Bekämpfung von Rapskrankheiten

Control of rape diseases II. Measures for disease reduction caused by Sclerotinia sclerotiorum with consideration to economical aspects The most widely distributed diseases of rape in the Federal Republic of Germany are Sclerotinia sclerotiorum (white stalk disease, formerly called rape canker) and Phoma lingam (root collar and stalk rot), and these can cause considerable yield losses. S. sclerotiorum occurs sporadically and is more prevalent in the marsh land of northwest Germany than in the hilly landscape of Schleswig-Holstein, where pockets of infection are found. Application of calcium cyanamid, formerly successfully used to control apothecia formation by S. sclerotiorum, has been replaced by fungicides (Vinclozolin) directed at preventing ascospore infection. Many experiments proved to be economically unsuccessful due to the low rate of infection and the high costs involved with such treatments. With an expected yield of 30 dt/ha, an 8 % increase in yield following spraying must be achieved in order to make the fungicide treatment profitable. In fields where only up to 12% of the plants were infected, 75 % of the experiments proved to be uneconomical. By a disease index of 13–25 ^%, 55 % of the trials were similarly uneconomical. Only where more than 25 % of the plants were infected did the fungicide application prove to have a considerable effect on the yield. A prophylactic treatment is not to be recommended. Only in those areas where severe disease occurs nearly every year should such treatment be practiced that is unless the Advisory Service advises otherwise due to extreme weather conditions (too wet or too dry) which may lead to only very slight infection.     

Überlebensstrategien von Regenwaldameisen

Survival strategies of rainforest ants The heavy rainfall in the humid tropics pose special challenges to plants and animals. Ants have developed a variety of adaptations to flooding. Measures against floods range from raft formation to various methods of nest drainage. In the intertidal zone nests are sealed watertight, while the ants react with physiological adaptations to the oxygen deficiency. In an obligate symbiosis between a carnivorous pitcher plant and a carpenter ant a unique coexistence has developed, in which the partner ant dives and forages unharmed in the digestive pitcher fluid for mosquito larvae and drowned prey.     

Rheologie von Fermentationslösungen

Rheological measurements can give interesting informations for the characterization of fermentation broth, especially concerning the depending of the oxygen transfer rate. Rheological measurements can report decisions for choosing the best reactor type or other process steps e.g. purification and separation. An advantageous method was used by the combination of a dynamic process-viscosimeter with the fermenter and the continuous measurement of medium density by X-ray absorption method.     

Mikrobielle umwandlung von gibberellinen—entacetylierung von O(3,13)-diacetylgibberellinsäure

The fungus Phoma medicaginis var. pinodella (L.K. Jones) Boerema has been shown to split off the O(3)-acetyl group of gibberellic acid acetates without affecting O(13)-acetyl 19,10-lactone, and methyl ester groups. Fungal deacetylation of O(3,13)-diacetylgibberellic acid (VII) yielded O(13)-acetylgibberellic acid (V), which has not previously been prepared.     

Zahlenverhältnisse von Häufigkeiten

In evaluating data, one acknowledges as a scientist the superiority of the K-procedure on account of the versatility of its application, e.g. in answering the question not only as to its causal context, in proving two features to be contemporaneous and equally strong effects of a material third factor, or in accordance with a “criterion of parallel problems”, but also in demonstrating the mutual matching of two frequency-ratios and the matching of one frequency-ratio with a given proportion, e.g. 3: 1, and the matching of a continuing proportion collected from observed frequencies with a given continuing proportion, e.g. 9:3:3: 1. This is demonstrated in the examples in the literature, which hitherto have been treated only according to the classical procedure.     

Gewässervegetation von Nordost-Uruguay

Im Nordosten von Uruguay, nahe der brasilianischen Grenze, wurde die Gewässervegetation untersucht. Die Tümpel werden von Schwimmfarngesellschaften (Azolla, Marsilea, Salvinia) eingenommen; beigemischt sind Arten wie Sagittaria montevidensis, Pistia stratiotes, Eichhornia azurea und Pontederia cordata. Abhängigkeiten zwischen Artenkombination, Wassertiefe und menschlichem Einfluß ließen sich aufzeigen.