Western Flower Thrips. They are very visible on light colored roses. They fly in from mowed areas. They are very hard to control because they get into the blooms before showing any color. Cut and bag the infested blooms. Rosarians who show their roses will spray the buds only with Spinosad and rotate with another insecticide, such as Acephate, or Bifenthrin. There has been some research that alyssum attracts predators that eat Thrips. For more information on beneficial insects look at Arbico organics website.
Cut down to the 5-leaves, and throw in trash (do not put in compost!). Apply Bio-Advanced Systemic 3 in 1 ( used to be called Bayer). See if it works. Good luck.
Jemima Seetha - Miami Valley Rose Society - Dayton, OH - Consulting Rosarian
I cut it down to the 5 leaves, now I need to go and buy the 3 in 1 spray…
thank you!
You only need to spray the buds before showing any color.
Thank you. I have a bottle of Neem oil, will that work?
Unfortunately, Neem is not very effective and in hot temperatures could burn your rose leaves, however, you could do an experiment. Remember oils only work when they contact the insect. So you could go out before sunset and lightly spray only the blooms every night (avoids exposure to bees). Then observe next morning, do this for two weeks, and see if this has helped keep your blooms clean. This experiment will help you determine if it controls the thrips. If yes, then the following weeks, spray every other night, if that still helps, then spray every 3 days. You could do this until you observe which spray interval is most satisfactory to you.
Your profile indicates you live in Palm Springs where it’s HOT. It appears your roses are surrounded by rock mulch, which is a passive solar collector. It heats up and literally cooks the soil and surrounding plant tissues. I would strongly suggest removing the rock surface from anywhere near the roses and replace it with something organic, whether it’s compost or even shredded bark. The old Rose History Walk at Descanso Gardens was nearly destroyed years ago when the powers that be decided they needed to mulch the rose garden with cinder stones. Literally the type used in bbq’s to absorb and retain heat. The roses took a turn for the worse because their feeder roots cooked due to the heated rock surface penetrating the soil and radiating and reflecting that heat up into the bushes. You may have thrip damage on the pictured blooms, it’s difficult to tell, but it also appears there is damage to the petals from some sort of spray. You might re think the use of any sprays in the kind of heat encountered in the Palm Springs area.