摘要:

AbstractIn a moist chamberPseudopeziza medicaginisascospores infected alfalfa(Medi sativaL.) moderately to abundantly within 6–10 h at 10–20 °C and within a longer time‐span outside this temperature range. Approximate limits of the range were 2.5 and 28 °C; no infection took place at 30 °C. At 14°C ascospores infected alfalfa abundantly at 98 %relative humidity (RH) and above, moderately at 97%, sparsely at 95 and 96%, but not at 94% and below. Ascospores were hydrophilic, germinating best at or near 100%, RH but did not germinate at or below 93 % RH. After infection was established, tiny leafspots became visible within 6–7 days at constant temperatures of 15–25°, 10 days of 10°C, 13 days of 5 °C, and 25 days of 2.5 °C. They failed to develop into normal size spots within 4 weeks at constant temperatures near 30 °C, or near 10 °C and lower. Temporary exposure of incipiently diseased plants 1–6 days to 30–38 °C adversely affected subsequent leafspot development at 20–24°C. Inhibition depended on temperature and on the extent of post‐

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00068.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPeak daily discharge ofPseudopeziza medicaginisascospores in the field occurred after sunrise with attendant rises in temperature, wind, speed, and. dissipation of moisture. Protracted discharge over many days rose with initial development of robust, uncrowded apothecia and fell as these became spent and were joined by less productive, small, crowded ones. In the laboratory, detached field‐infected leaves discharged ascospores at 5°C to 32.5°C and at relative humidities as low as 90% when fresh, and at 94% or higher when wilted or dried. Pathogen‐free alfalfa plants placed overnight in a diseased affalfa plot were inoculated but uninfeeted more frequently in July than they were inoculated and infected. Artificially‐inoculated plants placed at the same time in a nearby sugar beet plot became infected every overnight. From early September through early October artificially inoculated plants placed in a plot of sugar beets or a plot of nearly disease‐free alfalfa for 24 h periods, became infected in 18 and 19 of 29 such periods. Light rain, fog and dew were frequent during these periods and early morning temperatures fell between ‐ 3 °C and 5 °C‐ in one‐half of the overnights. Dormant ascospores on foliage remained fully infective in the greenhouse for

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPythiaceous fungi were isolated from irrigation water using a variety of natural and artificial baits. Isolates were also obtained by plating water samples directly on the surface of selective agar media. The selective medium of Ocana and Tsaq (1966) PlOVP, was modified by substituting rifampicin and ampicillin (10 and 500 μg cm−3respectively) for vancomycin to suppress bacterial growth from water samples.The pythiaceous fungi were identified asPythiitm dissotocitm, P. middletonii, P. mamillatum, P. rostratum, Pythium“group 1”, “group 2” and “group 3” andPhytophtbom gona‐podyides.All isolates ofP. gonapodyideswere the A1 strain and produced oospores when paired with an A2 isolate ofP. drechsleri.Isolates were tested for their pathogenicity toAntirrhinum, tomato andChatmaecyparis lawsonianacv. Ellwoodii.Pythium middletoniiandPythium“group 1” caused severe pre‐emergence damping‐off ofAntirrhinumseedlings,P. mamillatuni, P. rostratumandPythium“group 3” were less pathogenic to the same host whileP. dissotocum, Pythium“group 2” andPhytophthora gonapodyideswere non‐pathogenic. Only isolates ofPythium“group 1” were pathogenic to tomato seedlings. None of the fungi was pathogenic to rooted cuttings o

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe relationships between bean yellow mosaic (BYMV), bean common mosaic (BCMV), clover yellow vein (CYVV), lettuce mosaic (LMV), potato virus Y (PVY), turnip mosaic (TuMV) and celery mosaic (CeMV) viruses were studied in homologous and heterologous reactions, using simple and relatively rapid electron microscope serology decoration tests. The degree of relationship between these viruses was assessed by the intensity of antibody coating when the viruses were decorated by heterologous antibodies. A close relationship was observed between BYMV and CYVV, and between BYMV and LMV but not between CYVV and LMV. CeMV was quite closely related to BYMV and CYVV.Antibodies to BCMV and BYMV intensely decorated different strains of their own virus, but decoration was negligible in cross reactions.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractOn mycoflora analysis of dried fruits and seeds of chilli stored for six months,Aspergillus flavusandA. nigerwere the more frequent out of eighteen fungi isolated. Some terpenoids viz, Citral, Citronellal, Citronellol, Eugenol, Farnesol and Nerol showed absolute toxicity againstA. flavusandA. nigerat 0.5 per cent concentration. The minimum inhibitory concentration (MIC) and nature (fungistatic/fungicidal) of all the terpenoids against both these fungi were determined, Citral, Eugenol and Nerol exhibited a broad range of toxicity and were found to be more efficacious than some synthetic fungicides.

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractIn Surinam, the commercial cultivation of the yellow passion fruit(Passiflora edulis f. flavicarpa)is difficult due to the occurrence of dieback. Symptoms referred to as dieback include a decrease in elongation of the shoot end internodes after a period of normal growth leading to wilting and death of the shoots. Fruits from plants showing dieback symptoms are much smaller than those from healthy plants. From shoots with dieback symptoms, three fungi were isolated includingColletotrichum gloeosporioides.However, inoculation experiments with these fungi on shoots of vigorously growing plants were negative, even after wound inoculation.It appeared that plants with dieback symptoms had a poorly developed root system, From these rootsFusarium solaniwas isolated, which appeared to be highly pathogenic to roots of the yellow passion fruit. After inoculation of the roots of 3‐month‐old plants, roots became infected and the aerial plant parts showed typical dieback symptoms.Plants with their root system reduced either by inoculating withF. solanior by clipping, and subsequently inoculated withC. gloeosporioideson the aerial parts 2 weeks later, showed dieback symptoms and infection byC. gloeosporioidesin shoots with these symptoms. Thus, a badly functioning root system, for example caused by infection ofF. solanileads to dieback and predisposes plants to infection byC. gloeosporioides.The latter fungus itself is not a primary pathogen of shoots of the yellow passion fruit in Suri

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractNine isolates ofRhizoctonia solanifrom various hosts were selected for this study. The isolates were tested for their compatibility by an anastomosis test. Isolates were classified into two Egyptian anastomosis groups (EAG‐1 and EAG‐2). The isolates varied in virulence, thiamine requirement and quality and quantity of free and protein amino ac

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractFungitoxic phenolic compounds were released from cucumber mosaic virus (CMV)‐infected and noninfected cowpea protoplasts. These compounds were presumed by thin layer chromatography as similar compounds released into the leaf ambient fluids when CMV‐infected cowpea leaves were incubated in water. Larger amounts of the compounds were released from CMV‐infected cowpea protoplasts than from noninfected protop

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractPrevious work led to the characterization of, and the production of an antiserum to a closterovirus referred to as grapevine stem pitting‐associated virus (GSP‐AV). Using this antiserum and immunoelectron microscopy, we now show that GSP‐AV is widespread in grapevines and that a second serologically distinct closterovirus‐like particle is also widely present. One or both of the closterovirus‐like particles were often but not always associated with leafroll symptoms. However, some plants indexed as suffering from stem pitting also contained one or both of the particles.As “grapevine stem pitting‐associated virus” no longer seems appropriate as a name, we suggest changing it to grapevine virus A (GVA). We provisionally refer to the second closterovirus‐like virus as grapev

ISSN:0931-1785    

DOI:10.1111/j.1439-0434.1984.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY