TURF TIP
7/7/05

Velocity for Poa annua control….Potential and Precautions

Velocity (byspribac) was registered for Poa annua control in creeping bentgrass last November, so this is the first summer of potential widespread use. As with all new pesticides, we’ll learn more of the finer details as we use it. We have a number of studies at Purdue currently and I just stopped at a course who is experimenting with it extensively. Following are a few pointers:

• 1. It works, period. Probably too well on areas with higher Poa populations than you first thought.
  2. It also appears to control Poa trivialis, but this effect is not as consistent across our studies at Purdue and across the Midwest.
  3. Test it yourself. The effect of Velocity varies by cultivar and the environment, so we can’t be confident of the positive and negative effects in every given condition.
  4. Do not use on greens.
  5. Do not use on Kentucky bluegrass, some cultivars are sensitive.
  6. It’s more effective and safer as temperatures rise. Data show that applications made between 70 and 85F are most effective on Poa annua while being safest on bentgrass. However, this work was done in a growth chamber, so other stresses like humidity, disease, and/or drought common at high temperatures were not factored into the study. Therefore, it is likely safer to apply between 70 and 80F.
  7. Expect some yellowing of the bentgrass. This should not be serious or long-lasting, but it is possible.
  8. Do not tank mix it with other herbicides or Primo.
  9. Refer to the label for more information and come to Field Day on July 26 where we’ll visit three studies using Velocity on a variety of grasses.

Zac Reicher, Professor/Turfgrass Extension Specialist

Send corrections, suggestions, and comments to biehlj@purdue.edu