bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yellow‐net virus of sugar beet
Authors: WATSON MARION 
Published: February 2008

SUMMARYA virus found in sugar beet in England causes similar symptoms to the Californian virus called yellow‐net (YNV) by Sylvester (1948). It persists in the feeding vectors for at least 7 days. The minimum feeding time needed for aphids to acquire virus from infected leaves was 6 hr. and the minimum needed to acquire and transmit was 12 hr., but ability to transmit was greatly increased by increasing feeding time up to 2 days on infected and 24 hr. on healthy plants. These properties agree with those of the American virus. Experiments using different aphid numbers feeding for constant times suggested that susceptibility of sugar beet to infection varies and this may account for some of the delay in infecting healthy plants.YNV was accompanied in beet by a second virus, yellow‐net mild yellows (YNMYV). YNMYV did not infect Nicotiana clevelandi Gray or N. bidlovia, which are susceptible to YNV, but from which YNV could not be recovered by aphids. Neither virus is transmissible by inoculation with sap from infected plants. It is suggested that YNMYV is a ‘carrier’ virus, without which YNV cannot be transmitted. Possibly it combines with YNV to form an aphid‐transmissible combination, but it may merely help YNV to invade sugar beet.YNMYV causes similar symptoms and has similar properties and host range to other viruses that cause mild yellowing diseases of sugar beet, including avirulent strains of beet yellows virus (BYV), Irish mild yellows (IMSV) and ‘41 yellows’ (41 YV). No such virus has been reported associated with YNV in America, and possibly it is peculiar to the British isolate.
Studies on plant cuticle
Authors: BAKER E. A. , BATT R. F. , MARTIN J. T. 
Published: February 2008

SUMMARYWork is described on the isolation of wax‐free cuticular membranes by enzymic and chemical treatment, and on the products of hydrolysis of the membranes. Fatty acids in the approximate range C12 to C12 are associated with hydroxylated fatty acids in the apple cutin complex. Methods for the determination of cutin in cuticular membranes are discussed.
Studies on plant cuticle
Authors: SILVA FERNANDES A. M. S. 
Published: February 2008

SUMMARYA standardized test of permeability to aqueous solutions is described. No diffusion of copper from solutions of copper acetate or sulphate or of mercury from a solution of phenylmercuric acetate occurs through stomata‐free leaf membranes containing 0.1 mg./cm.2 or more of cutin, but diffusion occurs through membranes containing stomata. Wax is an important barrier to the penetration of mercury through cuticular discs of apple fruits, but the effect of the wax depends upon its composition. Sorption of mercury by the discs is increased by an increase in the percentage content of esters in the wax, by a rise in temperature or in the presence of wetter.
Greenhouse evaluation of chemicals for control of powdery mildews
Authors: KIRBY A. H. M. , FRICK E. L. , GRATWICK M. 
Published: February 2008

SUMMARY2,6‐Dinitro‐4‐s‐alkylphenols were found to protect apple foliage against powdery mildew more effectively than isomeric 2,4‐dinitro‐6‐s‐alkylphenols; regression lines for four para‐alkyl compounds were of similar slope but were much steeper than those for two ortho‐alkyl compounds (including dinocap phenol). The ED50 and ED95 values of the most active compound studied, 2,6‐dinitro‐4‐(I‐ethylhexyl)phenol, were in the ratios to those of dinocap phenol of 1:13 and 1:125, respectively, and the protective action of this compound was greater than the curative, especially at the higher ED values. Protection of barley seedlings against powdery mildew was also greater by I‐ethyl‐ or I‐propyl‐alkyl compounds than by I‐methylalkyl or n‐alkyl isomers.For phytotoxic and acaricidal actions, the ortho‐alkyl isomers are more effective than para‐alkyl. Nevertheless, the acaricidal activity of dinocap phenol is exceeded by that of the isomeric 2,4‐dinitro‐6‐(I‐ethylhexyl) phenol.The control of these powdery mildew diseases given by commercial products, supposed to be based on dinocap, cannot be accounted for by the activity shown for dinocap phenol. It can, however, be accounted for by the activities of 2,6‐dinitro‐4‐(I‐ethylhexyl)‐ and ‐(I‐propylpentyl)‐phenols, now known to be present in commercial products in larger amounts than dinocap phenol itself. The phytotoxic and acaricidal actions of such products, however, are mainly due to the ortho‐octyldinitrophenols present; in view of the small proportion that is dinocap phenol, the acaricidal activity is likely to be due almost entirely to the other ortho‐octyl isomers.It is suggested that the common name dinocap be retained for the mixture of dinitrooctylphenols now known to be present in commercial products, and that the two main groups be differentiated as 2,4‐dinocap and 2,6‐dinocap, respectively. The advantages for powdery mildew control of a product based on 2,6‐dinocap are discussed.
The redistribution of fungicides on plants
Authors: HISLOP E. C. 
Published: February 2008

SUMMARYIn field trials amounts of soluble copper were found in rain water collected form apple trees sprayed with copper fungicides, but the copper was relatively non‐toxic. The solution of copper did not appear to be correlated with the number of micro‐organisms on the leaves. Rain washings phate. Some evidence for beneficial redistribution by solution is presented.By contrast, in a greenhouse experiment small amounts of copper were washed by very light rain from coffee seedlings sprayed with copper oxychloride and Bordeaux mixture. The soluble fraction of these washings was generally small and did not vary with ageing of the deposit up to 32 days. There was no changes in the toxicity of the washings from deposits aged up to 32 days.Under static laboratory conditions more copper was usually solubilized form standardized deposits of Bordeaux mixture, copper oxychloride, and cuprous oxide on leaves than on glass. The amount of copper solubilized varied with the leaf used, the nature of the deposit, the presence of adjuvants and the length of time water was left in contact with the deposit. Deposits of Bordeaux mixture and Bordeaux mixture was equally toxic on a leaf surface which caused solution and one which did not. Soluble copper extracts leaves were less toxic than equivalent quantities of copper supplied as copper sulphate.
Studies on plant cuticle
Authors: BAKER E. A. , MARTIN J. T. 
Published: February 2008

SUMMARYThe cuticles of plants of the Saxifragaceae, Rosaceae and Leguminosae are compared by chemical methods. Wide differences occur in the deposits of surface wax and cuticular membrane even within species of one genus. The relative proportions of four hydroxy‐fatty acids in the cutin acids of plants of the families are assessed and the value of cutin analysis as a taxonomic criterion is discussed.
Phenylazothioformamide, the active principle in the fungitoxic action of 1‐phenylthiosemicarbazide
Authors: SIJPESTEIJN A. KAARS , PLUIJGERS C. W. , VERLOOP A. , TEMPEL A. 
Published: February 2008

SUMMARYLaboratory trials using Aspergillus niger indicate that the antifungal effect of 1‐phenylthiosemicarbazide is based upon its conversion into an oxidation product, phenylazothioformamide. This conversion takes place much more slowly at pH 5 than at pH 7 and is completely prevented by the reducing agent sodium thioglycollate. Both acidity of the medium and the presence of reducing agents lower the fungitoxicity of 1‐phenylthiosemicarbazide.
Parsnip mosaic virus, a new member of the potato virus Y group
Authors: MURANT A. F. , MUNTHE T. , GOOLD R. A. 
Published: February 2008

SUMMARYParsnip mosaic virus (PMV) occurs commonly in parsnip in Britain and is transmitted after acquisition access periods of 2–5 min by the aphids Cavariella aegopodii, C. theobaldi and Myzus persicae. It was transmitted by manual inoculation of sap, infecting parsnip, chervil, coriander and carrot plants systemically, and causing local lesions without subsequent systemic infection in eight Chenopodium spp., Spinacia oleracea, Gomphrena globosa, and Toreniafournieri. It lost infectivity in Chenopodium quinoa sap after dilution to 10‐3–10‐4, heating for 10 min at 55–58 °C, or storage at room temperature for 7–10 days. Preparations partially purified by n‐butanol or chloroform clarification, followed by acid precipitation and/or chromatography on columns of 2% agarose beads, contained filamentous particles, many of which were aggregated or fragmented. Preparations made with chloroform and without acid precipitation contained unaggregated particles of 755 nm normal length, with a sedimentation coefficient of 149 S. PMV did not react with antisera to any of fourteen other viruses with filamentous particles. The present cryptogram for PMV is */*: */*:E/E:S/Ap.
Transmission of rayado fino virus of maize (Zea mays) by Dalbulus tnaidis
Authors: GÁMEZ RODRIGO 
Published: February 2008

SUMMARYRayado fino virus (RFV) of maize (Zea mays) was transmitted by the leaf‐hopper Dalbulus maidis in a manner characteristic of viruses that multiply in their insect vectors. Individual insects fed on infected plants transmitted the virus after incubation periods of 8–22 days; males had shorter incubation periods than females but died sooner. Insects retained infectivity for 1–20 days. Transmission by most insects was intermittent. Inoculativity by D. maidis decreased with time, but the virus was recovered from insects that had lost their ability to transmit. Extracts of plants infected with RFV and viruliferous insects were injected into healthy insects, which became viruli‐ferous. Infectivity of the extracts was not affected by tetracycline hydrochloride (Achromycin). D. maidis was able to transmit simultaneously RFV and the corn stunt agent. Other than maize, Teosinte (Euchlaena mexicana) was the only plant susceptible to the virus, among a number of species of Gramineae tested.
Quantitative relationships between infection by the hop downy mildew pathogen, Pseudoperonospora hutnuli, and weather and inoculum factors
Authors: ROYLE D. J. 
Published: February 2008

SUMMARYExperiments are described in which successive groups of healthy, susceptible, potted hop‐plants were exposed, each 24 h, to the weather and to sources of Pseudoperonospora kumuli inoculum in an unsprayed hop garden for 48 h periods during May and June in 1969, 1970 and 1971. The infection which arose after standardized incubation in isolation was measured and then related, both by inspection and by multiple regression analysis, to the conditions during exposure.Severe infection could be associated with certain sequences of events in which rain contributed substantially to plant wetness; relatively light or no infection developed when dew provided the wetness of a period. Infection was markedly correlated with the occurrence of infection periods, as defined from earlier growth‐room studies, especially when dew‐wetness was omitted.The regression analysis showed that, in all years, infection was highly correlated with variables reflecting wet conditions. It was inconsistently correlated with vapour pressure deficit (VPD) and with sunshine, not at all with temperature, and with airborne spore concentration only in the combined years. The spore catches of a funnel trap, used in 1971, which depended upon rain varied closely with infection. R2 values for multiple regression equations indicated that, in the years separately and together, well over 70% of the variation in infection could be explained by the environmental variables and, in 1971, almost 90%. Variables (temperature, VPD, airborne spores) which singly were poorly correlated with infection often significantly improved regression equations which were based on variables expressing wetness. When prediction of each year's infection levels was attempted using selected regression equations calculated from data of the other 2 years there was, in general, very good agreement between measured and estimated values. The best predictions were given by an equation utilizing rain‐wetness duration, rainfall amount and airborne spore concentration while an equation based solely on relative humidity and rainfall was only slightly inferior.The results are discussed in relation to the possible value of the regression models for short‐term forecasting of hop downy mildew.
Infection of potato tubers with soft rot bacteria
Authors: WEBB L. E. , WOOD R. K. S. 
Published: February 2008

SUMMARYStolons attached to developing potato tubers were inoculated with the soft rot bacterium Erwinia carotovora var. atroseptica.Almost all the stolons rotted, but soft rots developed in less than 10% of new tubers; the bacterium was isolated later from these tubers. No rots developed in the other tubers but the bacterium was later isolated from about half of them. It could not be isolated from tubers attached to inoculated stolons where the rot on them did not extend to the tuber or from tubers attached to stolons that were not inoculated though many of these rotted.The bacterium was reisolated from almost all arrested lesions in tubers inoculated 8 month earlier with E. carotovora var. atroseptica. Blackleg did not develop from plants grown fom these tubers under various soil conditions. It did develop in a large proportion of plants from tubers inoculated shortly before planting and grown in cool, wet soil.Less than 1% blackleg developed in plants grown from tubers from plants with blackleg or from plants immediately adjacent.The presence of pectolytic bacteria and E. caratovora var. atroseptica in seed and new tubers was investigated during June, July and August. Although E. caratovora var. atroseptica was obtained from c. 40% tubers, only c. 0·3% of c. 8400 plants developed blackleg. The bacterium was isolated from only three of 160 new tubers sampled during the summer.
Effect of fungicides on the mycelial growth of soft fruit spoilage fungi
Authors: COHEN E. , DENNIS C. 
Published: February 2008

SUMMARYThe in vitro activity of a range of fungicides was tested on strains of Botrytis cinerea, Mucor mucedo, Rhizopus stolonifer, and R. sexualis. Di‐chlofluanid and dichloran were more active than the other fungicides against all of the strains of B. cinerea, while dichloran, dichlorophen and the dithiocarbamate fungicides were the most active against the Rhizopus species. Only dichlorophen and thiram markedly inhibited the growth of M. mucedo.
Studies on the possibility of increasing resistance to cocoa swollen‐shoot virus by breeding
Authors: KENTEN R. H. , LOCKWOOD G. 
Published: February 2008

SUMMARYIn tests using seed, the resistance of cocoa progenies to primary infection with cocoa swollen‐shoot virus by mealybugs was stable to inoculum pressure and effective against several virus strains. The results suggested that the resistance would be effective throughout the cocoa growing areas of Ghana. There were indications that resistance factors from different cocoa populations could be accumulated to give progenies of higher resistance than presently available.
Preliminary glasshouse and field tests of soil partial sterilants for clubroot control
Authors: BUCZACKI S. T. , WHITE J. G. 
Published: February 2008

SUMMARYExperiments were made on field plots and in individually dosed pots to investigate the effects of ten soil partial sterilants on percentage infection of cabbage with clubroot. Additionally, cores of naturally‐infested soil or samples of artificially infested and buried soil removed from some treated plots were also sown with cabbage in a glasshouse and the seedlings then assayed for the presence of clubroot. There was evidence that the partial sterilants were optimally effective at different depths. Dowfume M.C.2 and Basamid having the unique properties of effectiveness at deep and shallow horizons of the soil respectively. Chloropicrin at 60 ml/m2 and Dowfume M.C.2 at 98 g/m2 were the most effective partial sterilants in controlling clubroot while Basamid and Telone were also considered to merit further testing. All other partial sterilants reduced percentage infection in pot experiments and field crops to varying extents although formaldehyde was least effective.
Mutational tolerance to carbendazim in Botrytis cinerea
Authors: GEESON J. D. 
Published: February 2008

SUMMARYNo spontaneous mutation for tolerance to the fungicide carbendazim was detected in C. 108 conidia from each of eight carbendazim‐sensitive field isolates of Botrytis cinerea. Conidia of B. cinerea were highly insensitive to u.v.‐irradiation, although after severe irradiation treatments mutant strains showing the same levels of tolerance as two groups of carbendazim‐tolerant field isolates were selected at frequencies of between 10‐9 and 10‐6 of survivors. Mutants with low levels of tolerance (ED50 > 10 μg ml‐1 carbendazim; ‘partially‐tolerant’) were selected from irradiated conidia obtained from sensitive field isolates and a further series of mutants capable of growth on 10 000 μg ml‐1 carbendazim (‘fully‐tolerant’) were selected from irradiated conidia from either partially‐tolerant mutants or from partially‐tolerant field isolates. Both mutation steps were confirmed in similar experiments in which tolerance to an unrelated fungicide, 2, 6‐dichloro‐4‐nitroaniline (DCNA), was incorporated as a genetic marker in the parent strains.
Distribution of nematicides in soil and its influence on control of cyst‐nematodes (Globodera and Heterodera spp.)
Authors: BROMILOW R. H. , LORD K. A. 
Published: February 2008

SUMMARYIncorporation of nematicide granules by L‐bladed rotavator gave more reliable yield increases and better control of cyst‐nematode increase than incorporation by Roterra (rotary harrow), and measurements of granule distribution suggested that this could be attributed to the deeper distributions of granules achieved by rotavation. Pot tests showed that the variability of the granule distribution in the field is unlikely to limit the efficacy of oxamyl, but may limit the efficacy of fenamiphos, and these differences can be attributed to the greater mobility of oxamyl in soil.
Epidemiology and strategy for the control of halo‐blight of beans
Authors: TAYLOR J. D. , PHELPS KATHLEEN , DUDLEY C. L. 
Published: February 2008

SUMMARYA halo‐blight epidemic model based on the equation of Van der Plank (1963) is described. The model has been used to determine tolerance levels for seed infection and to compare the effectiveness of chemical control measures based on foliar sprays and seed treatments.Reduction of primary inoculum, derived from infected seed, by disease exclusion through seed testing, or by chemical seed treatment will give effective disease control under British conditions (i.e. with an expected apparent infection rate (r) of 0.15 per infected plant per day). Under climatic conditions more favourable for the disease where higher r values would occur, control treatments directed against primary inoculum only would be less effective. Under such conditions, it is predicted that chemical sprays, which have no effect on primary inoculum but cause a reduction in the rate of disease increase, would be more effective. The most effective disease control, however, would be a combination of treatments.
The distribution of poplar mosaic virus in hybrid poplars and virus detection by ELISA
Authors: COOPER J. I. , EDWARDS MARY LOU 
Published: February 2008

SUMMARYPurified poplar mosaic virus (PMV) at a concentration of 8 ng/ml was readily detected by enzyme‐linked immunosorbent assay (ELISA). Bioassay in Nicotiana megalosiphon was more sensitive (detecting 1–4 ng/ml) and latex flocculation less sensitive (c. 25 ng/ml) than ELISA assays. While the foliar sap of fresh, naturally‐infected poplars (e.g. Populus. euramericana cv. Robusta) was not infective at dilutions greater than 2 . 10–2, ELISA easily detected PMV antigen when sap was diluted 4 . 10–3 in buffer or when one part of infected tissue was triturated with 99 parts healthy leaf. Furthermore, although sap from poplar leaves stored at ‐20 °C for 6 months was not infective, PMV was still detectable in ELISA tests. PMV antigen in poplar leaves was not all pelleted after centrifugation for 2.5 h at 130 000 g yet parallel tests using unbuffered sap from systemically infected Nicotiana megalosiphon foliage showed that infectivity was restricted to the pellet. In poplar foliage, the concentration of PMV antigen was generally greatest where symptoms were most obvious; least antigen was detected in the overwintering leaves located at the bases of long shoots. In winter, when root and inner bark tissue in the trunk was an erratic source of PMV, the virus was readily detected in buds, the concentration being greatest in the bases, including the meristem, of terminal buds.Propagation from single node cuttings of P. euramericana cv. Regenerata allowed the selection of clones that consistently showed either ‘severe’ or ‘mild’ foliar symptoms. The associated virus isolates also infected another poplar clone causing symptoms characteristic of their source. ELISA consistently detected less PMV antigen in field‐grown cv. Regenerata than in cv. Robusta foliage, but this was reversed when the associated virus isolates were propagated in Nicotiana glutinosa at 24 °C.During 6 yr, 21 out of 127 poplars at a site in Western England, became infected with PMV. By contrast, in Eastern England, none of 46 were infected. The aphids Pterocomma populea and Myzus persicae did not transmit PMV.
Variation in monoculture and in mixture for grain yield and other characters in spring barley
Authors: VALENTINE J. 
Published: February 2008

SUMMARYFourteen north‐west European spring barley cultivars were grown alone or in binary mixtures sampled according to a partial diallel scheme. On the basis of the association between cultivars in mixture and monoculture, three groups of characters were distinguished. Group A characters, plant height, ear weight/tiller, grain yield/tiller, number of grains/tiller and 1000‐grain weight, showed strong positive associations between performance in monoculture and mixture. Group B characters, number of tillers/plant and harvest index showed incomplete positive associations, while for group C characters, dry matter/plant, ear weight/plant, grain yield/plant and number of grains/plant, associations were weak or non‐existent. Compound characters in group C showed less genetic variation in monoculture and lower general competitive effects in mixture than component characters in groups A or B.These results clearly indicate that while selection for grain yield and other characters on a per plant basis (group C characters) is confounded by intergenotypic competition, characters such as the yield components number of grains/tiller and 1000‐grain weight (group A characters) are hardly affected in this range of cultivars. Selection for opposing group A characters may start in the F2 generation, while any selection for group B and C characters should be delayed until later generations.The merits of indirect selection for yield using visual assessment of yield components are discussed.Separate analyses obtained by the inclusion of spring wheat cv. Timmo in monoculture and in the set of mixtures indicated that the use of spring wheat plants to minimise intergenotypic competition ranges from superfluous (group A characters) to useless (group C characters).A large degree of mixture advantage and the lack of complementary dominance and suppression between competitor and associate was attributed to the relatively low density of plants in the experiment which, though suitable for single plant selection, is not typical of normal seed rates for cropping.