ALBERT

Notes: Summary. Undisturbed natural infestations of annual weeds, mainly Digitaria sanguinalis (L.) Scop, and Richardia scabra L., reduced the yield of harvestable peanuts [groundnuts) by an average of 20% over an 8-year period. Yield reductions in individual years ranged from I to 50%, depending mainly on the density of the weed population. From one to 5%‘non-dirting’ cultivations generally did not reduce yield as compared with hand weeding, unless environmental conditions favoured development of the disease southern blight (Sclerotium rolfsii Sacc.) on uncultivated peanuts.

Notes: Summary. Under dry field conditions, vernolate (S-propyl dipropylthiocarbamate) incorporated by conventional methods controlled less yellow nutsedge (Cyperusesculentus L.) and injuied peanuts (Arachis hypogaea L., groundnuts) more than when injected in lines under the soil or subsurface-applied through sweep applicators. In glasshouse studies, vernolate eliminated production of new nutsedge tubers if it was applied below the soil surface either 1 in. above or 1 in. below the parent tuber. Method of placement was less critical in determining control of most annual weeds.When averaged over two soil types and 2 years, peanuts yielded 14% more after subsurface applications than after incorporated treatments of vernolate. In comparison with the optimum subsurface placement, the yield from incorporation was significantly lower in three of four field studies, the reduced yields probably resulting from a combination of herbicide injury and poor weed control. Factors affecting the distribution of vernolate vapours (such as method of placement, soil type and amount of rainfall after treatment) apparently determine the differential toxicity of this herbicide. Neither market quality nor germination of peanut seed was adversely affected by vernolate treatment.

Notes: Summary. Comparative studies of herbicides and herbicide mixtures in peanuts (groundnuts) were continued at Tifton, Georgia, U.S.A., on Tifton loamy sand during 1961–63. When applied on a dry soil surface at the ‘cracking’ stage, certain mixtures which contained dinoseb as one component with 2,4-DES, 2,4-DEP, or DMPA as the Other component gave control of Digitaria sanguinalis (L.) Scop. and Richardia scabra St. Hil. for the entire growing season. However, on wet soils with no subsequent rain during the first weeks or with prolonged excess moisture, mixtures were not appreciably more effective than herbicides applied singly at standard rates. Where mixtures were applied on wet soil, herbicide effectiveness was improved by timely follow-up sprays of dinoseb at 1.5 lb/ac.Timing of application was often critical for optimum weed control. The best time was when the peanuts were cracking the ground or when the first weeds were barely visible, whichever occurred first.Mixtures permitted the use of the lowest rate of each compound on the weeds for which it was most effective.A mixture of DMPA at 6 lb/ac 4—dinoseb at 3 lb/ac applied at the ‘ground-cracking’ stage increased the average yield of peanuts.The mixtures evaluated had no effect on shelling-%, % sound mature kernels (SMK), mean weight per nut, or % germination. Neither did they affect taste of the peanuts or other sensory. characteristics. However, preliminary chemical analyses indicated that peanuts treated with mixtures contained more linolein and less olein than did untreated peanuts.Essais d'herbicides et de mélanges herbicides pour le désherbage dans les arachides (Arachis hypogea L.), 1961–63

Notes: Summary. Thiocarbamate herbicides were applied with incorporation devices and new subsurface application equipment on loamy sand at Tifton, Georgia, U.S.A. Subsurface-applied ethyl N,N-dipropylthiolcarbamate (EPTC), S-propyl bulylethylthiocarbamate (pebulate), and S-propyl dipropylthiocarbamate (vernolate) generally gave better control of Cyperus esculentus L. and Richardia scabra St Hil, but injured peanuts more than applications made on the soil surface and then incorporated into the soil. For soil incorporation, the power-driven rotary hoe was generally better than a disc harrow.Depth of subsurface placement critically affected herbicidal activity, especially on Cyperus esculentus; placement 1·5 in. below the soil surface gave more effective control than placement at 5·5 in. Réactions de Cyperus esculentus, de Richardia scabra et de l'arachide mix herbicides à base de thiocarbamate, en relation avec la methode de placement dans le sol

Notes: Uncontrolled weeds reduced tobacco yields by 26% over a 4-year period, caused substantial changes in the grade distribution, significantly reduced the price index and affected the chemical composition of flue-cured tobacco (cultivar Hicks). Treatments with diphenamid, pebulate, or benfluralin-pubulate visibly injured transplanted tobacco. After diphenamid treatment, tobacco generally did not differ from the cultivated controls in yield or gross dollar returns. In contrast, the mixture of benfluralin-pebulate increased dollar returns per hectare. The most striking differences followed pebulate applied alone which increased tobacco yields, significantly increased dollar returns, and elevated the levels of total nitrogen and alkaloids in tobacco leaves. All herbicide treatments tended to improve the grading quality of Hicks tobacco. Effets du disherbage sur le rendement et la qualité du tabac séchéè I'air chaud Les mauvaises herbes non détruites ont provoqué, sur une période de 4 ans une réduction de 25% des récoltes de tabac, provoquant des changeinents importants dans la répartition des catégories, une réduction significative de l'index des prix et une modification de la composition chimique du tabac séchéè I'air chaud (cultivar ‘Hicks’). Des traitements avec le diphénamide, le pébulate, ou le mélange benfluraline-prébulate ont provoquée des dommages visibles sur des tabacs repiqués. Le tabac, après un traitement au diphénamide ne donnait généralement pas des rendements différents des témoins, ni en production, ni en rentabilité brute. Au con-traire, le mélange benfluraline-pébulate augmenta le revenu brut è l'hectare. Les différences les plus frappantes furent obtenues après application du pébulate seul, lequel augmenta la production ainsi que le revenu brut (significativement) et releva les niveaux d'azote total et d'alcaloïdes dans les feuilles de tabac. Tous les traitements herbicides eurent tendance è augmenter la qualité du tabac ‘Hicks’. Der Einfluss der Unkrautbekämpfung auf Ertrag und Qualität von röhrengetrocknetem Tabak Über eine Versuchszeit von 4 Jahren führte Verunkrautung zu 26% Minderertrag, verursachte wesentliche Veränderungen in den Güteklassen, verringerte deutlich den Preisindex und veränderte die chemische Zusammensetzung von röhrengetrocknetem (flue-cured) Tabak (Sorte Hicks). Behandlungen mit Diphenamid, Pebulate oder Benfluralin-Pebulate führten bei gepflanztem Tabak zu sichtbaren Schäden. Der Dollar-Rohertrag war beim mit Diphenamid behandelten Tabak und beim Tabak in Unbehandelt im allgemeinen gleich hoch. Dagegen wurde das Einkommen durch die Mischung Benfluralin-Pebulate erhöht. Der auffälligste Unterschied oirde durch alleinige Anwendung von Pebulate erzielt, was sich in höheren Tabak- und Dollarerträgen und höheren Gehalten an Stickstoff und Alkaloiden in den Tabakblättern niederschlug. Alle Herbizidbehandlungen verbesserten die Güteklasse von Hicks-Tabak.