摘要:

SummaryThe dispersal rates of wild and culture cabbage root fliesErioischia brassicaewere determined in release‐recapture experiments at Wellesbourne in 1971–3. The experiments were concerned mainly with the first 7 days of adult life. The flies, released from nine locations in the area, were recaptured in yellow water‐traps.Dispersal was affected by wind, rain and the terrain the flies were crossing. The flies least often recaptured were those released into the host crop when 6–12 days old. The results indicated the following pattern of behaviour.Flies moved little during the first 2 days of adult life but by the third day both sexes had dispersed toc.100 m from the release point. Flies are known to mate about the fourth day and after this the males continued to disperse atc.100 m per day for the three subsequent days. ‘Wild’ females from field‐collected pupae carried out a ‘migratory’ flight, however, and dispersed atc.1000 m per day during the fifth and sixth days, the days preceding the start of oviposition. Similar rates of dispersal were recorded from flies released across host crop and non‐host crop areas.Some females did not stop at the first crop they encountered. The culture females from the laboratory‐reared pupae dispersed onlyc.one‐third of the distance of the wild females. There was considerable intermingling of local populations. The percentage recapture of young culture and wild flies released during the pre‐oviposition period of this species was 38 ± 4 and 19 ±4 for males, and 15 + 2 and 8+1 for females, respectively.The dispersal range of the cabbage root fly is probably within a 2000–3000 m radi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00490.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYTwo lines ofViciafabawere as resistant toAphis fabaeas Rastatt, one of their progenitors, when compared with susceptible control varieties in glasshouse experiments. In short experiments, fewer adult aphids settled on plants of resistant varieties, which subsequently bore smaller total numbers of aphids. In a longer experiment, the aphids multiplied more slowly on the resistant varieties, which survived after susceptible beans had been killed.The bean varieties did not vary in numbers of aphids on the stem or growing point but resistant varieties had markedly smaller proportions of the total on the abaxial surface of the leaves; in particular the smaller veins supported fewer aphids.V. narbonensiswas very resistant toA. fabaebut was susceptible toMyzus persicae, indicating that its resistance mechanism is distinct from that withinV. faba.In infested field trials most of the variation in yield of bean varieties was attributable to the sizeof A. fabaecolonies, and resistant varieties outyielded susceptible varieties. Yields of resistant varieties in the presence of large numbers of aphids were, however, less than those from trials without aphids. In uninfested trials susceptible varieties usually gave the largest yields.The significance of these observations is discussed in relation to policies and methods for breeding for resistance toA. fabaeinV. faba.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00491.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYAfter inoculation ofAvena sterilisand the oat cultivars Algerian and Garry withPuccinia graminis avenaethe time required for the eruption of pustules of the rust was markedly less at 30–35 than at 20–25oC. In addition, the area of pustules and number of uredospores produced were significantly greater at 30–35 than at 20oC. Peaks of uredospore production occurred between 12 and 22 days after inoculation.In comparable experiments, the time required for pustules ofP. coronata avenaeto erupt, and the size of pustules, were relatively insensitive to change of temperature, although weight of uredospores produced was greater at 20 than at 30oC. Peaks of uredospore production occurred between 14 and 18 days after inoculation.Both rusts showed straight‐line relationships between pustule area and number of uredospores produced. The percentage of infection foci that developed into pustules was similar with both rusts and on all the oat cultivars examined. Both rusts produced susceptible reaction types on all the hosts tested.Pustules ofP. graminis avenaewere smaller and fewer and generation time longer on cv. Garry than on cv. Algerian orAvena sterilisand the numbers of pustules per unit of inoculum of both rusts were greatest on Algerian, least on Garry. It is suggested that these quantitative differences in phases of the infection process contribute towards the ‘slow‐rusting’ reaction

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00492.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYPre‐planting root dips and soil drenches with benomyl, carbendazim (MBC), thiabendazole and thiophanate‐methyl were used to reduce disease severity in mother plants. Transmission of the pathogenVerticillium dahliaethrough stolons and into young runners was prevented by two applications of benomyl or thiophanate‐methyl at o‐i% active ingredient applied at stolon appearance and 1 month later. Sufficient concentrations of fungistatic residues were detected in all plant tissues to suppress the internal spread of the p

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00493.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThree experiments designed to elucidate the effects and interactions of different inoculation methods, inoculation positions, strains ofPhoma exiguavar.foveataand clones of potato tubers inoculated were analysed using as data dimensions of the lesions and a more general surface score. The assessment of susceptibility was affected by all these factors. The ranking of varieties for resistance altered considerably depending upon whether the surface area or the depth of lesions was considered. Derivation of more complex scores combining these measurements reduced the relative genetic component and hence would be of no value to potato breeders.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00494.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYIn a factorial experiment on canker control the efficiency of phenylmercurie nitrate (PMN) applied at leaf fall, before bud burst or both was compared with the application of dodine, dithianon, triforine, thiabendazole, benomyl or carbendazim in May and June. Of the total number of cankers which developed in unsprayed trees 76–78% resulted from infections in April to August of each year of the experiment. Infection was reduced significantly by all of the fungicides applied in summer. Of these carbendazim was outstanding, controlling both summer and autumn infections. Sporulation throughout the summer was suppressed by carbendazim and to a lesser extent benomyl, but whereas the suppressant effect of carbendazim persisted until long after leaf fall that of benomyl was evident only until August. Dodine, dithianon, triforine and thiabendazole had no significant effect on spore production. Dithianon and dodine showed highest toxicity to the germination ofNectria galligenaspores of all fungicides used in summer. All of the fungicides controlled apple scab(Venturia inaequalis)although thiabendazole was the least effective.Autumn applications of PMN reduced canker incidence but their value alone was not as great as carbendazim, dithianon, benomyl or dodine applied in summer. PMN applied in spring reduced the number of cankers in trees receiving no other fungicides but tended to increase the incidence of infections, particularly in autumn, when used in conjunction with fungicides applied in May and June. PMN applied before bud burst reduced sporulation ofN. galligenafor a few weeks, after which production resumed and in late summer and autumn actually exceeded the controls. None of the fungicides had any direct effect on leaf fall.Infection of the crotch and basal leaf scars was more common in summer than in autumn whereas infection of leaf scars above the basal region was more common in autumn than in summer. The rootstocks of many of the trees became infected via callus tissue associated with adventitious root development and this was controlled by the carbendazim treatmen

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00495.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThree clones of potatoes bred fromSolanum verneiwere tested for their resistance to the white potato cyst‐nematode,Heterodera pallida, both by root‐ball counts and by estimates of total cysts produced. Two susceptible clones were used as controls. Root‐ball counts suggested a higher degree of resistance than that based on total cysts produced. There were differences in pathogenicity between the two populations. The degree of resistance found was such that in practice the resistant clones would be best used in conjunction with nematicide treatment in a system of integrated co

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00496.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYIn laboratory trials, fumigation with acetaldehyde vapour at 0–75 to 20 % concentration (v/v) for 0–5 to 120 min at 21oC killed six species of post‐harvest citrus pathogens grown on agar media. The fungicidal effect of acetaldehyde vapour at this temperature was a function of concentration and exposure.Penicillium digitatumandP. italicumwere not as susceptible to inhibition of spore germination asAlternaria citri, A. tenuis, Colletotrichum gloeosporioidesandGlomerella cingulata.A concentration of 10 % acetaldehyde vapour at 21oC for 10 min was fungitoxic to all the pathogens t

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00497.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYFour populations of the wheat‐bulb fly studied at Rothamsted incurred substantial and regulatory losses of larvae caused by food shortage. The following hypothesis is proposed to explain population changes of the fly. Fluctuations caused by weather are stabilized by density‐dependent larval mortality caused by food shortage. The effect of weather is, however, pervasive as it also affects food shortage by influencing the number of shoots available to lar

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00498.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1975.tb00499.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY