bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of temperature, light and host on prepenetration development of Puccinia graminis avenae and Puccinia coronata avenae
Authors: KOCHMAN J. K. , BROWN J. F.
Published: February 2008

The influence of temperature and light on prepenetration development of single and mixed isolates of Puccinia graminis avenae and Puccinia coronata avenae was studied on 0–2% water agar and on leaves of three oat cultivars and on three non‐cultivated species of Avena. Germination of uredospores of P. graminis avenae and P. coronata avenae occurred best at 10–30oC and at 20oC respectively. The optimum temperature for germ‐tube growth and for appressorial formation was 20oC for both rusts.

An inverse relationship was observed between light intensity and prepenetration development with maximal germination of uredospores, germ‐tube growth and appressorial formation occurring in darkness. Under optimum conditions maximum percentage germination and appressorium formation of both rusts was attained within 4 and 12 h after inoculation respectively. The proportion of germinated uredospores of crown rust which gave rise to appressoria was about twice that observed for stem rust.

No significant differences were observed in prepenetration development between the single and mixed race inocula of the two rusts. Although germination of uredospores was significantly greater on water agar than on oat leaves, there were no significant differences in prepenetration development of the rusts on the various oat cultivars and species examined. Consequently, the data failed to indicate the presence of resistance mechanisms operating during the prepenetration phase of the infection process on the cultivars and species examined.
Host and environmental effects on the penetration of oats by Puccinia graminis avenae and Puccinia coronata avenae
Authors: KOCHMAN J. K. , BROWN J. F.
Published: February 2008

The frequency of penetration from appressoria of Puccinia graminis avenae and P. coronata avenae varied among Avena species and between oat cultivars, although both rusts produced susceptible infection type pustules on the cultivars tested. Penetration on cv. Garry was significantly less than that on the Avena species (A. barbata, A.fatua and A. sterilis) studied and penetration of these Avena species was significantly less than on the cvs Algerian and Fulmark. When the rusts were allowed to develop into pustules on seedlings which had been inoculated with fixed amounts of inoculum, there was a direct relationship between number of pustules produced and penetration frequency.

The effects of temperature, light and dew period on penetration from appressoria of ‘single race’ and ‘mixed race’ inocula was also studied on these cultivars and species. Penetration by P. graminis avenae was greatest at 30–35 °C and at light intensities of 5625 lux and above, whereas that by P. coronata avenae was greatest at 20 °C and was unaffected by artificial light intensities up to n 250 lux. Maximal penetration by P. graminis avenae and P. coronata avenae was observed after inoculated plants had been exposed to dew periods of 16 and 12 h respectively. Some penetration was observed after a dew period of 8 h. The time taken for each rust to attain maximum penetration varied from 36 to 52 h after inoculation, depending on the environment, and was usually less for P. coronata avenae than for P. graminis avenae.
Weather and fireblight in England
Authors: BILLING EVE
Published: February 2008

A method for assessing potential fireblight activity in the field in southeast England is described. It is based on potential doublings (PD), derived from in vitro growth rates of Erwinia amylovora at different temperatures, combined with a rain score (R) derived from daily precipitation values. Where the incubation period (I) was known, the coefficient of correlation between I/R and PD was 085 (P < 0–001). When I was regressed on PD and R, the multiple correlation coefficient was 0–97. The low level of fireblight in England precluded direct testing of the predictive value of the relationship between PD, I and R but its application to growing season weather of 1955‐74 highlighted those years when fireblight activity was high in a particular host. Whilst within the range 65–86 oF (18–30 oC) there is good agreement between accumulated potential doubling values and accumulated degree days, the rain score would probably require modification in other climates.
Some factors affecting the control of Rhizoctonia solani by systemic and non‐systemic fungicides
Authors: KATARIA H. R. , GROVER R. K.
Published: February 2008

In laboratory tests, Rhizoctonia solani grew best on agar at 30 oC and pH 5‐5. Mycelial growth was strongly inhibited by benomyl, chloroneb and quintozene, less so by thiophanate‐methyl. The optimum temperature for inhibition was 25 oC for quintozene; the other three fungicides gave greatest inhibition at the lowest temperature tested (20 oC). Benomyl and thiophanate‐methyl were most inhibitory at pH 7–8, chloroneb and quintozene at pH 5–6.

In pot trials using mung bean, long melon, egg‐plant, common pea and sugar beet, R. solani caused maximum disease at 20 oC and in wet and alkaline soils. As seed treatments, benomyl and thiophanate‐methyl gave optimum control at 20 oC and pH 7‐6; chloroneb and quintozene were most effective at 30 oC and pH 5‐4. All four fungicides gave maximum control on plants growing in wet sandy loam.

Comparisons of host effects showed that, on all the four hosts tested, thiophanate‐methyl wettable powder at 0.25% (0.175% a.i.) gave 90% control, chloroneb w.p. at 0.3% (0.195% a‐i‐) gave 80% control on mung bean and sugar beet, benomyl w.p. at 0.3% (0.15% a.i.) was satisfactory on mung bean, egg‐plant and sugar beet but not on long melon, quintozene w.p. at 0.3 % (0.225 % a‐i‐) gave effective control on sugar beet only.

The senior author is grateful to the Council of Scientific and Industrial Research, New Delhi, India, for the award of a Research Fellowship for undertaking these studies. Thanks are due to Dr S. D. Gupta and Mr S. L. Verma for determining the soil characteristics.
The epidemiology of potato blight in the East Midlands 1923–74
Authors: CROXALL H. E. , SMITH L. P.
Published: February 2008

Examination of the East Midlands records of potato blight epidemics and the meteorological data on critical 90 % relative humidity infection periods for the years 1923–74 indicates the importance of the amount of inoculum carried over from one season to the next in influencing the rapidity of progress of the disease and the date of destruction of the haulm. The success of forecasting outbreaks based on 90% r.h. periods is reviewed. The importance of taking into account both amount of inoculum and weather conditions in devising a disease control programme is discussed. It is concluded that the succession of seasons since 1968 without a major potato blight epidemic was due mainly to a combination of low carry‐over of infection and sub‐optimal weather conditions for the development of the disease and that the current control measures have not yet been subjected to a severe test.
Benomyl tolerance in isolates of Botrytis cinerea from tomato plants
Authors: FLETCHER J. T. , SCHOLEFIELD SUSAN M.
Published: February 2008

Three hundred and forty‐nine isolates of Botrytis cinerea were collected from tomato crops on forty‐one nurseries and 173 (40/6 %) were found to be tolerant to benomyl. There was no obvious association between disease incidence and the occurrence of tolerance.

In a fungicide comparison experiment on tomatoes in 1973, twenty of the sixty‐four (31 %) isolates examined were benomyl tolerant, the majority of these were from benomyl sprayed plants. In 1974 in a similar experiment, 384 of the 394 (97‐5 %) isolates examined were tolerant.

Tolerance was monitored in two tomato experiments in relation to a spray programme in which benomyl and dichlofluanid were used in various combinations. There was no marked effect of the spray programmes on the incidence of tolerance on either site.

In the experiments B. cinerea was controlled and significant increases in yield were obtained with benomyl in 1973 but not in 1974. This difference is attributed to the change in the pathogen population with a large increase in the incidence of tolerance on the experimental site in 1974.
Systemic fungicides in the control of strawberry wilt (Verticillium dahliae)
Authors: TALBOYS P. W. , FRICK E. L. , DAVIES MOIRA K.
Published: February 2008

In a series of experiments between 1970 and 1973 the application of benomyl or thiophanate methyl to field‐grown strawberries, planted on Verticillium‐mtested land, gave control of wilt for up to 5 months, the duration of control being related to the amount of fungicide applied in the spring. Treatment of inoculated plants grown on in chloropicrin‐fumigated soil was effective for at least two seasons.

An autumn‐planted multi‐factorial experiment in heavily‐infested soil showed that, to achieve maximum wilt control, it was advantageous to grow cv. Gorella rather than cv. Cambridge Vigour; to drench the runners at planting rather than to dip them in the fungicide suspension; and to use a high concentration (0–075 % a‐i‐) and large volume (600 ml per plant) for a supplementary treatment in May rather than a lower concentration (0.025 %) or smaller volume (400 ml). There were small but significant advantages in applying benomyl rather than thiophanate methyl, and in using 0–2% a.i. suspension at planting rather than 0–05%. No advantage was gained by dividing the spring application into two equal doses applied 2 wk apart. Extrapolation from the logarithmic relation between wilt index and total dose of fungicide applied in the spring suggested that I.I g/plant would have given almost complete control until October; such control had been achieved in an earlier experiment in which 1–2 g/plant was applied. Crop yield in the second year was determined by the treatment applied in the first year, but although these treatments had given significantly better control of wilt in Gorella than in Cambridge Vigour, the greater growth and yield potentials of the latter cultivar had an over‐riding effect on crop production; Cambridge Vigour yielded more than Gorella under all chemical treatments, but in the absence of treatment Gorella gave a larger crop than Cambridge Vigour.

A proposed regime, entailing spring and autumn applications, is aimed at minimizing the colonization of the plant throughout the year, thus reducing the production of new inoculum and, by limiting the quantity of the pathogen in contact with the systemic chemicals, minimizing the probability of selecting fungicide‐resistant variants of V. dahliae.
The effect of time to emergence on head weight and variation in head weight at maturity in lettuce (Lactuca sativa)
Authors: GRAY D.
Published: February 2008

In lettuce, results of three experiments showed that between 60 and 90 % of the variation in mature head weight and the date of head maturity could be accounted for by variation in the date of seedling emergence. Sowing pre‐germinated seeds using a fluid drill considerably reduced the time spread of both emergence and maturity compared with size‐graded natural seed sown conventionally.
Development of biological methods for the control of Tetranychus urticae on tomatoes using Phytoseiulus persimilis
Authors: FRENCH N. , PARR W. J. , GOULD. H. J. , WILLIAMS J. J. , SIMMONDS S. P.
Published: February 2008

The biological control of red spider mite using the predatory mite Phytoseiulus persimilis was investigated in 1971, 1972 and 1974. Experiments in small glasshouse compartments showed that the predator should be introduced when the leaf damage index is < 0–3.

Uniform and/or patch introductions of P. persimilis at different rates were made into naturally occurring red spider mite infestations on commercial nurseries. In eleven of the seventeen experiments good control was achieved. Introduction of the predator soon after damage appeared on the crop was essential. Poor control was obtained when the predator failed to establish itself, where very large numbers of diapausing mites emerged and built up rapidly or where the predator, introduced into patches, failed to colonize infested plants elsewhere in the crop.

When spider mites and predators were introduced on to one‐fifth or one‐tenth of the plants in a propagating house, a satisfactory interaction was maintained for 4–6 wk after planting out. The predators then died unless red spider mites emerged from diapause or were introduced.

Petroleum oil sprays were sometimes used successfully in the presence of the predator to reduce high red spider mite infestations and re‐establish the biological equilibrium.
Laboratory studies on the fungus Verticillium lecanii, a larval pathogen of the large elm bark beetle (Scolytus scolytus)
Authors: BARSON G.
Published: February 2008

From 1972 to 1974, estimates of the natural larval mortality (> second instar) of elm bark beetles caused by pathogenic organisms were always below 7'5 % of the beetle population. The pathogenic fungus Verticillium lecanii was frequently isolated from field‐collected dead larvae, and in the laboratory all larvae were killed in 5 days when exposed to spore concentrations of 4·5 × 106 spores/ml. V. lecanii begins to lose its pathogenicity after prolonged culture on artificial media. The time taken for V. lecanii to kill Scolytus scolytus larvae when exposed to a logarithmic series of spore dilutions from 9·1 × 107/ml to 9·1 × 103/ml increased with decreasing amounts of inoculum. Even at spore concentrations as low as 9·1 × 103/ml the mortality of treated larvae was greater than that of untreated individuals. At 100% r.h. all treated larvae were killed over a temperature range of 5–30 °C; those maintained at 25 °C were killed most rapidly and those kept at 5 °C the slowest.
Glasshouse tests of quinones, polyhydroxybenzenes and related compounds against potato common scab
Authors: Mcintosh A. H.
Published: February 2008

Forty quinones, polyhydroxybenzenes and related compounds were tested for possible control of potato common scab, caused by Streptomyces scabies. They were incorporated, at 50 μg/g or less, into scab‐infected soil in which potato plants were then grown in the glasshouse. Quintozene at 50/μ g/g was used as standard.

The chemicals varied very widely in their effects on scab, and in their phytotoxicity, as measured by decrease in yield of tubers.

Corresponding 1,4‐benzoquinones and hydroquinones behaved similarly. The unsubstituted and the phenyl‐, chloro‐,2,5‐ and 2,6‐dichloro‐com‐pounds were as effective as quintozene; with the exception of chloro‐hydroquinone, they did not decrease yield. Chloranil and chloroneb (the dimethylether of 2,5‐dichlorohydroquinone) were much less effective, and chloroneb decreased yield as well.

4‐terf‐butyl catechol was more effective than any other compound tested, including quintozene, and at suitable rates (25 or 12‐5 μg/g) did not decrease yield.

Other hydroxybenzenes and some 1,4‐naphthaquinones (including dichlone) and anthraquinones were almost ineffective.
Control of seed‐borne Fusarium nivale on wheat and barley by organomercury seed treatment
Authors: BATEMAN G. L.
Published: February 2008

The effectiveness of organomercury seed treatments in controlling seedling disease caused by seed‐borne Fusarium nivale was studied in pot experiments. Ethyl mercuric chloride was more effective than phenyl mercuric acetate (PMA) on barley. Storing treated seed for 6 wk before sowing improved the performance of both compounds. PMA was less effective in controlling F. nivale than Septoria nodorum on wheat, although F. nivale was only slightly less sensitive to PMA in agar plate tests. Control of JF. nivale was usually more effective on wheat than on barley for the two seed samples used. PMA rates two to four times those applied commercially did not completely eliminate infection. Rates of PMA less than about 0–125μg Hg/seed did not significantly control F. nivale on wheat or barley.
The ultrastructure of the outer tissues of cold‐stored apple fruits of high and low calcium content in relation to cell breakdown
Authors: FULLER MORWENNA M.
Published: February 2008

The outer tissues of Cox's Orange Pippin apples from samples with initially high and low calcium content were examined in the electron microscope following 53, 81 or 99 days in air storage at 3 oC. Cell ultrastructure within tissues of both high and low calcium apples was comparatively normal in fruit stored for the shorter period but low calcium fruit showed symptoms of membrane breakdown after 81 days. The greatest structural differences were observed after storage for 99 days when low calcium fruits contained more cells exhibiting breakdown of membranes and organelles than high calcium apples and also showed more severe symptoms of cell wall breakdown.
A technique for osmotically pre‐treating and germinating quantities of small seeds
Authors: DARBY R. J. , SALTER P. J.
Published: February 2008

A single piece of equipment is described which will allow commercial quantities of celery seed to be osmotically treated and/or germinated prior to fluid drilling.
Gibberellin and growth inhibitor changes in potato tuber buds in response to cold treatment
Authors: THOMAS T. H. , WURR D. C. E.
Published: February 2008

Eye plugs removed from tubers of four potato cultivars previously stored for 14 days at 2 °C and then left at 15 °C for a further 14 days contained more gibberellin and less growth inhibitor activity than those kept at 15 °C for 28 days. Two gibberellin‐active peaks were obtained when the extracts from cold‐treated tubers were separated on paper chromatograms with an isopropanol/ammonia/water solvent. The main inhibitor did not appear to be abscisic acid.
A wet‐sieving and flotation technique for the detection of resting sporangia of Synchytrium endobioticum in soil
Authors: PRATT MARGARET A.
Published: February 2008

A wet‐sieving technique is described for the extraction of resting sporangia of Synchytrium endobioticum from soil. Fractions between 71 and 25 μm. were held on sieves of aperture size 40 and 25 μm. Resting sporangia in these fractions were then separated from soil particles of similar size by chloroform flotation and centrifugation. The viability of the sporangia was assessed microscopically by viewing them by transmitted light.
The effect of temperature on strains of soft fruit spoilage fungi
Authors: DENNIS C. , COHEN E.
Published: February 2008

Strains of Botrytis cinerea and Mucor mucedo germinated and grew over the range 0.25°C. There were differences in germination rates and growth rates between strains of B. cinerea at any given temperature. Five of the benomyl‐resistant strains germinated and grew more slowly than any of the other benomyl‐resistant or benomyl‐sensitive strains of B. cinerea tested. Strains of Rhizopus stolonifer and R. sexualis germinated and grew between 5 and 25°C, and although some spores germinated at 2°C, subsequent growth of the germ tubes and growth from a mycelial inoculum did not occur. Neither species germinated or grew at o°C.

The effect of temperature on mycelial growth in vitro was consistent with the ability of the strains of the four species to infect strawberry fruits.
A single immunodiffusion drop test for the detection of lily symptomless virus
Authors: SLOGTEREN D. H. M. VAN
Published: February 2008

A single immunodiffusion drop test has been developed for the serological detection of lily symptomless virus in lilies. The presence of virus is demonstrated by intra‐gel precipitation in drops of an antiserum‐agar mixture which are contiguous with droplets of pyrrolidine‐treated leaf extracts covered with paraffin oil.

Single immunodiffusion drop tests require c. twelve times less antiserum than radial diffusion plate tests. The results of virus detection by this technique agree closely with those obtained by electron‐microscopical screening of negatively stained leaf extracts.
Fumigation with D‐D or Telone on soils prone to Docking disorder
Authors: MAUGHAN G. L. , DUNNING R. A. , ATKINSON KAY M. , JOHN MARGARET E.
Published: February 2008

The liquid fumigants dichloropropane‐dichloropropene mixture (D‐D) or dichloropropenes (Telone), when applied at 64 or 43 1/ha respectively in bands 15–20 cm below the lines of the crop rows before sugar beet was sown on land with a history of Docking disorder, often led to appreciable increases in sugar yield; this occurred even in seasons that were not conducive to the development of the disorder, particularly in East Anglia. Treatment often increased yield economically but the crop response could not be forecast at the time of fumigant application. The effect of fumigation in Lincolnshire and Yorkshire was more variable, sometimes being favourable and occasionally unfavourable, whilst the same treatment in Nottinghamshire seldom increased and sometimes decreased the yield of sugar.

Yields of barley grain in the years following the sugar‐beet crops in Yorkshire and Nottinghamshire were not increased by the band application of nematicide but were sometimes increased by it when applied overall.
Glandular hairs on Solatium polyadenium lessen damage by the Colorado beetle
Authors: GIBSON R. W.
Published: February 2008

Four‐lobed glandular hairs on the leaves and stems of the potato species Solanum polyadenium provide a form of resistance to larvae of the Colorado beetle Leptinotarsa decemlineata. On contact, a sticky material was discharged from these hairs trapping a few larvae and encasing the feet of others. Larvae with encased feet fell from the plants to die.
Extractable protein from the by‐product vegetation of some cole and root crops
Authors: TEKALE N. S. , JOSHI R. N.
Published: February 2008

The amount of extractable protein from leaves taken at the time of harvest of the edible part was determined for brassicas, beet root, turnip and radish. These leaves yielded much more dry matter and total nitrogen per ha than did the edible material. With only one pulping, from 35 to 59% of protein nitrogen could be extracted and the yields of extractable protein from the leaves ranged from 76 to 170 kg/ha. It would be advantageous to obtain protein from these leaves which otherwise are discarded.
Nutrient status of apple blossoms and their susceptibility to fire blight
Authors: ALDWINCKLE H. S. , BEER S. V.
Published: February 2008

Blossoms of Malus sylvestris cv. Golden Delicious trees on M. 7 root‐stocks, maintained under various N‐P‐K nutrient regimes in sand culture in the glasshouse, were inoculated with Erwinia amyhvora, the incitant of fire blight. Widest differences between nutrient treatments occurred when about ten E. amylovora cells were applied to each blossom. Trees with high N and high P contents had most infections. Trees with lower P content were less susceptible. Of trees with low P content, those with higher K appeared more susceptible.
Inheritance of pathogenicity and cultural characters in Ceratocystis ulmi: hybridization of aggressive and non‐aggressive strains
Authors: BRASIER C. M. , GIBBS J. N.
Published: February 2008

When British isolates of Ceratocystis ulmi were surveyed for compatibility type, both A‐ and B‐types were found in the non‐aggressive strain, but only the B‐type in the aggressive strain. Single ascospore progeny from crosses between compatible aggressive and non‐aggressive isolates showed a near‐normal growth rate distribution, with a mean lying between the parents. Many grew either faster than the aggressive or slower than the non‐aggressive parent. The progeny were highly variable in culture morphology and could not be classified in terms of the parental types. When inoculated into English elm they showed a marked skewness towards low pathogenicity. None approached the aggressive strain in pathogenicity. It is concluded that the above characters are under polygenic control, and that the aggressive strain could not arise from the non‐aggressive by a simple mutation. The results suggest that the two strains may be reproductively isolated.
Barley yellow dwarf virus in aphids caught in suction traps, 1969‐73
Authors: PLUMB R. T.
Published: February 2008

Suction traps operating at low level (1 5 m) were used to catch live alate Rhopalosiphum padi, Macrosiphum (Sitobion) avenae and Metopolophium dirhodum which were tested for transmission of barley yellow dwarf virus (BYDV). The first species caught and infective was R. padi, followed by M. (S.) avenae infective some 2–3 wk later and M. dirhodum 3–4 wk later still. Never more than 11‐5% of the annual catch of any species transmitted BYDV and the proportion fluctuated from week to week and between seasons in different years.

The relative abundance of infective vectors of ths three species varied; annual numbers of infective M. (S.) avenae and M. dirhodum varied inversely with infective R. padi, the latter also usually transmitted severer virus. The results of the infectivity tests have been compared with the catches of these aphids by the Rothamsted Insect Survey and show that numbers of alate aphids do not necessarily indicate the likely incidence of BYDV.
The influence of soil‐applied fungicides and previous cropping on the development of violet root rot of sugar beet
Authors: BYFORD W. J. , PRINCE J.
Published: February 2008

The proportion of sugar‐beet roots infected by Helicobasidium purpureum increased most rapidly in September and October. Violet root rot was not controlled by fungicides applied at drilling or in July. Heavily infected roots yielded 31% less sugar than healthy or lightly infected roots. Sugar beet following infected carrots lifted or ploughed in during July had no more violet root rot than when following barley or fallow, but the beet crop became heavily infected when it followed carrots left in the ground until December, whether they were then lifted or ploughed in. Eight varieties of sno‐ar beet did nnt differ in siiscenrihilitv to violet root rot.
Experiments with fungicides to control Aphanomyces cochlioides in sugar beet
Authors: BYFORD W. J. , PRINCE J.
Published: February 2008

Aphanomyces cochlioides attacking sugar‐beet seedlings was controlled by fenaminosulf applied as seed treatment or to the seed furrow at sowing. In the absence of blackleg caused by A. cochlioides, fenaminosulf seed treatment at 0–75 % (of seed weight) and soil applications decreased seedling emergence, and soil applications of more than 2‐2 kg a.i./ha significantly depressed sugar yield. Controlling moderate attacks of seedling blackleg caused by A. cochlioides did not increase yield. Dichlone, benomyl and maneb applied as seed or soil treatments, captafol seed treatment, and quintozene and thiram soil treatments did not control A. cochlioides.
Seed treatments to lengthen the sugar‐beet growing period
Authors: LONGDEN P. C.
Published: February 2008

Although washing, thiram soaking, advancing and combinations of these treatments increased the rate of emergence of sugar‐beet seed, some combinations, particularly those involving ethyl mercuric phosphate steeps and advancing, interacted negatively and greatly reduced total seedling emergence and shoot weight without affecting the rate of emergence. This may have happened because each treatment is, to some extent, fulfilling the function of other treatments and if together the treatments go too far, mercury enters the embryo and damages it. Therefore, proposed seed treatments need careful testing in combination with other existing treatments.
The influence of temperature on weight loss from stored onion bulbs due to desiccation, respiration and sprouting
Authors: WARD C. M.
Published: February 2008

When onion bulbs were stored for 9 months at 2, 7.5, 15 or 25 °C and 70% r.h., the losses due to desiccation increased with temperature but less than 20 % was due to respiration at any of the storage temperatures. Respiration rates of onion bulbs transferred from 2 to 25 °C were higher from February onwards than those of bulbs stored continuously at 25 °C. Conversely, bulbs transferred from 25 to 2 °C respired less from February onwards than those kept at 2 °C. Sprouting, at the final assessment in June, was highest at 15 and 7.5 °C and lowest at 2 °C. Total weight loss was above 45 % in all the storage treatments except at 2 °C (12%). Storage at 7.5 °C is suitable until March but long‐term storage until June requires low temperatures.
Pathogenicity of benomyl‐tolerant variants of Verticillium dahliae to strawberry, cv. Cambridge Vigour
Authors: TALBOYS P. W. , DAVIES M. K.
Published: February 2008

Plants of cv. Cambridge Vigour were inoculated either with a benomyl‐sensitive isolate of Verticillium dahliae or with one of two variants selected from it in vitro; these variants, Ri/8 and Ri/ii, were tolerant of benomyl at concentrations of 5 and 10 ppm respectively in the culture medium.

The parent isolate and Ri/8 caused only mild wilt symptoms, but Ri/n was strongly pathogenic.

A single treatment with benomyl (0–04 g/plant, in 100 ml water), applied as a soil drench o, 14, 29 or 57 days after inoculation, tended to reduce the mild symptoms caused by the parent isolate; the treatments had no apparent effect on Ri/8, but they slightly increased the severity of the wilt caused by Ri/n, especially after the earlier applications.
Observations on Litomastix aretas, an encyrtid parasite of the strawberry tortrix moth
Authors: ALFORD D. V.
Published: February 2008

Observations on strawberry crops in East Anglia from 1969 to 1975 have shown that Litomastix aretas is an important parasite of the strawberry tortrix moth, Acleris comariana. Parasitism ranged from 63 to 758 % and was particularly high in the Wisbech area of Cambridgeshire and Norfolk. On average, more females (range, 11–65) than males (range, 12–55) were reared per host, and approximately twice as many hosts were infested with female rather than male parasites. Natural mortality of L. aretas brood appeared to be low.
Zearalenone‐producing species of Fusarium on barley seed
Authors: HACKING A. , ROSSER W. R. , DERVISH M. T.
Published: February 2008

Isolates of Fusarium were obtained from samples of barley grain at harvest in 1971, 1973 and 1974. The ability of these isolates to produce the myco‐toxin zearalenone was examined, the grain also being tested for its presence in 1974. The most common isolate was F. culmorum, 60% of which in 1974 produced zearalenone. Other species isolated which produced this myco‐toxin were F. monilijorme, F. graminearum, F. avenaceum, F. nivale and F. sambucinum var coeruleum, the last three species have not previously been recorded as producing zearalenone.
Occurrence of strains of Colletotrichum coffeanutn resistant to methyl benzimidazol‐2‐ylcarbamate (carbendazim) and chemically‐similar compounds
Authors: OKIOGA D. M.
Published: February 2008

Certain strains of Colletotrichum coffeanum (the causal fungus of coffee berry disease) which developed in coffee plots sprayed in 1973 and 1974 with carbendazim formulations Bavistin and Derosal and with Folicidin (cypendazol) were resistant to these fungicides and also to Benlate (benomyl). Strains resistant to cypendazol developed in plots sprayed with benomyl but these were not resistant to benomyl itself. There were also indications of strains resistant to carbendazim amongst the population of saprophytic species (C. acutatum and C. gloeosporoides) colonizing coffee bark.

Resistant isolates of C. coffeanum in culture produced colour variants by sectoring more frequently than normal isolates. These sectors were equally pathogenic to coffee berries and their growth was slightly enhanced on media containing carbendazim.
Laboratory studies of non‐preference resistance to cabbage root fly in radish
Authors: ELLIS P. R. , HARDMAN J. A. , CRISP P. , JOHNSON A. G.
Published: February 2008

First generation progenies selected from four radish cultivars on the basis of their attractiveness to ovipositing cabbage root fly in the laboratory were compared in the same environment. There were significant differences between and within cultivars in their attractiveness for egg‐laying, indicating that genetic variation existed and that selection had effected a heritable change. However, inconsistencies between experiments indicated that other, as yet unquantified, factors were compounded with the heritable component of non‐preference resistance. There was no evidence to suggest that seed weight, leaf area, or hypocotyl size affected the attractiveness of the plants.

The effects of eliminating any choice between selections was investigated in the laboratory by exposing 4‐wk‐old ‘high’ and ‘low’ preference selections of cv. Asmer Tip Top to the pest for 6 days. Three times as many eggs were laid on ‘high’ than on ‘low’ preference selections, indicating that the heritable non‐preference resistance to cabbage root fly in Asmer Tip Top was maintained when no choice was offered to the flies, an essential requirement for ‘resistant’ cultivars in the field.
Field trials of fungicides to control red core of strawberries
Authors: UPSTONE M. E.
Published: February 2008

In field trials in Kent soil drenches of captafol, drazoxolon, etridiazol and prothiocarb were applied to strawberries planted in red‐core‐infested soil. A single post‐planting drench of captafol (0–20%) and prothiocarb (0–28%) controlled red core and captafol also reduced non‐specific root rotting. Etridiazol (0–20%) was phytotoxic and caused severe root rotting. The addition of lime increasing the soil to pH 7‐5 had no effect on the incidence of red core infection or non‐specific root rotting.
Nicotiana velutina mosaic virus: purification, properties and affinities with other rod‐shaped viruses
Authors: RANDLES J. W. , HARRISON B. D. , ROBERTS I. M.
Published: February 2008

Nicotiana velutina mosaic virus (NVMV), found in Australia, was transmitted by inoculation of sap to twenty species in the Solanaceae and Chenopodiaceae, and to Gomphrena globosa; its host range closely resembles that of potato mop‐top virus (PMTV). Infectivity was abolished when sap was kept at room temperature between 1 and 4 days, or when heated for 10 min between 60 and 70 °C. NVMV was frequently transmitted through the seed of four Nicotiana spp.

NVMV and PMTV were purified by a method that involved redissolving virus particles sedimented by low speed centrifugation of leaf extracts, followed by sedimentation through sucrose cushions. NVMV preparations contain rod‐shaped particles about 18 nm wide and with a large range of lengths, the commonest being 125–150 nm. The particles have a helical structure with a pitch of 2–9 nm, break easily, and contain a single protein of apparent mol. wt. 21|400, slightly larger than that of PMTV (19 800). In serological tests assessed by electron microscopy, no relationship was detected between NVMV and PMTV, or barley stripe mosaic, beet necrotic yellow vein, soil‐borne wheat mosaic, tobacco mosaic or tobacco rattle viruses. However, antiserum to soil‐borne wheat mosaic virus reacted quite strongly with PMTV and weakly with tobacco mosaic virus. NVMV is considered to be a distinct member of the tobamovirus group; its frequent transmission through seed may be an adaptation to the arid environment where it was found. Its cryptogram is */*:*/*:E/E:S/*.
Some enzyme changes in chicory (Cichorium intybus) during forcing
Authors: PHILLIPS D. E. , RUTHERFORD P. P.
Published: February 2008

Changes in hydrolase (E.C. 3.2.1.7) and invertase (E.C. 3.2.1.26) were measured in various parts of chicory during forcing. Little change in invertase and hydrolase activity occurred in the roots but both hydrolase and invertase increased markedly in the chicon. The duration of cold storage prior to forcing was found to have little effect on either enzyme in the root or on hydrolase in the chicon. The increase of invertase activity in the chicon and the chicon yield on forcing were both affected by the duration of cold stage.
Competition by, and chemical control of, natural weed populations in spring‐sown field beans (Vicia faba)
Authors: GLASGOW J. L. , DICKS J. W. , HODGSON D. R.
Published: February 2008

A field experiment was done in 1974 to determine the effect of the presence of weeds for different periods on the yield of field beans (Vicia faba cv. Maris Bead). A critical period of weed competition of 2 wk duration occurred from 3 to 5 wk after 50% crop emergence. When weeds were not controlled, seed yield was reduced by 46%, from 4–6 to 2–5 t/ha.

In another experiment, in 1975, there was no evidence of a critical period. Seed yield was reduced by 48%, from 2–9 to 1–5 t/ha, when weeds were not controlled. Pre‐emergence applications of simazine and of dimefuron, a new soil‐residual herbicide, effectively controlled weeds and bean seed yields were similar to those of the regularly hand‐weeded control. Dinoseb‐acetate and early, but not late, post‐emergence applications of dimefuron controlled weeds satisfactorily. Dimefuron is potentially useful in spring‐sown field beans because it can be applied pre‐ or early post‐emergence without damaging the crop.
The effect of temperature on the infection of onions by Sclerotium cepivorum
Authors: Entwistle A. R. , Munasinghe H. L.
Published: February 2008

Studies on Sclerotium cepivorum infection of salad onions in artificially infested soil showed that under field conditions infection was greatest in late spring and summer and declined to a low level in the late autumn and winter months. Change of infection levels was found to be correlated with the effect of soil temperature in the field on the germination of sclerotia. This was substantiated in laboratory studies which demonstrated that sclerotium germination, mycelial growth and seedling infection were all markedly influenced by temperature.
Seed transmission of broad bean stain virus and Echtes Ackerbohnenmosaik‐Virus in field beans (Viciafaba)
Authors: COCKBAIN A. J. , BOWEN ROBERTA , VORRA‐URAI S.
Published: February 2008

When grown in a glasshouse during spring or autumn field bean (Vicia faba minor) seedlings infected with seed‐borne broad bean stain virus (BBSV) or Echtes Ackerbohnenmosaik‐Virus (EAMV) usually showed symptoms on some leaves within 4 wk of emergence. Symptoms caused by each virus were indistinguishable. The viruses were transmitted as often through unblemished seeds as through seeds with necrotic patches or stains on the seed coat, and sometimes as often through large as through small seeds. Soaking seeds for 24 h in solutions of 8‐azaguanine or polyacrylic acid did not decrease transmission. Both viruses were detected in nearly mature seeds by inoculation to Phaseolus vulgaris but neither virus was detected in fully ripened seeds by inoculation or serological tests.

The percentage of seeds from field plots that produced infected seedlings when sown in a glasshouse was closely related to the percentage of parent plants that showed symptoms of BBSV and/or EAMV at the end of flowering. The relationship seemed similar in different cultivars. On average EAMV was transmitted through more seeds than BBSV, probably because more parent plants were infected with EAMV. Inspection of seed crops for symptoms of BBSV and EAMV at the seedling stage and again at the end of flowering is probably the most practicable way of identifying progeny seed lots with little or no infection.
Control of potato cyst‐nematodes, Globodera rostochiensis and G. pallida, in different soils by small amounts of oxamyl or aldicarb
Authors: MOSS S. R. , CRUMP D. , WHITEHEAD A. G.
Published: February 2008

In eleven field trials on peaty, sandy or silt loam soils, aldicarb or oxamyl, incorporated in the soil to 15 cm deep before susceptible potatoes were planted, controlled potato cyst‐nematodes (Globodera rostochiensis (Woll.) Mulvey & Stone, 1976 and G. pallida (Stone) Mulvey & Stone, 1976) better at 5–6 kg than at 3–4 or 2‐2 kg a.i./ha. Incorporated in the soil to 7‐5 cm deep 5–6 kg/ha of aldicarb or oxamyl controlled the nematodes less effectively at some sites. At 3–4 kg a.i./ha there was no difference in nematode control between the two incorporation depths.
Studies on plant growth‐regulating substances
Authors: WILCOX E. J. , WAIN R. L.
Published: February 2008

A report of an alkoxypurine showing cytokinin activity is presented. This compound, 6‐benzyloxypurine, has been tested in three tests and in two of these, a wheat leaf senescence and a young coleoptile test, the compound is as active as benzyladenine or kinetin. Although it is much less effective on molar basis than these compounds in a tobacco tissue culture test, it is as active at its optimum concentration. In addition to promoting cell division the presence of 6‐benzyloxypurine leads to morphological differentiation within the tobacco stem tissue, and whole plants have been grown without altering the nutrient medium.
Studies on plant growth‐regulating substances XLV. Phenoxyacetaldehyde derivatives
Authors: ALONSO C. RIUS , WAIN R. L.
Published: February 2008

Plant growth‐regulating activity in a series of phenoxyacetaldehyde derivatives has been assessed in a number of tests. Metabolic experiments using labelled 14C compounds are discussed.
Heat inactivation of cucumber mosaic virus in cultured tissues of Stellaria media
Authors: WALKEY D. G. A. , COOPER JANICE
Published: February 2008

In vivo heat inactivation of cucumber mosaic virus (CMV) was studied in a low‐temperature‐tolerant species, Stellaria media. Infectivity remained high in infected 5. media cultures grown at 25 °C or less, but could not be detected in cultures incubated at 32 °C for 28 days. When infected tissues were grown at 12–32 °C for 24 days, virus was still detectable at a low level in cultures incubated at 30 °C. The highest level of infectivity was in cultures at 12 °C.
Investigations of carnation viruses
Authors: HOLLINGS M. , STONE OLWEN M. , ATKEY P. T. , BARTON R. J.
Published: February 2008

Carnation vein mottle virus (CarVMV) is rare in glasshouse carnations in Britain, although locally common in Dianthus barbatus in private gardens. In Sim carnations free from other viruses, CarVMV caused slight diffuse chlorotic mottling in the younger leaves, decreased flower yield by c. 22%, and caused flower breaking in cvs William Sim and Dusty. In non‐Sim cultivars Pink Shibiuya, Orchid Beauty and Vesta, leaf symptoms and flower breaking were more pronounced. In mixed infections with carnation mottle virus, symptoms were much more severe.

CarVMV was not eliminated from carnation or D. barbatus plants grown for 4 wk at 37oC, and only rarely from cuttings then taken from them, but it was readily eliminated by meristem‐tip culture.

Myzus persicae adults or nymphs acquired and transmitted the virus within a total time of 4 min, and remained infective for 30–60 min if feeding, or for 75 min if starved. The carnation aphid, M. persicae f. dianthi, transmitted the virus much less efficiently. The virus was not transmitted by dodder (Cuscuta campestris), or through seed of D. barbatus or Chenopodium quinoa. The maximum infective dilution in sap of D. barbatus, carnation and C. quinoa ranged from 10‐2 to 10‐5. The virus withstood 10 min at 60 but not 65oC, up to 9 days at c. 18oC or 3–4 wk at c. 2oC.

CarVMV infected twenty‐two of 107 plant species in six of thirty‐seven families; suscepts were confined to the Chenopodiaceae, Caryophyllaceae and closely allied families. C. quinoa was the best local lesion assay host. Seedling clones of D. barbatus, selected as resistant to carnation mottle virus, proved the best indicator and propagation species.

Up to 50 mg virus/kg tissue were obtained by butanol clarification followed by differential and density gradient centrifugation. The preparations contained a single sedimenting component, s20w= 144S, and had flexuous filamentous particles, c. 790 times 12 run; the particles contained a single polypeptide, mol. wt 34800, and 5% of a single‐stranded ribonucleic acid (RNA) with nucleotide base ratios of G21: A25: C25: U29.

Serologically CarVMV was related distantly to turnip mosaic (cabbage black ring strain), pea mosaic, watermelon mosaic (Strain 2) and bean yellow mosaic viruses, more closely to pepper veinal mottle virus, but unrelated to twelve other potyviruses.

CarVMV is not at present a danger to carnation crops in Britain, but the recent trend of sending carnation plants to overwinter outdoors in warmer countries involves potential risks of more rapid spread by effective vector races of M. persicae.
The elimination of ryegrass mosaic virus from Lolium multiflorum by meristem tip culture
Authors: DALE PHILIP J.
Published: February 2008

Meristem tips were cultured from Lolium multiflorum plants infected with ryegrass mosaic virus (RMV). Meristem tips within the size range O'2‐fi mm long were cultured on media with or without2,4‐D at 1 mg/1. The plants that regenerated in culture showed no symptoms over a 10 month period and no RMV particles were observed by electron microscopy. It was concluded that RMV had been eliminated. The method should prove useful in eliminating the virus from desirable genotypes used as parent material for seed production.
Genetic adaptation for vernalization requirement in Nepalese wheat and barley
Authors: RAO A. R. , WITCOMBE J. R.
Published: February 2008

A large number of accessions of covered and naked barley from eastern Nepal were grown without vernalization, and it was found that naked barley accessions were predominantly spring varieties while covered barley accessions were predominantly winter varieties. Seven accessions were subjected to a range of vernalization periods. Four naked varieties were spring varieties, although one showed some response to vernalization, but the three covered barleys were winter varieties.

Although the majority of naked barleys are spring forms, they are winter sown at high altitudes and this does not conform to the distribution of naked barley described by Takahashi (1955).

Wheat accessions which came from villages situated at high altitudes tended to have higher vernalization requirements than those which came from lower altitudes. This was taken to indicate local adaptation and a low movement of seeds (gene‐flow) between villages. The relationship between vernalization requirement and altitude was not found in barley.

Marked but contrasting regional patterns for vernalization requirement occurred in the wheat and covered barley. It was concluded that gene‐flow was greater within regions than between them. This regional isolation together with environmental heterogeneity are major diversity promoting mechanisms.
A laboratory method of screening fungicides for systemic activity against Bretnia lactucae
Authors: CRUTE I. R. , WOLFMAN S. A. , DAVIS A. A.
Published: February 2008

A soil‐free in vivo laboratory technique is described for the detection of systemic anti‐fungal activity against Bretnia lactucae, a representative of the Peronosporales. This system is not subject to some of the complications encountered with in vitro and glasshouse experiments. Two new compounds (prothiocarb and LS 73–1038 (Nina)) were found to have high systemic activity against B. lactucae using this technique and it was confirmed that zineb also has some systemic effect. Streptomycin sulphate and DPX‐3217 showed some activity but were phytotoxic. Dowco 269 was phytotoxic and showed no activity against B. lactucae. None of these chemicals showed any significant vapour activity.
Carbohydrate metabolism and respiration after harvest of the cultivated mushroom, Agaricus bisporus
Authors: Hammond J. B. W. , Nichols R.
Published: February 2008

The carbohydrate metabolism of the mushroom and the respiration of the sporophore after harvest at different stages of growth have been studied. Mannitol and trehalose were found to be the major soluble carbohydrates in the sporophore and mycelium respectively. Mannitol and trehalose levels fall during sporophore storage, and feeding experiments with14C‐labelled sugars indicate that they are metabolised. The results were discussed in relation to the post‐harvest development of the sporophore.