Getting the most from a Primo application
Dean Mosdell, Ph.D., is a technical manager in the Western U.S. for Syngenta. He has more than 25 years of golf course research experience with plant growth regulators and makes numerous golf course visits every year on behalf of Syngenta to assist superintendents. Mosdell can be reached at dean.mosdell@syngenta.com for more information.
Q: Occasionally superintendents remark to me that they feel Primo applications are not as effective as they once were. Do you hear this comment?
I hear this comment on occasion as well. When I hear the comment I try to engage the superintendent in a review of their practices to try and determine why Primo (trinexapac-ethyl) is not performing as expected.
Q: Where do you start the review process?
I start by asking the superintendent what has changed in their management program. In particular, I ask if they have changed the number or mix of products in their spray tank when they apply Primo. If the superintendent applies Primo along with several other products, I recommend that they apply Primo and water only to see if that solves the problem.
There are so many nutrient blends, stimulants and adjuvants, etc., on the market that a superintendent may include in a spray application (that) it is difficult to determine how a specific product or combination of products may interact with Primo. By applying only Primo and water, a superintendent can focus exclusively on Primo perform-
ance.
Q: What’s next in the process?
I discuss with superintendents that turfgrass plants are always producing gibberellic acid (GA) and the amount of GA produced by season varies with the growth of the plant. Cool-season grasses produce more GA in spring and fall and less in the summer, while warm-season grasses produce more GA in summer and less in spring and fall. It is important that superintendents adjust their Primo application program based on the growth and GA production of the turf plants.
Q: What about the application method itself?
Primo is foliarly absorbed, so it is important that a uniform spray application is made each time Primo is applied. The nozzles need to be checked regularly for wear and the sprayer calibrated to apply 1.0 to 2.0 gallons solution per 1,000 square feet, and avoid nozzles that produce very coarse droplet sizes.
Q: If after reviewing all their practices associated with a Primo application the superintendent is still disappointed in its performance, then what?
The first step is increase the frequency of applications. For instance, on fairways, shorten the application interval from 4 to 3 weeks and on greens shorten the application interval from 14 to 10 or 7 days and see what happens.
After that if a superintendent is not getting the desired response, I suggest increasing the Primo application rate by 10 to 15 percent.
Q: Anything else you would like to add?
In early spring the first application of Primo to bermudagrass or Kentucky bluegrass/ryegrass roughs that are mowed at a higher height will sometimes cause a bronzing/off-color appearance. The bronzing is a result of reduced new leaf appearance. When new growth is slow to replace the senescing older leaf tissue, the turf appears off-color or a bronze color. It’s much more noticeable at higher mowing heights. The older leaves may persist for a few weeks until the weather warms up and the turf starts to grow aggressively and the older leaves are replaced by the new green leaves.
To prevent this bronzing of the older leaves from occurring in higher-mown roughs, delay application of Primo until the weather is favorable for active growth or reduce the rate of Primo applied to mitigate any discoloration.
