Question
QUESTION: I have a climbing rose called 'Full Moon Rising' in my Houston Texas home.  Growth has been fantastic this spring and leaves and stems look great.  But the white blooms have brown edges.  I do not see any bugs.  Our spring has been extremely dry but I do keep it well watered.  What do you think is causing the brown edges.  All of the blooms are this way.  I also have two red blooming climbers and have no problems with them.

ANSWER: There is a very tiny little insect called a Thrip. This bug hides in the base of the flower's buds and sucks the juice. This causes the petals edges to go brown. If it is Thrips, there should be buds which have withered or are brownish coloured. Also there should be tiny brown spots farther down the petals. Take a flower and break it open and see if there are very tiny thin insects in the base. Thrips are very hard to get rid of because they are so small and can hide from sprays. The only way you can get rid of them is by using a systemic type of insecticide. This gets into the sap of the rose and when they bite on a rose petal they are killed. Thrips will attack all colours of roses but they really prefer white or pale pastels. Now it may not be Thrips and the problem can just be lack of water. Climbers take a LOT of water especially when there is no rain. The amount they would need would be like 2 large buckets of water. I would dig down alongside of the climber just to make sure the water did get down to 8 inches deep. Then use a mulch of any kind you can get in your area as this will make the climber grow and be more healthy, as it will keep the roots cool and damp.

---------- FOLLOW-UP ----------

QUESTION: Thanks.  It appears to be Thrips.  I saw the little buggers inside the red buds and the whites.  I sprayed insecticide directly on the buds and generally on leaves and stems.  How often is this necessary?  How about if I do it once per week to be proactive.?

Thank You.

Answer
If your insecticide spray is a systemic one, then once will be enough because thew thrips will die when the eat the petals, and thrips only last a short time.  Your changes of killing every one is slim as they are smaller and smarter than you.LOL They can easily hide at the base of the rose bloom. If it isn't a systemic, then just follow the instructions on the label for thrips.