摘要:

SUMMARYWindbreaks of coir netting were erected in apple orchards during the flowering period in 1969 and 1970 in an attempt to increase the number of insect pollinators present. Suction traps were used to sample flying insects; insects visiting trees were sampled by examination of flowers. The sheltered zone behind the windbreaks contained more of most species of insects than elsewhere. Increases in final fruit set of approximately 30% in 1969 (cv. Cox's Orange Pippin) and 20 % in 1970 (cv. White Jersey) occurred in trees receiving maximum shelter, and these were due mainly to the increased abundance, and possibly increased activity, of honey bees there. Fruit size was not reduced where yields were increased.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01289.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYPost‐blossom sprays of fungicides, repeated at 10‐day intervals until leader (syn. extension) shoots had stopped producing new leaves, provided the best protection of terminal buds againstPodosphaera leucotrichaon the apple cv. Lane's Prince Albert. Spraying was most effective in early summer, although many of these buds were not invaded until later, when the rate of shoot growth declined; applications from July to September did not compensate for the enhanced infection which followed interruptions of the post‐blossom programme between late May and early July. This early period was critical because most leaf infections occurred then, and because this phase of the epidemic on foliage determined the eventual intensity of mildew on terminal leaves, and hence the inoculum available for infecting terminal buds. Also, many lateral shoots ceased growth early and their apices were directly protected by sprays applied in June. Applications after early June were too late to protect newly formed fruit buds on spur bra

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01290.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYBenomyl (0.025% a.i.) and thiabendazole (0.05 % a.i.) applied in July, August and September to apple trees cvs. Sunset and Cox's Orange Pippin gave slightly better control ofGloeosporiumspp. rots in stored fruit than captan (0.1% a.i.) applied at similar intervals. On Cox's Orange Pippin, treatment with captan at 0.1 % a.i. in July and at 0.2% a.i. in August was as effective as three sprays at 0.1 % a.i. in July, August and September in controlling bothGloeosporiumspp. andNectria galligenarots. Benomyl applied in the spring and early summer to control apple scab on orchard trees reduced the incidence ofGloeosporiumspp. andMonilia fructigenain stored fruit. Pre‐harvest sprays of benomyl and captan gave good control of rotting caused byN. galligenabut thiabendazole was ineffective. Post‐harvest dips of thiabendazole controlled rotting byGloeosporiumspp. butnot byN. gallig

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01291.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYVarious strains ofPuccinia chondrillina, theChondrillarust, were collected during surveys in the Mediterranean, undertaken to discover biological control agents suitable for use in Australia against skeleton weed,Chondrilla juncea.Only the strain collected at Vieste (S.E. Italy) was highly virulent against the common Australian form ofC. juncea.The specificity of this strain of the rust was tested by inoculation of many unrelated cultivated plants, related cultivated plants and closely related wild plants; all were immune to the rust. These tests satisfied the Australian plant quarantine authorities and this strain of the rust has now been introduced into Australia as a biological control agent forC. juncea.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01292.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe six‐rowed winter barley cultivar Vulcan was found to be highly resistant toRhynchosporium secalisin the field, although this resistance was not apparent in routine screening tests of barley genotypes carried out at the seedling stage. More precise seedling tests, using graded inoculum levels to derive dose‐response curves, showed that cv. Vulcan had an ED50which was 4.8 times that of the susceptible, two‐rowed cv. Maris Otter, and 4.1 times that of cv. Maris Puma.The inheritance of resistance was investigated at the adult plant stage in a cross with cv. Maris Otter. Although a clear‐cut segregation of the F3progeny into resistant, segregating and susceptible phenotypes was not observed, the genetic variance of the F3family means was compatible with the hypothesis of monogenic control of resistance. Resistance was inherited independently of the factor for six‐rowed

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01293.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe optimum temperature for growth and sporulation ofColletotrichum gloeosporioidesfromHevea brasiliensiswas between 26 and 32oC, whereas spore germination exceeded 90% between 21.5 and 30.5oC. Germination decreased in culture after 3 days, and on exposure of spores to sunlight or oven heat (46oC) for 10 min.Spore viability and germination were sensitive to atmospheric humidity; at 99% r.h. germination was half that at 100% r.h. and was negligible below 97% r.h. Germination decreased by up to 30% after 3 h storage at 80% r.h. Continuous light favoured spore productionin vitro, but spores produced in the dark had a higher percentage germination.No differences were detected between the numbers of spores germinating on leaves of different ages, although there were slightly more on susceptible cultivars and in the presence of extracts of uninfected susceptible leaves. Extracts from, infected leaves depressed spore germination, as did concentrations above 5 times 105spores/ml. The highest % germination was observed when naturally infected leaves were dry‐stored for up to 20 days and then incubated for 2 days in a moist chambe

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01294.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe lower leaf surface ofHevea brasiliensiswas more susceptible to infection byColletotrichum gloeosporioidesthan the upper. Few lesions were produced if spore drops on susceptible leaves were allowed to dry. Lesion development after 72 h was quickest at 21oC, slower at 26.5oC and was stopped at 32oC, probably because of bacteria in the inoculation drop. On leaflets aged 7 days from bud‐burst, the effective spore dose for 50% of leaflets infected (ED50) after 16 h incubation, was 260 spores and after 46 h, 120 spores/infection droplet; the minimum ED50for the upper leaf surface was about 4 spores/mm2. Leaflets 15 days old, which are normally resistant, were rendered susceptible by abrading the surface with carborundum powder.Spores caught in a Hirst spore trap reached a daily maximum at 23 h, at rates of up to 440 spores/m3air/h, but fell to low concentrations as the humidity dropped during the daytime, and also during rain. There was some correlation between disease severity and duration of 97–100% relative humidity, and moderate to severe defoliation of clone PB 86 occurred when this reached 13.5 h/day. Rainfall increases infection by prolonging the period of atmospheric saturation and leaf wetn

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01295.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYBacterial canker is a serious disease of poplar and it is important for commercial planting to select those clones of poplar which show resistance to the disease. In inoculation tests, natural bacterial slime and a pure bacterial suspension gave similar extent of invasion. A study of the life‐cycle of the disease indicated the presence of inoculum and of potential infection courts throughout the growing season. It is suggested that the susceptibility of a poplar clone should be determined by assessment of both artificial inoculations and natural infectio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01296.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYWyerone acid at 100μg/ml prevented germination of conidia ofBotrytis cinereaFr. in aqueous extracts of leaves ofVicia fabaL., but it was inactive in water and some synthetic nutrient solutions though antifungal activity appeared when the pH of these media was adjusted to 4.0 or 4.5. In pollen diffusates (V.fabaorNicotiana glutinosd) wyerone acid had little activity even at pH 4.0. In malt extract at pH 4.5 wyerone acid was active against several other plant pathogenic fungi but not againstB. cinerea.It was concluded that both pH and unknown components of natural media affected the fungitoxicity of wyerone acid

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01297.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

SUMMARYIn peaty loam soil in Cambridgeshire, 5.2 or 10.3 kg aldicarb/ha incorporated in the top‐soil before potatoes were planted controlled potato cystnematode (Heterodera rostochiensisWoll.) better than 384, 769 or 1153 kg D‐D/ha injected 15 cm deep into the top‐soil in the preceding autumn. 10.3 kg aldicarb/ha applied in 1968 and 1969 permitted King Edward potatoes (susceptible toH. rostochiensis) to grow well in infested soil and prevented multiplication of pathotypes ofH. rostochiensison Maris Piper potatoes (resistant toH. rostochiensispathotype A). Although large amounts of D‐D applied in 1968 and 1969 increased the yield of King Edward potatoes in both years they did not control potato cyst‐nematode in the se

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1972.tb01298.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY