bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of formulation on chlorfenvinphos uptake and cabbage root fly control on radish
Authors: SUETT D. L.
Published: February 2008

Granular and liquid formulations of chlorfenvinphos were applied to a sandy‐loam as continuous logarithmically‐changing doses of approximately 0.2 to 4.0 kg a.i./ha and radish were sown immediately and 23 days after treatment. After 62 days, insecticide concentrations in the soil had not diminished detectably in the granule treatment but had declined by about 20% in the liquid treatment. In both sowings, residues in the harvested radish were higher, dose‐for‐dose, from the granule than from the liquid treatment and with both formulations were lower in the second than in the first sowing. Within treatments there were log‐log relationships between the dose of insecticide and residue concentrations in the soil and radish. In both sowings the residues were most variable between replicate soil and crop samples from the granule treatment. In the first sowing, cabbage root fly damage was reduced most by the liquid treatment but in the second sowing equivalent doses of the two formulations gave similar protection.

At 2.0, 2.24 or 3.0 kg a.i./ha, chlorfenvinphos incorporated before sowing protected radish better than pre‐sowing or pre‐emergence applications to the soil surface. When applied before sowing, the liquid formulation gave better protection and lower residue concentrations in the radish than the granules. As a post‐emergence spray, chlorfenvinphos was much more effective than fonofos, diazinon or triazophos but it was often phytotoxic, decreased yield significantly, left large residues in the radish in two of the four experiments and, in common with other surface treatments, substantially decreased the Z:E chlorfenvinphos isomer ratio. Although a single application of granules protected two successive radish crops, it was concluded that third and subsequent sowings on the same land should probably be treated with smaller doses to limit terminal residues.
The characteristics of isolates of Erysiphe graminis f. sp. hordei varying in response to tridemorph and ethirimol
Authors: WALMSLEY‐WOODWARD DIANNE J. , LAWS F. A. , WHITTINGTON W. J.
Published: February 2008

Single pustule isolates of E. graminis f. sp. hordei were collected from fungicide treated and untreated barley in the field and glasshouse. The isolates were maintained in culture on leaf segments of a mildew susceptible barley cultivar. Each isolate was assayed at least five times in 10 months for tolerance to tridemorph and ethirimol.

Variation was found among the isolates both in pathogenicity and in the level of tolerance to tridemorph and ethirimol. Tolerance to either fungicide tended to be stable during the 10 months of culturing, although a small number of isolates lost their tolerance in this time. No evidence of cross tolerance was found, although some isolates were tolerant to varying levels of both fungicides, perhaps due to a fortuitous combination of tolerance genes.
Transmission and differentiation of six viruses infecting hogweed (Heracleum sphondylium) in Scotland
Authors: BEM F. , MURANT A. F.
Published: February 2008

Six viruses, code‐named HV1‐HV6, were transmitted manually and/or by aphids (Cavariella spp. from symptomless wild plants of hogweed (Heracleum sphondylium) in Scotland. HV1 was identified as parsnip yellow fleck virus (PYFV); anthriscus yellows virus, on which it depends for transmission by aphids, was presumably also present in the hogweed plants. HV2 was transmitted manually and by aphids and had very flexuous filamentous particles c. 700–750 nm long; it has affinities with the closteroviruses, and the name heracleum latent virus is proposed. HV3, HV4 and HV5 were transmitted manually, HV3 and HV5 also by aphids, but their particle morphology is unknown. HV6 was transmitted only by aphids and has very flexuous particles up to 1400 nm long; it is presumably a closterovirus distinct from HV2. All the viruses infected cultivated umbelliferous species experimentally but only PYFV is known to infect umbelliferous crops.
Migratory plant parasitic nematodes as pests of cereals
Authors: JONES R. K.
Published: February 2008

Two field trials showed that initial populations of Tylenchus Bastian, Paratylenchus Micoletzky, Pratylenchus minyus Sher and Allen, P. crenatus Loof, P. penetrans Chitwood and Oteifa, Helicotylenchus pseudorobustus Golden and H. digonicus Perry did not decrease yield of cereals whereas a significant inverse relationship existed between populations of Tylenchorhynchus dubius Filipjev and yield of wheat. T. dubius and Longidorus spp. Filipjev were associated with early leaf‐yellowing of barley, though difficulty in controlling nematodes failed to firmly link yield reduction with nematode populations. The possible variability in tolerance of cereals to nematodes is discussed.
In situ bait plants as a method for detecting red core in strawberry fields
Authors: DUNCAN JAMES M.
Published: February 2008

The spread of strawberry red core root disease (Phytophthora fragariae) from a heavily infested field with a history of 40 yr continuous strawberry growing, to and across an adjacent field where strawberries had never before been grown, was charted by growing bait plants of the highly susceptible alpine strawberry ‘Baron Solemacher’ at the intersections of an 8 m grid. Initially the fungus could not be detected by a soil sampling/glasshouse baiting test or in field grown baits, but after a very wet winter it was detected in the field grown bait plants. Most infections occurred in plants growing in a shallow depression running the length of the field, receiving drainage water from the higher infested site and where there had been standing water for much of the winter. The importance of topography was further demonstrated when baits were planted at commercial densities in two small areas of the field, one adjacent to and the other 18 m distant from the central depression. In the former many plants were infected within 2 months of planting whilst in the latter bait plants remained free of the disease for at least 18 months.

The highly susceptible bait plants may be suitable for monitoring the health of commercial propagation stocks; they are easily propagated from seed and as they do not runner there is little hazard to stock purity.
Methyl bromide fumigation for the control of Aspergilli and Penicillia in stored grains
Authors: PASTER N. , BARKAI‐GOLAN R. , CALDERON M.
Published: February 2008

Fumigation with methyl bromide (MeBr) at a concentration of 120 mg/1 maintained for 4 h at 25°C caused 100% mortality of spores of Aspergillus ochraceus, A. flavus, Penicillium citrinum, P. chrysogenum and P. cyclopium. However, 40% of an A. niger spore population retained its viability after this treatment. Increasing the duration of fumigation to 24 h at a concentration of 40 mg/1 MeBr caused 100% spore mortality of all fungi tested. Total growth inhibition of 24 h‐old mycelia was achieved with 40 mg/1 for 24 h or 120 mg/1 for 4 h. These concentrations for the same period of exposure were not inhibitory for 7‐day‐old mycelia of any of the fungi tested. In A. niger‐inoculated wheat grains fumigated with 100 mg/1 MeBr for 24 h, 20% yielded fungal contaminants after 16 days of storage and 100% after 29 days. There was a marked drop in the percent germination of the grains after fumigation, whereas the free fatty acids level was higher than in unfumigated grain.

The results of the in vivo study suggest that MeBr given at a commercial dosage for 24 h is not only ineffective in destroying the internal inocula of wheat grains but also enables their subsequent development by weakening the resistance of grains to fungal attack.
Virus‐like particles in phloem tissue of chervil (Anthriscus cerefolium) infected with carrot red leaf virus
Authors: MURANT A. F. , ROBERTS I. M.
Published: February 2008

Isometric virus‐like particles c. 22–25 nm in diameter were found in ultrathin sections of chervil leaves infected with carrot red leaf virus (CRLV). The particles were confined to the phloem and occurred in less than 5% of the cells in the vascular bundles. They were commonest in companion cells, occurred frequently in sieve elements and were also found in phloem parenchyma cells. The observations support other evidence that CRLV should be classified in the luteovirus group.
Effects of crop thinning and reduced grain numbers per ear on grain size in two winter wheat varieties given different amounts of nitrogen
Authors: MARTINEZ‐CARRASCO R. , THORNE GILLIAN N.
Published: February 2008

To study the importance for final grain size in wheat (Triticum aestivum, L.) of assimilate supply and the storage capacity of the grain, two field experiments were done. In 1976 nitrogen was applied in the range from none to 180 kg ha‐1, part of the crop was thinned, and the top halves of some ears of the short variety Hobbit and of the tall variety Maris Huntsman were removed soon after anthesis. In 1977 ears of Maris Huntsman were halved 5 days after anthesis or at 30 days after anthesis when grain volume was maximum. Thinning the crop from 360 to 180 ear‐bearing shoots m‐2 30 days before anthesis increased the number of grains per ear, except in the absence of nitrogen fertiliser, but did not increase grain size, grain dry weight per ear or total dry weight per culm.

Removing the upper half of ears of Hobbit 5 days after anthesis increased dry weight per grain, but when this treatment was applied to Maris Huntsman either 5 days after anthesis in 1976 and 1977, or when grain volume was maximal in 1977, the grains failed to increase in dry weight. Non‐grain dry weight of both varieties was increased by halving the ear. In both varieties the maximum volume of grains in halved ears was larger than in intact ears. Grain dry weight increased relatively less than volume after halving the ear of Hobbit, and the decrease in volume up to maturity was greater in halved than intact ears of both varieties. The larger grain volume in halved ears of Maris Huntsman in 1977 was associated with more endosperm cells.
Phorid fly(Phoridae: Megaselia halterate) longevity and the disemination of nematodes (Allantonematidae: Howardula husseyi) by parasitised females
Authors: RICHARDSON P.N. , CHANTER D.O.
Published: February 2008

The longevity of male and female Megaselia haltherata, 75% of parasitised by the nematode Howardula husseyi, was studied for 16 days at 20‐ 21.5 OC. A statistical model fitted to the data indicated that parasitism reduced fly longevity significantly; predicted times to 50% mortality were about 6 days shorter for parasitised males, but only 2 days shorter for parasitised females.

An investigation of the number of nematode larvae liberated by female flies at intervals throughout the experiment showed that many had been liberated in the first 4 days, and that the rate of release then gradually declined. A statistical model for nematode dissemination rate was used to estimate the mean number of nematodes released at 4‐day intervals by surviving flies containing 1–5 adult H. husseyi.

Mass release of laboratory‐reared parasitised flies on mushroom farms has been suggested as a possible method of boosting the incidence of parasitism in farm fly populations. The results of the present study indicate that if such a measure were taken in spawn‐running rooms then the best effect might be attained by releasing the flies in two batches with one release occurring in the middle of each week of the spawn‐run.
Arracacha virus B, a second isometric virus infecting arracacha (Arracacia xanthorrhiza; Umbelliferae) in the Peruvian Andes
Authors: KENTEN R. H. , JONES R. A. C.
Published: February 2008

Arracacha virus B (AVB), a previously undescribed virus, was found together with arracacha virus A or with a 750 nm flexous filamentous virus in arracacha (Arracacia Xanthorrhiza; Umbelliferae) growing in the Huanuco region of the Peruvian Andes. AVB was transmitted by inoculation of sap to 30 species from eight families out of 45 species from 10 families tested. It was transmitted through seed of Chenopodium quinoa but not by Myzus persicae. AVB was best propagated in C. Quinoa or Tetragonia expansa and assayed in C. quinoa, C. murale or C. amaranticolor. Sap from infeted <C. Quinoa was occasionally infective after dilution to 10‐4 but not 10‐5, after 10 min at 65 d̀ C but not 70 d̀ C, and after 12 but not 14 days at 20 d̀ C.

In neutral phosphotungstate, AVB has isometric partilces c. 26 nm in diameter with a hexagonal profile. About 50‐ 150 A1 cm260 units of purified virus were obtained from 1 kg infected C. quinoa leaf by extraction in 0.5 M phosphate buffer at pH 7.5, containing 0.05 M ethylene‐daiminetetra‐acetate (EDTA) and 0.2% mercaptoethanol, and clarificatin with chloroform, followed by two precipitations with polyethylene glycol and three cylces of differential centrifugation. Purified virus coefficent (Sd̀20 w,) of 126 S and A260/A280 ratio of 1.80, bnut formed two isopycnic bands in CsC1 of buoyant density 1.481 and 1.492 g/cm3 with estimated nucleic acid contents of 40 and 41% respectively. AVB particles contained two proteins of mol.wt 26 000 (major component) and 20 000. AVB was not serologically related to any of 20 other morphologically similar viruses. Its properties suggest that it does not fall into any recognised group of viruses.

the cryptogram of AVB is */*:*/40–41:S/S:S/*
The effects of application of distillery pot ale to hill vegetation and lowland crops
Authors: BUCKNALL SALLY A. , McKELVIE A. D. , NAYLOR ROBERT E. L.
Published: February 2008

Pot ale is a waste product of malt whisky distilling. Experiments were performed to establish the effects of its disposal on hill land and whether it could be used as a liquid fertiliser on rotational grass and on barley. Heather cover was drastically reduced by frequent low doses of pot ale, but infrequent heavy doses left heather moorland relatively unchanged. Total annual applications of pot ale of over 100 m3/ha to lowland grass swards increased yields of dry matter. Yield of barley was also increased by applications exceeding 100 m3/ha application. Other aspects of disposal of pot ale are considered.
Cavity spot of carrots.
Authors: PERRY D. A. , HARRISON J. G.
Published: February 2008

Cavity spot was induced after compacted carrot beds were watered to excess in July or August, but not after treatment in October. Roots grown in pots containingfield soil from the site of a cavity spot outbreak had fewer lesions when supplied witha minimal amount of water than when waterlogged, and when the soil was mixed withpeat instead of sand.

Soft rot lesions developed on roots which had been inoculated with the field soiland sealed in pots with wax and stood in water. Anaerobic pectolytic bacteriabelonging to the genus Clostridium were isolated from the lesions and were proven tobe pathogenic to carrot roots. The lesions later resembled cavity spot after the rootswere returned to dry, aerobic conditions.
Monitoring codling and tortrix moths in United Kingdom apple orchards using pheromone traps
Authors: ALFORD D. V. , CARDEN P. W. , DENNIS E. B. , GOULD H. J. , VERNON J. D. R.
Published: February 2008

Studies of pheromone traps for Cydia pomonella, A rchips podana and A doxophyes or ana (Lepidoptera: Tortricidae) were made in United Kingdom apple orchards from 1974 to 1976. Compared with light traps, they proved easier to operate and, with the exception of those set for Adoxophyes orana, were more effective monitors. There was considerable site‐to‐site variation in the pattern of weekly catches, and in total catches for each season, such variability often masking inter‐regional differences. The data proved useful for deciding if and when sprays should be applied in individual orchards, and were also used as a basis for district spray warnings. Thresholds below which treatment was generally unnecessary were five moths/trap/ wk for C. pomonella and 20 moths/trap/wk for Archips podana, but results for Adoxophyes orana were inconclusive. Fruit damage in monitored orchards sprayed as advised was generally low.
Dispersal of Erysiphe graminis and Lycopodium clavatum spores near to the source in a barley crop
Authors: BAINBRIDGE A. , STEDMAN O. J.
Published: February 2008

In experiments to study dispersal of spores in a crop of barley, a 4‐m wide strip of the cultivar Zephyr (a mildew‐susceptible variety) was a source of mildew (Eyrsiphe graminis) conidia. Small suction traps, previously calibrated in a wind tunnel, were used to measure spore concentration within and above the crop. Large concentrations of conidia were measured in the crop at the downwind edge of the Zephyr strip but these decreased rapidly with distance downwind. At 1 m concentrations were halved and by 4 m they were no greater than the background concentration measured in the crop upwind of the source. Next to the source, concentrations were much greater within than above the crop and net spore movement (flux) was upwards out of the crop; by 4 m downwind concentrations were greater above the crop and spore flux was reversed.

Lycopodium clavatum spores were released in the same crop from a line of point sources. Concentrations also decreased rapidly downwind but, with no background of spores, numbers remained greater within than above the crop further from the source than for E. graminis. Even so by 7 m downwind concentrations in the crop had declined to less than those above.

Deposition of L. clavatum spores onto horizontal glass slides in the crop agreed with that expected by settling. However, impaction onto vertical cylinders among plants was much greater than predicted. The reason is not known although turbulent air‐flow around plants may, in some way, enhance impaction. Many E. graminis conidia near the source were deposited in clumps. This prevented any accurate prediction of deposition rates as fall speeds of clumps (necessary for prediction) were not known. Not surprisingly, deposition on horizontal slides often exceeded that expected from settling of single spores although it was not always greatest where clumps predominated.

The proportion of spores deposited on vertical cylinders and horizontal slides located among plants ranged from 0–02 to 0–27 and from 0–019 to 0–127 of the area dose, respectively. Although these may seem to be small trapping efficiencies, the same deposition rates in a crop with many leaves and stems would rapidly filter most spores from air in the crop and can explain why concentrations were observed to decline so rapidly.
Investigations on fungicides. XXI. The fungitoxicity and systemic antifungal activity of some aromatic quaternary ammonium salts
Authors: CARTER G. A. , HEYNS A. J. , KNIGHT B. E. , WAIN R. A.
Published: February 2008

Root application of certain quaternary ammonium salts, most notably tri‐n‐butyl‐and tri‐n‐pentyl‐4‐chlorobenzylammonium bromides, to wheat seedings grown in water culture enhanced their resistance to powdery mildew (Erysiphe graminis) but not to brown rust (Puccinia recondita). Anti‐mildew activity was much less apparent if the compounds were applied to sand‐ or soil‐grown seedlings. Systemic activity is considered in relation to the fungitoxicity, phytotoxicity and growth‐retardant activity of these compounds.
Testing Fi hybrids of Brassica oleracea for sibs by seed isoenzyme analysis
Authors: WILLS A. B. , FYFE SHEENA K. , WISEMAN EVELINE M.
Published: February 2008

Extracts of seeds of Brassica oleracea L. cultivars were separated by electrophoresis on polyacrylamide gels and stained for 14 enzymes to investigate the possibility of utilising isoenzyme variation to determine sib frequencies in hybrid cultivars. Acid phosphatase (EC 3.1.3.2), cr‐amylase (3.2.1.1), carboxylesterase (3.1.1.1), β‐galactosidase (3.2.1.23), β‐glucosidase (3.2.1.21), leucine aminopeptidase (3.4.11.1) and peroxidase (1.11.1.7) reactions gave discrete bands. Three broad zones of acid phosphatase activity occurred and control of banding patterns in the intermediate zone by a series of co‐dominant alleles was confirmed. The locus is designated acp‐1. Sib frequencies could be estimated in eight of 21 F1, cultivars examined, since their parent lines were homozygous for different acp‐1 alleles. This method of estimation has several advantages and offers a practical alternative to current methods. Routine determination of sib frequencies by using any of the other enzymes investigated is impractical.
Patterns of unobstructed splash dispersal
Authors: STEDMAN O. J.
Published: February 2008

Unobstructed splash dispersal patterns were measured in the absence of rain over mown grass using a fluorescent tracer, and a colorimetric method was used indoors in still air. When drops fell into a thin horizontal water film 0–1 mm deep, the volume of the incident drops dissipated as splash droplets was similar to the volume splashed from the film, irrespective of the distance of fall of the drops. Drop size, angle of inclination and distance of fall had significant effects on the volume of drops splashed from an inclined surface. The effects of rigidity, inclination and nature of surface were found to be significant when drops impacted onto surfaces with or without a wax covering and either rigidly or loosely supported. When splash‐ and dry‐air‐dispersed Lycopodium spores were simultaneously released, many more splashed spores were caught close to the source, but the dispersal gradient of splashed spores was steeper than that of dry‐air‐dispersed spores. Splash‐dispersed spores were caught on slides, cylinders and rotorods but trap efficiency could not be evaluated.
The occurrence of Phytophthora syringae in fallen apple leaves
Authors: HARRIS D. C.
Published: February 2008

Fallen apple leaves from orchards at East Malling Research Station contained oospores of Phytophthora syringae, often in large numbers. Oospores identical in appearance were also observed in pear leaves but their incidence was less than in apple. The colonisation of fallen leaves by P. syringae is considered the principal means of inoculum accumulation in orchard soil and therefore of great importance in the epidemiology of the fruit rot caused by this fungus.
Control of Botrytis cinerea on glasshouse tomato by high volume sprays
Authors: MORGAN W. M.
Published: February 2008

The new fungicides iprodione, vinclozolin and prochloraz, and also a mixture containing carbendazim and maneb, were compared with the established protectant fungicides dichlofluanid and chlorothalonil for effectiveness against grey mould (Botrytis cinerea) in an unheated tomato crop. Iprodione and vinclozolin gave the best control of lesions on leaves and stems but dichlofluanid was the most effective in controlling ghost‐spotting of fruit. The carbendazim/maneb mixture was effective against a carbendazim‐sensitive isolate but not against an insensitive isolate of B. cinerea. When applied 1 or 2 days after inoculation, all five protectant fungicides controlled the insensitive isolate better than the sensitive isolate.
Improved growth of white clover in hill grasslands by mycorrhizal inoculation
Authors: HAYMAN D. S. , MOSSE B.
Published: February 2008

Field trials in a hill grassland area of mid‐Wales showed that growth of white clover could be improved by inoculation with selected vesicular‐arbuscular (VA) mycorrhizal fungi. After one growing season mycorrhizal inoculation had approximately doubled shoot dry weight, runner number and nodulation at two sites previously improved by adding lime and fertiliser and by replacing the native vegetation mainly with rye‐grass and white clover. At a previously unimproved site, limed at the time of planting, mycorrhizal inoculation increased shoot dry weight by up to two and a half times, almost doubled runner formation, and increased nodulation up to five‐fold where 90 kg P/ha as basic slag had been applied. Responses to mycorrhiza at this site were smaller with 22‐5 kg P/ha as basic slag and were absent where no P was added. After two growing seasons inoculation responses were even more pronounced at this previously unimproved site; where clovers were being overgrown by adjacent native grasses only those given both 90 kg P/ha and mycorrhizal inoculation survived well.
Bud necrosis of groundnut (Arachis hypogaea) in India caused by tomato spotted wilt virus*
Authors: GHANEKAR A. M. , REDDY D. V. R. , IIZUKA N. , AMIN P. W. , GIBBONS R. W.
Published: February 2008

Chlorotic ringspots or chlorotic leaf specking, terminal bud necrosis, axillary shoot proliferation and severe stunting of groundnut (Arachis hypogaea) were shown to be caused by tomato spotted wilt virus (TSWV).

All 28 species of plants tested were susceptible to the virus. Cowpea (Vigna unguiculata cv. C‐152) was found to be a good assay host. TSWV remained infective in buffered sap of groundnut at a dilution of 10‐2.5, after storage for 4 h at room temperature (30 oC) and for 10 min at 40 but not 45 oC.

The haemagglutination test was adapted to detect TSWV in crude extracts of groundnut. Sap from infected groundnut and tomato contained spherical membrane‐bound virus particles 70 to 90 nm diameter. The virus was transmitted by thrips (Scirtothrips dorsalis).

The prevalence of TSWV in India and the high incidence in groundnut indicates that the virus is economically important.
Evidence for the involvement of calcium in the hatching of Globodera rostochiensis
Authors: ATKINSON H. J. , BALLANTYNE A. J.
Published: February 2008

Low concentrations of ruthenium red and lanthanum chloride inhibited hatching of juveniles from eggs in cysts of Globodera rostochiensis in potato root diffusate. Pro‐bit analysis for 31 cysts at seven concentrations of ruthenium red showed that 50% inhibition with 95% fiducial limits occured at 47 ± 23 μm; a similar value of 59 ± 14 μm was obtained using eggs removed from cysts. Results for 10 to 20 cysts at six concentrations of lanthanum chloride suggested a somewhat higher value for 50% inhibition of 110 ± 83 μM. In contrast hatching of eggs in cysts of Heterodera schachtii in water was unaffected by 5 ITIM lanthanum chloride and 625 μM ruthenium red, concentrations which cause over 90% inhibition of hatch in G. rostochiensis.

Two calcium ionophores synergised hatching of a 1971 population of G. rostochiensis in dilute diffusate. Optimal concentrations of 2 μM for A23187 and 10 μM for BrX537A increased the hatch from 17 ± 3–6 juveniles/cyst to 114 ± 44 juveniles/cyst and 138 ± 40 juveniles/cyst respectively. Ionophores in the absence of diffusate hatched very few eggs of this population but caused a greater hatch in a second (1975) population which gave a high hatch in water of 43 ± 10 juveniles/cyst. This was increased by A23187 to 181 ± 41 juveniles/cyst. The results with both the inhibitors and the ionophores suggest that hatching in G. rostochiensis might be a calcium‐mediated process.
An explanation of the decimal code for the growth stages of cereals, with illustrations
Authors: TOTTMAN D. R. , MAKEPEACE R. J. , BROAD HILARY
Published: February 2008

The decimal code for the growth stages of cereals devised by Zadoks, Chang & Konzak (1974) is reproduced here with expanded definitions of some of the descriptive phrases and stylised drawings of selected stages of wheat, barley and oat plants.
Control of aphids in glasshouses with the fungus, Verticillium lecanii
Authors: HALL R. A. , BURGES H. D.
Published: February 2008

In small glasshouses, aqueous sprays of spores of the entomopathogenic fungus, Verticillium lecanii, eliminated small populations of the aphid Brachycaudus helichrysi in the vegetative tips of chrysanthemum plants but not when they were in an exposed position on mature flower buds. Control of the chrysanthemum aphid, Macrosiphoniella sanborni, was however variable and usually commercially unsatisfactory. In contrast, in both small and large glasshouses, sparse populations of the major aphid pest Myzus persicae were successfully and consistently controlled, sometimes spectacularly. The inherent susceptibilities of these aphid species, measured by laboratory bioassay, did not account for the differences in control observed in the glasshouse. It is thought that a combination of species‐characteristic feeding site preferences on the exposed parts of plants, where microclimate humidity was probably low, and relative immobility of M. sanborni and B. helichrysi explain why these aphids were less well‐controlled than My. persicae. However, it should be possible to control satisfactorily all aphid species in large commercial glasshouses where humidity might be higher than in the small experimental glasshouses. A single spray was sufficient to introduce infection that controlled aphids for the duration of the crop.
The elimination of cocksfoot streak virus, cocksfoot mild mosaic virus and cocksfoot mottle virus from Dactylis glomerata by shoot tip and tiller bud culture
Authors: DALE PHILIP J.
Published: February 2008

Shoot tips from 0.2 to 4.8 mm long and tiller buds 0.2 to 5.1 mm long were cultured from cocksfoot (Dactylis glomerata) plants known to be infected with combinations of cocksfoot streak, cocksfoot mild mosaic and cocksfoot mottle viruses. Regenerated plants were tested for the presence of viruses by electron microscopy, serology and the expression of symptoms. All viruses were eliminated by culturing shoot tips and tiller buds less than 1.2 mm long but the maximum explant size capable of regenerating healthy plants depended upon the infecting virus. Viruses were not detected in shoot tip and tiller bud samples of similar size to the explants that gave healthy plants. The method is of value in eliminating viruses from desirable stocks of D. glomerata that must be vegetatively propagated.
Detection of potato leafroll and potato mop‐top viruses by immunosorbent electron microscopy
Authors: ROBERTS I. M. , HARRISON B. D.
Published: February 2008

Attachment of virus particles to antiserum‐coated electron microscope grids (immunosorbent electron microscopy) provided a test that was at least a thousand times more sensitive than conventional electron microscopy for detecting potato leafroll (PLRV) and potato mop‐top (PMTV) viruses. The identity of the attached virus particles was confirmed by exposing them to additional virus antibody, which coated the particles.

PLRV particles (up to 50/μm2 of grid area) were detected in extracts of infected potato leaves and tubers, infected Physalis floridana leaves, and single virus‐carrying aphids. On average, Myzus persicae yielded 10–30 times more PLRV particles than did Macrosiphum euphorbiae.

PMTV particles (up to 10/μm2 of grid area) were detected in extracts of inoculated tobacco leaves, and of infected Arran Pilot potato tubers with symptoms of primary infection. Particles from tobacco leaves were of two predominant lengths, about 125 nm or about 290 nm, and fewer particles of other lengths were found than in previous work, in which partially purified or purified preparations of virus particles were examined, using grids not coated with antiserum.
Measurement of the adenosine triphosphate content of cysts of Globodera rostochiensis as a method for assessing the efficacy of fumigant nematicides
Authors: STOREY R. M. J. , ATKINSON H. J.
Published: February 2008

The measurement of the adenosine triphosphate (ATP) content of samples of 50 cysts of Globodera rostochiensis collected from 40 fields in the Netherlands has been tested as a method for determining the mortality of the nematodes achieved by fumigation of these field soils. The technique used is based on bioluminescent photometry and it has been fully described previously. The ATP assessment has been compared with results obtained by the advisory service in the Netherlands using hatching tests based on samples of 100 cysts from the same field soils. The ratio of the values before and after soil treatment showed that the methods usually provided similar estimates of mortality. The relationship between ATP and hatched juveniles was also similar from pre‐treatment and post‐treatment samples. The amount of ATP, calculated from these results, which is equivalent to the maximum post‐treatment hatch allowed for a successful treatment in the Netherlands was used in conjunction with the mortality estimates to assess the success of the fumigation. On this basis the two methods disagreed in the overall assessment of fumigation in only five of the 40 fields. This frequency of disagreement is not significantly greater than expected from the variability of either method. The ATP technique clearly offers a reliable and relatively inexpensive method for estimating the efficacy of fumigant nematicides and is much more rapid than the alternative hatching tests or egg counts. Therefore, it could replace these in situations where the grower wanted a rapid assessment on the success, or otherwise, of his fumigation.
Effects of short‐term waterlogging on the growth and yield of peas (Pisum sativum)
Authors: CANNELL R. Q. , GALES K. , SNAYDON R. W. , SUHAIL B. A.
Published: February 2008

The effects of waterlogging the soil for up to 5 days on the growth of peas at different stages of development were investigated in glasshouse and outdoor experiments. During waterlogging the oxygen content of the soil declined to less than 2% within 2–3 days. Subsequently, leaf senescence was hastened, stem growth rate was slowed and yield was decreased. The effects on yield were mainly attributable to the development of fewer nodes and fewer pods. Waterlogging for 24 h or more just before flowering restricted growth and yield. The effects of waterlogging at earlier and later stages were less marked. Waterlogging at any period after flower buds were visible prevented further increase in root dry weight.
Date of onset of regrowth dieback and its relation to summer drought in eucalypt forest of southern Tasmania
Authors: WEST P. W.
Published: February 2008

‘Regrowth dieback’, a disease of Eucalyptus obliqua and E. regnans is causing serious degradation of high yield, even‐aged, regrowth forest in south‐eastern Tasmania. Dieback symptoms in crowns of diseased trees were first observed in the region in 1964 and since then the disease has continued to develop. Visual symptoms of the disease can be discerned only in crowns of dominant and co‐dominant trees since sub‐dominant and suppressed trees show similar symptoms due to normal stand competition. This work shows that for increment periods which finished in 1958 or earlier, basal area increments of dominant and co‐dominant trees from a number of growth plots in the region were slightly lower in trees which were affected by the disease in 1971 than in those which were not. There were much larger reductions in increments of affected trees measured in increment periods which finished in 1960 or later. It was concluded that an agent very damaging to forest health appeared in the region in 1959 or early 1960. This coincides with the start of a period of several years of unusually dry summers in the region. These findings conform with an earlier suggestion that the disease may have been initiated by drought with secondary damage by the root‐rotting fungus Armillaria sp. and/or the defoliating beetle Chrysophtharta bimaculata. The fungus is ubiquitous in the region and has frequently been associated with decayed roots of affected trees. The beetle is believed to have caused episodic tree defoliation in the region. It is suggested that the secondary agents normally cause death or ill‐health of a few trees in otherwise healthy forest. Physiological weakening of trees by drought may have allowed the effects of these agents to increase substantially after 1959.
Hirsutella thompsoniU a fungal pathogen of mites. II. Host‐pathogen interactions
Authors: GERSON U. , KENNETH R. , MUTTATH T. I.
Published: February 2008

The moniliaceous fungus, Hirsutella thompsoniU grown on potato‐dextrose agar (PDA) or on sterile wheat bran, was highly pathogenic to the carmine spider mite, Tetranychus cinnabarinus, and, grown on PDA, to the oriental spider mite, Eutetranychus orientalis. The fungus penetrated the mites' integument mainly through the legs and formed hyphal bodies in chains in the haemolymph. Hyphae, on which the spores were produced, began to emerge through the genital and anal apertures and then all over the body. Various mycophagous mites, a predaceous species and the tick Argas persicus were immune. H. thompsonii grew well on cadavers of diverse insects and mites.

The fungus killed most mites and quickest, usually by the 2nd day, at 25o, 27o and 30 oC; least at 13o and 35 oC. It sporulated best on mites at 24o, 27o and 30 oC (full sporulation at 27 oC took place within 12 h after death); it was good, but slower, at 13o and 35 oC. The fungus germinated, penetrated mites and sporulated there very poorly below 100% r.h. When the daily number of hours at 100% r.h. was reduced from 24 to 18 or 6 h, fungus‐associated mortality dropped greatly.

In the field, use of the fungus for mite control would be suitable particularly in tropical and humid subtropical areas, and its success in Israel would not be assured. In glasshouses, H. thompsonii could induce epizootics in Israel and elsewhere only if humidities were raised to saturation and the daytime temperature kept below 37 oC.
Fungitoxic and phytotoxic effect of some surface‐active agents applied for the control of apple powdery mildew
Authors: BURCHILL R. T. , FRICK E. L. , COOK M. E. , SWAIT A. A. J.
Published: February 2008

Mixtures of methyl esters of fatty acids (‘Off‐Shoot O’) and mixtures of fatty alcohols (‘Off‐Shoot T’), applied during the late autumn (November), eradicated apple powdery mildew (caused by Podosphaera leucotricha) from infected buds. Applications in the spring at bud‐burst were less effective.

The autumn sprays caused little damage to the cultivars Bramley's Seedling, Cox's Orange Pippin and Golden Delicious but on Worcester Pearmain 50% of the buds were killed by a 5% Off‐Shoot O spray. The bud‐burst sprays were damaging and reduced yield on the Cox and Bramley trees.

A 5% a.i. mixture of nonanol/lissapol applied to a range of commercial cultivars was effective in eradicating powdery mildew but was more phytotoxic than the Off‐Shoot compounds. Spraying Cox trees later in the winter failed to reduce the damage.

Eradication of the overwintering stage of the disease resulted in low spore concentrations during the following spring and early summer, enabling some economies to be made in the summer mildew fungicide programme.
The detection of apple chlorotic leafspot virus by a modified procedure of enzyme‐linked immunosorbent assay (ELISA)
Authors: FLEGG CAROLINE L. , CLARK M. F.
Published: February 2008

The technique of enzyme‐linked immunosorbent assay (ELISA) was modified to enable detection of apple chlorotic leafspot virus (CLSV) both in herbaceous hosts and in several naturally infected fruiting and ornamental woody host species. Some of the characteristics of the modified method as used with different virus‐host combinations are described.
The effect of infection with potato leaf roll virus (PLRV) on yield and some of its components in a variety of potato (Solanum tuberosum)
Authors: KILLICK R. J.
Published: February 2008

In a trial of over 2000 potato plants 11 ‐8% of them were found to be infected with potato leaf roll virus. Infection caused reduction in the number of stems and reduced the number, weight and mean weight of both chats and ware tubers produced per hill. It also reduced the number and weight of ware tubers produced per stem. The health status of neighbouring plants was found to influence the weight and mean weight of ware tubers of healthy, but not of infected plants. This yield compensation is described in an appendix.
Effect of ryegrass mosaic virus on the quality of perennial ryegrass
Authors: HOLMES S. J. I.
Published: February 2008

In 1976 fields of perennial ryegrass located on two farms in the west of Scotland were found to be far more severely and extensively infected by ryegrass mosaic virus (RMV) than had been seen in earlier surveys of ryegrass fields in 1972 and 1973.

The chemical analysis of samples of ryegrass from 10 of the fields examined in 1976 showed that RMV significantly reduced the organic matter content, organic matter digestibility, water soluble carbohydrate content and D value of the grass. Furthermore, the losses suffered by grass with the severe necrotic symptom of RMV were significantly greater than those incurred by the grass with the mild mottle only.

A correlation analysis between water soluble carbohydrate level and D value showed that whilst the loss in water soluble carbohydrates in mottled grass accounted for much of the loss in digestibility this was not the case in the necrotic grass where loss of green tissue appeared to be a more important contributory factor.
The influence of tillage and method of straw disposal on the survival and growth of black‐grass, Alopecurus myosuroides, and its control by chlortoluron and isoproturon
Authors: MOSS S. R.
Published: February 2008

A winter wheat crop was established in a field infested with black‐grass. Three cultivation systems were used ‐ ploughing, tine cultivation and direct drilling. Straw of the previous wheat crop was either spread and burnt or removed by baling. Chlortoluron at 1–60 and 3–20 kg/ha pre‐emergence and isoproturon at 1 14 and 2–27 kg/ha pre‐ and post‐emergence were applied to sub‐plots of all cultivated treatments.

Ploughing substantially reduced black‐grass infestation compared with the other two cultivations. Straw burning was effective in destroying many seeds and resulted in less black‐grass in the crop.

The pre‐emergence herbicide applications were more effective after ploughing than after direct drilling, irrespective of straw disposal method. When the straw was burnt, black‐grass control on the tine cultivated plots was at least as good as after ploughing but where the straw was baled, poorer control was obtained. Chlortoluron gave better control than isoproturon but the relative effects of cultivations and straw disposal method were similar with both herbicides. The post‐emergence herbicide treatments gave excellent control after all cultivations.

Many black‐grass seeds in the surface soil were shown to remain dormant, but viable, from autumn until the following April.
A comparison of the excretion rates of Aphis fabae on artificial diet and on bean plants
Authors: HO S. H.
Published: February 2008

The performance of Aphis fabae on an artificial diet was assessed by comparing the aphid's excretion rate on the diet with that on bean plants to investigate the possibility of using this diet in toxicological studies. No significant difference was found in the rates of honeydew excretion, but the diet‐fed aphids were noticeably smaller than those fed on beans.
Field studies on the effects of ryegrass mosaic virus on the yield of Italian ryegrass cv. S 22
Authors: HOLMES S. J. I.
Published: February 2008

A simple and effective technique for the large scale inoculation of field plots with ryegrass inosaic (RMV) was used in 1977 and 1979 to study the effects of RMV on the yield of Italian ryegrass cv. S 22.

In 1977, symptoms of RMV developed rapidly in inoculated plants following the first cut. At the second and third cuts necrosis was recorded in many plants, particularly in plots receiving high levels of nitrogen. At the fourth cut the incidence of symptoms was 72% in plots which received 189 kg ha‐1 N during the growing season and 83.5% in the plots which received 378 kg ha‐1 N. RMV infection reduced total dry matter yield by the equivalent of 3.03 t ha‐1 and 3.57 t ha‐1 in the low and high nitrogen plots respectively.

In 1979 in both the high (360 kg ha‐1 N) and the low (120 kg ha‐1 N) nitrogen plots, symptom development was slower than in 1977 and never reached either the incidence or severity in the earlier trial. The low incidence of plants with symptoms was reflected in the relatively small loss in total dry matter yield due to RMV infection recorded in the low (4.4%) and high (6.3%) nitrogen plots.

Possible reasons for these differences in symptom development and yield loss in the two trials are discussed.
Physiological responses of apple fruits to oxygen concentrations
Authors: KNEE MICHAEL
Published: February 2008

The effects of oxygen concentration on respiration and ripening processes in apple fruits at storage temperatures have been investigated. The response of carbon dioxide production to a change in O2 concentration occurred after a delay of 1–4 days, depending upon the time and direction of change. When apples were stored in flowing streams of oxygen/nitrogen mixtures the time of onset of ethylene production was inversely related to oxygen concentration and the maximum rate of production was directly related to oxygen. However when apples were stored in product‐generated atmospheres low ventilation caused rapid accumulation of ethylene. The retardation of ripening processes by low oxygen concentrations observed under these conditions was not, therefore, a result of inhibition of ethylene synthesis. When permanganate was present in the storage container the build up of ethylene was delayed, especially at low oxygen concentrations. In these conditions there was sometimes a further retardation of softening and soluble polyuronide formation. Rates of chlorophyll degradation in peel and cortex, flesh softening and soluble polyuronide formation were all half maximal at 2.5–4.0% O2.
Field control of take‐all of wheat by avirulent fungi
Authors: WONG P. T. W. , SOUTHWELL R. J.
Published: February 2008

In field experiments in New South Wales, wheat inoculated with Gaeumannomyces graminis var. tritici had less take‐all and yielded significantly more grain (P≤ 0·05) when simultaneously inoculated with G. graminis var. graminis and a lobed hypho‐podiate Phialophora sp. synonymous with Phialophora radicicola Cain var. radicicola sensu Deacon than when unprotected with these fungi. An isolate of P. radicicola var. graminicola did not confer any protection. The yields of cross‐protected wheat approached those of healthy wheat where take‐all incidence was slight to moderate while control was less economically significant where disease was severe. If this form of control proved similarly effective against natural inoculum it might be best employed at the beginning of a wheat monoculture after a break crop and serve to delay the onset of severe take‐all.

A preliminary survey of 28 wheat fields in New South Wales using a bait technique and examining for characteristic fungal structures showed that G. g. graminis was rarely present in the soil and the lobed hyphopodiate Phialophora sp. and P. r. graminicola were absent. Significant populations of G. g. graminis only occurred in first wheat crops after a long period of native pasture. In New South Wales, at least, these avirulent fungi would have to be introduced to wheat fields for take‐all control.
The detection by serological methods of viruses infecting the rose
Authors: THOMAS B. J.
Published: February 2008

Homogenates of herbaceous test plants infected with arabis mosaic virus (AMV), prunus necrotic ringspot virus (PNRSV), or strawberry latent ringspot virus (SLRV), and purified virus preparations were used to assess the sensitivities of four serological methods (the enzyme‐linked immunosorbent assay ‐ ELISA, immunodiffusion in gels, the latex flocculation assay, and serologically specific electron microscopy ‐SSEM) for the detection of these viruses. The latex test was up to 250 times more sensitive than gel immunodiffusion, but SSEM and ELISA were respectively up to 1000 and 200 times more sensitive than the latex test.

Gel immunodiffusion and latex tests failed to detect any of the viruses in infected roses. Although ELISA reliably detected PNRSV and SLRV when leaves from infected roses were homogenised in a leaf: buffer ratio of 1 g:10 ml, AMV was occasionally undetected. However, when a modified ELISA technique, which reduced non‐specific reactions, was used some PNRSV‐infected roses were also not detected. Detection by SSEM was c. twice as sensitive as ELISA for all three viruses in rose extracts. The relative advantages of ELISA and SSEM for the detection of plant viruses are discussed.