Julius-Kühn-Archiv (Mar 2012)
Multiannual results on the influence of different application techniques on the efficacy of selective grass control in cereals
Abstract
The successful control of Alopecurus myosuroides (ALOMY) depends on the application date, the product selection and the dose rate and is also influenced by the correct application technology. Small and large plot trials were conducted at locations with heavy ALOMY infestation in the years 2004 - 2010. Atlantis WG (mesosulfuron & iodosulfuron) with different water dose rates, nozzle types and at different times of day was applied to control ALOMY in winter wheat. The droplet size as well as the water rate had the strongest impact on ALOMY control, while the application speed played a rather subordinated role. The applications with very coarse droplets (90 % drift-reducing potential) lead to efficacy reductions. This becomes particularly visible with applications in the early growth stages of ALOMY. Coarse drops roll off faster. On the other hand, applications with fine or medium droplets tend to result in a better control but they can lead to drift at high wind velocities and evaporation at high air temperatures and therefore cause lower efficacy. There was no visible difference between the types of the tested nozzle tips like standard flat jet, compact injector nozzle and double flat spray nozzle. The herbicidal efficacy was clearly affected by the moisture of the weed leaves. With moist leaf surfaces, the risk of run-off effects exists. This was more expressed with high spray volumes (250 l/ha) and has to be considered at early day or night applications. In situations of moist leaves, the spray volumes can be reduced to 100-150 l/ha. It is recommended to use the 90 % drift reducing nozzles only in the sensitive field bark area and to secure the efficacy of Atlantis WG against ALOMY by adjusting the pressure, the driving speed or by changing the nozzles outside of this sensitive area. From these test results, the following nozzle recommendation is concluded: Compact injector nozzles like AIXR, Air-mix, IDK should be used with a caliber of 03 or 04 at about 3 bar. Hereby the registration related buffer zone distances have to be considered.
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