Effect of benomyl on soil fungi associated with rye. 2. Effect on fungi of culm bases and roots

The mycoflora of culm bases and roots of rye was assessed in field trials, where benomyl was applied at dose rates ranging from 0.24 to 4.80 kg ha^?1. Samples of culm bases were taken three times during the growing season, those of roots only at the harvest date. On culms with various symptoms from untreated plots,Pseudocercosporella herpotrichoides, Alternaria spp. andGerlachia nivalis were prevalent and on those from benomyl-treated plotsAlternaria spp. andFusarium culmorum. In later stages of growth,G. nivalis sharply declined andAlternaria spp. andF. culmorum increased. At the end of the season,Periconia macrospinosa andTyphula incarnata appeared in treated plots. In samples of roots taken more than two months after the last spray, porosporous dematiaceous species (Alternaria, Ulocladium andDendryphion), Mortierella spp. and other resistant fungi were prevalent in plots treated with 1.20 kg ha^?1 or more, but not in those that received 0.24 kg ha^?1, which is recommended for disease control. Lower counts were recorded only for species that are highly sensitive in vitro, e.g.Microdochium bolleyi andTrichoderma spp. Some fusaria were either not affected or tended to be slightly stimulated by the treatment. An attempt was made to attribute the incidence of these moderately sensitive fungi to the effect of the fungicide on non-pathogens.     

The haustorial host-parasite interface in rust-infected bean leaves after high-pressure freezing

The haustorial fine structure of the bean rust fungus, Uromyces appendiculatus var. appendiculatus, was studied within the cells of its host, Phaseolus vulgaris. Results were obtained after high-pressure freezing and subsequent freeze-substitution or freeze-fracturing. Good preservation of leaf tissue after freeze-substitution needed cryoprotection with 8% methanol. For freeze-fracturing, no chemical treatment was applied. In addition to the organelles which are generally found in fungi after cryo-fixation, tubular-vesicular complexes were found in the cytoplasm. Both techniques revealed an extrahaustorial matrix of even width, surrounding the haustorial body. The extrahaustorial membrane was not undulated, and the side facing the plant cytoplasm was lined with a delicate fringe of well-stained material. The extrahaustorial membrane was nearly devoid of intramembrane particles. The host plasma membrane in infected tissue, especially the protoplasmic face, had fewer intramembrane particles than those in uninfected tissue. The haustorial plasma membrane contained many intramembrane particles.     

Check-list for scientific names of common parasitic fungi. Series 3b: Fungi on bulbs: Amaryllidaceae and Iridaceae

This list is a continuation of Series 3a (Neth. J. Pl. Path. 94 (1988), Supplement 1), an account of the nomenclature of common parasitic fungi on bulbs as used in official publications of the Netherlands Society of Plant Pathology and the Netherlands Ministry of Agriculture and Fisheries. The selected names include one new species,Curvularia gladioli Boerema & Hamers, one new pathogenic form,Fusarium oxysporum f.sp.croci Boerema & Hamers, and one new combination,Sclerotium narcissi (Sacc.) Boerema & Hamers.A contribution towards the costs of publication provided by the Landbouw Export Bureau Fund, Wageningen, is gratefully acknowledged.     

Systemic fungicidal and insecticidal activities of 1- and 2-[bis (dimethylamido)phosphoryl]-3-alkyl-5-anilino-1,2,4-triazoles

The compounds referred to in the title have been investigated for fungicidal, insecticidal and acaricidal activities in laboratory and greenhouse tests. Several representatives of this class of compounds were active against powdery mildew on apple, cucumber, and barley, and against aphids and spider mites, both when applied to the leaves and when added to the nutrient solutions of test plants. Treatment of leaf halves resulted in protection of the entire leaves. A striking difference in pesticidal activity was observed between two series of isomers. Representatives of the series with the phosphoryl group in the 1-position showed much greater pesticidal activities than their corresponding isomers with the phosphoryl group in the 2-position. The optimum activity within the two homologous series (R-H, CH₃ ... C₆H₁₃) was determined: generally the lower homologues (R-H, CH₃, C₂H₅ and i-C₃H₇) showed the greatest pesticidal activity in the systemic tests. After leaf-application the influence of the length of R was less pronounced or even reversed.Samenvatting De in de titel genoemde stoffen zijn onderzocht op fungicide, insecticide en acaricide werking in laboratorium en kasproeven. Verscheidene vertegenwoordigers van dit type verbindingen waren werkzaam tegen echte meeldauw van appel, komkommer en gerst, en tegen bladluizen en spint, dit zowel na toepassing op de bladeren als na toevoeging aan de voedingsoplossingen van proefplanten. Behandeling van bladhelften resulteerde in bescherming van de gehele bladeren. Een opvallend verschil werd waargenomen tussen de werking van twee reeksen isomeren. Vertegenwoordigers van de reeks met de fosforylgroep op de 1-plaats waren veel werkzamer dan hun isomeren met de fosforylgroep op de 2-plaats. Het optimum binnen de twee homologe reeksen (R-H, CH₃ ... C₆H₁₃) werd bepaald: in het algemeen waren de lagere homologen (R-H, CH₃; C₂H₅ en i-C₃H₇) het werkzaamst in de systemische proeven. Na een preventieve bladbespuiting was de invloed van de lengte van R minder uitgesproken of zelfs omgekeerd.     

Seasonal activity of EPTC for Cyperus rotundus L. control in a tropical climate*

Four experiments were conducted at six week intervals to determine the seasonal activity and persistence of soil-incorporated EPTC (5-ethyl N,N-dipropyl(thiocarbamate)) for Cyperus rotundus L. control and tolerance of okra (Hibiscus esculentus L.), cucumber (Cucumis sativus L.), lettuce (Lactuca sativa L.), red beet (Beta vulgaris L.) and carrot (Daucus carota L.) during the dry and wet seasons in Viçosa, Brazil. Satisfactory control of C. rotundus was obtained at 2 kg/ha EPTC during the dry season and 4 kg/ha or more during the wet season. Only red beet and carrot tolerated these doses of EPTC when the crops were planted five days after application. However, selective control of C. rotundus was obtained when the planting date of lettuce was delayed for three or six weeks after EPTC application. EPTC controlled C. rotundus at half the dose that was required to control three species of annual grass that germinated near the soil surface. EPTC persisted longer when applied to air dry soil and incorporated with a rototiller than when incorporated into moist or wet soil.     

The application of picloram-14C to bracken

Experimental systems were produced from fragments of bracken rhizome and picloram-¹⁴C was applied to frond laminae, rhizome apices, frond buds and roots and translocation assessed 7 days after treatment. The isotope was readily taken up by all organs and freely translocated to associated fractions of the rhizome except in the case of laminae from which distribution was very poor. Accumulation of activity in the roots was considerable following treatment of the frond buds but was limited in the frond buds. Poor translocation of herbicide from treated frond laminae is considered a possible explanation of poor control in the field when bracken is sprayed in July. Lapplication du picioram e¹⁴C à la fougère Des systèmes expérimentaux ont étéétablis en utilisant des fragments de rhizome de fougére et du piciorame ¹⁴C a été appliqué sur les limbes des frondes, les apex des rhizomes, les bourgeons des frondes et les racines. La migration fut évaluée sept jours aprés le traitement. L'isotope a été facilement absorbé par tous les organes et librement transporté aux fractions correspondantes du rhizome, sauf dans le cas des limbes è partir desquels la distribution a été très faible. L'accumulation de ractivité dans les racines a été considérable è la suite du traitement des bourgeons de frondes mais a été Iimitée dans les bourgeons de frondes. Une faible migration de I'herbicide depuis les limbes des frondes est considérée comme une explication possible du désherbage mediocre auchamp, lorsque la fougère est traitée en juillet. Die Anwendung von PicIoram-¹⁴C zu Adlerfarn Aus Rhizomstücken von Adlerfarn wurden Versuchsp-flanzen gezogen und auf die Wedelspreiten, Rhizomapices, Wedelknospen und Wurzein- Picloram-¹⁴C appliziert. Die Transiokation des Herbizids wurde eine Woche nach der Behandlung gemessen. Das lsotop wurde von alien Pflan-zenorganen schnell aufgenommen und in die dem Rhizom benachbarten Pflanzenteile transloziert; bei Behandlung der Wedelspreiten war jedoch nur eine geringe Verteilung fest-zustellen. Nach Behandlung der Wedelknospen war in den Wurzein eine beträchtliche, aber in den Wedelknospen nur eine geringe Aktivitätsanreicherung feststellbar. Für den schwachen Bekämpfungserfolg des Adierfarns im Freiland bei Spritzungen im Juli, wird die geringe Transiokation des Herbizids aus den Wedelspreiten als mögliche Erklärung angesehen.     

RESUME:Studies on the Chemical Control of Aonidiella aurantii (Mask.)

Aonidiella aurantii (Mask.) which was accidentally introduced in Sicily in 1968 has since become a dangerous pest requesting special treatments in citrus groves. Experiments have been carried out on Citrus lemon to evaluate the efficacy of several organophosphorous compounds partly in mixture with white oil and this latter applied sole (cf. table 1). The results obtained against young females are set out in table 2; they show excellent results with almost all compounds whereas the same pesticides had a rather poor effect on mature females (cf. table 3).
It is concluded that the replacement of white oils by organophosphorous compounds is not justified providing that the control is directed against larvae and young females. This means that a proper timing is essential to obtain a satisfactory mortality, thus avoiding the use of detrimental broad acting pesticides.     

Effect of 2,4,5-T and picloram on the regeneration of blackberry (Rubus procerus P.J. Muell) from root segments

The formation of roots and shoots on root segments of Rubus procerus P.J. Muell was prevented by soaking the segments for 24 h in a 10^?4M solution of 2,4,5-T or a 10^?5M solution of picloram. Shoot numbers were significantly increased after treatment with 10^?9M and 10^?10M 2,4,5-T, but picloram did not cause a significant increase in shoot numbers. Measurement of the concentration of 2,4,5-T in the extracambial tissue showed that roots treated with 10^?4M 2,4,5-T contained 5× 10^?8 mmole 2,4,5-T per mg dry weight, and by extrapolation, roots treated with 10^?9M 2,4,5-T contained 2× 10^?10 mmole/mg dry weight. Action du 2,4,5-T et du piclorame sur la régénération de la ronce (Rubus procerus P.J. Muell) è partir de fragments de racines La formation de racines et de tiges è partir de fragments de racines dc Ruhus procerus P.J. Muell a été supprimée par trempage des fragmenls pendant 24 heures dans une solution a 10^?4M et de 2.4,5-T, ou dans une solution 10^?5M de piclorame. Le nombre de pousses s'est accru significativement après traitement avec le 2,4,5.-T è 10^?9M et 10^?10M, mais le piclorame n'a pas provoqué d'accroissemcnt significatif du nombre de pousses. La mesure de la concentration de 2,4,5-T dans le tissu extra-cambial a montré que les racines trailées avec du 2,4,5-T è 10^?4M contenaient 5×10^?8 mmole de 2.4,5-T par mg de poids sec et par extrapolation, quc les racines traitées avec du 2,4,5-T k 10^?9M devaient contenir 2 × 10^?12 mmole/mg de poids sec. Die Wirkiing von 2,4,5-T und Picloram auf den Wuchs der Wurzehegmenten von Bromheeren (Rubus procerus P.J. Muell). Die Bildung von Wurzeln und Sprossen aus Wurzelsegmen-ten von Ruhu.i procerus P.J. Muell wurde durch 24-stündiges Einlegen der Wurzelstücke in 10^?4M 2,4,5-T bzw 10^?5M Picloram verhindert. Die Anzahl neugebiideter Sprosse wurde nach Einlegen in 10^?9M und 10^?10M 2,4,5-T, nicht jedoch durch Picloram, signifikant erhöht. Im extracambialen Gewebe von Wurzeln, die mit 10^?4M 2,4,5-T behand-elt worden waren, wurden 5×10^?8mMol 2,4,5-T je mg Trockengewiclu bestimmt. Durch Extrapolation wurde ermittclt. dass mit 10^?9M 2,4,5-T behandelte Wurzeln 2× 10^?12mMol/mg Trockengewicht cnthielten.     

THE EFFECT OF MCPA ON THE AMINO ACID AND SUGAR COMPOSITION OF VICIA FABA LEAVES

Summary. The effect of spraying Vicia faba leaves with 5000 ppm MCPA is described. Three to 4 days after spraying, a marked increase (× 5 approx.) was found in the concentrations of leucine iso -leucine and valine in the leaves. No significant changes were detected in the other amino acids. Treatment with MGPA also caused a significant increase (× 4 approx.) in the glucose and fructose content of the leaves. Detached leaves (sprayed and unsprayed), when kept in a moist atmosphere for 3–4 days, exhibited very similar increases in amino acids and sugars to sprayed intact plants. Experiments using ¹⁴CO₂ revealed that in short term photosynthesis (30 min) of sprayed and unsprayed plants, 80–90% of the radioactivity was incorporated in sucrose, with about 5% in each of glucose and fructose. Over photosynthelic periods of 4 days, glucose and fructose were found to be almost as heavily labelled as sucrose in sprayed plants, but in the controls the distribution of radioactivity was similar to that in short term photosynthesis. It is suggested that the build up of amino acids and sugars in plants treated with MCPA is due to an interruption of the translocatory flow from the leaves, and that this build up of metabolites may be a contributory factor in the toxic action of this herbicide.
Effet du MCPA sur la composition en amino-acides et en sucre des feuilles de Vicia faba