摘要:

SUMMARYSpecimens ofMyzus persicaehave been collected from field populations in Scotland and scored electrophoretically for their phenotypes at three polymorphic loci. These phenotypes were almost invariably present in individuals in one of a small number of favoured combinations, suggesting that these populations may be oligogeneous, that is, composed of large numbers of copies of a few favoured combinations of alleles.Temporal and spatial sampling at sites in East and West Scotland in 1976 has shown that different allele combination types were present in the two areas. Populations in E. Scotland contained very few specimens belonging to the organophosphorus (OP) resistant clone types (using esterase activity to infer resistance); instead there were large numbers of an OP susceptible type which has not been detected in England, but which came to predominate on cabbage and potato host plants at every site sampled during the period of rapid population increase. In contrast, populations in W. Scotland were characterised by substantial numbers of specimens belonging to OP resistant clone types and by an almost complete absence of this susceptible type. Two other distinguishable OP susceptible types were found to be common to both areas. The W. Scotland populations closely resemble N. England populations while those in E. Scotland appear to be unique to that area. Specimens of OP resistant types were only detected in E. Scotland after the beginning of June and in such relative proportions as to strongly suggest that they were migrants from W. Scotland or N. England.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00672.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYThe majority ofEpitrimerus pirion pear, cv. Williams' Bon Chretien, moved from their hibernation sites in small permanently dormant buds on spurs and under loose bark to fruit buds between the stages of green cluster and petal fall. Peak numbers of mites occurred in mid‐June on fruit and early August on leaves with the return to hibernation beginning in July. Development time from egg hatch to adult was 17–1, 6–9 and 4–8 days at 10, 16 and 22 °C, respectively. Mites were dispersed by wind. They were found only on species in the generaPyrus, CydoniaandPyronia.Mite feeding caused browning on the ventral, sides of leaves and russet on fruit which was confined to the calyx end on Williams'. Populations of over 2000 mites/leaf reduced the length and dry weight of new shoots on potted pears by 8 and 14% resp

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00673.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYStalk rot was present in each of 78 maize crops and six hybrid maize trials examined between 1971 and 1975.Fusarium culmorumwas the main cause of the disease and was isolated from 67 of the 82 samples from which isolates were made. Lodging was found to be related to, and a natural succession of, the earlier wilting symptom caused by infection withF. culmorum.Yield losses were estimated in 39 crops between 1973 and 1975 and the disease caused a mean reduction of 18‐7% in cob weight and 11‐2% in 1000‐grain weight of infected plants over the 3 yr of the s

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00674.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYContamination with infected soil has led to high wastage of apples in storage due to rotting byPhytophthora syringae.At 3‐3oC lesions formed 3–4 wk after inoculation with zoospores; the percentage infection fell if the suspensions dried after 48 h at this temperature and after 22 h at 15oC. Infected soil rotted fruit only if kept moist; at 3‐3oC a 3‐day period of wetness resulted in 37‐5% rotting after 8 wk. Fruit dipped in soil slurry remained wet in some parts of a 4361(12 bushel) bin for at least 3 wk. There was a 10‐fold increase in rotting by contact between sound and rotting fruit after 11 wk at 3‐3oC. Captan gave effective protection against rotting derived from zoospores or infected soil; it had no era

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00675.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYLeptosphaeria coniothyrium, the cane blight pathogen, was the fungus most commonly isolated from vascular lesions developing from mechanical harvester wounds on first‐year red raspberry canes. When inoculated to scalpel wounds, it induced similar lesions which were later associated with bud failure and cane death as were infected wounds on machine damaged canes. Cane resistance increased from May until August, inoculations later than July inducing only small lesions and rarely causing bud failur

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00676.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYAll isolates ofPeniciUium simplicissimum, P. verrucosumvar.cyclopium, P. brevicompactum, P. multicolor, P. oxalicum, P. paxilli, Botrytis cinerea, and of aGliocladiumsp. obtained from necrotic virus‐tested narcissus twin‐scales previously dtoped in benomyl were tolerant to 1000 μg/ml of this fungicide in agar. Every necrotic twin‐scale examined was infected with at least one of these species. The first two species were the most frequently isolated and a similar range of species infected different narcissus clones or different cultivars. It is argued that the use of benomyl during the twin‐scaling programme should be discontinued as soon as a suitable alternative fungicide

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00677.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYIn experiments extending over 3 yr, King Edward tubers harvested on various dates from early September until early November were uniformly wounded and kept at 15oC andc.95% r.h. for periods of up to 21 days for wounds to cure. When tubers were subsequently inoculated withPhoma exigua var.foveataand incubated at 5oC for 12 wk, curing for 3 and 7 days decreased gangrene incidence to respectivelyc.13 and 4% of the non‐cured controls. When tubers were inoculated before curing and immediately after wounding, curing for 7 days decreased gangrene incidence to onlyc.68% of the non‐cured controls. Curing was also progressively less effective the later the date of harvesting, suggesting that there would be advantages in harvesting potato crops early in the aut

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00678.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYA series of hydroxy‐and methoxy‐2‐phenyl benzofurans, structurally related to the phytoalexin vignafuran, have been synthesised and their antifungal activity assessed both as inhibitors of spore germinationin vitroand as protective foliar sprays against three pathogens. All fungitoxic compounds have a hydroxy group in the molecule although most di‐ and tri‐hydroxy compounds were inactive. Methoxy compounds were inactive but substituting methoxy groups into the molecule of monohydroxy compounds sometimes enhanced their fungitoxicity. No close correlation was established between antifungal activity and either Hansennvalues or the n.m.r. chemical shift of the phenoli

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00679.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYField‐baled hay was incompletely preserved using propionic or formic acids. Results were most satisfactory, although moulding byAspergillus glaucusgroup was still frequent, when die hay contained less than 30% water and propionic acid was used. However, much more propionic acid was needed than in laboratory experiments probably because poor distribution of acid in the bale, resulted in under‐treated pockets of hay where moulds tolerant to propionic acid could grow and then spread to areas that would otherwise have been adequately treated.In Dewar flasks, moulds, particularlyPaecilomyces variotiand theA. glaucusgroup, could spread from untreated hay into hay containing 2% w/w of propionic acid. Addition of 4 or 10% of propionic acid protected adjacent untreated hay from moulding. The concentration of propionic acid necessary to prevent flasks from heating and moulding increased with thickness of the untreated layers and with water content. Redistribution of acid in the bale after treatment was slow and much variation in acid levels occurred even between adjacent 1 cm segments of grass following storage. Spontaneous heating of moulding hay could cause migration of propionic acid in hay, assisting the spread of fungi. A proprietary additive did not prevent moulding at any hay water content tes

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00680.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

SUMMARYField trials on sites infested with trichodorid nematodes in Scotland tested the effects of dichloropropene‐dichloropropane mixture (D‐D), thiofanox, and granules and foliar sprays of oxamyl on the incidence of spraing disease in potato (cv. Pentland Dell) tubers. D‐D was effective in controlling spraing on all three sites, thiofanox was ineffective on the one site tested. On two sites oxamyl granules and sprays, alone and together, significantly decreased the amount of spraing. Those treatments including a spray were more effective than granules alone. At the third site different rates and times of application of sprays were t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1978.tb00681.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY