Stem canker (Rhizoctoniu solani) on three early and three maincrop potato cultivars: effects of seed tuber size on growth and yield
Authors: HIDE G. A. , READ P. J. , HALL SHARON M.
Published: February 2008

Large seed tubers (mean 134 g) and small seed tubers (50 g) of three early and three maincrop potato cultivars, spaced respectively 48 and 30 cm apart within rows, were inoculated with Rhizoctonia solani at planting in 1985 and 1986. All seed of early cultivars was sprouted and maincrop seed was either sprouted or not sprouted.

In all cultivars, plant emergence was slower from small than large seed and with both was delayed by inoculation. From 11 wk after planting numbers of stems and tubers and weights of foliage and tubers/m2 were usually similar from small and large seed when not inoculated, but inoculating delayed plant growth and decreased tuber numbers and yield more from small than large seed.

Inoculating decreased mean yields from large and small seed of early cultivars at 11 wk by respectively 24% and 31% (Arran Comet), 12% and 18% (Estima) and by 10% and 28% (Wilja) and losses were greatest with saleable sized tubers (3–4 cm). When grown to maturity inoculating decreased yields by 7% (Arran Comet), 5% (Estima) and 14% (Wilja).

With maincrop cultivars, yields in October from large and small seed were decreased by respectively 4% and 10% (DCsirke), 9% and 12% (Maris Piper) and by 14% and 22% (Pentland Squire). In all cultivars yields of tubers < 44 mm and 44–70 mm were decreased and, with Pentland Squire, tubers > 82 mm were increased.

The incidence of stem canker and of black scurf on progeny tubers was not affected by seed size but in all cultivars the percentage of greened tubers was slightly increased by inoculation.
Almond brown line and decline: a new disease probably caused by a mycoplasma‐like organism
Authors: UYEMOTO J. K. , CONNELL J. H. , HASEY J. K. , LUHN C. F.
Published: February 2008

Young almond (Prunus dulcis, cvs Carmel, Peerless and Price) orchards established on the plum rootstock Marianna 2624 (P. cerasifera×P. munsoniana) contained trees that exhibited poor terminal shoot growth and wilted, chlorotic leaves. The scion/rootstock graft union showed an external splitting of the bark and an internal line of necrotic bark tissues that extended into the woody cylinder of the union, which was deeply pitted. Affected trees declined. The disease was named almond brown line and decline (ABLD). Incidence of ABLD ranged up to 55% per cultivar in some orchards. Numerous attempts to graft‐transmit orchard collections of ABLD to healthy almond/Marianna 2624 indicators failed. Also, ABLD does not appear to be soil‐borne. However, ABLD was serendipitiously determined to be bud‐perpetuated when infected scion buds from an apparently healthy appearing Peerless almond/peach tree located in a foundation orchard were grafted onto healthy rooted cuttings of Marianna 2624 to produce yearling trees. Also, graft‐inoculations on the almond scion portion of healthy trees, but not the plum rootstock portion, with the peach yellow leafroll mycoplasma‐like organism (PYLR‐MLO) caused symptoms resembling ABLD. Laboratory and glasshouse assays of several symptomatic trees did not detect tomato ringspot virus and two ilarviruses. These results suggest that an MLO, possibly PYLR‐MLO, may be the causal agent of ABLD and that Marianna 2624 is probably resistant to the PYLR‐MLO.
Sri Lankan passion fruit mottle virus, a potyvirus infecting golden passion fruit in Sri Lanka
Authors: DASSANAYAKE E. M. , HICKS R. G. T.
Published: February 2008

A sap‐transmissible virus, provisionally named Sri Lankan passion fruit mottle virus (SLPFMV), was isolated from Passiflora edulis f. flavicarpa and shown to induce leaf mottling and distortion in that host. The virus infected 23 species in five plant families with systemic infection being common in the Passifloraceae. Chenopodium amaranticolor was a good local lesion host and Passiflora foetida was a useful systemic host for purification. In P. foetida extracts, SLPFMV lost infectivity after 10 min between 70–75°C, 6–7 days at 20–23°C and at dilutions of 10‐‐5 ‐W‐6. The virus had flexuous, filamentous particles with a normal length of c. 841 nm. Two polypeptides of mol. wt c. 33 200 and 28 700 were detected in purified virus preparations, and a major species of double‐stranded RNA (mol. wt 7.0 × 106), was detected in infected plants. Pinwheels, tubular and laminated inclusions were found in ultrathin sections of infected P. edulis f. plavicurpa and cylindrical inclusions were observed in epidermal strips.

SLPFMV was transmitted by the aphids Myzus persicae, Aphis spiraecola, A. gossypü and A. cruccivora after brief acquisition feeds. SLPFMV reacted with antisera to several potyviruses including passion fruit woodiness virus, passion fruit ringspot virus, potato virus Y and watermelon mosaic virus 2 and thus, apparently, is a member of the potyvirus group.
Transmission of Pythium aphanidermatum to greenhouse cucumber by the fungus gnat Bradysia impatiens (Diptera: Sciaridae)
Authors: JARVIS W. R. , SHIPP J. L. , GARDINER R. B.
Published: February 2008

The fungus gnat (Bradysia impatiens) was examined for its ability to transmit Pythium aphanidermatum to cucumber plants. Larvae that had ingested oospores and mycelium, and then fed on the roots of young cucumber plants growing in rockwool readily introduced the fungus to them. Trans‐stadial transmission of oospores from the larval to the adult stage of B. impatiens was demonstrated, although decreasing to a very low level (1.67%) in adults. However, external transmission of P. aphanidermatum on the surface of adults could not be shown. These results suggest that the larval stages of fungus gnats play a role in the dissemination of the fungus between cucumber plants but that adults probably play only a minor role.
Susceptibility to purple blotch (Alternaria porri) in garlic (Allium sativum)
Authors: BISHT I. S. , AGRAWAL R. C.
Published: February 2008

Experiments were conducted to study the progress of purple blotch disease of garlic caused by Alternuria porri in the field, to determine the relationship between garlic leaf age and susceptibility to Alternaria porri, and also to assess loss in bulb characters due to purple blotch of garlic. Per cent disease severity and number of purple blotch lesions on four garlic genotypes of known susceptibility, Sel‐10 (highly susceptible), G‐41 (highly susceptible), IC‐49382 (moderately susceptible) and IC‐49373 (moderate to less susceptible) were monitored from bulb formation to bulb maturity at weekly intervals. Lesions appeared early on highly susceptible cultivars, Sel‐10 and G‐41. Rapid progress of disease development was noticed during the last 3 wk before bulb maturity. Peak severity at the maturity of the crop was significantly higher on highly susceptible genotypes. No definite correlation could be established between number of lesions and disease severity. A logistic curve was fitted to predict the disease progress on different weeks before bulb maturity. Levels of leaf tissue found damaged by A. porri at weekly intervals from bulb initiation to bulb maturity were significantly lower on younger leaves than on older leaves. Leaves that emerged 7 wk before bulb maturity required more than a 5 wk period to reach 50% leaf damage, whereas leaves emerging 2, 3 and 4 wk before bulb maturity exceeded 50% leaf damage within a 2–3 wk period. Individual garlic leaves became more susceptible to purple blotch as they aged and emerging leaves were more susceptible the closer they emerged to bulb maturity. Per cent loss in bulb weight and bulb volume was found to be significantly higher on highly susceptible genotypes. No significant reduction in number of cloves/bulb was observed. We propose 4 wk before bulb maturity as the action threshold for initiation of fungicidal application to prevent damaging levels of disease.
Study of multiplication of cucumber mosaic virus in susceptible and resistant Capsicum annuuum lines
Authors: NONO‐WOMDIM R. , GEBRE‐SELASSIE K. , PALLOIX A. , POCHARD E. , MARCHOUX G.
Published: February 2008

A previous survey on pepper lines (Capsicum annuum L.) indicated that a susceptible cultivar, Yolo Wonder, reacted to cucumber mosaic virus (CMV) by producing a systemic yellow mosaic. By contrast, CMV caused no symptoms on lines Perennial and Vania. The virus is recoverable from the uninoculated leaves of Perennial, while in Vania CMV is restricted to the inoculated leaves. To interpret these phenomena, a comparative study on CMV multiplication rates, yield, specific infectivity and relative proportion of RNAs was made in the inoculated leaves of the three pepper varieties. The rate of CMV multiplication, as estimated by the double antibody sandwich form of enzyme‐linked immu‐nosorbent assay, was lower in Perennial than in Vania or Yolo Wonder. The yield of virus purified from Perennial was very low when compared with Vania or Yolo Wonder. The specific infectivity of the virus extracted from Perennial was less than that from Vania or Yolo Wonder. These results suggest that Perennial is resistant to CMV multiplication, while restriction of the virus in inoculated leaves of Vania is not due to the inhibition of the virus replication. However, polyacrylamide gel electrophoresis revealed that the RNA profiles of CMV purified from the three pepper lines were similar.
Interaction between two synthetic pyrethroids and the spread of two non‐persistent viruses in cowpea
Authors: ROBERTS JULIA M. F. , HODGSON C. J. , JACKAI L. E. N. , THOTTAPPILLY G. , SINGH S. R.
Published: February 2008

The effectiveness of the synthetic pyrethroids deltamethrin and lambda‐cyhal‐othrin in preventing (i) aphid colonisation of four cowpea cultivars with different levels of aphid resistance and (ii) the introduction and subsequent spread of cowpea aphid‐borne mosaic virus and cucumber mosaic virus was investigated under tropical field conditions.

Sprays of these pyrethroids eight days apart prevent aphid colonisation and within crop spread of virus by the colonising Aphis craccivora. However, neither deltamethrin nor lambda‐cyhalothrin prevented the initial introduction of virus into the cowpea crop and, when incoming alate incidence was high, virus incidence was higher in the sprayed than in the unsprayed plots. In addition, the degree of aphid resistance of each cultivar affected secondary virus spread within the crop, with greatest spread in the most resistant cultivar.
Classification of cowpea cultivars for field resistance to the legume pod borer, Muruca testulalis in Nigeria using cluster analysis
Authors: OGHIAKHE S. , ODULAJA A.
Published: February 2008

Cluster analysis was used to classify cowpea cultivars developed for resistance to M. testulalis in Nigeria based on data collected on four damage parameters. The cultivars were grouped into classes for each of two locations under two protection regimes. Differences were observed in the groupings for the two locations while one cultivar, MR×6–84F was found to have wide adaptability in the presence or absence of M. testulalis infestation. This is particularly useful for the selection of breeding materials in cultivar improvement for specific or general ecological zones.
Exploitation of the resistance to carrot fly in the wild carrot species Daucus capillifolius
Authors: ELLIS P. R. , HARDMAN J. A. , CROWTHER T. C. , SAW PAMELA L.
Published: February 2008

Under field conditions a wild Daucus species from Libya, D. capillifolius, supported less than one tenth as many carrot flies (Psila rosae) as the susceptible carrot cultivar Danvers Half Long 126. Breeding lines developed from crosses between D. capillifolius and three different carrot types were grown in a series of field experiments at Wellesbourne between 1980 and 1989. Each year selections were made for agronomic quality and/or for increased resistance to carrot fly. The programme produced lines which for size, shape and colour represented most of the commercially‐important carrot types. Some of these lines were also significantly more resistant to carrot fly than selections from the partially‐resistant cv. Sytan. However, the best lines were not as resistant as the wild parent. The highest quality resistant lines were sold to seed companies for variety production.
Responses of potato genotypes to drought. I. Expansion of individual leaves and osmotic adjustment
Authors: JEFFERIES R. A.
Published: February 2008

The expansion of individual leaves was examined in 19 genotypes of potato (Sofunum tuberosum L.) grown either with irrigation or droughted from the time of plant emergence. Drought reduced the thermal time from emergence to leaf appearance in 10 genotypes but had no significant effect in the other genotypes. In all the genotypes, final size of leaves was reduced by drought, but the magnitude of the effect differed significantly (P < 0.001) with genotype. In the droughted treatment, the final size of leaves was correlated (P < 0.001) with the maximum rate of leaf expansion suggesting that reductions in final size of leaves were the result of reduced expansion rate rather than of effects on the duration of expansion.

Both the constant and the slope of the relation between leaf expansion rate and soil moisture deficit differed between genotypes. Osmotic adjustment was limited, maximally 0.16 MPa, and did not correlate with the ability to maintain leaf expansion with increasing soil moisture deficit.
Responses of potato genotypes to drought. II. Leaf area index, growth and yield
Authors: JEFFERIES R. A. , MACKERRON D. K. L.
Published: February 2008

Canopy expansion, growth and yield were examined in 19 genotypes of potato (Solanurn tuberosum L.) grown either with irrigation or droughted from the time of plant emergence. In the irrigated treatment, genotypes differed both in the maximum leaf area index (Lai) achieved and in the duration the canopy was maintained. Drought reduced both the rate of canopy expansion and the maximum Lai achieved.

In the droughted treatment, biomass production was correlated with leaf area duration. The relation between the effect of drought on the growth of individual leaves and biomass or yield is examined. It is concluded that selection for early leaf appearance combined with the ability to sustain leaf growth with increasing soil moisture deficit (SMD) would improve productivity in the presence of drought.
The rapid determination in controlled environments of parameters for predicting seedling growth rates in natural conditions
Authors: BREWSTER J. L. , SUTHERLAND R. A.
Published: February 2008

Parameters which characterise the response of seedling growth rate to temperature and mean daily radiant exposure were determined for cultivars of eight vegetable species and two ornamental bedding plant species using controlled environments. All species were grown for approximately four weeks in a series of four controlled environments consisting of factorial combinations of 20°C or 15°C with 7.78 or 0.98 MJ m‐2radiant exposure per day to photosynthetically active radiation. Four of the vegetable cultivars had been used previously in a study of growth in the glasshouse at different seasons. The parameters derived from controlled environments were used, with temperature and light measurements from the glasshouse, to predict seedling shoot growth in the glasshouse. These predictions accounted for 92% of the observed variance in log shoot dry weight in a series of glasshouse experiments involving thirteen combinations of species and sowing date, each grown at four plant densities and sampled on four occasions. Equivalent parameters derived previously from the glasshouse data themselves accounted for 92% of the variance in the same predictive exercise. Differences in base temperature for growth, the responsiveness of relative growth rate to daily radiant exposure (light), and the potential relative growth rate were apparent between species and were quantitatively characterised by the parameters. To determine these parameters for a cultivar requires the equivalent of one square metre of controlled environment growing area for approximately sixteen days. Such parameters could be applied for scheduling and management in crop production, particularly in transplant production.
Field evaluation of alpha‐chlorohydrin against the Indian mole rat: studies on toxic and antifertility effects
Authors: SAINI MANJIT S. , PARSHAD V. R.
Published: February 2008

Field acceptance and efficacy of a toxicant‐sterilant, alpha‐chlorohydrin (α‐CH), at its 0.5% concentration in bait were evaluated against rodents in sugarcane fields which harboured high populations of the Indian mole rat Bandicota bengalensis (Trap Index (TI) = 53.6 rats/100 traps/24 h) followed by that of the Indian bush rat Golunda ellioti (TI = 28.6) and soft‐furred field rat Rattus meltada (TI = 1.8). Acceptance of the α‐CH bait by rodents in the fields was evident from complete consumption of the offered bait at most of the baiting points. The treatment (72 h exposure to the poison bait) resulted in 63.7% to 82.9% rodent mortality. Survey of the mature sugarcane crop revealed that the percentage of rodent cut canes in the treated fields (7.6% to 16.2%) was significantly less than that of the reference fields (26.3%). Most of the surviving male B. bengalensis, captured after 15 days of the treatment, had developed sterility as revealed by the functional abnormalities in their testes and epid‐idymides. They showed decreased thickness of the seminiferous tubules, lower population of spermatogenic cells, cauda epididymal sperm concentration, live sperm and sperm mortality. A nonsignificant positive correlation between the testicular weight and sperm motility in males from treated fields indicated the effect of α‐CH at maturation level in the cauda epididymides. Overall, it was evident that a significant proportion of the surviving B. bengalensis had become permanently sterile as a consequence to the development of spermatocoeles in the caput epididymides and the remaining had significantly low numbers (< 30%) of motile sperm in their cauda epididymides which was, obviously, a handicap for successful fertilisation.
A review of white rust (Puccinia horiana Henn.) disease on chrysanthemum and the potential for its biological control with Verticillium lecanii (Zimm.) Viégas
Authors: WHIPPS J. M.
Published: February 2008

The biology, aetiology and epidemiology of Puccinia horiana, the cause of white rust disease of chrysanthemum (Chrysanthemum spp.) is reviewed in relation to current environmental, cultural and chemical methods for its control. Importantly, basidiospore release, germination and infection can take as little as 5 h at optimum r.h. (96%) and temperature (between 17–24°C). Recent developments using the fungus Verticillium lecanii for the control of insects on glasshouse‐grown all‐year‐round chrysanthemums rely upon the maintenance of r.h. during night periods in excess of 95%, thus predisposing plants to white rust attack. However, V. lecanii is unusual in that it can also parasitise spores and fruiting structures of a range of rust fungi including P. horiana. This mycoparasitic ability is also reviewed, and against this background, the potential for an integrated insect and white rust control programme on all‐year‐round chrysanthemums is assessed.
The influence of black bean aphid, Aphis fabae Scop., and its honeydew on leaf growth and dry matter production of sugar beet
Authors: HUREJ MICHAL , WERF WOPKE VAN DER
Published: February 2008

A. fabae populations, started at the 3–4 leaf‐stage of sugar beet in the glasshouse and peaking at 3000 individuals per plant, reduced leaf area by 64% at the 14 leaf‐stage. The size of the heavily‐infested leaves number 5 to 10 was reduced by 80% or more. The rate of leaf growth regained normal values after the aphid populations collapsed, but the infested plants did not make up for the decrease in leaf area production that had been incurred during the infestation. Total dry matter production over a period of 15 weeks was reduced by 47%. Honeydew had no effect on leaf size or dry matter production. Sugar beet plants in the field became infested with A. fabae at the 2–3, 4–5 and 6–8 leaf stages. Maximum populations of 800, 2100 and 2200 aphids per plant were recorded, respectively. The pertinent reductions in leaf area were 91%, 67% and 34% at the 10–12 leaf‐stage and 79%, 65% and 14% at harvest while the total dry matter produced was reduced by 91%, 79% and 16%. Neighbouring plants of the early‐infested sugar beet plants gained significantly higher weights than control plants. Honeydew had no effect on leaf area or dry matter production. The consequences of these results for our understanding of Aphis fabae injury in sugar beet and aphid control in the field are discussed.
Sexual generation and overwintering of the peach leaf curling aphid Brachycaudus helichrysi (Kalt.) in Himachal Pradesh, India
Authors: GUPTA P. R. , THAKUR J. R.
Published: February 2008

Autumn migrants preferred to settle on the dorsal leaf surface of peach with gynoparae being more numerous than alate males. These return migrants on peach were similar to those described by others except for a comparatively smaller processus terminalis. Among the oviparae with metatibial pseudosensoria. most (62.5%) had six antennal subdivisions; 25% possessed five antennal subdivisions and half of these were parasitised. Oviparae were bigger than those previously described on plum/damson but their processus terminalis was comparatively shorter. Ultimate instar nymphs were without pseudosensoria and had 5–seg‐mented antennae, the VI segment being cleaved from the meriston during the final moult. Alate males mated with the oviparae, mating duration being 3 to 6 min. Oviparae contained, at the most, two well developed eggs at one time, and normally deposited eggs singly during November‐December. Most eggs hatched within 20–28 days but those laid in December during colder weather took up to 50 days to hatch. By midJanuary most eggs had hatched. Fundatrix developmental rate was dependent on sap‐flow. Overwintering occurred as the fundatrix.
Field tests of bacteria and soil‐applied fungicides as control agents for take‐all in winter wheat
Authors: HORNBY D. , BATEMAN G. L. , PAYNE R. W. , BROWN M. E. , HENDEN D. R. , CAMPBELL R.
Published: February 2008

Putative biological and chemical treatments for controlling take‐all were used in each of three consecutive years at two locations where winter wheat crops were grown in naturally‐infested fields. The chemical treatments more often decreased take‐all than the biological treatments, but no treatment consistently and significantly decreased take‐all, nor did any cause a significant increase in yield.

An isolate of Bacillus cereus var. mycoides and one of B. pumilis, applied as soil drenches in autumn or spring, or in the seed furrows, were usually ineffective. Of the few significant effects on disease, half were associated with increases and half with decreases, and most occurred in April and did not persist to late June. Two strains of Pseudomonas pluorescens applied to the seed were ineffective.

The fungicide benomyl, applied as a drench in autumn and spring at 20 kg/ha was ineffective, while nuarimol, applied as a drench in autumn at 2 kg/ha was sometimes effective. Nuarimol incorporated into the seed bed at 2 kg/ha was the most effective treatment.

In analyses using a functional relationship model for data from treated and untreated plots 12% of 176 data sets for biological treatments, 38% of 96 data sets for chemical treatments and 81% of 16 data sets for combined treatments showed increasing efficiency of the treatment with increasing disease intensity. These findings also demonstrate an additional advantage of the experimental design, namely that treatments are tested at different disease intensity levels within fields.
The detection of single‐stranded RNA in an isometric virus‐like particle from Shiitake mushroom [Lentinus edodes (Berk.) Sing.]
Authors: XUEREN SHEN , MINGJIE CHEN , JUYING SHEN , YANGJIE PAN , ZUXUN GONG
Published: February 2008

Isometric virus‐like particles (VLPs) with diameter of approximately 34 nm containing ss‐RNA were purified from abnormal mycelium of Shiitake mushroom, Lentinus edodes (Berk.) Sing. SDS‐polyacrylamide gel elec‐trophoresis demonstrated that the virions contain a single capsid polypeptide with molecular weight of about 22 000 daltons. The nucleic acid extract from purified VLPs preparations showed only one band with a size of approximately 7.3 kilobases. The susceptibility to RNase 1 and S1 digestions, resistance to DNase and thermal denaturation behaviour of the viral genome indicated that it is a single‐stranded RNA. To our knowledge, isometric single‐stranded RNA VLPs isolated from Shiitake mushroom mycelia have not been reported before.
The virobacterial agglutination test as a rapid means of detecting cocoa swollen shoot virus
Authors: HUGHES J. d'A. , OLLENNU L. A.
Published: February 2008

The virobacterial agglutination (VBA) test was developed as a means of detection of cocoa swollen shoot virus (CSSV). Identification of CSSV‐infected Theobroma cacao in the field has only been possible by visual examination of symptoms, by virus transmission using mealybugs and by grafting to induce symptom expression in Amelonado cocoa seedlings. Detection of latent infection has not been possible even using enzyme‐linked immunosorbent assays (ELISA). The VBA test successfully detected CSSV in infected sap diluted to 1/2560. Antisera to a range of mild and severe CSSV isolates were tested, and the results suggest a close relationship between seven isolates (1A, Bosomtwi, Bosomuoso, Nkrankwanta, Nsaba, Seidi‐Nkawie and SS365B) while the mild isolate N1 appears to be less closely related. The VBA test was compared with both direct and indirect ELISA in the field. Only VBA detected all the cocoa trees which were known to be infected and additionally identified infection in many symp‐tomless trees.
Monoclonal antibodies specific for potato mop‐top virus, and some properties of the coat protein
Authors: TORRANCE L. , COWAN G. H. , PEREIRA L. G.
Published: February 2008

A method was devised which gave consistent yields (1–2 mg/kg leaves) of potato mop‐top furovirus (PMTV) particles. Monoclonal antibodies (MAbs) were produced and some properties of 10 of them were studied. Four MAbs readily detected PMTV isolates from six countries in Northern Europe and Japan when the isolates were trapped with polyclonal antibody; and diagnostic tests based solely on MAbs (SCR 68 to coat plates and biotin‐ or enzyme‐labelled SCR 69 to detect trapped virus) were devised. The pattern of reactions of the MAbs in ELISA and immunoblots suggested that they react with at least five different epitopes.

PMTV coat protein preparations were analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) and immunoblotting. Three bands of 23.9 kd, 21.5 kd and 20.5 kd were visible in silver‐stained gels and all three reacted with PMTV specific MAbs. The relative amounts of the three bands varied between different virus preparations, but the 21.5 kd band was usually the most abundant. The three bands were probably not produced by anomalous behaviour in SDS‐PAGE. Moreover PMTV protein was readily degraded by trypsin treatment giving a band of 20.5 kd. Therefore the results suggest that PMTV coat protein sub‐units are sensitive to degradation by plant proteases. At least two degraded forms were found when purified preparations were analysed by SDS‐PAGE, and the undegraded protein was estimated to be 23.9 kd.

The PMTV MAbs did not react in immunoblots with SDS‐treated coat protein preparations of beet necrotic yellow vein furovirus or Indian peanut clump furovirus.
Predation of annual grass weed seeds in arable field margins
Authors: POVEY F. D. , SMITH H. , WATT T. A.
Published: February 2008

Seeds of three species of annual grass weeds (Alopecurus myosuroides, Avena fatua and Bromus sterilis) were placed in field margins around arable fields in a randomised block split‐plot design experiment. The field margin vegetation was either sown or naturally regenerated and either cut or uncut. The seeds were either placed in cages designed to exclude small mammals and birds or were uncaged. The proportion of seeds removed was monitored on 10 occasions and mean seed loss was analysed.

In general, a greater proportion of weed seeds was removed from uncaged trays in uncut swards, suggesting predation by small mammals, which inhabit tall grass. This effect was mainly due to removal of seeds of the two large‐seeded species (A. fatua and B. sterilis), with A. fatua being especially favoured.

It is therefore likely that small mammals play a role in the population dynamics of major crop weeds by feeding on their seeds in field margins, especially when these are dense and uncut.
Fenoxycarb, a fairly new Insect Growth Regulato: review of its effects on insects
Authors: GRENIER SIMON , GRENIER ANNE‐MARIE
Published: February 2008

To reduce the impact of pesticides, new more selective chemicals need to be developed. Insect Growth Regulators such as Juvenile Hormone Analogues seem promising because of their specific mode of action on insects and their lower toxicity against Vertebrates than conventional insecticides. Nevertheless they remain toxic compounds. Fenoxycarb, a non neurotoxic carbamate shows a high JH activity, but also has other non JH specific effects. Effects of fenoxycarb on different pest and non‐target insects were reviewed from nearly 200 scientific papers dealing with this chemical used as insecticide.
Competitive interaction between strains of Verticillium lecanii on two insect hosts
Authors: CHANDLER D. , HEALE J. B. , GILLESPIE A. T.
Published: February 2008

Differences were observed in the pathogenicities of two strains of Verticillium lecanii (strain numbers 1.72 and 19.79) to the whitefly Trialeurodes uaporariorum and the aphid Macrosiphoniella sanborni. The mean pathogenicity of a mixture of the two strains was intermediate to that of the individual strains, attributable to a competitive interaction during infection. Differences between strains were observed in the production of conidia in vitro and on host insect cadavers. When hosts were infected with the dual‐strain suspension, conidia of strain 19.79 only were recovered from T. vaporariorum whereas conidia from both strains were recovered from M. sanborni.
The induction of systemic resistance in barley to powdery mildew infection using salicylates and various phenolic acids
Authors: WALTERS D. R. , MITCHELL A. F. , HAMPSON J. , McPHERSON A.
Published: February 2008

Treatment of the first leaves of barley seedlings with either 5, 10, 15 or 20 mM salicylic acid, sodium salicylate or acetylsalicylic acid resulted in significant reductions in powdery mildew infection on the upper, second leaves. In general, the greatest reduction in mildew infection on the second leaves was obtained by spraying the first leaves with a 15 mM concentration of the compounds. Although the largest reduction in mildew infection of the upper leaves was obtained when the compounds were applied to the first leaves 1–2 days before inoculation, very substantial reductions in infection were still obtained if the first leaves were treated 12 days before inoculation. The three compounds had little direct effect on mildew infection. When 14C‐salicylic acid was fed to first leaves of barley seedlings, uptake was rapid and increased with time. Within 6 h, 0.2% of the salicylic acid appeared in the second leaf and by 24 h after feeding, this had increased to 1.4% (1.1 μmol salicylic acid g‐1 fresh wt).

The application of various phenolic acids to first leaves also led to reductions in mildew infection on the second leaves. In particular, treatment of the first leaves with 1 mM vanillic acid, isovanillic acid or syringic acid, reduced mildew infection of the second leaves by 81–87%.
Identification and classification of a resistance breaking strain of barley yellow mosaic virus
Authors: BENDIEK J. , DAVIDSON A. D. , SCHULZE S. C. , SCHELL J. , STEINBISS H.‐H.
Published: February 2008

A “resistance breaking” isolate of barley yellow mosaic virus‐2 (BaYMV‐2) was cloned as a cDNA and characterised. Restriction mapping and comparison with a German and a Japanese isolate of BaYMV (BaYMV‐G and BaYMV‐J) revealed a high level of restriction site conservation for RNAl and the majority of RNA2. However, in a box of approximately 600 nucleotides located on RNA2, striking differences in the restriction pattern could be identified. The nucleotide sequence of this box, as well as of the 3‘‐terminal region of RNA1 including the coat protein coding region, and the deduced amino acid sequences were analysed. Identity at the amino acid level was between 99.3% and 92.3% in comparison with the corresponding sequences of BaYMV‐G and BaYMV‐J, suggesting that BaYMV‐2 is closely related to BaYMV. Consequently, the classification of BaYMV‐2 as a “resistance breaking” strain of BaYMV is justified.
Effects of cereal borders, admixture with cereals and plant density on the spread of bean yellow mosaic potyvirus into narrow‐leafed lupins (Lupinus angustifolius)
Authors: JONES R. A. C.
Published: February 2008

In studies of virus control measures, field experiments in 1987–1991 investigated the effects of cereal and fallow borders, admixture with cereals and plant density on spread of bean yellow mosaic potyvirus (BYMV) from pastures dominated by subterranean clover (Trifolium subterraneum) into plots of narrow‐leafed lupins (Lupinus angustifolius). Virus spread was mainly monocyclic because BYMV killed infected lupin plants and between systemic movement and death there was only a brief period for BYMV acquisition and transmission to other plants by vector aphids. In plots with cereal borders, the rate and extent of BYMV spread into the lupins was decreased; at final assessment the numbers of infected plants were 43–60% less than in plots with fallow borders. Admixture with cereals also decreased the rate and extent of BYMV spread into lupin plots, numbers of infected plants being decreased by 76–96% at the time of final assessment. When lupins were sown at different seeding rates to generate a range of plant densities and weeds were removed, high densities decreased BYMV infection. The higher incidences of BYMV infection in sparse stands were attributed partly to smaller plant numbers and partly to incoming viruliferous vector aphids being more attracted to plants with bare earth around them, than to a plant canopy. BYMV infection decreased grain yield of samples from infected lupin plants by 94–100%. In plots with 34% infection and sparse stands, grain yield was decreased by about one third.

Plotted progress curves for the accumulated numbers of alate aphids of the BYMV vector species Acyrthosiphon kondoi and Myzus persicae resembled those for numbers of BYMV infected plants in 1990, but in 1991 only the curve plotted for M. persicae did so. There was a 2 week delay between the curves for aphid numbers and virus counts which reflected the time taken for obvious systemic necrotic symptoms to develop in lupins.
Long‐term recovery of bracken (Pteridium aquilinum (L.) Kuhn) after asulam spraying
Authors: PAKEMAN R. J. , MARRS R. H.
Published: February 2008

This paper investigates the effects of a single asulam application, sprayed from the air, on the rhizome biomass, bud density, fronds and carbohydrate reserves of bracken (Pteridium aquilinum (L.) Kuhn) using a time sequence approach. Regression models were used to investigate how these characteristics varied with time after spraying, and were used, where appropriate, to calculate the time taken for full recovery after treatment. Frond density and biomass recovered in approximately eight years, bud numbers in seven, but rhizome biomass and total carbohydrate reserves required 10 to 12 years to recover. The consequences of these results are compared with predictions from a computer model and discussed in relation to the best timing of re‐treatment and the management needed for long term control.
Priming responses of leek (Allium porrum L.) seeds to different dissolved oxygen levels in the osmoticum
Authors: BUJALSKI W. , NIENOW A. W. , MAUDE R. B. , GRAY D.
Published: February 2008

Leek seeds (Allium porrum L.) cv. Winterreuzen were treated for 5 days in stirred bioreactors containing a ‐1.0 MPa polyethylene glycol (PEG 6000) solution. The level of dissolved oxygen was controlled from zero to approximately two and a half times that of saturation with respect to atmospheric air by bubbling through 02/N2 gas blends from 0% O2 to 50% O2. The treatment with 0% O2 (i.e. bubbling with N2) gave no reduction in germination time compared to untreated seeds after allowing for the time for water imbibition. As the proportion of oxygen was increased, a rapid reduction was observed until a concentration equivalent to air was used. Further increases to the maximum, produced only a marginal further improvement. The reduction in germination times for seeds that had been cabinet dried was longer for all treatments due to the time required for re‐imbibition of water but the general response to priming was the same as with undried seeds. Only dried seeds treated with air or higher oxygen concentrations showed enhanced synchronicity of germination times. The percentage germination of seeds from all treatments was the same, including the treatment with nitrogen gas. These tests help to explain the recently reported advantages of using enriched air for seed priming and are one of the necessary protocols for ensuring satisfactory bulk priming.
Physiological and developmental aspects of increased plant growth in solarised soils
Authors: GRUENZWEIG J. M. , RABINOWITCH H. D. , KATAN J.
Published: February 2008

Soil solarisation enhances plant growth even in the absence of known major pathogens. This phenomenon is known as increased growth response (IGR). Corn, cucumber, sorghum, tobacco and tomato plants under controlled conditions revealed distinct IGR in solarised soil as compared to control non‐treated soil. IGR was recorded in shoots of tomato (Lycopersicon esculentum Mill. cv. Rehovot 13) seedlings, 15 days after transplanting and in roots only two weeks later. Detailed studies on the third true tomato leaf showed significantly higher levels of chlorophyll and protein contents in plants from solarised soil as compared to those from the control. In addition, the degradation of these compounds, decrease of net photosynthesis at near‐saturation light intensity and of photochemical yield with ageing were delayed in plants growing in solarised soil as compared to the control. The ratio of variable to maximal chlorophyll fluorescence was independent of soil treatment and was comparable to normal levels measured in other plants. Therefore, no apparent environmental stress seems to be involved in either of the soil‐plant systems. It is concluded that the initial IGR in solarised soil is independent of improved root growth. Delayed leaf senescence appeared to be a plant response contributing to IGR.
Comparative studies of the quality of fresh and stored mushrooms of Agaricus bisporus with two tropical Agaricus bitorquis strains
Authors: SMITH J. F. , LOVE M. E. , BURTON K. S.
Published: February 2008

Three white strains of mushroom were grown for quality assessment tests, a commercial Agaricus bisporus strain SOMYCEL U3 currently popular in most major mushroom producing countries and two tropical Agaricus bitorquis strains, ATCC 32675 and AGC W20. Mushrooms were harvested as stage 2 mushrooms (closed buttons with universal veil intact) and stored at 18°C (± 0.5°C) for 5 days during which time colour development, the rate of fruitbody maturation and weight loss were assessed. Throughout the storage period, a reflectance colormeter was used to monitor colour changes on the tops and sides of mushroom fruitbodies.

The tops of both A. bitorquis strains were significantly more yellow than the A. bisporus strain, whereas the sides were significantly less yellow. Overall, the A. birorquis strain AGC W20 was clearly the least discoloured and least yellow at the time of harvest. Although all the three strains tested gave similar fresh weight losses during storage, i.e. approximately 10% per day, ATCC 32675 exhibited a very slow maturation rate. Both U3 and AGC W20 matured at a similar much faster rate forming open cups within the 5 day storage period. ATCC 32675 also showed the least increase in the degree of discolouration with time, whether readings were taken from the sides or tops of mushrooms. A breeding programme to combine the most salient features of AGC W20 (an intensely white mushroom at harvest, high yielding with distinct flush pattern) and ATCC 32675 (very slow maturation rate during storage) is suggested.
Ultra‐violet radiation damage to Metarhizium flavoviride conidia and the protection given by vegetable and mineral oils and chemical sunscreens
Authors: MOORE D. , BRIDGE P. D. , HIGGINS P. M. , BATEMAN R. P. , PRIOR C.
Published: February 2008

Metarhizium flavouiride conidia formulated in oil or water were exposed to simulated solar radiation. Radiation below 320 nm killed conidia and caused delays in the germination of survivors; germination was greater after 48 h of incubation than after 24 h. UV exposure of conidia formulated in oil for 2 h reduced germination from 99% to 37.5% after incubation for 48 h. Exposure of conidia in water to UV for 1 h resulted in 4.7% germination after 24 h incubation compared with 36.5% for conidia formulated in oil. The addition of 1% oxybenzone resulted in 81.9% conidial germination after 3 h exposure and 48 h incubation compared with 28.1% in oil without the sunscreen.
Application of Metarhizium anisopliae (Metsch.) Sor. conidia to control Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae) larvae on glasshouse pot plants
Authors: MOORHOUSE E. R. , GILLESPIE A. T. , CHARNLEY A. K.
Published: February 2008

The efficacy of the entomogenous fungus Metarhizium anisopliae was assessed against vine weevil (Otiorhynchus sulcatus) larvae in the glasshouse. Prophylactic application of M. anisopliae conidia to begonia resulted in total larval control, but curative applications were less effective with only 65% control when conidial application was delayed until 8 weeks after egg infestation. Prophylactic applications also provided effective larval control on begonia plants which received multiple egg applications over a six week period. Larval mortality was monitored on cyclamen plants which had received a prophylactic drench of M. anisopliae conidia. The population was reduced by 78% within 5 weeks of egg application and control rose to 90% after 17 weeks, although the increase was not significant. Prophylactic conidial drenches were compared with a similar number of compost incorporated conidia on cyclamen, but there was no significant difference between the two spore application strategies. Application of M. anisopliae conidia to impatiens modules before potting‐on resulted in over 89% larval control compared to over 97% control when a similar number of conidia were applied to the plants after potting. Larval control was further reduced to 79% when the module drenches were reduced to one quarter of the highest dose (5 × 107 compared to 2 × 108 conidia per module). The persistence of three M. anisopliae strains was examined over a 20 week period on impatiens. There was no overall decline in efficacy over this period, although there was variability in the performance of the different strains and it was suggested that this was linked to temperature. The results of these experiments suggest that M. anisopliae has considerable potential as a microbial control agent for O. sulcatus on glasshouse ornamentals.
The effect of cereal break crops on barley mild mosaic virus
Authors: ADAMS M J , JONES D R , O'NEILL T M , HILL S A
Published: February 2008

The effects of growing one, two or three years of resistant barley or winter wheat on barley mild mosaic virus were studied in experiments on two naturally‐infested sites in Gloucestershire and Cambridgeshire. Disease incidence and yield of the susceptible cultivars Igri and Maris Otter following a three year break were not significantly different from those of control plots that had grown continuous susceptible barley. The effects of cropping sequence treatment on soil populations of the fungus vector, Polymyxa graminis, were assessed by estimating most probable numbers of propagules following bioassays. Variability was large and neither total numbers of propagules, nor those carrying virus, was significantly affected by the cropping treatments.
Effect of canopy size and shape on the tuber yield of sixteen potato genotypes
Authors: LYNCH D R , KOZUB G C
Published: February 2008

An experiment was conducted to evaluate the utility of visual assessment of canopy characteristics in the selection of high‐yielding clones for the southern Canadian Prairies. Over a 3‐yr period the yield development characteristics of 16 genotypes, selected to represent a range of canopy types, both in size and shape, were studied by destructive sampling at five stages during the growing season. While the response over harvest dates was not consistent for the canopy size or shape groups for most yield variables, it was demonstrated that under the short season growing conditions in southern Alberta, canopies intermediate in size and degree of upright growth habit appear to be most efficient in terms of maximising tuber bulking rates. It was concluded that for the southern Canadian Prairies, selection of genotypes with these types of canopy structure is consistent with the objective of developing early‐maturing cvs with high tuber yield.
Development of a low input system for growing wheat (Triticum vulgare) in a permanent understorey of white clover (Trifolium repens)
Authors: JONES LEWIS , CLEMENTS R O
Published: February 2008

In three field experiments carried out during 1989‐91, a permanent sward of pure white clover (Trifolium repens) was established to provide a source of N for winter or spring wheat crops (Triticum vulgare) directly drilled into the legume. Spring‐sown wheat failed to compete with the clover, but wheat sown in the autumn established successfully. N fertiliser was applied to all three experiments at rates of 0, 50 and 100 kg N ha“1 measurements of grain and whole‐crop silage yields were made. Yields were low for all treatments, probably because of the dry conditions prevailing and the low soil N status of the site used. Yield responses to fertiliser were significant, despite the contribution to plant nutrition that the clover was intended to make. A key feature of the work was that the clover survived successive cereal crops and could be grazed and used as an understorey for later crops. Further, response to fertiliser N diminished with a successive crop implying a build‐up of available soil N, which measurements confirmed had occurred. Use of the system obviated the need to use pesticides, although reasons for the lack of pest damage were not clear.
The origin of variation in seed density in celery (Apium graveolens L.)
Authors: TOORN P VAN DER , KARSSEN C M
Published: February 2008

Seeds were harvested separately from the sequentially formed umbels to obtain information about the origin of variation in seed density in celery. The study involved seeds from the lowest order (primary) to the highest order (quarternary) umbels from the cvs Mars, Monarch, Selfira and Tall Utah. With increasing umbel order the percentage germination decreased and the mean germination time increased. Seed density increased with increasing umbel order, but was more highly correlated with the length of the seed ripening period which differed for each umbel order due to simultaneous harvesting. The decrease in seed density during seed development was correlated with an increase in air volume in the seeds. It is concluded that the variation in seed density in celery seed lots originated from differences in seed maturity.