Bud necrosis,a storage disease of tulips IV. The influence of ethylene concentration and storage temperature on bud development

Ethylene in concentrations as low as 0.05 ppm inhibited the elongation growth of the main generative bud within tulip bulbs during storage after lifting. The sooner the ethylene was administered after lifting and the higher the storage temperature, the higher the concentration of ethylene needed to obtain the same degree of inhibition. Fifty percent inhibition was found at concentrations between 0.05 and 10 ppm. Stamens within the buds were inhibited to a degree which was generally lower compared with the leaves; the largest differences were found at 13°C, whereas at 23°C the degree of inhibition was nearly equal. Open buds (which result from unequal growth of stamens and young leaves and are the prerequisite of bud necrosis) were induced by exposure to ethylene in concentrations as low as 0.1 ppm. This phenomenon occurred in bulbs exposed to ethylene for 6 weeks at 17°C shortly after lifting; at other temperatures and later exposure times, higher concentrations were needed to obtain the effect. During storage after exposure to ethylene, growth resumed and the degree of bud deformation mostly decreased; in bulbs that had been treated later, an increase was found when the ethylene concentration had been higher than 1 ppm. After planting, shoots emerging from ethylene-treated bulbs were shorter, basal internodes of the stem were shorter if the concentration was 1 ppm or higher, and the width of leaves was reduced after early exposure.     

Bud necrosis,a storage disease of tulips. I. Symptoms and the influence of storage conditions

The symptoms of bud necrosis in tulip bulbs are described. This disorder is neither contagious nor hereditary. It is found more often and more severely in certain cultivars (viz Red Champion and White Sail) than in others (viz Rose Copland) in which it appears less frequently or not at all. The disease originates in the stamens of the flower-producing main bud during dry storage between lifting and planting of the bulbs. The occurrence of the disease in sensitive cultivars is promoted by storage of the bulbs under conditions of poor ventilation (viz packed in cardboard boxes) and at higher temperatures later in the storage period (after September 1).The experimental results suggest that there are several pathogenic factors and that the combined action of these factors can lead to bud necrosis; the primary factor is probably of physiological nature.Samenvatting Kernrot is een afwijking in tulpebollen die een bloeibare maat hebben. De ziekte ontstaat tijdens de droge bewaring van de bollen en begint met afwijkingen aan de meeldraden. Bij de beschrijving is onderscheid gemaakt tussen symptomen welke zich tijdens de droge bewaring voordoen aan de knoppen waaruit zich de bloeiende spruit zal ontwikkelen en symptomen welke zich voordoen aan de bollen tijdens de bloei te velde. Naar de mate waarin de knoppen en planten afwijken, wordt gesproken van meeldraadnecrose (Fig. 1A en 2), bloemnecrose (Fig. 1B en 4A), spruitnecrose (Fig. 1C en 4B), kernnecrose (Fig. 1D en 4C) en bolnecrose (Fig. 4D).Het is gebleken, dat de ziekte bij bepaalde cultivars (Red Champion en White Sail) vaak voorkomt, bij andere minder vaak (Rose Copland) of in het geheel niet. Er kon worden vastgesteld, dat de ziekte niet besmettelijk of erfelijk is.In de proeven werd het ontstaan van de afwijking bij Red Champion en White Sail bevorderd door de bollen te verpakken in kartonnen dozen (ventilatiebeperking) en door de bollen later in het seizoen (na 1 september) te bewaren bij hogere temperaturen dan daarvoor. Op grond van de proefresultaten wordt aangenomen dat de primaire oorzaak van de afwijking van fysiologische aard is. De aanwezigheid van schimmels, bacteriën en mijten moet als tweede oorzaak worden beschouwd.     

Bud necrosis,a storage disease of tulips. II. Analysis of disease-promoting storage conditions

The syndrome of bud necrosis, a storage disease of tulips, is analysed and relationships between several phenomena are described:

1. In ‘White Sail’, bud necrosis occurred in cardboard boxes only when bulbs infected withFusarium oxysporum f. tulipae were present.
2. Buds with symptoms of bud necrosis were open at the tip.
3. Whereas in ‘White Sail’, open buds occurred in boxes only whenFusarium-infected bulbs were present, in ‘Red Champion’, open buds occurred also in well-ventilated open trays with wire-gauze bottoms stored at higher temperatures but withoutFusarium-infected bulbs. In ‘Rose Copland’, open buds were only found exceptionally.
4. In buds with symptoms of bud necrosis, mites were almost always present.
5. In boxes in whichFusarium-infected bulbs were present, ethylene concentrations up to 23 ppm were found.

On the basis of these findings it seems highly probable that bud necrosis develops only if mites penetrate into the buds and reach the stamens. A prerequisite for penetration is the presence of a pore in the bud tip. Ethylene, emanated byFusarium-infected bulbs or from other sources and accumulating under conditions of poor ventilation, is probably the direct cause of open buds. In ‘Red Champion’, however, this aberration can also be caused by higher storage temperatures even with good ventilation. In a subsequent paper proof of this hypothesis will be presented.     

A fungitoxic substance extracted from tulips and its possible role as a protectant against disease

A specialized strain ofFusarium oxysporum is the cause of a disease important in tulip bulb cultivation. From observations in the field it was concluded that the fungus is not able to penetrate into the tulip bulb during the greater part of the growing season. A protecting barrier was demonstrated to be present in the white skin. From extracts of this white skin (and from other parts of the tulip plant) a fungitoxic substance was isolated, which was identified as α-methylene butyrolactone. A possible precursor of this lactone has been isolated which, under certain conditions, yields the lactone in vitro. The implications of the presence of the fungitoxic substance in extracts made from different parts of the plant in relation to the susceptibility toFusarium are discussed.     

Distribution and migration of insects and mites in flat storage containing wheat

Studies were conducted in a flat storeroom in central Greece, filled with approx. 90 tons of wheat, in order to evaluate insect and mite species abundance, and changes in population density and distribution among sampling units and locations. The surface of the grain bulk was divided into two sampling zones: the central and the peripheral (edge). At 10-day intervals, five wheat samples were taken from the central zone and eight from the peripheral zone, with a non-partitioned grain trier (1.6-m length, 250-g capacity). Fifteen insect species and 12 mite taxa were found during the sampling period, (June 1999–Feb. 2000). The most abundant insect species wereSitophilus oryzae (L.),Cryptolestes ferrugineux (Stephens),Tribolium castaneum (Herbst) andLatheticus oryzae Waterhouse; the most abundant mite species wereAcarus siro L.,Lepidoglyphus destructor (Shrank), and the predatorsBlattisocius tarsalis (Berlese) andB. keegani Fox. Grain temperature decreased during the storage period, more slowly in the central than peripheral zone; grain moisture content increased. The highest population densities for both insects and mites were recorded during September and October. The most numerous species of insects and mites showed an aggregated spatial pattern, as indicated by Iwao’s Patchiness Regression.     

Parasitic mites of Surinam. XXXII. New species of feather mites (Sarcoptiformes, Analgoidea).

Seven new species of feather mites belonging to families Analgidae, Falculiferidae, Pterolichidae, Pteronyssidae and Xolalgidae are described from Columbiformes, Cuculiformes, Piciformes and Passeriformes of Surinam.     

MYC 8005, an antibiotic against spider mites. 2. Growth inhibition and pseudo-sterilization in insects and mites

The antibiotic MYC 8005, known as an acaricide, appeared to possess strong growth inhibiting properties, not only in immature stages of spider mites but also in larvae of several insect species. Adult mites and insects seemed not to be affected. However, the fecundity of femaleTetranychus cinnabarinus was strongly reduced by deposits of MYC 8005 on the leaves of bean plants. The feeding of adult houseflies and Colorado potato beetles with MYC 8005 resulted in complete or almost complete sterilization of the insects. The sterilizing effect appeared to be caused by inhibition of maturing processes, in particular of yolk formation in the eggs, whereas follicles looked normal. These facts, and the strong reduction of the fat body in treated insects, suggest that the lipid and protein metabolism are disturbed by MYC 8005.     

Seasonal abundance and vertical distribution of mites in flat storage containing wheat

The present study was carried out in a flat storeroom in central Greece, filled with approximately 60 tons of newly harvested wheat, in order to evaluate the population dynamics of stored-product mites and their predators in connection with horizontal and vertical distribution. At 15-day intervals, from July 2000 until March 2001, three replicates were taken from each sampling point at depths of 0–40, 40–80 and 80–120 cm, with a partitioned grain trier. The sampling points were divided into two zones, namely, central and peripheral. Air temperature, relative humidity, grain moisture and grain temperature were recorded during the sampling period. Twenty-four mite taxa were found, the dominant species beingTyrophagus putrescentiae (Schrank) andAcaropsis docta (Berlese). The numbers of these species varied significantly in the two zones and at the three depths. More individuals were found in the center compared with the periphery of the wheat bulk, and at the surface of the bulk than at greater depths. The highest mite population densities for the total mite species were recorded during October–November and after the middle of January. http://www.phytoparasitica.org posting Nov. 4, 2005.     

The influence of temperature on the development of Moniezia expansa (Rudolphi, 1810) in oribatid mites

The life cycle of Moniezia expansa was studied experimentally using 10 species of oribatid mites as intermediate hosts. Four of them became infected, namely Scheloribates laevigatus (76.2%), Sch. latipes (70.8%), Liacarus coracinus (20%) and Platynothrus peltifer (1.1%). The last was found for the first time to serve as intermediate host of M. expansa in Czechoslovakia. The development of the cysticercoid of M. expansa in the oribatid mites at 28 degrees C and 85% relative humidity is completed within 27 days. At 18-20 degrees C and the same relative humidity the development lasts even 97 days.     

The influence of light upon blueing of tulip bulbs,a disease of a physiological nature

Summary The blueing of tulip bulbs is a physiological disease resembling in some ways physiological diseases of other plants. Recent experiments indicate that sunlight influences blueing. By shading the plants the extent of the disease was considerably reduced or even eliminated. The influence of light was found to apply only during a certain period of the season, the most susceptible period being in the last week of April and the first two weeks of May.A hypothesis has been developed concerning the origin of the necrotic spots in the bulb, which may also hold good for toppling of tulips. It is assumed that cell sap, possibly together with sugars, are excreted from the cell into the intercellular spaces of the parenchymatous tissue, thus bringing about a necrosis.Samevatting Het blauwgroeien van tulpebollen is een fysiologische ziekte, die in bepaalde opzichten overeenkomst vertoont met fysiologische ziekten bij andere gewassen.Nadat vroeger werd aangetoond, dat er een duidelijke correlatie bestaat tussen de bolgrootte en het percentage zieke bollen en dat de groei van de bol waarschijnlijk verband houdt met de ziekte (fig. 4), is door recente veldproeven duidelijk geworden dat het zonlicht of de straling een grote invloed op het blauwgroeien heeft. De verspreiding van de zieke bollen in de bedden op het veld is niet willekeurig. Er is een duidelijk randeffect waar te nemen, d.w.z. dat de bollen in de regels aan de padkant verhoudingsgewijs een groter aantal zieke bollen hebben dan de bollen in de regels midden in de bedden (zie fig. 1–3). Dit randeffect werd in hoofdzaak toegeschreven aan de werking van het zonlicht. Door het gewas te beschaduwen met een scherm van plastic horregaas (lichtabsorptie ongeveer 50%) of van jute doek (lichtabsorptie ongeveer 75%) kon de ziekte sterk worden verminderd of zelfs geheel worden geëlimineerd. Door periodiek te schermen kon in veldproeven een bij uitstek gevoelige periode, wat de lichtinvloed betreft, worden aangetoond. Deze periode viel ongeveer in de laatste week van april en in de eerste twee weken van mei (fig. 3). Het afschermen van het gewas tijdens de gevoelige periode zou met het oop op de ziekte het bruikbare deel van de geoogste bollen aanzienlijk vergroten (fig. 6). Het bolgewicht wordt door deze periodieke afscherming slechts matig ongunstig beïnvloed. Of deze maatregel met het oog op de kosten ook economisch verantwoord is, valt te betwijfelen.Behalve het feit dat het licht effect zal hebben op de groei en de grootte van de bol en daarmede het ziektepercentage zal beïnvloeden, kon worden aangetoond dat het licht of de straling een zeer specifieke werking op de ziekte heeft (zie fig. 5). Welke werking het zonlicht of de straling heeft, is niet geanalyseerd. In de discussie zijn over het ontstaan van de necrotische plekken inde bol suggesties gedaan, die echter bij gebrek aan nadere gegevens een speculatief karakter dragen. Als basis voor verder onderzoek wordt aangenomen, dat analoog aan wat zich bij het kiepen van tulpen voordoet, een excretie van vloeistof celinhoud) in de intercellulaire ruimten van het parenchymweefsel plaats heeft, die een necrose zou veroorzaken.     

Synopsis of type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. III. Nematoda

The paper comprises a list of the nematode type specimens deposited in the helminthological collection of the Institute of Parasitology, Czechoslovak Academy of Sciences, in Ceské Bud?jovice. These materials include a total of 110 species and subspecies.     

影响捕食螨防治柑橘害螨效果的主要因素与对策

由于过渡依赖化学农药防治柑橘病虫害,诱发柑橘害螨猖獗,为害程度加剧。为提高害螨综合防控效果,推广以螨治螨技术,本文对影响捕食螨防治柑橘害螨田间效果的果园生态系统、释放时机、田间管理与化学防控等主要因子进行了分析,同时提出了应对策略。     

放牧对小针茅荒漠草原枯落物及植被生产力的影响

在内蒙古苏尼特右旗荒漠草原试验示范基地,设置不同放牧强度和围栏对照5个处理,于2014年的5 ～10月生长季测定不同放牧强度下小针茅草地枯落物的蓄积量、蓄积动态、地上生物量和地下生物量月动态,并探讨了小针茅荒漠草原枯落物蓄积量及地上、地下生物量对放牧强度的响应.研究结果表明:1)围封条件下小针茅群落枯落物蓄积量最大,平均值为29.22g/m2;随着放牧强度的增加枯落物蓄积量减少;极重度放牧条件下小针茅群落枯落物蓄积量比围封对照区减少了57.77％.2)5-10月生长季,小针茅群落枯落物蓄积量在不同放牧强度下均随时间呈”Ⅴ”型的变化规律.3)小针茅群落地上和地下生物量均随着放牧强度的增加而减少,地下根系主要分布在0 ～ 10cm深度土层中,占0-30cm地下生物量的57.23％ ～ 66.83％,该比例随着放牧强度的增加而减少.     

Factors affecting the activities of nitrophenol fungicides III. The influence of substituents on the hydrogen bonding characteristics of nitro- and halogeno-phenols

The hydrogen bonding characteristics of alkyl, halogeno- and cyanonitrophenols and some halogenophenols were determined from a study of their i.r. spectra. Relative strengths of inter- and intramolecular bonds are quoted.     

Purification of lily symptomless virus. Use and value of antisera against intact and pyrrolidine-degraded virus for testing lilies and tulips

Lily symptomless virus (LSV) was purified by clarification with chloroform, precipitation with polyethylene glycol and NaCl, and differential centrifugation. The influence of the source material and some buffers on virus yields were determined.Antisera were prepared against intact and pyrrolidine degraded LSV. It was concluded that intact and degraded LSV have very few antigenic determinants in common or none at all. The sensitivities of the micro-precipitin test and the single immunodiffusion drop test were about the same, but lower than that of electron microscopy.In the testing of lilies for LSV the most reliable results in leaves were obtained during the period from two weeks after flowering until close to the end of the growing season, and in leaves growing at a level about one-fourth of the distance from the top of the stem. In contrast to secondary infections, primary infections were detected more successfully in stored bulbs than in leaves taken from plants in the preceding growing season.In the testing of tulips, LSV was detected better in flowers than in leaves. Detection of primary infections was almost impossible. Except for those with a pink flower, experimentally infected tulips remained symptomless.Samenvatting Het symptoomloos lelievirus (LSV) were gezuiverd door klaring met chloroform, precipitatie met polyethyleenglycol en NaCl en differentieel centrifugeren. Het effect van het uitgangsmateriaal en enkele buffers op de virusopbrengst werd nagegaan.Antisera werden bereid tegen intact en met pyrrolidine afgebroken LSV. Geconcludeerd were dat intact en afgebroken LSV geen of slechts enkele antigene determinanten gemeenschappelijk hebben.De gevoeligheid van de microprecipitatietoets en de enkele immuno-diffusiedruppeltoets is ongeveer gelijk. Met het elektronenmicroscoop kunnen echter lagere virusconcentraties worden aangetoond.Het toetsen van lelies op LSV gaf de betrouwbaarste resultaten met bladeren die op ongeveer driekwart hoogte van de stengel groeien en in de periode tussen 2 weken na de bloei en vrijwel het einde van het groeiseizoen worden geplukt. Primaire infecties konden, in tegenstelling tot secundaire infecties, beter worden vastgesteld aan bolmateriaal tijdens de bewaring dan aan bladeren in het voorafgaande groeiseizoen.Bij het toetsen van tulpen werd het LSV met grotere zekerheid vastgesteld in bloemen dan in bladeren. Het vaststellen van primaire infecties was bijna niet mogelijk. Na infectie van tulpen met LSV vertoonden alleen die met een rose bloemkleur symptomen.     

The influence of growth conditions on biomass, toxins and pathogenicity of Fusarium oxysporum f. sp. orthoceras, a potential agent for broomrape biocontrol

The influence of different combinations of illumination and shaking on the growth dynamics, pathogenicity and toxin production of the fungus Fusarium oxysporum f. sp. orthoceras, a biocontrol agent of Orobanche cumana, was studied. The fastest biomass accumulation was obtained under shaking, with or without illumination, with the highest biomass obtained after 3–4 weeks of growth. The biological activity of chloroform extracts of the culture filtrate was characterised: it contained at least two main toxic metabolites that caused necrosis and wilting of various plants and led to mortality of germinating seeds of O. cernua, O. aegyptiaca, O. ramosa and O. cumana. The highest toxic activity of the chloroform extract was obtained under illumination without shaking after 3–4 weeks of growth. The two toxic metabolites were purified and identified as fusaric acid (FA) and 9,10‐dehydrofusaric acid (DFA). Both FA and DFA production began in the first week of growth, increasing gradually to their maxima after 4 weeks. The highest level of pathogenic activity of the fungus was obtained after three or more weeks of fungal growth. It can be concluded that in order to produce high levels of toxin and pathogenic activity, the fungus should be grown under illumination without shaking for 4 weeks.     

The feather mites of the family Proctophyllodidae (acari, sarcoptiformes) from Nepalese birds

Eight species of birds of the families Fringillidae (3), Motacillidae (2), Prunellidae (1), Pycnonotidae (1) and Turdidae (1) were found to be parasitized by 8 species of the genus Proctophyllodes, 3 of them being new to science: P. danieli sp. n. from Pycnonotus leucogenys, P. macrophallus sp. n. from Prunella collaris and P. puniceus sp. n. from Pyrrhospiza punicea. Other species recorded are P. anthi, P. cotyledon, P. glandarinus, P. leucosticti and P. aff. poublani. All hosts were collected in the region of the Barun river valley in East Nepal in the altitude of 3,600-4,900 m a. s. l.     

The influence of herbicides, nitrogen fertilizer, seed rate and method of sowing, on the establishment and long-term composition of a perennial ryegrass ley.

Changes in ihe species composition of a ryegrass pasture were examined over a 2 year period from a spring establishment. Seed of S23 perennial ryegrass was sown in main plots, eilher broadcast or drilled, at rates of 15, 25 or 35 kg/ha in a field experiment at Oxford. The whole area was oversown withfour weed grasses (Agrostis siolonifera.Holcus lanatus. Poa annua and P trivialis). Five cultural and three herbicide treatments were applied across the plots. These consisted of three levels of nitrogen (0. 50 and 100 kg N per ha), two companion species (Italian ryegrass and white clover) and 2.4-D, benazolin and methabenzihiazuron applications. Ten weeks after sowing, broad-leaved weeds accounted for nearly half the lotal dry-matter yield, except where controlled by the three herbicides. Grass yields were nol increased by herbicide treatment. The only cultural treatment checking broad-leaved weeds was ihe 35 kg/ha seeding rale. Seven months after sowing, the only treatment which had decreased the abundance of weed grasses was melhabenzthiazuron especially againsi A. stolonifera and Poa spp. Two years afler sowing, perennial ryegrass had only 34% ground cover and had been replaced largely by H. lanatus (38%), Poa spp, (15%) and A. stolonifera (7%), Where methabenzthiazuron had been used the ryegrass ground cover was 48%. with less P. trivialis and A. stolonifera. but H. lanatus was nol altered. White clover decreased H. lanatus cover. In two supplementary pot experiments, methabenzthiazuron sprayed pre-emergence damaged perennial ryegrass unless the seed was covered with at least 4 mm of soil. Only H. lanatmand F. rubra out of sixteen grasses were relatively resistant to methabenzihiazuron when applied at ihe tillering stage, confirming that this herbicide has potential for preventing the ingress of many unsown grasses in new leys.