ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03812.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYApplications of streptomycin sulphate or protectant fungicides reduced numbers of secondary infections in severely infected hop plantings. When primary infected shoots treated with streptomycin were left on plants for 3 weeks no significant increase in secondary disease resulted. Streptomycin, which was absorbed rapidly by hop plants, could not be detected in expressed shoot sap by early June and had no effect on crop yield or quality.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03813.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYApparently normal pea seeds from pods bearing lesions ofMycosphaerella pinodeswere often internally infected with the fungus. When infected seeds were sown in sterile grit almost all the seedlings showed disease lesions, at or below soil level, 4–6 weeks after sowing.Seed infected withAscochyta pisigave only 40% infection of seedlings: these showed lesions on the stem and first two leaves within 4 weeks of sowing.Infection of seeds by both pathogens could be eradicated by soaking the seeds for 24 hr. in 0.2% suspensions of thiram or captan at 30d̀C. In laboratory or greenhouse tests these treatments did not check germination, but in the field the captan treatment reduced emergence.The treated seeds became fully imbibed but could be dried and stored: the thiram treatment was used for semi‐commercial treatment of quantities of seed up to 3

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03814.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYPercentage germination, and growth of hyphae from single conidia ofErysiphe cichoracearumDC., were measured on leaf discs from topped and intact tobacco plants, grown in aerated nutrient solutions consisting of basal medium plus large or small amounts of potassium. The effect of supplying sodium was also studied. Discs were incubated on water and on 10% sucrose solution. Changes in free amino nitrogen and carbohydrate in comparable uninfected leaf discs, before and after incubation, were also measured.Potassium deficiency resulted in more free amino nitrogen and soluble carbohydrate and less insoluble carbohydrate, per cm.2of leaf. Spore germination was not greatly affected by treatments, though it was usually less on discs from potassium‐deficient leaves. The pathogen grew slower on potassium‐deficient leaf discs, whether they were incubated on water or on sucrose.Incubating discs from some leaves on sucrose, compared with water, gave greatly increased sugar content and less fungal growth; discs from other leaves had a much smaller increase in sugar, and hyphal length was similar to that on discs incubated on water.Sodium, when potassium was scarce, increased potassium deficiency symptoms, free amino nitrogen and sugar content, and resistance to powdery mil

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03815.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARY2,6‐Dinitro‐4‐s‐alkylphenols were found to protect apple foliage against powdery mildew more effectively than isomeric 2,4‐dinitro‐6‐s‐alkylphenols; regression lines for fourpara‐alkyl compounds were of similar slope but were much steeper than those for twoortho‐alkyl compounds (including dinocap phenol). The ED50and ED95values of the most active compound studied, 2,6‐dinitro‐4‐(I‐ethylhexyl)phenol, were in the ratios to those of dinocap phenol of 1:13 and 1:125, respectively, and the protective action of this compound was greater than the curative, especially at the higher ED values. Protection of barley seedlings against powdery mildew was also greater by I‐ethyl‐ or I‐propyl‐alkyl compounds than by I‐methylalkyl or n‐alkyl isomers.For phytotoxic and acaricidal actions, theortho‐alkyl isomers are more effective thanpara‐alkyl. Nevertheless, the acaricidal activity of dinocap phenol is exceeded by that of the isomeric 2,4‐dinitro‐6‐(I‐ethylhexyl) phenol.The control of these powdery mildew diseases given by commercial products, supposed to be based on dinocap, cannot be accounted for by the activity shown for dinocap phenol. It can, however, be accounted for by the activities of 2,6‐dinitro‐4‐(I‐ethylhexyl)‐ and ‐(I‐propylpentyl)‐phenols, now known to be present in commercial products in larger amounts than dinocap phenol itself. The phytotoxic and acaricidal actions of such products, however, are mainly due to theortho‐octyldinitrophenols present; in view of the small proportion that is dinocap phenol, the acaricidal activity is likely to be due almost entirely to the otherortho‐octyl isomers.It is suggested that the common name dinocap be retained for the mixture of dinitrooctylphenols now known to be present in commercial products, and that the two main groups be differentiated as 2,4‐dinocap and 2,6‐dinocap, respectively. The advantages

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03816.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYSix isomers, isolated from the mixture of dinitrophenols obtained by the hydrolysis of commercial formulations containing dinocap, were tested in the greenhouse against apple mildew caused byPodosphaera leucotricha.The two most active compounds were 4‐(Ié‐ethylhexyl)‐ and 4‐(Ié‐propylpentyl)‐2,6‐dinitrophenols, which appear to account for most of the antimildew activity of the mixture. The crotonate of the latter phenol was considerably more effective than dinocap itself, but both crotonates were less effective than the corresponding free phenols.Little evidence of synergism between two ethylhexyldinitropheno

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03817.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYThe uptake of captan from aqueous solution by conidia ofNeurospora crassacan be markedly reduced by pretreatment of the cells with thiol reagents such as iodoacetic acid (IOA). The nature of this reaction has been investigated and it is shown that IOA largely reacts with the soluble thiol pool of the spores. Captan, however, reacts with both soluble and insoluble thiols and it is suggested that whilst the former is a detoxication process the latter may provide the key to its toxic action.Using glutathione as a model soluble thiol the molar ratio and pH dependence of the captan detoxication process has been determined and compared with the cellular reactions. Assay of35S‐labelled captan has shown that captan is almost completely decomposed by the spores and that one‐third of the accumulated captan is converted to sulphur compounds fixed to insoluble cell entit

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03818.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYWhen used in tests against eggs of Heterodera schachtii, sodium ethylenebisdithiocarbamate (nabam) solutions break down to give a number of compounds, some being hatch‐inhibiting and others hatch‐stimulating. The compound mainly responsible for the hatch‐stimulating activity of nabam solutions is ethylenethiuram monosulphide. Stored solutions of sodium ethylenebisdithiocarbamate lose activity because the ethylenethiuram monosulphide disappears.Zinc and manganese ethylenebisdithiocarbamates were more active hatching agents than equimolar mixtures of zinc or manganese sulphates with nabam. Hatch stimulation was least with a zinc sulphate/nabam mixture of mole ratio 1.5:1, in which the dithiocarbamate ion became largely replaced by the sparingly soluble zinc dithiocarbamate. Increasing the zinc concentration in the mixture increased hatching because of the hatching activity of the zinc ion.Nabam solutions containing manganese sulphate were inactivated because the manganese ion catalysed decomposition to the hatch‐inhibiting carbon disulphide.SodiumN‐methyldithiocarbamate (metham‐sodium, Vapam), which readily decomposed in aqueous solution, was toxic to, and prevented the hatching of,H. schachtii. Methylisothiocyanate, the major decomposition product, was toxic toH. schachtiiat concentrations greater

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03819.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYLeaf and tiller development in vegetative plants of S.37cocksfoot (Dactylis glomerataL.), S.215meadow fescue (Festuca pratensisHuds.) and S.24perennial rye‐grass (Lolium perenneL.) were measured in photoperiods varied by extending a basic period of natural light with low‐intensity artificial illumination so that all plants received approximately the same amount of light each day. Increasing the photoperiod usually increased leaf length and sometimes leaf width, but decreased rate of production of leaves. However, the rate of production of new leaf surface increased with photoperiod. Increasing the photoperiod generally decreased the rate of tillering; thus, plants grown in long days had few tillers with large leaves and sheaths, in short days, plants developed more but smaller till

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03820.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

SUMMARYLong photoperiods provided in growth cabinets and consisting of a conventional extended photoperiod or of a ‘light‐break’ in the middle of a long, dark period, generally increased leaf length and sometimes leaf width and consequently the rate of expansion of leaf surface, but decreased rate of leaf production and tillering in vegetative plants of S.37cocksfoot (Dactylis glomerataL.), S.215meadow fescue (Festuca pratensisHuds.) and S.24perennial rye‐grass (Lolium perenneL.) compared with short photoperiods. All plants received the same total amount of light each day. These effects were observed both in single plants and in plants grown close together to simulate sward conditions. The total dry weight of plant material was greater in long than in short photo

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1966.tb03821.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY