bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of egg counts and suction trap samples to forecast the infestation of spring‐sown field beans, Vicia faba, by the black bean aphid, Aphis fabae
Authors: WAY M. J. , CAMMELL M. E. , TAYLOR L. R. , WOIWOD I. P. 
Published: February 2008

SUMMARYDaily suction trap samples at a height of 12·2 m collected throughout the year, winter egg and ‘spring’ population counts on the spindle tree, Euonymus europaeus, and initial infestations of the black bean aphid, Aphis fabae, on field bean, Vicia faba, crops are available from Southern England since 1970. In different areas, estimates of the sizes of the autumn migrations, the over‐wintering egg populations, the spring fundatrigeniae and the spring migrations, have been used to forecast field bean crop infestation levels which, in turn, project subsequent trap catches of alatae.The forecasts of crop infestation become progressively more accurate from the autumn migration to the following spring migration, accounting for 28%, 54%, 54% and 64% of the variance respectively. In areas where traps are sited, the spring migration trap samples give the most accurate estimate of the size and timing of crop infestation.Autumn trap catches are particularly useful as very early forecasts of likely very large or very small populations on field beans about 8 months later, but otherwise they lack precision. Egg sampling in winter provides a considerably more accurate forecast approximately 5 months before crop infestations. In spring (May), fundatrigeniae sampled on spindle are most useful for predicting time of migration, and provide approximately 2 weeks' warning for insecticide application, if needed. Finally, trap sampling of the spring migration provides the latest estimate of both the sizes of crop infestations and the timing of insecticide treatment.The E. europaeus and aerial sampling systems are complementary, the traps providing systematic, continuous information and the E. europaeus samples greater detail. Combined, they can provide excellent long‐term fore‐warning of the need for chemical control and short‐term warning of control timing. Forecasts have been 90% correct in eight years out of nine. The error in the ninth year may be due to immigration from the European mainland.
The effect of benomyl on some invertebrate inhabitants of a red raspberry, Rubus idaeus, plantation in relation to fruit yield
Authors: MASON D. T. , WOODFORD J. A. T. , TRUDGILL D. L. 
Published: February 2008

SUMMARYThe growth and yield increases in red raspberry which followed the repeated application of benomyl were not due to the suppression of pests. Benomyl had little effect on numbers of aphids and nematodes which, anyway, were insufficiently abundant to cause damage. Benomyl did, however, decrease the earthworm population.In the following years, when benomyl was no longer applied, significantly more canes died from midge blight in the plots treated most frequently with benomyl than in the untreated. This was probably a consequence of increased infestation by larvae of the raspberry cane midge (Resseliella theobaldi) in the benomyl‐treated plots because benomyl increased the extent of cane splitting and hence the number of egg‐laying sites for cane midge.
Some epidemiological aspects of post‐bloom fruit drop disease (Colletotrichum gloeosporioides) in citrus
Authors: DENHAM T. G. , WALLER J. M. 
Published: February 2008

SUMMARYFluctuations in the incidence and amount of post‐bloom fruit drop disease of citrus caused by Colletotrichum gloeosporioides in Belize prevent economic disease control. During the cooler drier months of the year when blossom infection is common there are variations in the incidence of rainfall and associated climatic parameters, and in the pattern of flowering. Large amounts of disease develop when periods of rain followed by prolonged wetness occur during peak blossoming periods. Blossoms are most susceptible during the open flower stage and infection of terminal flowers invariably results in infection of all other flowers on the spike. Disease incidence is greater in the lower parts of the trees, but flowering is greater in the upper regions. Large numbers of Colletotrichum spores are produced during wet conditions from apparently healthy leaves and from diseased flowers, but these rapidly lose viability when dried. Few spores are produced from old persistent calices (buttons). Although spores from leaves were a less potent inoculum source than those from flowers, they could provide the initial inoculum to commence flower infection when blossoming starts.
Effects of some fungicides used against cereal pathogens on the growth of Rhizobium trifolii and its capacity to fix nitrogen in white clover
Authors: FISHER D. J. , HAYES ANN L. 
Published: February 2008

SUMMARYFungicide residues in soils may affect nitrogen fixation by legumes. Effects of nine systemic fungicides, used against cereal pathogens, on Rhizobium trifolii and white clover were measured. Fenarimol and oxycarboxin inhibited growth of R. trifolii in vitro. The weight of clover plants after 10 weeks' growth in soil containing carboxin, oxycarboxin, benodanil, tridemorph and pyracarbolid was reduced. Symbiotic nitrogen fixation was decreased by carboxin, oxycarboxin and tridemorph present in soil at concentrations somewhat greater than that likely to result from several applications of the fungicide. Only tridemorph reduced nodulation. None of the compounds seems likely to affect nitrogen fixation in the field if applied at the recommended rate.
Cellulose xanthate as a soil conditioner: implications for weed control with some soil‐applied herbicides
Authors: ROBERTS H. A. , BOND W. , WALKER A. , PAGE E. R. 
Published: February 2008

SUMMARYApplications of cellulose xanthate equivalent to 50 kg cellulose/ha to fresh seedbeds preserved surface microtopography and prevented capping after rainfall. Numbers of weed seedlings were up to 50% greater than on untreated soil where capping occurred. The efficiency of nine soil‐acting herbicides was not impaired when applied at normal rates either before or after cellulose xanthate. There was no evidence of interaction and the numbers of surviving weeds were proportional to the numbers where no herbicide had been applied. With propachlor, however, weed control was consistently less when applied shortly before or after cellulose xanthate, and analyses showed that in the presence of the soil conditioner the rate of herbicide loss was enhanced. This effect decreased the longer propachlor application was delayed, but was still evident with an interval of 96 h.
Genetic aspects of resistance to cocoa swollen‐shoot virus in Ghana
Authors: LOCKWOOD G. 
Published: February 2008

SUMMARYThe inheritance of resistance in cocoa to infection with cocoa swollen‐shoot virus was studied in seed inoculation experiments with progenies of Upper Amazon, Trinitario and West African Amelonado parents. In an eight parent diallel cross grown in two seasons and in six male × female factorial experiments, general combining abilities were much more important than specific combining abilities. The diallel cross revealed significant maternal effects but there was little evidence of specific reciprocal differences. Estimates of general combining abilities corresponded with expectation and were positively correlated with maternal effects, the latter indicating that tester parents should be used as males.The results from scaling tests with hybrids between selections from the River Nanay (a Peruvian tributary of the River Amazon) and Amelonado fitted a model with additive resistance; there was no evidence of dominance.Attempts to obtain stronger sources of resistance by hybridisation and selection were unsuccessful. In three crosses the resistance of individual seedlings was compared with that of the parents using test crosses but no evidence of transgressive segregation was obtained. In further experiments seedings of two hybrids between contrasting parents were heavily inoculated with virus so that few healthy survivors remained. Test crosses showed that these survivors and randomly selected seedlings of the same parentage did not differ as resistance sources.
The effect of different water regimes on plant growth and nodule structure of greenhouse‐grown winged bean (Psophocarpus tetragonolobus)
Authors: RATHFELDER ERICA L. 
Published: February 2008

SUMMARYPlants of Psophocarpus tetragonolobus cv. Chimbu Illinois were germinated under uniform conditions, after which they were transferred to three water treatments, ‘wet’, control and ‘stress’. Those plants given most water (i. e. ‘wet’) grew best and produced most root nodules.Water stress delayed nodule formation and quantitative microscopic examination showed that nodules from stress plants had more bacteroid‐containing cells per unit area up to 4 wk than nodules from either of the other treatments. Bacteroid‐containing cells were found to be vacuolated in P. tetragonolobus.
Benefits of ethylene removal during apple storage
Authors: KNEE M. , HATFIELD S. G. S. 
Published: February 2008

SUMMARYThe potential use of an ethylene absorbent in controlled atmosphere storage of two varieties of apple has been investigated. With Golden Delicious, the rise in ethylene concentration during controlled atmosphere storage can be delayed for about 40 days but not prevented by inclusion of potassium permanganate in the storage container. But with Bramley's Seedling, potassium permanganate can delay ethylene accumulation for over 200 days. Ethylene treatment of Bramley's Seedling in a flowing stream of 5% CO2:3% O2:92% N2 caused accelerated softening, accumulation of α‐farnesene and earlier onset of superficial scald. Use of potassium permanganate to remove ethylene during storage in static controlled atmosphere conditions retarded all three processes in Bramley's Seedling kept in 5% CO2:3% O2 and in 9% CO2:12% O2. However, in one experiment, ethylene removal in 5% CO2:3% O2, led to external and internal symptoms of CO2 damage. A subsequent investigation of the combined effects of harvest date, store temperature and ethylene removal in 5% CO2:3% O2 did not show any damage or accumulation of succinic acid which is known to be involved in CO2 injury. This experiment revealed that ethylene removal could be successfully accomplished on Bramley fruit harvested up to a month after the usual date and little α‐farnesene accumulated in this fruit. Nevertheless scald did develop on late picked fruit and this raises doubts about the causal role of farnesene in scald.
Quantitative studies on the uptake and retention of potato leafroll virus by aphids in laboratory and field conditions
Authors: TAMADA T. , HARRISON B. D. 
Published: February 2008

SUMMARYEnzyme‐linked immunosorbent assay (ELISA) was adapted for the efficient detection and assay of potato leafroll virus (PLRV) in aphids. Best results were obtained when aphids were extracted in 0.05 M phosphate buffer, pH 7.0, and the extracts incubated at 37 °C for 1 h before starting the assay. Using batches of 20 green peach aphids (Myzus persicae), about 0.01 ng PLRV/aphid could be detected. The virus could also be detected in single aphids allowed a 1‐day acquisition access period on infected potato leaves. The PLRV content of aphids depended on the age of potato source‐plants and the position of source leaves on them. It increased with increase in acquisition access period up to 7 days but differed considerably between individual aphids. A maximum of 7 ng PLRV/aphid was recorded but aphids more usually accumulated about 0.2 ng PLRV per day. When aphids were allowed acquisition access periods of 1–3 days, and then caged singly on Physalis floridana seedlings for 3 days, the PLRV content of each aphid, measured subsequently, was not strongly correlated with the infection of P. floridana. The concentration of PLRV in leaf extracts differed only slightly when potato plants were kept at 15, 20, 25 or 30 °C for 1 or 2 wk, but the virus content of aphids kept on leaves at the different temperatures decreased with increase of temperature. PLRV was transmitted readily to P. floridana at all temperatures, but by a slightly smaller proportion of aphids, and after a longer latent period, at 15 °C than at 30 °C.The PLRV content of M. persicae fed on infected potato leaves decreased with increasing time after transfer to turnip (immune to PLRV). The decrease occurred in two phases, the first rapid and the second very slow. In the first phase the decrease was faster, briefer and greater at 25 and 30 °C than at 15 and 20 °C. No evidence was obtained that PLRV multiplies in M. persicae. These results are compatible with a model in which much of the PLRV in aphids during the second phase is in the haemocoele, and transmission is mainly limited by the rate of passage of virus particles from haemolymph to saliva.The potato aphid, Macrosiphum euphorbiae, transmitted PLRV much less efficiently than M. persicae. Its inefficiency as a vector could not be ascribed to failure to acquire or retain PLRV, or to the degradation of virus particles in the aphid. Probably only few PLRV particles pass from the haemolymph to saliva in this species.The virus content of M. euphorbiae collected from PLRV‐infected potato plants in the field increased from early June to early July, and then decreased. PLRV was detected both in spring migrants collected from the plants and in summer migrants caught in yellow water‐traps. PLRV was also detected in M. persicae collected from infected plants in July and August, and in trapped summer migrants, but their PLRV content was less than that of M. euphorbiae, and in some instances was too small for unequivocal detection.
Effects on straw decay of the herbicides paraquat and glyphosate in combination with nitrogen amendments
Authors: GROSSBARD E. , HARRIS D. 
Published: February 2008

SUMMARYThe effects of paraquat were studied at 4.7 kg a. i./ha and of glyphosate at 9.4 kg a. i./ha on the weight loss and rate of oxygen uptake by stems of barley straw, incubated on the soil surface for various periods of time, and stems and leaves of wheat straw on the soil surface or covered with a shallow layer of soil. In general, paraquat reduced weight loss and frequently oxygen uptake. Glyphosate normally had no effect but occasionally it was stimulatory. However, in isolated instances, paraquat was inactive and glyphosate slightly inhibitory. Leaves decayed faster than stems. Burial, as well as the addition to straw of leaf protein, Nitrochalk, urea and clover plants increased decomposition in all treatments, but nitrogen amendments were less effective in those with paraquat. For example, urea enhanced weight loss after 21 wk from 19 to 34% of the initial weight in unsprayed wheat straw, from 12 to 24% in paraquat‐treated and from 20 to 37% in glyphosate‐treated straw, indicating that conditions stimulating decomposition may attenuate but not entirely eliminate the inhibitory effects of paraquat. A repeated addition of nitrogen to straw in various stages of decay increased oxygen uptake in all treatments but least in the paraquat‐treated straw, implying that a complete recovery from the initial curtailment of microbial activity, brought about by this herbicide, did not occur. Although the concentration of paraquat used was nine times greater than the minimum recommended for field application, the degree of inhibition observed in these laboratory experiments was probably not sufficiently great to be of marked economic importance.
Resistance of rin and nor tomato mutants to postharvest Rhizopus infection
Authors: BARKAI‐GOLAN RIVKA , KOPELIOVITCH E. 
Published: February 2008

SUMMARYFruits of the two non‐ripening mutants of tomato, rin and especially nor, were markedly more resistant to Rhizopus stolonifer infection than the normal Rutgers fruit. Following artificial inoculations by contact with a diseased normal tomato covered with mycelium and sporangia, no infection of unwounded nor fruit occurred at its mature‐green stage. At the mature stage the resistance of nor mutant fruit was manifested by a prolongation of the incubation period of the disease as well as by a markedly reduced incidence of rotted fruits. Chilling injury of fruit, prior to spore inoculation, was found to be a good means for indicating the relative resistance of the mutants as compared with the normal tomato.The relationship between the resistance of the mutant tomatoes to Rhizopus infection and their response to induced peel damage as a result of the contact or the chilling procedure, led to the assumption that fruit resistance is associated with the inability of the fungus to penetrate the periderm, rather than with fungal development within the fruit.
Growth compensation for destroyed and replaced plants in Central African field tobacco*
Authors: SHAW M. J. P. , WIXLEY R. A. J. 
Published: February 2008

SUMMARYPlants surrounding a gap in stand compensated to some extent for leaf yield lost to missing plants. The contribution of plants in an adjacent row was much less than that of plants next to the gap within the row. Losses were reduced and quality was improved by replacing destroyed plants within two weeks of the original planting.
Effect of 2, 4‐D analogues on the induction and maintenance of callus in maize tissue culture1
Authors: JIMÉNEZ ESTELA SÁNCHEZ DE , ALBORES MARTHA , LOYOLA‐VARGAS VICTOR M. 
Published: February 2008

SUMMARYSix analogues of 2, 4‐D: 2(2‐methyl‐4‐chlorophenoxy) propionic, 2(2,4‐dichloro‐phenoxy) propionic, 2(2‐methyl‐4‐chlorophenoxy) butyric, 2(2,4‐dichlorophenoxy) butyric, 2(2,4‐dichlorophenoxy) butyric acids and the separated enantiomers of 2(2, 4, 5‐trichlorophenoxy) propionic acid were examined for their ability to induce callus development and maintain its growth in maize (Zea mays) tissue cultures. The results indicate that the analogues were more effective than 2, 4‐D in both respects and that alkyl substitution on the carbon side chain of the acids increased the auxin effect. It was also shown that only the (+) isomer of the two enantiomers studied, had auxin activity.
Effects on dry weight and nitrogen content of grains of semi‐dwarf and tall varieties of winter wheat caused by decreasing the number of grains per ear
Authors: THORNE GILLIAN N. 
Published: February 2008

SUMMARYThe number of grains in ears of six varieties of winter wheat growing in the field was decreased by removing the top half of the ear 6 days after anthesis (halving). In the semi‐dwarf varieties Hustler, Sentry and Hobbit, and in the taller varieties Armada and Flanders, the mean dry weight per grain in the lower six spikelets of halved ears was about 23% greater than the dry weight of grains in the comparable part of intact ears. In Maris Huntsman the increase in grain size amounted to only 13%. Halving increased the number of grains in the semi‐dwarf varieties but not in the others. Consequently, the increases caused by halving in the total weight of grain in the lower six spikelets ranged from 41% in Hustler and Hobbit to 7% in Maris Huntsman.Halving increased the amount of nitrogen in the grain of the lower half of the ear similarly in all varieties, and relatively more than it increased dry weight. So nitrogen per cent dry weight of grain was increased, especially in Armada, Flanders and Maris Huntsman which responded least in dry weight. The uptake of nitrogen into the stem plus ear after anthesis was unaffected by halving. Most of the nitrogen that normally moved to the upper grains accumulated in the lower grains of halved ears.More nitrogen moved into the grain of intact ears of tall than of semi‐dwarf varieties after anthesis, because there was greater uptake of nitrogen into the shoot from the roots.
Fungus diseases on potato seed tubers planted in England and Wales, 1963‐76
Authors: HIDE G. A. 
Published: February 2008

SUMMARYDuring 1963‐76 samples of potato tubers from commercial seed stocks of cvs King Edward (14 yr), Pentland Crown (9 yr), Majestic (7 yr), Pentland Dell (3 yr), Record and Arran Pilot (2 yr) were received from farms in England and Wales. Fifty tubers from each sample were examined macroscopically for fungus diseases and eyes were excised from a 20‐tuber sub‐sample, incubated and examined for pathogenic fungi; 50 tubers were stored on trays to sprout and examined for diseases and sprouting in May and in most years samples of 50 tubers were wounded by dropping onto expanded metal, stored at 5° C and examined for gangrene and dry rot after 12 wk.Amounts of disease varied between years and during 14 yr black scurf and powdery scab on King Edward tended to increase and skin spot and late blight decrease. On average 44% of King Edward tubers were affected with skin spot, 25% with black scurf and 16% with powdery scab. Gangrene affected 5% of tubers and 97% of the isolates from rots were identified as Phoma exigua var. foveata. Wounding tubers increased the incidence of gangrene three‐fold.During 1963‐69 late blight affected 2% of King Edward tubers but fewer in later years and in other cultivars. Majestic had most common scab (44% tubers) and Arran Pilot most dry rot (9% tubers) and this disease was increased by wounding tubers. Conidiophores of Helminthosporium solani (silver scurf) were more common on excised eyes of Pentland Crown, Record and Arran Pilot than of other cultivars, and isolations from verticillate conidiophores that developed on the side of incubated eye plugs of King Edward and Majestic stocks gave pure cultures of Verticillium tricorpus (78%), V. nigrescens (9%) and V. nubilum (3%).Proportions of tubers with different diseases were affected by their country of origin; Scottish seed had most skin spot and gangrene, Irish seed most powdery scab and English seed most common scab, late blight and H. solani. There was also evidence of differing disease incidence in seed from different geographical areas in Scotland and England.Up to half the King Edward and Pentland Crown stocks examined in 1975 and 1976 were derived from stem cuttings and average amounts of diseased tubers were similar to those in stocks not derived from stem cuttings.Annual and cultivar differences in disease incidence and effects of date of receipt of seed on farms are discussed.
Studies on the survival and infective ability of dicarboximide‐resistant strains of Botrytis cinerea
Authors: DAVIS R. P. , DENNIS C. 
Published: February 2008

SUMMARYFew dicarboximide‐resistant strains of Botrytis cinerea produce macroconidia either on culture media or on natural substrates, although, the viability of such conidia was similar to those of sensitive strains. The ability of dicarboximide‐resistant strains to infect strawberries was similar to that of sensitive strains and most of the resistant strains competed successfully with sensitive strains when inoculated in equal numbers onto detached strawberries and onto flowers of field‐grown plants, especially after treatment with dicarboximide fungicides. All resistant strains tested survived for at least 9 months on inoculated strawberry leaf litter although their incidence was ‘diluted’ by wild type sensitive strains. Sporulation and dispersal of resistant strains from the litter was very limited resulting in a low incidence of fruit infection even after treatment with dicarboximides. Consequently, there was no significant increase of resistant strains in the plantation and control of infection was maintained with iprodione and dichlofluanid. Poor sporulation of dicarboximide‐resistant strains of B. cinerea is considered to be the single most important factor in limiting their development in the field.