3,621 research outputs found
Control of apple scab by curative applications of biocontrol agents
In organic apple growing protective applications with copper, sulphur or lime sulphur are
used for apple scab control. Protective applications have to be repeated when new leaves
unfold. The timing of protective sprays depends on the weather forecast. If forecasted
infection conditions fail to appear, treatments were for nothing. With curative control
agents available, the number of treatments could be reduced. In greenhouse trials we
tested control agents for their protective and curative efficiency against apple scab after
artificial inoculation of potted apple trees. Applications were done 2 hours before
inoculation, 5 hours after inoculation on wet leaves, 5 hours after inoculation during
simulated rainfall or 24 hours after inoculation on wet or dry leaves. The optimal time of
application differed between the preparations tested. Vitisan and OmniProtect had their
highest activity when sprayed curative 24 hours after inoculation. Combinations were
found, which revealed a high efficiency against apple scab from 2h before to 24 hours after
inoculation. In a field trial apple scab was effectively controlled by curative applications of
OmniProtect
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
In-Plane Focusing of Terahertz Surface Waves on a Gradient Index Metamaterial Film
We designed and implemented a gradient index metasurface for the in-plane
focusing of confined terahertz surface waves. We measured the spatial
propagation of the surface waves by two-dimensional mapping of the complex
electric field using a terahertz near-field spectroscope. The surface waves
were focused to a diameter of 500 \micro m after a focal length of approx. 2
mm. In the focus, we measured a field amplitude enhancement of a factor of 3.Comment: 6 pages, 4 figure
Microoptical Realization of Arrays of Selectively Addressable Dipole Traps: A Scalable Configuration for Quantum Computation with Atomic Qubits
We experimentally demonstrate novel structures for the realisation of
registers of atomic qubits: We trap neutral atoms in one and two-dimensional
arrays of far-detuned dipole traps obtained by focusing a red-detuned laser
beam with a microfabricated array of microlenses. We are able to selectively
address individual trap sites due to their large lateral separation of 125 mu
m. We initialize and read out different internal states for the individual
sites. We also create two interleaved sets of trap arrays with adjustable
separation, as required for many proposed implementations of quantum gate
operations
Lamp reliability studies for improved satellite rubidium frequency standard
In response to the premature failure of Rb lamps used in Rb atomic clocks onboard NAVSTAR GPS satellites experimental and theoretical investigations into their failure mechanism were initiated. The primary goal of these studies is the development of an accelerated life test for future GPS lamps. The primary failure mechanism was identified as consumption of the lamp's Rb charge via direct interaction between Rb and the lamp's glass surface. The most effective parameters to accelerate the interaction between the Rb and the glass are felt to be RF excitation power and lamp temperature. Differential scanning calorimetry is used to monitor the consumption of Rb within a lamp as a function of operation time. This technique yielded base line Rb consumption data for GPS lamps operating under normal conditions
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