摘要:

SUMMARYFoam‐rubber, carpet‐underlay discs placed in position around the base of the stem directly after transplanting were as effective as certain recommended insecticides in protecting brassica plants from damage by cabbage root fly (Delia radicum). The three factors that contributed to the overall effectiveness of the discs were that only half as many eggs were laid around plants protected with discs as around unprotected plants, that predatory ground beetles preferred to aggregate in the humid microhabitat beneath the discs and consequently ate proportionally more fly eggs/larvae and that the discs acted as a mulch, conserving water around the roots of the plants, and thereby permitting them to tolerate greater amounts of damage.Application of the repellent benzyl benzoate to the discs improved effectiveness but 12 other insect repellents and two sticky compounds gave no improvement and most were phytotoxic. Root drenches of the insecticide chlorfenvinphos were repellent, reducing oviposition by approximately 25%. The costs of protecting brassica transplants with either discs or insecticide were similar and discs thus appear to be a reasonable method of cabbage root fly control for small‐scal

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01960.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYWhen mixed into the casing or compost layers of a mushroom bed in the absence of pests, bendiocarb decreased yield and number of mushrooms according to concentration. The most severe effects were on mushroom number at the two highest rates used (100 and 1000 μg/g), and there were large increases in mushroom size. Effects of bendiocarb incorporation in the compost diminished with time, and there was partial compensation in yield and numbers at the fourth flush. The action of bendiocarb persisted when it was mixed into the casing.Diflubenzuron showed some opposite effects at lower concentrations. When either mixed into, or drenched onto the casing at the commercial rate (30 μg/g), yield and size were both increased and the timing of the flushes was unaffected. At the two higher concentrations (180 and 1080 μg/g), reductions in yield and number and an increase in mushroom size were shown. However, these effects became more severe with time, especially those on mushroom number, possibly due to the accumulation of a toxic breakdown produ

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01961.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYIn two apple orchard trials, single high volume sprays of 25–50 mg permethrin/ litre greatly reduced numbers of the phytosend predatory miteTyphlodromus pyriwhether the spray was timed pre‐bloom at growth stages from ‘bud‐burst’ to ‘late green cluster’ or post‐bloom in June. At ‘bud‐burst’T. pyriwere partially protected in hibernating sites on the bark, but the lethal effect of the spray was only delayed; no appreciable selectivity could be obtained by this early timing. Bioassays showed that the persistent toxicity of permethrin residues on bark or on leaves declined to a low level within 20 days, and was related to the decline in residue levels determined by G.C. analyses. Residues were detectable for 3 months or longer. Resurgence of spider mites,Panonychus ulmi, occurred within 2 months after all spray timings, and effective predation byT. pyriwas only fully re‐establised after several months. In one trial, apple rust mite,Aculus schlechtendalialso increased whenT. pyriwas reduced by spraying. Tydeid mites we

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01962.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYThe effects of cultivar, virulence of isolates ofLeptosphaeria coniothyrium, cane maturation and wound healing were examined in a series of inoculation experiments carried out over a 3–yr period in three countries in an attempt to explain why cane blight has caused serious yield losses in machine‐harvested red raspberries in Europe, but not in the Pacific Northwest of America. Three isolates ofL. coniothyriumfrom Puyallup (USA), Dundee (UK) and Dossenheim (FRG) were pathogenic on the three test cultivars Willamette, Malling Jewel and Glen Isla in all the experiments. Isolates and cultivars differed for aggressiveness and susceptibility respectively but their ranking was dependent on the test conditions and the differences were small and unlikely to explain the differences in incidence and severity of cane blight in raspberry fields in Scotland and the Pacific Northwest. Conditions at Dossenheim were most favorable for lesion development. At all sites, canes inoculated in late summer produced shorter lesions than those inoculated earlier. A delay between wounding and inoculation produced shorter lesions than simultaneous wounding and inoculat

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01963.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYA previously undescribed isometric virus, named ginger chlorotic fleck virus (GCFV), was detected in ginger (Zingiber officinale) imported into Australia from a number of countries. The geographical distribution of the virus is uncertain, but is thought to include India, Malaysia and Mauritius. The virus apparently does not occur in Australian commercial ginger plantings.The virus has isometric particlesc. 30 nm in diameter, with a sedimentation coefficient of 111 S, and was readily purified from infected ginger with yields of 50–90 mg/kg leaf tissue. Purified preparations contained a major species of single‐stranded RNA of mol. wt 1.50 × 106and a major coat protein species of mol. wt 29.0 × 103. At pH 7, the particles formed a single zone in both caesium chloride and caesium sulphate gradients, with buoyant densities of 1.355 g cm‐3(fixed virus) and 1. 297 g cm‐3(unfixed virus), respectively. The virus particles migrated as two electrophoretic components and were labile when treated with 10 mM EDTA, 1 M NaCI, 10 mM tris pH 8.25 or when negatively stained with potassium phosphotungstate. GCFV was mechanically transmitted only to ginger, and was not transmitted by the aphidsMyzus persicae. Pentalonia nigronervosa, Rhopalosiphum maidisorR. padi. Possible affinities of GCFV with the sobemo‐virus group are discussed.The present cryptogram of GCFV isR/l:1.5

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01964.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYSamples of soybean plants with virus‐like symptoms were collected from several locations in the People's Republic of China in 1981. These samples were used to prepare inocula for mechanical inoculation to soybean. Twenty‐one virus cultures were obtained, the identities of which were determined by serology, symptomatology and host range. Sixteen cultures contained only soybean mosaic virus, four of which were more pathogenic than any previously studied; one culture contained only tobacco ringspot virus, another only southern bean mosaic virus, and three other cultures mixed infections of soybean mosaic and southern bean mosaic viruses. This is the first report of the occurrence of tobacco ringspot virus and southern bean mosaic virus in soybean in the People's Republic of Ch

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01965.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYBean yellow vein‐banding virus (BYVBV) has been found occasionally in mixed infection with pea enation mosaic virus (PEMV) in spring‐sown field beans (Vicia faba minor) in southern England. Glasshouse tests confirmed that, like PEMV, BYVBV is transmissible by manual inoculation and by aphids in the persistent manner. However, BYVBV can be transmitted by aphids only from plants that are also infected with a helper virus, usually PEMV. Thus after separation from PEMV by passage throughPhaseolus vulgarisit was no longer aphid‐transmissible. It became aphid‐transmissible again only after re‐mixing in plants with PEMV or with a substitute helper, bean leaf roll virus (BLRV). It was not transmitted by aphids that fed sequentially on plants singly infected with PEMV and BYVBV. Thus the interaction between BYVBV and PEMV (or BLRV) that enables BYVBV to be transmitted by aphids seems to occur only in doubly infected plants. However, it was not transmitted by aphids from plants doubly infected with BYVBV and broad bean wilt virus (BBWV). BYVBV and PEMV were transmitted more readily byAcyrthosiphon pisumthan byMyzus persicae;neither virus was transmitted byAphis fabae.Phenol extracts of BYVBV‐infected leaves were more infective than phosphate buffer or bentonite‐clarified extracts and were sometimes infective when diluted to 1/1000. The infectivity of BYVBV in phosphate buffer extracts of leaves singly infected with BYVBV, unlike that in extracts of leaves doubly infected with BYVBV and PEMV (or BLRV), was destroyed by treatment with organic solvents. BYVBV infected 11 of 28 plant species that were inoculated with phenol extracts; seven of the infected species were legumes. No transmission of BYVBV was detected through seed harvested from infected field bean plants. Isometric particles c. 30 nm in diameter were seen in extracts of plants doubly infected with BYVBV and PEMV but not in extracts of plants infected with BYVBV alone. Leaves of plants infected with BYVBV, alone or with PEMV, contained membrane‐bound structures c. 50–90 nm in diameter associated with the tonoplast in cell vacuoles. These structures were not found in healthy leaves.BYVBV has several properties in common with other known aphid‐borne viruses that are helper‐dependent and transmitted in a persistent manner. Possibly, as suggested for some of them, aphid transmission of BYVBV depends on the coating of its nucleic acid with help

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01966.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYMelon necrotic leaf spot virus (MNSV) caused a major outbreak of a leaf necrosis disease of hydroponically‐grown cucumber plants at Humberside in 1983. The virus hadc. 33 nm diam. particles which reacted serologically with MNSV antiserum of Dutch or American origin. Virus particles, which contained a single polypeptide (mol. wt 45 × 103) and a presumed RNA species (mol. wt 1.5 × 106), had a sedimentation coefficient (s20.w) of 134 S and a buoyant density in caesium chloride of 1.35 g/cm3. The virus was mechanically transmissible, confined to species ofCucurbitaceae, transmitted by zoospores ofOlpidium radicaleand retained in the resting spores of the fungus. MNSV is thus both water‐borne and soil‐borne.O. radicalezoospores were killed in<5 min in suspensions containing 20 μg/ml of the surfactant Agral (alkyl phenol ethylene oxide). The disease did not reappear in 1984 when the cucumber crops were fed with nutrients containing 20μg

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01967.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYSix potato cultivars with different levels of resistance to the white potato cyst nematode (PCN)Globodera pallidaPa2 were grown for three seasons in field plots to whichG. pallidaPa2 cysts had been introduced earlier. There were two planting times, corresponding to early and maincrop commercial planting times, and two initial PCN population densities, high and low.The effect of cultivar on PCN population density was far greater than the effect of planting time or initial nematode population. The final PCN populations for the cultivars Ilam Hardy, Wha, 4696A(2), Sovereign, D40/6 and V390 were 151, 74, 27, 1.4, 0.2 and 0.06 eggs per g of soil respectively.It is concluded that resistant potato cultivars can be very effective in controllingG. pallidaPa2 in the field.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01968.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

SUMMARYThe effects of invasion by the cereal cyst nematode,Heterodera avenae, on the root growth of susceptible and resistant oat seedlings were similar. Nematode invasion directly inhibited root extension and lateral root production, which was dependent upon the developmental status of the invaded root tissue and the nematode density cm‐1root. Both responses are caused by mechanical damage due to nematode invasion leading to decreased top growth in the host. Reduced root development, decreased efficiency of water and nutrient uptake in invaded plants being indirect effects of nematode invasio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1986.tb01969.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY