Species and site selection for timber production on farm boundaries in the humid Atlantic Lowlands of Costa Rica and Panama

In 1987–89 the CATIE-GTZ Agroforestry Project set up experiments with five timber tree species planted in single lines on twelve farm boundaries in cooperation with local farmers. When the trees were five years old, their height, diameter and total stem volume were: Acacia mangium 17 m, 19 cm and 67 m³ km^–1, Cordia alliodora 14 m, 20 cm and 46 m³ km^–1, Eucalyptus deglupta 22 m, 24 cm and 85 m³ km^–1, Tectona grandis 17 m, 20 m and 64 m³ km^–1, Terminalia ivorensis 18 m, 23 cm and 104 m³ km^–1. Considering these excellent growth rates, planting of Cordia alliodora, Eucalyptus deglupta and Tectona grandis in lines on farm boundaries should be promoted. T. ivorensis and A. mangium are not recommendable for sites with impeded drainage because of mortality caused by root rot, mostly due to Rosellinia sp.     

Fine-root dynamics of coffee in association with two shade trees in Costa Rica

Fine-root dynamics (diameter < 2.0 mm) were studied on-farm in associations of Coffea arabica with Eucalyptus deglupta or Terminalia ivorensis and in a pseudo-chronosequence of C. arabica-E. deglupta associations (two, three, four and five years old). Coffee plants were submitted to two fertilisation types. Cores were taken in the 0–40 cm soil profile two years after out-planting and subsequently in the following year in depth layers 0–10 and 10–20 cm, during and at the end of the rainy season, and during the dry season. Fine root density of coffee and timber shade trees was greater in the coffee fertilisation strip as compared to unfertilised areas close to the plants or in the inter-rows. Coffee fine roots were more evenly distributed in the topsoil (0–20 cm) whereas tree fine roots were mostly found in the first 10 cm. Although the two tree species had approximately the same fine root length density, lower coffee / tree fine root length density ratios in T. ivorensis suggest that this shade tree is potentially a stronger competitor with coffee than E. deglupta. Coffee and tree fine root length density for 0–10 cm measured during the rainy season increased progressively from two to five-year-aged associations and coffee fine root length density increased relatively more than E. deglupta fine root length density in the four and five-year-aged plantations suggesting that contrary to expectations, coffee fine roots were displacing tree fine roots.     

Effect on maize growth of the interaction between increased nitrogen availability and competition with trees in alley cropping

Maize growing next toErythrina hedgerows had 44% lower biomass (p<0.01) and 35% lower N content (p<0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p<0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize.Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture.A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.     

Floristiese verskille tussen ekotope in die Potchefstroom distrik

Floristic differences between eeotopes in the Potchefstroom area. Eeotopes are generally used, in the Highveld Region, as a basis for the division of camps when planning a farm. The possible floristic differences which support this ecological approach, as well as the factors which could possibly cause these differences, were investigated. This study showed that eeotopes differ significantly in species composition and that they should be fenced off and managed separately. The abiotic factors which have the greatest influence in a specific ecotope are aspect, clay percentage and soil depth.     

The effect of simulated rain on deposits of some cotton pesticides

Commercially grown cotton and potted cotton plants were sprayed with five pesticides, and simulated rain was applied 1–72 h later. Leaf samples were analysed to determine the effect of the rain on the original deposits. It was found that 2 to 5 mm of simulated rain applied 1 h after spraying, washed off 50% or more of the original deposit. An increase in rainfastness of the pesticides occurred over a period of time after spraying. The type of formulation seemed to affect rainfastness, but the origin of a formulation, the addition of wetting agents and the intensity of the simulated rain did not.     

Trichomonad infections of the oral cavity in cats in south Germany]

In this investigation trichomonads were isolated from the oral cavity in 21 of 110 examined cats, and only from those which were simultaneously FeLV, FIV or FIP positive. By means of scanning electron microscopy the trichomonads were shown to be round or piriform parasites which were on average 7.9 microns long and 6.2 microns wide at maximum width. They had 4 anterior flagella, which were on average 9.4 microns long, an undulating membrane measuring 6.7 microns with no trailing flagellum as well as an axostyle extending on average 5.0 microns beyond the body, and therefore should be attributed to the genus Trichomonas.     

Evaluation of serological tests for detecting tick-borne encephalitis virus (TBEV) antibodies in animals

Tick-borne encephalitis (TBE) in animals is not well understood yet. TBE virus (TBEV) serology in several host species could be valuable for epidemiological analyses in the field as well as for the detection of clinical cases. However, performance and suitability of the available test systems are not well assessed. Therefore, we evaluated two commercial TBEV-ELISA kits in a pilot study and compared them for their suitability in veterinary applications. For this purpose, we tested 163 field collected goat sera and evaluated the results by serum neutralization test (SNT) as "gold standard". Twenty-eight SNT positive sera (17.2%) were detected. The best suited ELISA kit was used for determination of a species-specific cutoff for horses, cattle, sheep, goats, pigs, mice, dogs, rabbits and monkeys with defined sera from animals without known or with improbable contact to TBEV. The level of non-specific ELISA results does not only differ between animal species but may also be influenced by the age of the tested animals. The number of sera which tested false positive by ELISA was higher in older than in young sheep. In order to obtain defined polyclonal sera as references, two dogs, cattle, goats, sheep, rabbits and pigs each, as well as one horse and 90 mice were immunized four times with a commercially available TBEV vaccine. In conclusion, our results demonstrated that commercial TBEV-ELISA kits are suitable for application in veterinary medicine for both, verification of clinical TBE cases and epidemiological screening. However, positive ELISA results should be verified by SNT. Only a very low number of false negative ELISA-results were found.