Tips and Techniques
Interesting Article from University of Minnesota Extension Service
Found first Japanese Beetle today. Right on time in comparison to past five years. Will monitor to determine if JB’s become an issue. If so will treat with bifenthrin and deltamethrin.
Between now and August 15th is the time to apply your final nitrogen containing fertilizer to your roses. Application before the 15th gives the fertilizer time to work without encouraging new growth that will not have time to harden off before winter.
Got blackspot? Try spraying with a combination of Maneb (Manzate or Mancozeb also work) with tebuconazole (Bayer Advanced Disease Control for Roses, Flowers & Shrubs Concentrate). Not Bayer 3 in 1. Spray at 7 to 10 day intervals to avoid possible phytotoxic effects such shortening of internodes. Use only as directed!
Bayer Advanced Disease Control for Roses, Flowers & Shrubs Concentrate is available from Amazon.com and DoMyOwnPestControl.com. There may be local sources to the Twin Cities, but I have not found any in the East side of the Twin Cities.
If your roses have leaves it is time to begin your preventative fungicide spray program.
Northern rose growers, if your soil temperature is above 50F, then it is time to begin fertilizing your roses.
With warmer temperatures and rain in the forecast, it is now a good time to begin removing the winter mulch from your rose beds. Only remove the mulch that is thawed. Let the frozen mulch thaw before removing.
Do not uncover your roses just yet. Just remove the mulch.