bluuebunny/crossref_metadata_2025 huggingface dataset:
Attempts to eliminate chrysanthemum stunt from chrysanthemum by meristem‐tip culture after heat‐treatment
Authors: HOLLINGS M. , STONE OLWEN M.
Published: February 2008

‘Mistletoe’ chrysanthemums infected with stunt were grown at 35°C for 14–37 weeks, and meristem‐tips cultured from them at intervals. Of 337 meristems, seventy‐two survived to plants but their development took 50% longer than did that of stunt‐free meristem‐tips. All plants were symptomless for at least 5 weeks after planting in 75 mm pots of soil‐mix, and only three showed symptoms after 9 weeks. No more plants developed symptoms during the next 5 (winter) months, but between mid‐March and late May sixty‐seven did so. Only two plants were freed from stunt. ‘Mini‐cuttings’ rooted from shoot tips of infected chrysanthemums grown at 35°C for 37 weeks all developed stunt symptoms within 27 weeks.
Augusta disease in tulip ‐ a reassessment
Authors: MOWAT W. P.
Published: February 2008

In an experiment in which the roots of field‐grown tulip were commonly infected with tobacco necrosis virus (TNV), Augusta disease did not develop in the year of infection or when progeny bulbs were grown in the field or glass‐house. When tulip bulbs of other stocks, including grades of 11 and 12 cm circumference, were forced, the disease developed sporadically, in some instances as the result of infection with TNV from the soil in which they were planted and in others as a result of infection by bulb‐borne virus. The incidence of disease produced by current year infection was increased by warming the plunge bed.

Different strains of TNV were obtained from field‐grown plants with Augusta disease and different strains of the virus produced the disease when inoculated to tulip. Some, but not all, naturally diseased plants contained satellite virus, which therefore does not cause or prevent disease development. The disease was produced in some plants by TNV transmitted by Olpidium brassicae, but neither a vector nor a non‐vector isolate of O. brassicae completed its life cycle in tulip. However, Olpidium‐like zoospores were observed in some washings of tulip roots from TNV‐infested soils.

TNV was not obtained from all tulip plants with necrotic leaf symptoms resembling Augusta disease. Some were infected with tomato bushy stunt virus or cucumber mosaic virus, or with another agent that was transmitted by inoculation of sap to Nicotiana clevelandii and Chenopodium quinoa, and carried by bulbs of up to 11 cm circumference.
The infection of oranges by Trichoderma viride and mixed infection by Trichoderma viride and Penicillium digitatum
Authors: COLE A. L. J. , WOOD R. K. S.
Published: February 2008

Trichoderma viride spores applied in water to apparently uninjured skin of oranges do not cause lesions. Adding orange juice, rind extract, citric acid or orange essential oil did not influence infection. Oranges became infected only when the stem‐end cuts or wounds deeper than 6 mm into oil vesicles were inoculated. Sound oranges in contact with decayed oranges did not become infected. Diphenyl‐impregnated wrappers reduced infection. A mixed inoculum of T. viride and Penicillium digitatum caused as fast rotting as P. digitatum, which caused faster rotting than T. viride alone. Lesions infected with P. digitatum could become infected by T. viride but those caused by T. viride did not become infected by P. digitatum.

T. viride was antagonistic to P. digitatum in vivo and in vitro, possibly because it produces a heat‐labile diffusible substance toxic to P. digitatum.
Effects of water potential on the infection of potato tubers by Streptomyces scabies in soil
Authors: LEWIS B. G.
Published: February 2008

When soil was maintained at a mean water potential (Slatyer & Taylor, 1960) of the order of ‐80 J kg‐1 at 25 cm depth throughout the growing period, much infection of potato tubers by Streptomyces scabies occurred, but when soil was irrigated to maintain it at potentials greater than ‐ 13 J kg‐1 at 10 cm depth infection was negligible. Until about 5 weeks after initiation, tubers were very susceptible to infection; irrigation during this period reduced scab considerably, but subsequent irrigation reduced it only slightly.

At the low water potential, actinomycete populations on lenticels were high and bacterial populations low; these effects were reversed at the high water potential. Since also actinomycetes were more frequently isolated in the absence than in the presence of bacteria it was deduced that there was an interaction between these two groups. It is suggested that irrigation may decrease the population of S. scabies in tuber lenticels by increasing populations of bacteria antagonistic to it.
Distribution patterns of assimilated 14C in vegetative and reproductive shoots of Lolium perenne and L. temulentum
Authors: RYLE G. J. A.
Published: February 2008

The movement of 14C‐labelled assimilate to the terminal meristem, stem, mature leaves, tillers and roots was measured in Loliurn perenn and Lolium temulentum after exposure to 14C02 of the youngest fully‐expanded leaf and, on fewer occasions, the oldest healthy leaf on the main shoot.

During early vegetative growth, the terminal meristem, tillers and roots received most of the 14C exported from the youngest leaf. As the shoot aged, more 14C was exported to the terminal meristem and tillers and less to roots. When the stem became a sizeable sink for 14C at the six‐leaf (L. temulentum) or eleven‐leaf (L. perenne) stage, less 14C moved to tillers and much less to roots. The terminal meristem continued to receive 14 at a steady rate throughout late vegetative growth.

The transition from vegetative to reproductive growth in both species was marked by an abrupt increase in the export of 14C to stem from the upper leaf, but there was little change in the proportion of 14C which moved to the developing leaves and incipient inflorescence at the terminal meristem. At the same time, less 14C moved to tillers and much less to roots. Immediately before ear emergence, the export of 14C from the upper leaf (flag leaf) to the stem declined and the proportion moving to the ear increased, reaching a maximum of 55–75% as the ear emerged.

The relative patterns of export of upper and lower leaves showed that while some 14 moved from each leaf to all meristems, the proximity of actively growing meristems appeared to be the main factor which determined the destination of most exported 14C. The distribution of 14C from upper and lower leaves was most alike in young vegetative plants of L. perenne. At later stages of development of both species, the terminal meristem and stem received most 1414C from the upper leaf, while roots and tillers received mos 1414C from the oldest leaf at the base of the shoot.
Resistance of sugar beet to the cyst‐nematode Heterodera schachtii Schm.
Authors: CURTIS GODFREY J.
Published: February 2008

Lines exhibiting heritable resistance and susceptibility to beet cyst nematode were selected from a heterogeneous cultivated variety of beet but no major gene resistance was detected although many hundreds of lines of wild and cultivated varieties were tested. Recurrent selection improved the resistance of one line, selected originally for yield and non‐bolting qualities, when progenies in each generation were compared with susceptible controls and with the original ancestral lines. Resistance was inherited by progenies from selections crossed with susceptible plants, but evidence of some reduction in resistance was detectable where fewer eelworms were available to invade from the soil. There was no evidence of heritable cytoplasmic influence on the resistance. Resistance is probably controlled by a polygene system in sugar beet, although immunity in Beta procumbens and B. webbiana and near‐immunity in B. patellaris suggest that in other species of Beta major gene resistance may occur.
Studies on the seed transmission of cucumber mosaic virus in chickweed (Stellaria media) in relation to the ecology of the virus
Authors: TOMLINSON J. A. , CARTER ANNE L.
Published: February 2008

Cucumber mosaic virus (CMV) was transmitted in the seed of infected Stellaria media plants. The rate of seed transmission varied both in manually infected plants (3–21%) and in plants grown from infected seed (21–40%). In naturally infected plants the rates of transmission found were 4–29%.

Seeds recovered from field soil carried 4–5% infection and in infected seed placed in the soil the virus persisted for at least 5 months.

Seed transmission of CMV also occurred in infected Lamium purpureum (4%), Cerastium holosteoides (2%) and Spergula arvensis (2%) but it could not be demonstrated in six other more common weed species in five botanical families.

Seed transmission in Stellaria media occurred with a British (W) and an American (Y) strain of CMV. The virus was shown to occur in S. media pollen.

The importance of CMV‐infected S. media seed in the soil in relation to the epidemiology of the virus is discussed.
Potato coiled sprout in relation to seed tuber storage treatment and to infection by Verticillium nubilum Pethybr
Authors: ALI M. A. , LENNARD J. H. , BOYD A. E. W.
Published: February 2008

Inoculation of seed potato tubes with Verticillium nubilum produced infection on the underground stem bases to subsequent growth in the form of brown lesions, often accompanied by longitudinal or transverse cracking. Some inoculation tests provided further evidence of a causal relationship between infection with V. nubilum and coiled sprout, but it was not possible to define the conditions in which the fungus gave rise to coiling.

Seed tubers sprouted in light before planting produced more coiling than unsprouted or desprouted tubers. Sprouting had this effect whether V. numbilum was present or not and coiling induced by sprouting and that induced by V. nubilum occurred independently. The increased coiling of stem bases from sprouted tubers was often accompanied by fasciation, whereas this symptom was not usually associated with the coiling from unsprouted or desprouted seed tubers inoculated with the fungus. Brown lesions associated with V. nubilum were readily distinguishable from those of Rhizoctonia solani but not from those caused by Oospora pustulans. Neither of these fungi was found to cause coiling.

Different varieties of potatoes showed differences in the incidence of coiling in response to sprouting treatment. There was no apparent differences in varietal response to infection by V. nubilum.
A bivane direction indicator and a sensitive vertical anemometer for measuring components of wind in sheltered places
Authors: DIBLEY G. C. , LEWIS T.
Published: February 2008

Two instruments are described: (1) a bivane direction indicator; (2) a vertical anemometer with the ancillary electronic recording equipment, for examining wind structure near windbreaks. Both instruments were designed to operate in slow winds.
Air movement near windbreaks and a hypothesis of the mechanism of the accumulation of airborne insects
Authors: LEWIS T. , DIBLEY G. C.
Published: February 2008

Different components of wind were measured to leeward of artificial windbreaks to show which most affected accumulations of airborne insects there. Horizontal motion was the most important. Accumulations of small airborne insects in sheltered places are probably caused when the insects are diffused or convected into the recirculating air behind barriers. The concentrations likely to occur theoretically in this way were compared with concentrations measured in the field.
The control of paedogenetic cecid larvae in mushroom beds by the use of thionazin
Authors: WYATT I. J.
Published: February 2008

Thionazin incorporated in the casing layer of mushroom beds was shown to be highly phytotoxic even at 5 ppm, but when incorporated in compost it caused little phytotoxicity up to 20 ppm. A rate of 8 ppm gave satisfactory control of Heteropeza pygmaea Winnertz (Dipt.: Cecidomyiidae), but was less suitable against Mycophila speyeri (Barnes), for which the use of γ‐BHC in the casing should be retained. A severe infestation of M. speyeri was shown to depress the total yield of mushrooms by 59% and the saleable yield by 87%.
The toxicity of certain herbicides to hens' eggs assessed by the egg‐injection technique
Authors: DUNACHIE J. F. , FLETCHER W. W.
Published: February 2008

Twenty‐five herbicides have been tested for their toxicity to hen embryos at various concentrations, using an egg‐injection technique. Paraquat was the most toxic, giving a complete kill at a concentration in the egg of 0.3 ppm; two other compounds related to it were almost completely lethal at 10 ppm. Of the other compounds, seventeen had little or no effect at 50 ppm and of these eight had none at 100 ppm. Except for feather blanching, caused by some of the substituted phenoxy‐acids, no teratogenic effects were found.
The effect of small doses of nematicides on migratory root‐parasitic nematodes and on the growth of sugar beet and barley in sandy soils
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E.
Published: February 2008

Smaller amounts of D–D (6–12 gal/acre) (68–135 1/ha) or ethylene dibromide (9 gal/acre) (100 1/ha) than are customarily used to disinfest field soils killed many root‐parasitic nematodes (Trichodorus, Pratylenchus, Tylenchorhynchus and Longidorus attenuatus) when injected 6–8 in (15–20 cm) deep during early autumn in rows 10 in (25 cm) apart in well‐drained sandy soils. They also increased the yield of sugar beet grown in fields infested with Trichodorus or Longidorus attenuatus, without affecting sugar percentage or juice purity of the roots, and in some places increased the yield of barley grown after the beet. D–D was much less effective when injected 8–12 in deep during late autumn or winter. Increasing nitrogen dressings to the seedbed from 1·5 to 3 cwt/acre (188 to 376 kg/ha) increased sugar beet yield in one field, decreased it in another and decreased juice purity in both. In two other experiments extra nitrogen did not affect sugar beet yield.

Even smaller amounts of the nematicides ‘placed’ in the rows, before or after sowing sugar beet in them, killed many of the nematodes and also increased sugar yield. Phytotoxic nematicides can be placed in the rows during autumn, winter or spring but placement is simpler during spring, when the treated rows are indicated by the position of the marks of the tractor wheels left when the nematicide was applied. When applied during autumn or winter, the rows need to be indicated by drilling wheat or grass.
The effect of light wavelength on the susceptibility of plants to virus infection
Authors: COAST E. M. , CHANT S. R.
Published: February 2008

Plants exposed for 24–72 h to light of different wavelengths differed in their subsequent susceptibility to virus infection. French bean leaves were less susceptible to infection by tobacco necrosis virus and Nicotiana glutinosa leaves were less susceptible to infection by tobacco mosaic virus when previously exposed to blue or red light than when exposed to green light. These differences were most pronounced at low energy levels. Leaves exposed to each kind of light were less susceptible than those kept in darkness.
Chemical treatment of cereal seed in relation to plant vigour and control of soil fungi
Authors: RAWLINSON C. J. , COLHOUN J.
Published: February 2008

Treating oat seeds not contaminated with any known pathogen of this crop with an organo‐mercury preparation (Ceresan) increased seedling vigour only when they were grown in natural or simulated winter conditions with periods of frost. This beneficial effect on vigour was largely confined to seedlings and young plants.

The fungicide protected the mesocotyls from contamination or invasion by certain soil‐borne fungi normally regarded as saprophytes. Cylindrocarpon radicicola and Fusarium sambucinum were closely associated with discoloured mesocotyls bearing lesions and reduced vigour of untreated plants. Protection from such fungi enabled mesocotyls to grow thicker, and, when seedlings were grown in unsterilised soil and exposed to frost, reduced the number with lesions or discolouration. Thus the ability of the saprophytic soil‐borne fungi to cause damage seems to be influenced by environmental conditions.
Studies on the fate in plants of ethylenebisdithiocarbamate fungicides and their decomposition products
Authors: VONK J. W. , SIJPESTEIJN A. KAARS
Published: February 2008

A study was made of the fate in plants of ethylenebisdithiocarbamate fungicides and their decomposition products. Nabam (disodium ethylenebisdithiocarbamate) is known to decompose rapidly in aqueous environment, mainly to ethylenethiourea and ethylenethiuram monosulphide. Only ethylenethiourea was taken up by the roots and leaves of cucumber seedlings and by the roots of wheat seedlings. It was converted to a slight extent into an unknown compound.

The fate of maneb (manganese ethylenebisdithiocarbamate) and zineb (zinc ethylenebisdithiocarbamate) does not differ essentially from the fate of nabam.
Quantities and qualities of leaf protein concentrates from wild species and crop species grown under controlled conditions
Authors: LEXANDER K. , CARLSSON R. , SCHALÉN V. , SIMONSSON Å. , LUNDBORG T.
Published: February 2008

The amount of protein produced per m2 by plants cultivated in soil in a greenhouse at three levels of fertilizer application, for c. 10 weeks, was estimated by Kjeldahl analysis of the TCA‐insoluble fraction of freeze‐dried material. The quantity of protein extractable for production of leaf protein concentrates was determined by Kjeldahl analysis of non‐dried but frozen material after disintegration with a meat mincer and an Ultra‐Turrax homogenizer, hydraulic pressing and filtration, and protein precipitation by heat (in two steps) or by TCA. The precipitability was also studied by Folin‐Ciocalteu determination of protein. The quality of each protein concentrate was studied by determining nitrogen content (Kjeldahl), digestibility by pepsin and by pepsin + pancreatin, nutritive value in Tetrahymena tests, and lysine and methionine content (analysed microbiologically). Twenty‐nine species and varieties were investigated. Large differences between species were found in all the properties studied. Protein extractability varied between 5 and 80%, while the extractable protein produced per m2 ranged between 1 and 140 g. The highest digestibility was two to three times greater than the lowest one. In the most digestible species (Amaranthus caudatus), 82% of the N of the chloroplastic protein concentrate was digested by pepsin + pancreatin. The Tetrahymena value generally ranged between 40 and 98, whereas casein gave values of about 75. The lysine content always exceeded the FAO minimum. The methionine content of most species varied between 2.0 and 2.2% of the hydrolyzed protein.

Amaranthus caudatus and the Chenopodiaceae investigated were the most suitable species for large‐scale production of leaf protein concentrates for human consumption because they gave high yield of extractable protein and high‐quality protein concentrates.
Analysis of differences in yield between six sugar‐beet varieties
Authors: LOACH K.
Published: February 2008

The basis of differences in yield between six sugar‐beet varieties was studied by measuring the changes in their leaf areas and dry weights throughout the season. Initially, dry‐matter production was determined by the rate at which leaf area developed, but this effect did not persist to final harvest. Varieties that maintained the largest net‐assimilation rates in September produced largest sugar yields. Characteristically, these varieties showed the smallest losses in lamina dry weight through leaf senescence late in the season, and put the largest proportion of their photosynthate into root production.
Relative ability of two strains of Pucccinia graminis tritici to survive when mixed
Authors: OGLE HELEN J. , BROWN J. F.
Published: February 2008

The relationship between relative survival ability and the number of genes for virulence in two strains of Puccinia graminis tritici was investigated using a differential variety to determine the proportion of each race in the mixture. The strain with the widest host range (21 Anz‐2,3,7) became predominant after a number of uredial generations, regardless of its proportion in the original inoculum mixture. However, despite the higher relative survival ability of strain 21 Anz‐2,3,7, strain 21 Anz‐2,7 persisted at c. 1% frequency after four successive uredial generations. The longer the period between successive inoculations, the more rapidly strain 21 Anz‐2,3,7 became predominant in the mixture. The variety on which the mixture was cultured did not influence the relative survival ability of the two strains.
Infection periods in relation to the natural development of hop downy mildew (Pseudoperonospora humuli)
Authors: ROYLE D. J.
Published: February 2008

The relationships between temperature and surface wetness and subsequent infection of hop tissues by P. humuli were examined on potted plants and detached leaves kept in temperature‐controlled growth rooms. Periods of wetness which would just allow leaf infection ranged from 1 1/2 h at 30d̀ to 24 h at 5d̀. The corresponding ranges for shoots were: light infection, 3 h at 19–23d̀ to 6 h at 8–10d̀; severe infection, 4 h at 19–23d̀ to 8 h at 12–13d̀. These data were used to relate the development of downy mildew in an unsprayed hop garden during 1967 and 1968 to periods with temperature/surface wetness suitable for minimum (minor infection periods) and severe infection (major infection periods).

In 1967 a sudden outbreak of infected basal shoots (spikes) was related to an isolated major infection period. By contrast, early in 1968, major shoot infection periods did not arise and spikes appeared gradually in response to a succession of minor infection periods. More spikes were formed in 196 than in 1967; this was not related to the incidence of infection periods but probably reflected the relatively higher concentrations of airborne sporangia early in 1968.

In both years outbreaks of leaf and lateral shoot infection could be traced to major infection periods caused by rain; sudden disease increases again originated from isolated infection periods. There was a close similarity between the incubation period for each principal disease outbreak and that expected from growth‐room experiments. Major infection periods occurred more frequently at the end of June 1968, resulting in a higher final concentration of diseased tissue than in 1967. Predicted major infection periods failed to induce large disease increases when dew alone provided wetness or when no airborne sporangia could be detected.
The susceptibility of verieties of carrot to attack by the aphid, Cavariella aegopodii (Scop.)
Authors: DUNN J. A.
Published: February 2008

Representative varieties from the carrot groups, Chantenay, Nantes, Berlikum and Autumn King, together with three Australian varieties, were tested for susceptibility to attack by Cavariella aegopodii (Scop.). Tests were done at different average temperatures in cages in the insectary by inoculating plants with apterous forms of the aphid and frequently checking the extent of colonization over the next 20 or so days. Field sowings of the varieties were also made in each of 3 years, and over the immigration period and the subsequent population development and decline of the aphid, regular counts were made of the alates settling on a standard number of plants of each variety, and of the progeny produced. Some differences in susceptibility to attack were noted but, because the main development of C. aegopodii on field carrots is limited to two generations, these were too small to be of practical value in terms of plant resistance, and on all varieties large numbers of aphids could be found. Although the Australian variety Osborne Park was thought to have some resistance to C. aegopodii in New Zealand, it proved to be of average susceptibility. Autumn King appeared to be the most aphidsusceptible variety but could be tolerant to motley dwarf virus. Nantes was not as tolerant to aphid attack as the other varieties and as it is also intolerant to motley dwarf virus, might suffer much damage in years favouring aphid expansion. Berlikum seemed to be the least susceptible to aphid attack. Temperature differences affected expressions of varietal susceptibility less than they affected aphid fecundity and a few degrees increase in temperature more than halved the number of young born in a generation.
The action of some systemic aphicides on the nymphs of Anthocoris nemorum (L.) and A. confusus Reut
Authors: ELLIOTT W. M.
Published: February 2008

The aphicides phorate, dimethoate and menazon were compared to elucidate the different pathways by which they can affect Anthocoris nymphs and their aphid prey.

When nymphs were caged in contact with deposits on bean leaves phorate and dimethoate had contact LC 50s of 20 and 3 μg/cm2 respectively to Anthocoris nemorum and 46 and 6 μg/cm2 to A. confusus. When the nymphs were confined on treated leaves on the opposite surface to the deposits, neither phorate nor dimethoate killed them. Menazon did not kill anthocorids at any dosage. All three aphicides killed over 50% of Acyrthosiphon pisum (Kalt.) on bean leaves at 1.6 μg/cm2 whether the aphids were on the treated or untreated surface.

Experiments with 35S‐labelled phorate showed that anthocorids confined on phorate‐treated bean plants, with or without insect food, accumulated the insecticide or its labelled derivatives. In field experiments in which A. nemorum were caged on plants treated with phorate, many were killed on young newly treated plants but not on older plants. A. confusus was relatively unaffected.

Anthocorids were reared from 2nd‐instar nymphs to adults on aphids killed systemically with phorate, dimethoate or menazon without ill effects, despite evidence that 35S‐labelled phorate was ingested from the aphids and excreted in the faeces.

In the field, fewer large A. nemorum nymphs were found in August in plots of tick beans treated with phorate granules at 6 lb/acre (6.7 kg/ha) when sown, than in plots treated at 1.5 lb/acre (1.7 kg/ha) with phorate or menazon or untreated plots.
Control of Myzus persicae on year‐round chrysanthemums by introducing aphids parasitized by Aphidius matricariae into boxes of rooted cuttings
Authors: SCOPES N. E. A.
Published: February 2008

Complete control of Myzus persicae on the chrysanthemum cultivar Tuneful was achieved within 2 months or less of planting using the parasite Aphidius matricariae. The success of the technique depends on introducing a small population of parasitized aphids into boxes of rooted cuttings, and the rapidity of control is determined by the ratio of aphids to parasites present at the time of introduction. The method is likely to be even more successful where cultivars less susceptible to aphids are grown.

A. matricariae cannot be used to control M. persicae if the aphids are infected with the fungus Cephalosporium aphidicola.
Green mould of oranges caused by Penicillium digitatutn Sacc.; effect of additives on spore germination and infection
Authors: KAVANAGH J. A. , WOOD R. K. S.
Published: February 2008

Water extracts of rind, essential oil and juice from oranges, also citrus pectin and citric acid promoted the formation of lesions when spores of Penicillium digitatum were placed in wounds 1·0 mm deep in flavedo of oranges; fructose, glucose and sucrose had little effect.

Rind extracts were less effective in wounds 0·5 mm deep but orange juice and pectin still increased infection. None of the substances allowed the parasite to infect fruit through unwounded surfaces.

Germination of spores in water increased as spore concentration decreased but was poor even at low concentrations. Almost all spores germinated in aqueous extracts of flavedo, albedo or whole rind, or in wounds on the surface of fruit. Fructose, glucose, sucrose and xylose were less effective but still caused over two‐thirds of spores to germinate but only in the presence of phosphate buffer. Without buffer, germination was little different from that in water. Arabinose and galactose stimulated germination to a lesser extent but with the same phosphate effect. Carboxymethylcellulose and pectin did not affect germination.

A variety of substances containing nitrogen increased germination but to different degrees, decreasing in the order, casamino acids, yeast extract, ammonium salts, nitrate. Thiamin and to a lesser extent biotin were also effective.

Volatile substances from rind infected with P. digitatum stimulated spore germination and growth of germ tubes.

The significance of these results is discussed in relation to infection.
Rainfall and cropping patterns in relation to coffee berry disease*
Authors: GRIFFITHS ELLIS , WALLER J. M.
Published: February 2008

Both the increase in severity and extent of coffee berry disease (CBD) during the 1960s and the failure of early‐season sprays to control it have been attributed to changes in climatic conditions and cropping patterns. A critical analysis of rainfall data since 1951, when CBD first appeared in the East Rift coffee districts of Kenya, produces no evidence that conditions affecting CBD development were any different in the 1960s than in the 1950s, in either high‐or low‐altitude coffee‐growing areas. A marked increase in overlapping crops occurred during the late 1950s, and this was caused mainly by a change in pruning methods. The increased disease hazard from this change of cropping pattern cannot account for the failure of early season sprays, which were successful before 1962.

An estimate of the time of main crop flowering shows that only in those years when flowering was early and the rainy season finished early did early‐season sprays achieve substantial benefits. It is concluded that their effect in these years was obtained by fungicidal protection of the crop throughout most of the rainy season, and that their failure in other years contributed to the worsening disease situation.
Chemical control of Didymascella thujina on Western red cedar in forest nurseries
Authors: BURDEKIN D. A. , PHILLIPS D. H.
Published: February 2008

Didymascella thujina causes a serious needle blight in nursery stock of Western red cedar. It may be controlled by cycloheximide applied at a concentration of 85 ppm of active ingredient and at a rate of 100 gal/acre (1123 1/ha) at the end of March and again at the end of April. In south Wales and south‐west Scotland a third application may be needed in mid‐June.

Other fungicides tested were not effective against this disease.
Characterization of the components of plant cuticles in relation to the penetration of 2,4‐D
Authors: BAKER E. A. , BUKOVAC M. J.
Published: February 2008

Quantitative comparisons were made of the components of the cuticles of leaves of plantain, fat hen, dandelion, dock, chickweed and forget‐me‐not. Hydrocarbons and triterpenoids were prominent in the surface wax of plantain; esters and alcohols in the other surface waxes. Polar compounds predominated in the cuticular waxes. Cuticle development in plantain, dandelion and chickweed was similar, but the cutins differed in the relative proportions of hydroxy‐fatty and fatty acid components. Sorption of 2,4‐D by the cuticular membrane was inversely related to the amount of cuticular wax. Hydrocarbons and an aldehyde fraction isolated from surface wax most effectively reduced the penetration of water in a model system.
The reproductive behaviour of Metopolophium festucae (Theobald) at different temperatures and on different host plants
Authors: HILL A. R.
Published: February 2008

Metopolophium festucae is a cold‐hardy species: on young oat seedlings nymphs are produced from apterae at temperatures below 6 °C. Alatae are less well adapted to low temperatures: in a laboratory experiment the average daily production of nymphs from apterae was 0·96 at 10·2 °C and 2·71 at 22·8 °C; the corresponding figures for alatae were 0·42 and 1·81.

Aphids on oats, wheat and Italian ryegrass have a slightly higher progeny production than on barley, timothy and cocksfoot: the adults produced on the cereals are heavier than those on the grasses.

It is postulated that the aphids require a perennial crop on which to overwinter as nymphs or parthenogenetic adults; consequently successful colonization of cereal crops is rare.
The biology of Peronospora viciae on pea: factors affecting the susceptibility of plants to local infection and systemic colonization
Authors: MENCE M. J. , PEGG G. F.
Published: February 2008

Peronospora viciae (Berk.) Casp. penetrated leaf disks of Pisum sativum L. through the cuticle. Resistance of pea plants and of individual leaves to infection by P. viciae increased with age, but decreased again at senescence. Resistance was shown by a restriction in fungal growth and sporulation and by a chlorotic reaction in the leaves. Systemic invasion followed infection of meristematic tissue, and was induced by inoculation into the apical bud of young plants, or on to the epicotyl or hypocotyl, but not roots of germinating seedlings. Most plants whose growth was retarded showed an increased resistance to systemic infection. Pods were infected externally by sporangia, rather than by mycelial growth through the peduncle and pedicel. Oospores and mycelium were found in the testas of some seeds, but seeds from infected pods did not give rise to infected seedlings.
Control of raspberry stamen blight
Authors: MONTGOMERIE ISABEL G.
Published: February 2008

Evidence from field observations suggests that where stamen blight (Hapalosphaeria deformans Syd.) is prevalent dissemination of spores by wind may account for the establishment of the disease in initially healthy plantations. Captan and dichlofluanid were equally effective in significantly decreasing the level of disease.
Pathogenicity of Fusarium oxysporum to Easter lily, narcissus and gladiolus
Authors: BALD J. G. , SUZUKI TERRY , DOYLE ANNA
Published: February 2008

Isolates of Fusarium oxysporum from roots, bulbs and stems of Easter lilies (Lilium longiflorum) differed widely in pathogenicity and also, apparently, in tissue specificity. Virulent isolates caused a typical basal rot and root rot (but not a wilt) in which the mycelium advanced intercellularly through the scales and basal plates. Mildly pathogenic isolates became established in mature or senescent outer scales, at first producing only superficial effects, but further growth of mycelium occurred as the outer scales died and sometimes continued until the dead tissues were permeated and chlamydospores were formed. The underlying scales were then colonized.

The modes of pathogenicity and survival in Easter lily were compared with those of the F. oxysporum formae causing bulb rots of gladiolus and narcissus.

It is suggested that advance of hyphae by penetration between the cells of the vascular parenchyma, which is common in isolates causing rots in bulbs and corms, represents a stage in the evolution of the truly vascular habit among fusaria.
Some factors influencing the performance of spray programmes for the control of coffee berry disease*
Authors: GIBBS J. N.
Published: February 2008

In 1968 in a field trial at Kamundu, Kenya, early‐season (Jan.‐Mar.) sprays of copper, captafol and Tuzet failed to control coffee berry disease (CBD), in the late (main) crop of cultivars S.L.28 and S.L.34. Copper and captafol caused some delay in disease development but eventually infection reached over 50 % in all treatments and final yields of sprayed plots were below those from unsprayed plots.

In a similar trial in 1969 at Yara on the cultivar French Mission a similar spray programme achieved significant benefits: copper and captafol kept the level of disease below 20% and gave improved yields compared with unsprayed plots. A continuation of the sprays until June increased yields still further.

In a second trial in 1968 at Kiamara on the cultivar French Mission substantial quantities of early crop were present and disease in this was effectively controlled by early‐season sprays of captafol, although the late crop on the same trees became severely affected. Removal of this overlapping early crop in January caused only a limited delay in disease development in the late crop, despite the fact that with some treatments this stripping resulted in the removal of a large source of potential inoculum from the tree.

The results are considered in relation to differences between seasons and fungicides and it is concluded that further evidence has been provided for the importance of the protective role of fungicides against CBD. It is considered that stripping of the early crop is never likely to be a necessary management practice.
The integration of chemical control of the melon aphid with predatory control of glasshouse red spider mite on cucumbers
Authors: BINNS E. S. , BOCION P. , GOULD H. J.
Published: February 2008

The suitabilities of eleven chemical aphicides were compared for application to plants on which biological control of Tetranychus urticae by Phytoseiulus persimilis was in progress. It was concluded that currently used aphicides offer insufficient selectivity to provide a basis for integrated control programmes, although some older insecticides may have value.
Morph determination in the bird cherry‐oat aphid, Rhopalosiphum padi L
Authors: DIXON A. F. G. , GLEN D. M.
Published: February 2008

Both crowding and poor nutrition induce the appearance of emigrants in Rhopalosiphum padi L. No emigrants developed when the aphid was reared in isolation for six successive generations on actively growing leaves of bird cherry. However, emigrants developed as soon as the leaves ceased to grow or when the aphids became crowded.

Crowding of mothers and postnatal crowding of the nymphs of apterous exules both influenced the induction of alate exules. The highest proportion of alate exules developed when both mother and offspring were crowded.

Short day‐length induced the appearance of gynoparae and males. For 50% production of gynoparae and males, over the range of temperature 10–18d̀C, a 1.75 h reduction in day‐length is required for every 4d̀ increase in temperature. At 18 d̀C, even at day‐lengths as short as 6 h, exposure for three generations is required before all offspring become gynoparae or males. Low temperature and short day‐length was ineffective in inducing the development of gynoparae or males in the first three generations developing from the fundatrix.
Interactions between Heterodera rostochiensis Woll. and Verticillium dahliae Kelb. on potatoes and the effect of CCC on both
Authors: CORBETT D. C. M. , HIDE G. A.
Published: February 2008

H. rostochiensis (British pathotype A) increased the severity of the disease caused by Verticillium dahliae in potato plants grown in pots when there were more than ten eggs/g of soil and both pathogens parasitized the root system together. The growth‐suppressing chemical CCC, which severely stunted plants, prevented the disease and decreased H. rostochiensis reproduction. An estimate of foliage symptoms measured the effects of the disease more precisely than did tuber yields.
Analysis of growth and yield of inbred and crossbred maize
Authors: ALLISON J. C. S.
Published: February 2008

In experiments with young widely spaced plants grown in sand culture, net assimilation rate (E) of two single‐cross hybrids, N x S and W x M, was respectively > 20% and 13–19% greater than that of their parental inbreds, N and S, and W and M. Relative growth rate (R) of W x M exceeded that of W or M, and R of N x S exceeded that of S, but not that of N because leaf area ratio (F) of this inbred was greater than that of N x S. E of N x S was about 10% greater than that of an open‐pollinated variety, OP. When the size of plants of N x S was varied by sowing seeds of different sizes, E was little affected but R increased as plant size decreased, because F increased with decrease in plant size.

In a field experiment total dry weights at final harvest of N, S and OP were respectively 66, 46 and 98% of that of N x S; their respective grain weights were 47, 20 and 70% of that of N x S. N, S and OP flowered later than N x S and accumulated respectively 56, 26 and 89% as much dry matter after flowering as N x S. Grain formed 71, 65, 83 and 65% of the dry matter accumulated after flowering in N, S, N x S and OP, respectively.

Up to about the time of flowering, E and R of the relatively small N and S plants were greater than those of N x S plants, but later E of N and S was smaller than that of N x S. Before flowering, when leaf area of OP was less than that of N x S, E was greater in OP than in N x S. After flowering leaf area was greater, and E smaller, in OP than in N x S.
Effects of plant density and nitroǵen fertilizer on growth and yield of short varieties of wheat derived from Norin 10
Authors: THORNE GILLIAN N. , BLACKLOCK J. C.
Published: February 2008

The short varieties of spring wheat, Lerma Rojo 64 (R) and Mexico 120 (M), derived from Norin 10, had similar yields of grain to the taller European variety, Kloka (K), when the nitrogen applied ranged from 50 to 200 kg/ha. All varieties had their maximum yields, of about 500 g/m2 of grain, with 125 kg/ha of N. Yields of R and M were unaffected by change in plant population from 75 (M) or 105 (R) to 298 plants/m2. There were 213 plants of K per m2. When compared at similar plant populations, all varieties had a similar number of ears of similar weights. Ears of K had many small grains borne on many spikelets. Those of R had fewest spikelets and most grains per spikelet. With 213 plants/m2 about 60% of shoots of K and 70% of those of R and M survived to produce ears.

The short variety of winter wheat Gaines (G), derived from Norin 10, had a similar yield of grain to the taller European variety Cappelle‐Desprez (C), when nitrogen ranged from 75 to 300 kg/ha and there were 240 plants/m2. The largest grain yields of both varieties, about 670 g/m2, were obtained with 150 kg/ha of N. Increasing the plant population of G to 400 plants/m2 decreased grain yield by 10%. G had more ears than C and the ears weighed less because the grains were smaller. The numbers of grains per ear were similar: ears of G had fewer spikelets than C, each bearing more grains. G always had more shoots than C and about 70% of the shoots produced by each variety survived to form ears.

The dry weight per m2 of stem plus leaves of the short varieties was less than of the tall ones at flowering and at maturity. Hence harvest index (ratio of grain yield to total dry weight), and the proportion of total dry weight in the ears at flowering, were greater for the short than for the tall varieties.

Grain leaf ratio, the apparent efficiency of the leaf area present after flowering in producing grain, estimated as grain dry weight divided by leaf area duration after flowering, was greatest for M and least for K in the spring experiment. No similar difference occurred between the winter varieties. When leaf area of either spring or winter varieties was increased by nitrogen fertilizer or denser sowing, grain yield did not increase proportionately and so grain leaf ratio decreased.
The resistance of three Solanum species to Myzus persicae, Macrosiphum euphorbiae and Aulacorthum solani (Aphididae: Homoptera)
Authors: GIBSON R. W.
Published: February 2008

A study was made of the resistance of three wild potato species, Solanum chacoense, S. stoloniferum and S. demissum, to three aphid species, namely Myzus persicae (Sulz.), Aulacorthum solani (Kalt.) and Macrosiphum euphorbiae (Thomas), which all commonly infest the cultivated potato, S. tuberosum. The resistance of each Solanum species differed with the species of aphid, with the part of the plant and with the physiological condition of the leaf. As a result, it may be difficult to utilize such resistance, since it is ineffective against some of the pest aphid species and may break down as the physiological condition of the plant changes.
Methods of assessment celery leaf spot (Septoria apiicola) in relation to fungicide evaluation
Authors: KAVANAGH T. , RYAN E. W.
Published: February 2008

Six criteria for evaluating fungicides for control of celery leaf spot (Septoria apiicola) were compared. Two of these criteria consisted of yield measurements, of which marketable yield gave better statistical separation of the fungicides than gross yield. Of the other four criteria, assessment of leaf spot on a whole‐plot basis was the most valuable. Overall disease rating on individual intact plants, rating of each petiole and numbers of diseased petioles per plant were less useful assessment criteria.
Some factors affecting the concentrations of sugars in leaves of inbred sugar‐beet lines
Authors: RUSSELL G. E. , BARFORD I. A.
Published: February 2008

In the glasshouse, large differences in concentrations of glucose and sucrose were observed between leaves of inbred sugar‐beet lines that are known to differ from each other in resistance to pests and diseases. Differences between these lines in concentrations of fructose, glucose and sucrose were more pronounced in the petiole than in the lamina.

The concentrations of glucose and fructose were lower in the first two leaves (primary leaves) than in those produced subsequently (secondary leaves); both types of leaf contained similar concentrations of sucrose.

Secondary leaves from plants that had been kept in darkness for 17 h contained less fructose, glucose and sucrose than those of plants kept in sunlight for 5 h. Longer period of darkness lowered the concentrations of monosaccharides in the leaves further but did not affect the sucrose content.

Primary and secondary leaves from the same sugar‐beet plant often differ in non‐race‐specific resistance to pests and diseases; and darkness can affect suscetibility of beet to downy mildew and to the aphid Myzus persicae. The results of the sugar determinations therefore support the hypothesis that the concentrations of certain carbohydrates in sugar‐beet leaves are important in non‐race‐specific resistance to pests and diseases.
Tests of aryltin compounds as potato blight fungicides
Authors: McINTOSH A. H.
Published: February 2008

Triphenyl(phenylthio)tin and triphenyl(p‐chlorophenylthio)tin were as effective as fentin acetate in controlling potato blight (Phytophthora infestans) in laboratory tests on detached leaflets. Diphenyltin dichloride and bis(triphenyltin)sulphide were moderately effective. Dibenzyltin and some diphenyltin compounds were ineffective.

A small change in the bioassay conditions, bringing them slightly closer to field conditions, increased the relative effectiveness of bis(triphenyltin)‐sulphide, making it about one‐quarter as effective as fentin acetate; however, the change did not increase the relative effectiveness of triphenyl(phenylthio)tin or dibutyltin diacetate.
Studies on plant growth‐regulating substances: XXXIII. The influence of ring substituents on the plant growth‐regulating activity of phenylacetic acid
Authors: CHAMBERLAIN VALERIE K. , WAIN R. L.
Published: February 2008

A comprehensive range of phenylacetic acids substituted with nitro, halogen, methyl, amino, hydroxyl and N‐acetylamino groups have been synthesized and their growth‐regulating activities assessed in the wheat cylinder, pea curvature and pea segment tests. The influence of substituents on molecular shape is shown to be more important in determining activity than their effects on electron distribution.

Studies with 2,6‐disubstituted phenylacetic acids have indicated that the most active compounds can attain a certain spatial configuration in which one surface of the molecule, including the plane of the ring system, is flat and the carboxyl group is above with its axis of rotation perpendicular to this surface.

Positional requirements for growth‐regulating activity in phenylacetic acids are shown to be less important than in the phenoxyacetic and benzoic acids.