Don't neglect your nozzles!

As your college interns start to filter to the course from academic studies, now is the perfect time to fire up the sprayer in preparation for the 2009 season. This gives you the opportunity to ensure that your equipment is in proper working order AND gives the students the opportunity to get hands-on experience with calibration techniques that many have only heard about in the classroom.

Many websites and books are available to assist in the calibration of your equipment. In preparing for this update, I also came across a calibration software package that TORO offers for download from their website. While calibration of your equipment is important, another factor that should not be overlooked are the nozzles that you select to control turfgrass diseases.

Research conducted in the past few years has revealed that nozzle selection plays an important role in the suppression of turfgrass diseases (Read GCM Article). In particular, the control of foliar diseases such as dollar spot and brown patch can be improved by selecting nozzles that improve spray coverage. One major problem with this is that nozzles producing excellent coverage generally have increased potential for drift. Our research has shown that utilizing nozzles that incorporate air into the droplets (air induction) provide the best of both worlds. Here are some keys to improving disease control.

1. Consider the location of the pathogen. Fungicides for root diseases generally need to be applied in greater volumes of water (>2.0 gal/1000 sq ft) and/or watered-in following application. Foliar pathogens should be suppressed with a nozzle that produces excellent coverage.

2. Air induction nozzles provide excellent control of foliar pathogens and have relatively low potential for drift. TurfJet nozzles (typically supplied with many sprayers) generally offer poor disease control, especially where lower water volumes (~1.0 gal/1000 sq ft) are utilized.

3. Nozzles should be changed at least once per year (twice per year in some cases). Always buy an extra nozzle to use as a comparison when determining if your nozzles need to be replaced.