1,345 research outputs found
Fruitgrowers towards a new approach to enhance biodiversity in organic orchards
In the frame of the project âArbeitsnetz zur Weiterentwicklung der Anbauverfahren des
ökologischen Obstbausâ (BOEL-project Nr. 03OE178) a group of fruitgrowers and advicers
started to discuss new measures and new concepts to enhance biodiversity in organic
orchards. Strips with flowering plants that can be integrated in the normal mulching system
and thus, do not originate vole problems, are actually tested on the farms. Other measures
as single bushes at the top and end of the rows are in discussion.
If such measures are to be integrated successfully in the practice of organic fruit growing,
the impulse must spring from growers themselves and their requirements regarding the
different risks must be considered. Otherwise, an acceptance in practice is not very
probable. This activites are reported here since we want more people to join us
Codling moth populations less susceptible to CpGV: What about higher concentrations?
In an organic orchard with a codling moth (CM) population less susceptible to CpGV it was tested,
whether an increased dosage of CpGV by factor 10 would result in any increased efficacy.
The applications were set in shorter than weekly intervals with 10 ml/ha Madex (low dosage plot)
and 100 ml/ha Madex (high dosage plot). The higher dosage showed also a better efficacy, especially
on the âactive damageâ (live larvae).
The orchard where the experiments were conducted was known to have a less susceptible CM
population (2004) although there were no serious CM problems reported by the farmer despite the
CM control was done only with CpGV. It was investigated, whether natural antagonists might have
been a reason for the absence of serious problems in this orchard. No signs of a strong presence of
other antagonists were found but CM the population was increasing very much in the year the experiment
was conducted (2005). Thus, probably the reason for the absence of CM problems seems
to be just a delayed increase of the CM population after the development of a lower susceptibility of
CM against CpGV
Experiences with entomopathogenic nematodes for the control of overwintering codling moth larvae in Germany
Entomopathogenic nematodes were tested for their potential as tool in resistance
management of codling moth Cydia pomonella L. in organic fruit growing. In two field tests,
the adults emerging from stems treated with nematodes were monitored. In one trial, 90 %
of efficacy could be shown. On-farm trials with favourable weather conditions showed an
efficacy about 50-60 % on fruit infestation by codling moth in the year following the
application. On-farm trials with unfavourable weather conditions showed no results. The
favourable weather conditions for the application are discussed with reference to German
conditions
Field tests with Madex Plus against CpGV-resistant codling moth populations in organic orchards in 2006
When resistance to the Mexican isolate of Cydia pomonella Granulovirus (CpGV-M) arose
in several organic orchards in Germany in 2004 and 2005, the future of codling moth
control became a serious concern of organic fruit growing. In 2006, a new virus isolate
from Andermatt Biocontrol AG (Madex Plus) was first tested in two field trials in organic
orchards on codling moth populations resistant against the Mexican isolate of CpGV.
Madex Plus showed a better efficacy on these populations than Madex 3. However, larval
mortality larvae seemed to be somewhat delayed. A very good effect was shown in
population control. The number of larvae in corrugated card board belts was significantly
reduced after treatment with Madex Plus. In addition to these trials, on-farm trials in all
orchards concerned of the CpGV-M resistance were carried out. The results of on-farm
trials showed the same tendency: high efficacy in population control against a background
of slightly delayed larval death. In 2007, Madex Plus was applied successfully in all
organic orchards with CpGV-M-resistant codling moth populations in Germany
Impact of different Agents on the Efficacy of Codling Moth Granulovirus in Tank Mixtures
In the control of codling moth it is common to combine the granulovirus with other agents,
especially fungicides, in spray application. Therefore the knowledge about the influence of
these agents on the efficacy of the virus in tank mix is very important. Studies on this
subject were part of a project supported by BMELV (German Federal Ministry for Food,
Agriculture and Consumer protection) at the Institute for Biological Control of JKI in
Darmstadt.
The granulovirus of Cydia pomonella (L.) (CpGV) was mixed with 10 different agents at
concentrations as applied in the field. After the exposure the virus activity was calculated
from larval mortality determined in bioassays with neonates of a susceptible codling moth
strain.
Only two agents with a pH of 11 (sodium silicate (water glass) and calcium polysulfide
(lime sulphur)) reduced the virulence of CpGV significantly
Environmental and fishing effects on the dynamic of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)
This analysis of the variations of brown tiger prawn (Penaeus esculentus)
catch in the Moreton Bay multispecies trawl fishery estimated catchability
using a delay difference model. It integrated several factors responsible for
variations in catchability: targeting of fishing effort, increasing fishing
power and changing availability. An analysis of covariance was used to define
fishing events targeted at brown tiger prawns. A general linear model estimated
inter-annual variations of fishing power. Temperature induced changes in prawn
behaviour played an important role in the dynamic of this fishery. Maximum
likelihood estimates of targeted catchability (
boat-days) were twice as large as non-targeted catchability ( boat-days). The causes of recent decline in fishing
effort in this fishery were discussed.Comment: revised manuscript following reviewers comments + adding data and
code for reader
Control of the apple sawfly Hoplocampa testudinea Klug in organic fruit growing
The best application technique and application data for the treatments with Quassia extract against the apple sawfly Hoplocampa testudinea Klug were tested. The spraying solution was distributed best on the receptacle of the blossom â the place where the sawfly larvae feed before the enter the blossom â when the treatment was effecttuated at fading blossom with a high amount of water (about 500 l/ha/mTh). The addition of T/S forte, a wetting agent, could also improve the efficacy of Quassia treatments in a lower dose. Thus, it is recommended to apply in fading blossom with addi-tion of T/S forte and high amounts of water to obtain the best effect. If the conditions for applica-tions are good and the infestation is not too high, the normally recommended dose of 6 g/ha/mTh can even be reduced
Efficacy of Quassia extract on the apple sawfly Hoplocampa testudinea Klug
The efficacy of Quassia extract with a standardized content of Quassin was proved in various field trials in
different regions during three years. The amount of Quassin of 6 g/ha/m tree height will be recommended to
practice. It is not important to have a contact effect on the eggs. The larvae must feed on the product before
they enter the fruit. There is a very good efficacy on primaray infestation. Furthermore, there is even an efficacy
on secondary infestation. Thus, even if due to difficult conditions during application or not optimal termination
of the treatment the efficacy on the primary infestation is not entirely sufficient, the secondary infestation
will be controlled better
Wirkung von Quassiaextrakt auf die ApfelsÀgewespe Hoplocampa testudinea Klug
The efficacy of Quassia extract with a standardized content of Quassin was proved in various field trials in different regions during three years. The amount of Quassin of 6 g/ha/m tree height will be recommended to practice. It is not important to have a contact effect on the eggs. The larvae must feed on the product before they enter the fruit. There is a very good efficacy on primaray infestation. Furthermore, there is even an effi-cacy on secondary infestation. Thus, even if due to difficult conditions during application or not optimal ter-mination of the treatment the efficacy on the primary infestation is not entirely sufficient, the secondary in-festation will be controlled better
Direct Distances to Cepheids in the Large Magellanic Cloud: Evidence for a Universal Slope of the Period-Luminosity Relation up to Solar Abundance
We have applied the infrared surface brightness (ISB) technique to derive
distances to 13 Cepheids in the LMC which span a period range from 3 to 42
days. From the absolute magnitudes of the variables calculated from these
distances, we find that the LMC Cepheids define tight period-luminosity
relations in the V, I, W,
J and K bands which agree exceedingly well with the corresponding Galactic PL
relations derived from the same technique, and are significantly steeper than
the LMC PL relations in these bands observed by the OGLE-II Project in V, I and
W, and by Persson et al. in J and K. We find that the tilt-corrected true
distance moduli of the LMC Cepheids show a significant dependence on period,
which hints at a systematic error in the ISB technique related to the period of
the stars. We identify as the most likely culprit the p-factor which converts
the radial into pulsational velocities; our data imply a much steeper period
dependence of the p-factor than previously thought, and we derive p=1.58
(+/-0.02) -0.15 (+/-0.05) logP as the best fit from our data, with a zero point
tied to the Milky Way open cluster Cepheids. Using this revised p-factor law,
the period dependence of the LMC Cepheid distance moduli disappears, and at the
same time the Milky Way and LMC PL relations agree among themselves, and with
the directly observed LMC PL relations, within the 1 sigma uncertainties. Our
main conclusion is that the previous, steeper Galactic PL relations were caused
by an erroneous calibration of the p-factor law, and that there is now evidence
that the slope of the Cepheid PL relation is independent of metallicity up to
solar metallicity, in both optical, and near-infrared bands.Comment: ApJ accepte
- âŠ