Knockout Roses - Knowledgebase Question

Blountville, Te
Question by clketron7124
October 22, 2009
In the latter part of the summer, here in Eastern Tennessee, the buds on my knockout roses started drying up and not opening up. The moisture has been good. They are still doing the same thing here in Oct. My neighbors roses are doing the same thing. It seems to be worse on the Double Knockout Roses. What could be causing this?

Carl Ketron

Answer from NGA
October 22, 2009


There are two or three problems associated with the flower buds browning before they open up. One is a fungal disease, the other is feeding by thrips. Thrips damage the petals and they become distorted. Try cutting a few of the unopened buds in half. If the petals are dried out and you see black spots or even a powdery material on the petals, it's a fungal disease. If you open them up and the petals are intact but distorted, thrips are the culprits. If the petals are almost completely gone, little bud worms have been feeding inside the unopened bud. Until you can determine just what the cause might be, cut off all the obviously dead flowers. Suggest to your neighbors that they do the same. Hope you figure it out soon!

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