bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors affecting the development of cane blight (Leptosphaeria coniothyrium) on red raspberries in Washington, Scotland and Germany
Authors: WILLIAMSON B. , BRISTOW P. R. , SEEMÜLLER E.
Published: February 2008

The effects of cultivar, virulence of isolates of Leptosphaeria coniothyrium, cane maturation and wound healing were examined in a series of inoculation experiments carried out over a 3–yr period in three countries in an attempt to explain why cane blight has caused serious yield losses in machine‐harvested red raspberries in Europe, but not in the Pacific Northwest of America. Three isolates of L. coniothyrium from Puyallup (USA), Dundee (UK) and Dossenheim (FRG) were pathogenic on the three test cultivars Willamette, Malling Jewel and Glen Isla in all the experiments. Isolates and cultivars differed for aggressiveness and susceptibility respectively but their ranking was dependent on the test conditions and the differences were small and unlikely to explain the differences in incidence and severity of cane blight in raspberry fields in Scotland and the Pacific Northwest. Conditions at Dossenheim were most favorable for lesion development. At all sites, canes inoculated in late summer produced shorter lesions than those inoculated earlier. A delay between wounding and inoculation produced shorter lesions than simultaneous wounding and inoculation.
Purification and properties of ginger chlorotic fleck virus
Authors: THOMAS J. E.
Published: February 2008

A previously undescribed isometric virus, named ginger chlorotic fleck virus (GCFV), was detected in ginger (Zingiber officinale) imported into Australia from a number of countries. The geographical distribution of the virus is uncertain, but is thought to include India, Malaysia and Mauritius. The virus apparently does not occur in Australian commercial ginger plantings.

The virus has isometric particles c. 30 nm in diameter, with a sedimentation coefficient of 111 S, and was readily purified from infected ginger with yields of 50–90 mg/kg leaf tissue. Purified preparations contained a major species of single‐stranded RNA of mol. wt 1.50 × 106 and a major coat protein species of mol. wt 29.0 × 103. At pH 7, the particles formed a single zone in both caesium chloride and caesium sulphate gradients, with buoyant densities of 1.355 g cm‐3 (fixed virus) and 1. 297 g cm‐3 (unfixed virus), respectively. The virus particles migrated as two electrophoretic components and were labile when treated with 10 mM EDTA, 1 M NaCI, 10 mM tris pH 8.25 or when negatively stained with potassium phosphotungstate. GCFV was mechanically transmitted only to ginger, and was not transmitted by the aphids Myzus persicae. Pentalonia nigronervosa, Rhopalosiphum maidis or R. padi. Possible affinities of GCFV with the sobemo‐virus group are discussed.

The present cryptogram of GCFV is R/l: 1.5/20: S/S: S/*.
Identification of soybean mosaic, southern bean mosaic and tobacco ringspot viruses from soybean in the People's Republic of China
Authors: XU ZHIGANG , POLSTON JANE E. , GOODMAN ROBERT M.
Published: February 2008

Samples of soybean plants with virus‐like symptoms were collected from several locations in the People's Republic of China in 1981. These samples were used to prepare inocula for mechanical inoculation to soybean. Twenty‐one virus cultures were obtained, the identities of which were determined by serology, symptomatology and host range. Sixteen cultures contained only soybean mosaic virus, four of which were more pathogenic than any previously studied; one culture contained only tobacco ringspot virus, another only southern bean mosaic virus, and three other cultures mixed infections of soybean mosaic and southern bean mosaic viruses. This is the first report of the occurrence of tobacco ringspot virus and southern bean mosaic virus in soybean in the People's Republic of China.
The effects of applications of gibberellins to the parent plant, harvest date and harvest method on seed yield and mean seed weight of crisp lettuce
Authors: GRAY D. , STECKEL JOYCE R. A. , WURR D. C. E. , FELLOWS JANE R.
Published: February 2008

The effects on bolting and flowering of treating crisphead lettuce plants cv. Pennlake with gibberellins 4 and 7 (GA4+7) at the rosette stage were compared with cutting open the mature heads in three experiments (1981–83). In addition, to the effects of GA4+7 treatment, those of two methods of harvesting (‘shake’ and ‘windrow’) and time of harvest on seed production were examined.

Compared with plants induced to produce flowering shoots by cutting the mature heads, GA4+7‐‐treatment increased the proportion of plants surviving to produce flowers. It gave more synchronous flowering and it increased seed yields by between 11 and 278% for the ‘shake’ method and by between 33 and 125% for the ‘windrow’ method. There was no consistent effect of method of harvest on seed yield. For windrow harvests, maximum yields were obtained from plants cut between 30 and 45 days after the appearance of the first flowers. Mean seed weight varied between 1. 25 and 1. 62 mg depending on the year of production and harvest date. In 1982 and 1983, the differences in seed weight within any one year were positively associated with differences in mean temperature during the period of seed growth but temperature could not account for the differences in mean seed weight between years.
The effects of seed production techniques on seed characteristics, seedling growth and crop performance of crisp lettuce
Authors: WURR D. C. E. , FELLOWS JANE R. , GRAY D. , STECKEL JOYCE R. A.
Published: February 2008

Seed crops of crisp lettuce were produced in three years with and without gibberellin 4 plus 7 (GA4+7) application to the young seedlings. The effects on seed and seedling characters and field performance of harvesting seed at different times, either by shaking out mature seed or by ‘windrow’ harvests, were assessed.

Differences between treatments in seed and seedling characters within any one year were relatively small although those treatments producing large seed gave large seedlings and those giving uniform seed gave uniform seedlings. There were no important effects of seed production treatments on field characters in any one year. However, when different years of seed production were compared directly there was a large effect of year of production on seedling establishment and the size and uniformity of seedlings. Application of GA4+7 resulted in heavier and more uniform seedlings in two of the three years. The results suggest that major differences between commercial seedlots occur as a result of differences in the environment rather than in the technique of seed production.
The effect of barley yellow dwarf virus on the amino acid composition of spring wheat
Authors: AJAYI OLUPOMI
Published: February 2008

Leaf extracts of barley yellow dwarf virus‐infected and healthy spring wheat (cv. Highbury) plants at three growth stages were analysed by gas liquid chromatog‐raphy to determine their free amino acid content. Eleven free amino acids were identified. Virus infection increased the total amino acid content of sampled leaves at each growth stage but more so at the later stages. Alanine and glutamine were consistently present in greater amounts in infected than in healthy leaves at all three growth stages.
Self‐ and open‐pollination as factors influencing seed quality in leek (Allium porrum)
Authors: GRAY D. , STECKEL JOYCE R. A.
Published: February 2008

The effect of self‐pollination compared with open‐pollination on leek seed weight, and subsequent seedling emergence and growth were observed for two years of seed production.

Open‐pollination gave higher mean seed weights and lower seedling losses during plant establishment than self‐pollination. Depending upon the year, the individual plant and pollination method, between 2. 4 and 56.6% of the variation in seedling weight c. 4–5 wk after sowing under controlled conditions was accounted for by differences in seed weight and time of seedling emergence. In 1984 but not 1983, a greater proportion of the variation in seedling weight was accounted for by seed weight and time of seedling emergence in open than self‐pollinated seeds.
Inheritance of a dwarf seed stalk character in onion
Authors: HOROBIN J. F.
Published: February 2008

Results are reported of crossing a dwarf seed stalk line (mean height 44.8 cm) from Israel with five inbred lines of the Rijnsburger type each having normal tall seed stalks (mean heights 83.1–105.9 cm). The seed stalk height of F1 generations from these crosses was slightly greater than that of the Rijnsburger parents but segregation occurred in the F2 giving plants which could be considered ‘dwarf’ and ‘normal’ with respect to seed stalk height. Selfing individual F2‘dwarf’ plants produced F3 progenies whose mean heights were in the dwarf range, and were significantly correlated with those of their F2 parent. The results obtained in the F2 and F3 families suggest that although a major recessive gene for dwarfness may be present, substantial minor gene and environmental variation is also involved.
Effect of temperature on the population dynamics of three Dalbulus leafhopper species
Authors: MADDEN L. V. , NAULT L. R. , HEADY S. E. , STYER W. E.
Published: February 2008

Adult survival and fecundity of three Dalbulus leafhopper species were determined at constant temperatures of 20, 23, 26 and 29°C. Survival was measured by quartiles (i.e. time to 75%, 50% and 25% survival) and estimated parameters of the Weibull model fitted to the survival distributions. D. gelbus lived as long or significantly (P= 0.05) longer than the other species at all temperatures. D. maidis (the corn leafhopper) had survival times equal to or significantly shorter than D. elimatus (the Mexican corn leafhopper) at all temperatures except 29°C where D. maidis lived the longest. The shape of the survival curves did not vary among species or change with temperature.

The fecundity of D. gelbus, as measured by the average number of eggs laid per female per generation, was equal to or significantly lower than the other species at all temperatures. D. maidis and D. elimatus had similar fecundity at all temperatures except 29°C, where D. maidis produced significantly more eggs. The mean development time from egg to adult declined with temperature between 17 and 29°C. At all temperatures, D. maidis developed the fastest, D. gelbus the slowest, and D. elimatus was intermediate. The results can be explained on the basis of the geographic distribution, plant host species, and life‐history strategies of the leafhoppers. Models for describing the population dynamics of leafhoppers are evaluated and discussed.
The collection and selection in Europe of isolates of Phragmidium violaceum (Uredinales) pathogenic to species of European blackberry naturalised in Australia
Authors: BRUZZESE E. , HASAN S.
Published: February 2008

Phragmidium violaceum is a rust fungus with potential for the biological control of European blackberry (Rubus fruticosus) in Australia. The collection, selection, purification and multiplication in Europe of isolates of the rust is described. Species of European blackberry naturalised in Australia showed different levels of susceptibility when inoculated with a pool of 15 isolates highly pathogenic to Rubus procerus. Selection of individual isolates on the four most widespread blackberry species showed that only two of the isolates would be required to obtain the best attack on these four species.
Acquisition and transmission of corn stunt spiroplasma by its leafhopper vector Dalbulus maidis
Authors: ALIVIZATOS A. S. , MARKHAM P. G.
Published: February 2008

As the acquisition access period of Dalbulus maidis on infected maize increased from 15 min to 7 days, the incubation period of corn stunt spiroplasma (CSS) in the insect decreased from 27 days to 8 days and the final proportion of transmitting insects increased from 5% to 100%. After 7 days access the median incubation period (IPsO) was 14.3 days (IP50 females = 12.9 days: IP50 males =16.8 days), while the proportion of transmitting insects increased from 4. 3% (9 days after the start of acquisition access) to a maximum of 93% (after 22 days), before decreasing. Females started transmitting significantly earlier and a greater proportion transmitted each day than males, until day 22 when both sexes transmitted equally.

Of the insects which transmitted CSS, 29% did so continuously until death; 66% failed to transmit during the last 1–3 days, and 5% transmitted intermittently towards the end of their life. During daily transfer, females were more likely to infect plants consecutively (up to 25) than males, and females infected the higher proportion of test plants.

As the transmission access period was increased from 1 h to 72 h, the proportion of transmitting insects increased from 22.5% to 97.3% and the incubation period in maize decreased.
Host specificity of the rust Phragmidium violaceurn, a potential biological control agent of European blackberry
Authors: BRUZZESE E. , HASAN S.
Published: February 2008

The host specificity of the rust fungus Phragmidium violaceum, a potential biological control agent of European blackberry (Rubus fruticosus) was studied by inoculating a mixture of 15 isolates of the rust on 108 plants of importance to the Australasian region. A scale of infection types was developed based on the results of microscopic and macroscopic observations of the reaction of host and non‐host plants to the rust. The results showed that P. violaceum has a limited host range in the genus Rubus. The rust was able to reproduce on 17 taxa of Rubus previously unrecorded as hosts, including Australasian species of Rubus subgenera Dalibarda and Lampobatus. All other taxa attacked were species of Rubus subgenus Eubatus and the majority were hybrid cultivars containing European blackberry species.
The effects of ethylene concentration in controlled atmosphere storage of tomatoes
Authors: GEESON J. D. , BROWNE K. M. , GUARALDI FRANCESCA
Published: February 2008

Previous studies have demonstrated that mature green tomatoes can be stored for up to 10 wk at 12. 5°C, 93–95% r.h. in a controlled atmosphere (CA) containing 5% CO2, 5% O2 and 90% N2, and will then ripen satisfactorily in air at 20°C. The effects of different concentrations of ethylene between <0.1 and 30 μl/litre in this storage atmosphere on ripening changes and fruit quality after 5 wk CA storage and a further 8 or 9 days ripening in air were investigated using cv. Sonatine glasshouse tomatoes.

Maintaining ethylene concentrations in the storage atmosphere to.1 plllitre resulted in poor and uneven ripening of the tomatoes after storage, and increased their susceptibility to infection by Botrytis cinerea and Penicillium spp. Fruit previously stored in atmospheres containing 5 to 30 μl/litre ethylene were significantly softer after ripening than tomatoes stored in lower ethylene concentrations. Overall, the best results in terms of fruit quality (colour, firmness) and a low incidence of fungal infection were achieved with 1–3 μl/litre ethylene. The practical problems in achieving and maintaining optimum conditions, including the correct ethylene level, in CA storage of tomatoes are also discussed.
Temperature response and flowering of white clover (Trifolium repens) varieties in controlled environments and the field
Authors: NORRIS I. B.
Published: February 2008

Floral initiation of 10 white clover varieties growing in three controlled day/night temperature regimes, 22“/10°C, 20°/10°C, 17°/10°C, was recorded. Effects of artificial soil heating on floral initiation of the same plants subsequently transferred to the field were also examined.

In the controlled environments only a slight increase in day temperature (2–5°C) was necessary to significantly increase flowering. Defoliation at the three temperatures had contrasting effects on subsequent flower production.

Results from the soil heating experiment suggested that increased temperature might compensate for short daylengths, by bringing forward reproductive bud initiation by 1 month.

Soil heating increased the total number of inflorescences produced.
Russeting of apples caused by apple rust mite Aculus schlechtendali (Acarina: Eriophyidae)
Authors: EASTERBROOK M. A. , FULLER MORWENNA M.
Published: February 2008

Significant correlations were found between the numbers of apple rust mites Aculus schlechtendali feeding on fruitlets shortly after the blossom period and the amounts of russet on the calyx‐end and cheek of apples at harvest. Stalk‐end russet was not usually affected. Fruits from clusters or trees on which rust mite numbers had been reduced with an acaricide pre‐blossom had less calyx‐end and cheek russet than apples from untreated comparisons. Histological studies showed that feeding by mites on flower receptacles/fruitlets in May and June damaged epidermal cells, resulting in russet formation.
Allozymatic diagnosis of four economically important Liriomyza species (Diptera, Agromyzidae)
Authors: MENKEN STEPH B. J. , ULENBER SANDRINE A.
Published: February 2008

Liriomyza bryoniae, L. huidobrensis, L. sativae and L. trifolii are leafminers of great economic importance; morphologically they are difficult to separate, many being inseparable at the pre‐adult stages. Horizontal starch gel electrophoresis of larvae, pupae and adults was carried out in order to search for diagnostic allozymic characters. Analysis of the variation patterns at 15 genetic loci reveals that each species can be identified at all three stages of the life cycle. A biochemical key is presented.
The fate, distribution and biological performance of insecticide residues in vegetable crops following seedling treatment
Authors: SUETT D. L. , WHITFIELD C. E.
Published: February 2008

Carrot, cauliflower and radish seedlings raised in sand culture and treated with aqueous suspensions containing chlorfenvinphos, diazinon, iodofenphos or triazophos were planted into the field in 1982 and 1983 to compare the performance against cabbage root fly and carrot fly of these treatments with that of bow‐wave applications of granular formulations at sowing.

Initial residue concentrations were up to 4100 mg kg‐1 in the seedlings at planting. Thereafter the amounts of insecticides per root system declined. Residue concentrations in mature carrot and radish roots were smaller when plants had been treated as seedlings rather than by bow‐wave application. Chlorfenvinphos was the most effective insecticide against both pests. Amounts of insecticide applied in transplanted seedlings were < 5% of the amounts applied by the bow‐wave method but short‐term control of cabbage root fly on radish was similar. Carrot fly damage was reduced by 60% by some of the seedling treatments after 16 wk in 1982 but in 1983 they were less effective.

Pot experiments with chlorfenvinphos showed that most of the insecticide in the seedlings was transferred rapidly into the surrounding soil and it was concluded that the bioactivity resulted mainly from uniform distribution of the released insecticide between and around individual plants.
Failure of in vitro growth inhibition by cysteine to differentiate between Australian Gaeumannomyces graminis isolates pathogenic and non‐pathogenic to oats
Authors: YEATES J. S.
Published: February 2008

Radial growth of oat and non oat‐attacking Australian isolates of Gaeumannomyces graminis was greatly inhibited by increasing concentration of DL‐cysteine in basal medium agar, and growth was completely inhibited by cysteine concentrations of 3 μM. As a group, isolates of G. graminis var. tritici (both oat and non oat‐attacking forms) were more inhibited than isolates of G.graminis var.avenae at 1 μM cysteine, but differences did not occur at other concentrations. Isolates of a lobed‐hyphodiate fungus similar to G. graminis var. graminis were more tolerant of cysteine than other isolates.

The findings indicate that in vitro inhibition of Australian G. graminis isolates by cysteine is not useful for differentiation between oat and non oat‐attacking types, and is unlikely to be fundamentally related to the ability of isolates to attack oats.
Cross pathogenicity studies with isolates of Fusarium oxysporum from either cucumber or watermelon pathogenic to both crop species*
Authors: MCMILLAN R. T.
Published: February 2008

Isolates of Fusarium oxysporum from Abaco, the Bahamas, whether obtained from wilted plants of cucumber (Cucumis sativus) or watermelon (Citrullus lanatus), were pathogenic to cucumber, watermelon, and cantaloupe (Cucumis melo var. reticulatus). The West Indian gherkin (Cucumis anguria), pumpkin (Cucurbita pepo), and three cultivars of summer squash (C. pepo var. melopepo) were not susceptible. Strains of F. oxysporum from wilted cucumber or watermelon plants from Florida were highly pathogenic only to their original host species and are regarded as different formae speciales.
Further evidence that dioscorea latent virus is a potexvirus
Authors: PHILLIPS SUE , PIGGOTT J. D'A. , BRUNT A. A.
Published: February 2008

Dioscorea latent virus (DLV) was isolated from Dioscoreafloribunda but was not detected in any of 37 cvs of D. alata, D. bulbifera, D. esculenta or D. rotundata from eight countries. It was readily sap‐transmitted to 13 of 34 species from five of 12 families; it induced symptomless systemic infection in Nicotiana benthamiana and N. megalosiphon, but only symptomless local infection in other hosts. DLV was stable in vitro: sap from infected N. megalosiphon was still infective after 10 min at 75–80 oC but not 85 oC, after dilution to 10‐6 but not 10‐7, and after at least 12 months at 23 oC. DLV was not transmitted through seed, by contact or by the aphids Aphis gossypii and Myzus persicae.

DLV had filamentous particles most of which measured c. 350–900 nm in purified preparations, with two modal lengths of 445 and 875 nm; the particles sedimented as two components with sedimentation coefficients of 111 S and 131 S and had a buoyant density in caesium chloride of 1–33 g cm‐3. The virus had a single nucleic acid species with a mol. wt of 2–3 ± 04 × 106 and usually produced two protein bands (mol. wts 24 900 and 23 100) in SDS‐PAGE, although virus preparations made in the presence of chloroform yielded only the larger polypeptide. DLV was serologically distantly related to commelina X and lily X viruses, but not to 11 other established or possible members of the potexvirus group.

These results provide further evidence that DLV is a distinct but definitive potexvirus.
Beet necrotic yellow vein virus: different isolates are serologically similar but differ in RNA composition
Authors: KUSZALA MARIA , ZIEGLER VÉRONIQUE , BOUZOUBAA S. , RICHARDS K. , PUTZ C. , GUILLEY H. , JONARD G.
Published: February 2008

Twelve isolates of beet necrotic yellow vein virus, agent of rhizomania in sugar beet, have been obtained from five European countries and the USA. The isolates were cloned and multiplied in the local lesion host Chenopodium quinoa. By ELISA, a close serological relationship was observed among all the isolates. The isolates differed, however, in the number of viral RNA species present (2, 3 or 4) and in the lengths of RNAs 3 and 4, the two smallest RNAs. A comparison of the symptoms induced by the different isolates in C. quinoa revealed a correlation between the presence of a full‐length RNA 3 (about 1850 nucleotides) and the appearance of severe chlorotic local lesions.
Stable resistance to bacterial blight disease in rice
Authors: NAYAK P. , CHAKRABARTI N. K.
Published: February 2008

Ten rice cultivars were evaluated for stable resistance to 18 isolates of Xanthomonas campestris pv. oryzae. Stable performance of the host cultivar was evaluated by regressing the cultivar means on the mean level of pathogenicity of the isolates averaged over all cultivars. A cultivar with low disease incidence, a regression coefficient near or equal to zero (b= 0) and the deviation from regression as small as possible (S2d= 0) was considered highly stable while that with low disease incidence, b= 1 ‐0 and S2d= 0 was considered to possess average stability. Accordingly, cvs TKM‐6, CB II, DV 85 and Ramakrishna were considered to possess average stability while IR 20 and Indira were the most stable. Cvs Cemposelak, IR 1545, BJ 1 and IR 8 showed high response to disease incidence with relatively small changes in level of pathogenicity of the isolates and hence were considered most unstable. The regression technique was considered as a valuable tool for identification of stable resistance to bacterial blight disease of rice.
Effects of hydroxamic acids on the resistance of wheat to the aphid Sitobion avenae
Authors: BOHIDAR K. , WRATTEN S. D. , NIEMEYER H. M.
Published: February 2008

Resistance to the aphid Sitobion avenae F. was assessed on six wheat cultivars of known concentrations of total hydroxamic acids. A range of values for intrinsic rate of increase (rm) were obtained, 96% of the variation in which was explained by acid concentrations. Of the components of rm, age‐specific fecundity was the most significant factor contributing to resistance.
Genetic analysis of resistance in Brussels sprout to cauliflower mosaic and turnip mosaic viruses
Authors: PINK D. A. C. , SUTHERLAND R. A. , WALKEY D. G. A.
Published: February 2008

A total of 28 inbred lines of Brussels sprout were assessed in the glasshouse for their reaction to inoculation with cauliflower mosaic (CaMV) or turnip mosaic (TuMV) virus. There was significant variation for resistance to both viruses. From the 28 inbred lines parents were chosen for two 9 × 9 diallel crossing programmes. The parents and their F1 progeny were assessed for their reaction to CaMV or TuMV in the field.

There was significant additive and non‐additive (dominance) variation but no maternal effects. Resistance to both viruses was generally dominant but with some evidence of a recessive gene for resistance to CaMV. Resistance to TuMV and CaMV was apparently controlled by at least four genes and two genes respectively. The heritability of resistance to each virus was high.

The implications for breeding F1 hybrid Brussels sprout cultivars are discussed.
Comparative transmission of soybean dwarf virus by three geographically diverse populations of Aulacorthum (= Acyrthosiphon) solani
Authors: DAMSTEEGT V. D. , HEWINGS A. D.
Published: February 2008

Three populations of Aulacorthum (=Acyrthosiphon) solani were compared as vectors of the two strains of soybean dwarf virus (SDV). United States (CA = California) and New Zealand (NZ) populations transmitted both SDV strains less efficiently than did the Japanese population. The CA and NZ populations most readily colonised leaflettuce, curled dock, or wild geranium and the Japanese aphids readily colonised soybeans and curled dock. CA and NZ aphids were smaller, more pigmented, and less prolific on the hosts tested than were Japanese aphids. Nymphs were more efficient vectors than adults. Alatae and apterae transmitted the virus with equal efficiency. All aphids transmitted the dwarfing strain more efficiently than the yellowing strain.
Infection of strawberry flowers by Botrytis cinerea and its relevance to grey mould development
Authors: BRISTOW P. R. , McNICOL R. J. , WILLIAMSON B.
Published: February 2008

Newly‐opened strawberry flowers of several cultivars were inoculated in the glasshouse, growth chamber and field with conidia of Botrytis cinerea from cultures of seven isolates. Infection in pistils, stamens, petals, sepals and receptacles was detected by u.v. microscopy after softening fixed tissues in 1 N sodium hydroxide and staining in 0–1% aniline blue. For all isolates, cultivars and environments, conidia germinated on the stigmas and their hyphae grew into the transmitting tissue of the styles, but so slowly that they sometimes took 4–6 wk to reach the style bases. Cv. Troubadour was the only cultivar in which hyphae grew from the style into the carpel, but growth there was limited and did not progress into the receptacle. The fungus produced conidiophores and conidia on the stigmas of 15 of the 23 cultivars tested in the field but did not do so in the growth chamber or glasshouse tests. It readily colonised the anthers and connective between the anther lobes and sporulated on anthers in the field; in some cultivars it grew to the base of a few stamen filaments and into the receptacle. In the glasshouse, conidia remained ungerminated on the petals and sepals for at least 6 days, but in a moist chamber they germinated and hyphae rapidly penetrated the epidermis and colonised internal tissues of these flower parts. Results indicated that stamens may be more important than styles as a source of latent infection.
The susceptibility of stems of different potato cultivars to blackleg caused by Erwinia carotovora subsp. atroseptica
Authors: LAPWOOD D. H. , READ P. J.
Published: February 2008

The susceptibility of stems of six potato cultivars to Erwinia carotovora subsp. atroseptica was assessed in two years (1981 and 1982) either by direct inoculation in the field or by inoculation of detached stems in the laboratory. These six and a further 22 cultivars were also assessed in three years (1982‐84) by inoculating stems of glasshouse‐grown plants.

Different methods of inoculation and types of inocula were tested. In the field, wooden toothpicks rubbed in bacterial slime were more successful in establishing infection than when dipped in a bacterial suspension, but injection of bacterial suspension with a hypodermic needle was reliable in establishing infection over a range of concentrations. Detached stems were more readily infected and gave more consistent results compared with inoculation in the field.

The range of reaction of the six cultivars was similar in both detached stem and glasshouse tests. The early cultivars Pentland Javelin and Ulster Sceptre were most susceptible and of the maincrop cultivars, Maris Piper was intermediate and Desiree and King Edward least susceptible whereas Pentland Crown showed greater resistance in the glasshouse than in the field. Glasshouse tests using hypodermic inoculation indicated a range of susceptibilities; the early cultivars Manna, Maris Bard and Estima were most susceptible and the maincrop Pentland cultivars Crown, Dell, Hawk, Ivory and Squire least susceptible.
Synergistic action between ioxynil, bromoxynil acids and aminotriazole
Authors: BALAYANNIS P. G.
Published: February 2008

Two halogenated organic compounds, ioxynil acid and bromoxynil acid, were shown to inhibit the oxidation of aminotriazole in a free radical generating system. When hypotoxic concentrations of aminotriazole plus ioxynil acid or bromoxynil acid were applied as sprays to wheat plants synergistic action was observed; whereas the three chemicals applied separately caused no damage to wheat plants, the combined spray destroyed them. The statistical analysis of the results confirms that the above combinations act synergistically.
Common resistance in red raspberry to Botrytis cinerea and Didymella applanata, two pathogens occupying the same ecological niche
Authors: WILLIAMSON B. , JENNINGS D. L.
Published: February 2008

Comparisons were made between Botrytis cinerea and Didymella applanata, which occupy the same ecological niche on canes of red raspberry. Isolates of B. cinerea from diverse localities within the British Isles were pathogenic to the SCRI selection M30 when internodal wounds on young canes were inoculated. A single inoculation frequently caused the buds at several nodes to fail the following spring. Differences in the lengths of the stem lesions that formed indicated differences in isolate pathogenicity, but these were not related to isolate origin. Bud suppression and lateral shoot failure also occurred when petioles of cvs Mailing Orion, Mailing Jewel and Glen Clova were wound inoculated with B. cinerea up to late August.

The relative resistance of seven cultivars to three isolates of each pathogen was determined. Principal components analysis of data from five estimates of resistance to each pathogen showed that 40% of the variation described a common resistance to the two diseases.

Further analysis showed that cvs Chilcotin and Meeker had the strongest common resistance and that cvs Glen Prosen and Mailing Jewel had the weakest. The remaining variation described cultivar differences in relative bud length after petiole inoculation with either pathogen, and differences in the relative importance of spring and autumn symptoms. Only 7% of the variation indicated independent resistance to the two pathogens and this was not influenced by cultivar differences.
Effects of shading and plant density on leaf growth of Viciafaba
Authors: KASIM K. , DENNETT M. D.
Published: February 2008

Faba beans (Viciafaba cv. Maris Bead) were grown in the field at densities of 20 and 60 plants m‐2 and under zero, 34 and 56% reduction in incoming solar radiation. Measurements of the area of individual leaves were made every two days. Rates of leaf appearance and the duration of expansion of a leaf were virtually unaffected by the experimental treatments. Leaves required approximately 200 oC days (above 1 oC) from appearance to full expansion. Shading consistently increased specific leaf area but decreased leaf weight only at the greater shading level. At low density leaves were largest under 34% shade and smallest under 56% shade, but at high density there were no significant differences in leaf size.
Alternatives for gold wire electrodes in electronic measurement systems for studying insect probing behaviour
Authors: KIMSEY R. B. , MARKHAM P. G. , KINSEY M. G. , ULLMAN D. E. , McLEAN D. L.
Published: February 2008

Single stranded materials including individual silk fibres and human hair were gold plated with a sputter coater and used in place of gold wire electrodes in electronic systems for monitoring insect feeding behaviour.
Short‐term forecasting of peak population density of the grain aphid (Sitobion avenae) on wheat
Authors: ENTWISTLE J. C. , DIXON A. F. G.
Published: February 2008

The trends in population density of Sitobion avenae in wheat fields were analysed for a total of 32 sites over the period 1975 to 1983 in eastern England and the Netherlands. The peak population density on each field was positively correlated with the population densities at the end of ear emergence, mid‐anthesis and the end of anthesis. It was also positively correlated with the observed rates of increase of the aphids on the crop immediately before these stages. Both parameters were incorporated in multiple regressions to forecast peak population density, and data from a further nine populations monitored in 1984 was used to validate the model.

The accuracy of these forecasts, based on two counts on the crop, increased from ear emergence to the end of anthesis, the forecast at mid‐anthesis of peak density being much more accurate than any other published method.
Chemical control of wheat bulb fly (Delia coarctata) attacking winter wheat in Eastern England, 1969–1981
Authors: MASKELL F. E. , GAIR R.
Published: February 2008

Several insecticides were applied to the soil and/or plant foliage as granule or spray treatments to control wheat bulb fly larval damage to late‐sown winter wheat in eastern England between 1969 and 1981. Treatment effects in preventing larvae from entering plants or in killing larvae within attacked shoots and effects on yield were compared with controls and with a standard chlorfenvinphos seed treatment.

Granules of chlorfenvinphos, fonofos or terbufos at rates between 1–40 and 2–24 kg a.i./ha were highly effective when applied at sowing in mineral soils, and fonofos granules were also effective in organic soils. Single spray applications of chlorfenvinphos, and especially of fonofos, applied at sowing at rates between 0–84 and 1–40 kg a.i./ha were effective in both soil types.

Sprays applied when wheat bulb fly eggs began to hatch were more effective in mineral than in organic soils and gave lower yield increments than the standard chlorfenvinphos seed treatment.

Single sprays of chlorpyrifos, formothion, omethoate or pirimiphos‐methyl, applied to the foliage when larval damage was first seen (‘deadheart’ stage) significantly increased yields; dimethoate spray or granule treatments applied at this stage were not significantly better than control and ‘deadheart’ treatments were generally less effective than chlorfenvinphos seed treatment.

Multiple treatments involving two or more of the above methods were extremely effective in both soil types; their economic and environmental implications are discussed.
Definition of leaf health in Agrostis palustris at the time of infection and colonisation by Curvularia lunata
Authors: MUCHOVEJ J. J.
Published: February 2008

The state of leaf health of intact Penneagle creeping bentgrass leaves into whichCurvularia lunatawas able to ingress was determined by reducing cuticle/wax formation with trichloroacetic acid (TCA) and stressing plants with high air temperatures. Leaf health was estimated throughout the growing period of the plants by extracting chlorophyllaand then regressing the values with respect to time. In this manner, leaves at each nodal position could be classified as either juvenile, mature or senescent. The addition of TCA to plants decreased leaf and plant life. Stressing plants with high air temperatures accelerated leaf senescence as did higher levels of TCA. Inoculation withDrechslera sorokinianaresulted in lesion formation within 2 days. Symptoms commonly attributed to Curvularia blight were present on plants treated with 140 ^M TCA when high‐air‐temperature stressed and inoculated withC. lunata.Histochemical procedures failed to show the presence of mycelium ofC. lunatawithin the cells of Curvularia blight symptom areas. Results demonstrated that C.lunatahad the ability to colonise heat stressed and/or old leaves but did not have the ability to infect and colonise juvenile or mature tissues.
Regional variation of Puccinia coronata avenae in Australia and its implications for oat breeding
Authors: BROUWER J. B. , OATES J. D.
Published: February 2008

A virulence survey of Puccinia coronata avenae was conducted in Australia from 1977 to 1980 with a chosen series of resistant oat lines as a tester set, viz., Ascencao, Pc‐38, Pc‐39, Pc‐45, Pc‐48, Pc‐50, Pc‐55, Pc‐56 and TAM 0–312. Isolates of the pathogen were classified by using these nine tester lines in combination with the International Differential Set. The survey area was divided into six zones (1) ‐Queensland; (2) ‐ northern New South Wales; (3) ‐ southern New South Wales; (4) ‐ Victoria; (5) ‐ South Australia and (6) ‐ Western Australia.

Virulence for Pc‐38 was widespread throughout Australia and virulences or partial virulences for lines Pc‐39, Pc‐45, Pc‐48 and Pc‐55, although not as frequent, were common in Zones 1, 2 and 3. No isolates were found with virulences for oat lines Pc‐56 and TAM 0–312, while virulences for Ascencao or Pc‐50 were rare. The combination of virulences or partial virulences for lines Pc‐39, Pc‐45 and Pc‐48 was relatively common only among samples from Zones 1, 2 and 3.

The diversity of the pathogen population varied between zones. Isolates from Zones 1 to 6 comprised 16, 21, 9, 8, 5 and 4 different standard races and mean virulence values were 5‐0, 3–8, 3‐0, 2–7, 2–6, 3‐1 and 3‐0, respectively. The proportion of complex strains (virulence value 5 or higher) decreased from 48‐5% (Zone 1) and 17‐0% (Zone 2) to 1–7% (Zone 3), 6‐3% (Zone 4), 0% (Zone 5) and 13‐9% (Zone 6). Greater diversity of the pathogen population in Zones 1 and 2was indicated by a higher incidence of strains with virulence for one or more of the nine resistant oat tester lines.
Propagation of black raspberry necrosis virus (BRNV) in mixed culture with solanum nodiflorum mottle virus, and the production and use of BRNV antiserum
Authors: JONES A. T. , MITCHELL MARGARET J.
Published: February 2008

The concentration of particles of black raspberry necrosis virus (BRNV), which is normally extremely low in herbaceous plants, increased about 1000‐fold when Nicotiana clevelandii plants were inoculated with a mixture of BRNV and an unrelated virus, solanum nodiflorum mottle (SNMV). In sap from N. clevelandii infected with the mixed culture, BRNV infectivity survived dilution to 10˜4 but not 10˜5, and storage for 6 but not 8 days at 20 oC, for 6 but usually not 10 days at 4 oC and for more than 13 days at – 15 oC. When plants were inoculated with the mixed culture, BRNV induced typical symptoms in several Chenopodium species and infected several previously unreported hosts. Purified preparations of particles of the mixed culture contained only a small proportion of BRNV particles, which sedimented in sucrose density gradients as two components, one, probably non‐infective, of c. 505, and the other, infective, of 120‐130S. An antiserum prepared to purified particles of the mixed culture was cross‐absorbed with SNMV particles and used in indirect ELISA to detect BRNV in herbaceous plants infected with the mixed culture, and also in a wide range of Rubus species, cultivars and hybrids infected naturally, by grafting or by inoculation with the aphid Amphorophora idaei. The reliability of ELISA for detecting BRNV in raspberry leaves depended on the cultivar and time of year. Some cultivars, such as Glen Clova, had low concentrations of BRNV, which was detected reliably only in late spring/early summer, whereas other cultivars, such as Lloyd George and Mailing Enterprise, had greater BRNV concentrations.

In small‐scale surveys in eastern Scotland, BRNV was detected by ELISA in many raspberry cvs, including some that contain major gene resistance to the vector, A. idaei; in five of nine raspberry stocks entered for the Standard grade certificate but in none of five stocks entered for the Stock Cane certificate; and in 40% of wild raspberry and 14% of wild bramble plants growing near commercial raspberry crops. The significance of these findings for the control of BRNV is discussed.
Maize rough dwarf virus (Reoviridae) in its planthopper vector Laodelphax striatellus in relation to vector infectivity
Authors: CACIAGLI P. , CASETTA ALDA
Published: February 2008

The infectivity of females of the planthopper vector Laodelphax striatellus given access to maize rough dwarf virus (MRDV) infected plants was assessed for up to 55 days from the end of the access period. A 3‐day inoculation access period was used, and this avoided intermittent transmission. Maximum infectivity was reached c. 30 days after acquisition access and the proportion of transmitter insects then remained constant.

There was no difference in the efficiency of female L. striatellus in acquiring MRDV as third instar nymphs or as adults when compared in transmission tests 24, 30, 35 and 40 days after access to the virus.

ELISA tests for MRDV subviral particles (SVPs) discriminated between individual viruliferous and non‐viruliferous insects from the 30th day after access.

Of the viruliferous (ELISA positive) insects about 30% did not transmit MRDV and the proportion remained similar from 30 to 55 days after access. None of the non‐transmitter insects tested in serial transfer transmission tests was positive in ELISA.

The concentration of SVPs detected by ELISA in the transmitter hoppers continued to increase exponentially, even after maximum infectivity was reached.
Relationship between pectin content of stems of flax cultivars, fungal cell wall‐degrading enzymes and pre‐harvest retting
Authors: BROWN AVERIL E. , SHARMA H. S. S. , BLACK D. L. R.
Published: February 2008

Of five flax cultivars suitable for fibre production Ariane retted most rapidly and Belinka and Hera were the slowest to ret after treatment with the herbicide glyphosate. Prematurely senescing stems of the different cultivars bore the same populations of saprophytic, filamentous fungi.

More polygalacturonase (PG) activity was detected in retting, naturally‐colonised stems of Belinka, Hera and Regina than in stems of Ariane or Natajsa but pectin‐lyase (PL) activities were not significantly different. The pectic substance content of stem cell walls varied between cultivars; Hera and Belinka contained significantly the greatest amount, 34‐0 and 32‐5% w/w respectively and Ariane contained the least, 26‐3% w/w. Significant differences in xylan content of cell walls were not obtained but the highest levels of xylanase activity were detected in colonised stem tissues of Belinka. Fibres of this cultivar were found to be slightly weaker than those of the other cultivars but also the finest.
Ryegrass establishment and yield in relation to pesticide treatment, irrigation and fertiliser level
Authors: SPAULL ALISON M. , CLEMENTS R. O. , RIDOUT M. S. , G. MEWTON P.
Published: February 2008

The effects of irrigation, four fertiliser rates, fungicide, insecticide + molluscicide, and nematicide treatments were tested on an Italian ryegrass sward sown in May 1983, in a multi‐factorial experiment that allowed treatment interactions to be examined.

Pests and fungal diseases were monitored over a 2‐yr period. No recognised grassland insect pests or slugs were found in the seedbed but there were an estimated 17 300 plant parasitic nematodes/litre soil. Other, non‐pest invertebrate populations, e.g. earthworms, were not assessed.

In the first year yields were increased most by irrigation. There were also large yield responses to fertiliser over the range 50–900 kg N/ha/yr. Responses to pesticide application were relatively small. However, there were significant yield responses in the first year to nematicide and to insecticide + molluscicide treatments.

Yields in the second year were affected more by increased fertiliser use than by irrigation; increases after pesticide use were similar to the previous year, and there was also a small but significant yield gain over untreated plots at the second harvest from those treated with fungicide.

Interactions between main factors occurred in both years, affecting yields and nematode abundance. Nematode numbers were decreased in both years where the larger, compared to the smaller fertiliser applications had been made. In the first year these differences were only apparent on irrigated plots.

It was concluded that, in this trial, irrigation had the greatest effect on yields of spring‐sown ryegrass during its establishment year but that increasing fertiliser rates had a greater effect the year after; that fungi had had little effect on ryegrass yields, and that nematodes were more important pests than insects during establishment but insects were more important subsequently.
The effect of pollen irradiation on segregation in spring barley crosses
Authors: ELLIS R. P.
Published: February 2008

Observations on the Ml, M2 and M3 generations from three barley crosses confirmed that pollen irradiation can cause deviations from expected segregation ratios for certain characters. The reduced fertility observed in the Ml and M2 generations of these crosses could be problematical in breeding programmes. It was of particular interest that at the highest dose rate used for the cross TS117 × Scots Bere there was no expression of the 6‐row character, which is controlled by a recessive paternal factor.