Trouble Shooting - What's Wrong with Your Roses

Symptom
The edges of the blooms are brown. Roses looked deformed when they open.
Diagnosis
Thrips. These are tiny tan bugs that suck the moisture out of the petals. They get into the bud when the color first begins to show. They like light colored roses the best (white, pink, yellow). To control the damage, fill a small spray bottle with insecticide and spray the buds every few days as they begin to open. Recommended insecticides are Bayer Rose & Flower Insect Killer, Ortho Isotox Insect Killer or Ortho Orthenex Garden Rose Insect & Disease Control.

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Symptom
Tiny green bugs.
Dianosis
Aphids. These bugs like to feed on the new growth and buds. Best control is to wash your roses off with a sharp stream of water. If that does not work, use an insecticide weekly. (See recommended insecticides under Thrips.)

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Symptom
Sticky substance on leaves.
Dianosis
Aphids. See above.

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Symptom
Gray powder on leaves.
Dianosis
Powdery Mildew. This fungus is caused by spores and generally forms when daytime temperatures are in the 80's and the nighttime temperatures are in the 50's. It is much easier to prevent than to treat mildew once it gets stared. The best prevention is to wash off your roses with a hose daily, preferably in the morning. If you prefer, you can use an fungicide such as Ortho Orthenex Garden Rose Insect & Disease Control or Green Light FungAway.

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Symptom
Black Spots on leaves.
Dianosis
In Arizona, most likely Anthracnose but possibly Black Spot. Treatment is the same for both - spray weekly with a fungicide such as Ortho Orthenex Garden Rose Insect & Disease Control Green Light FungAway.

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Symptom
Leaves and blooms are droopy.
Dianosis
Not enough water or watering too shallow. Always be sure you are deep watering to a depth of 18 to 24 inches. You should flood the beds if you water by hand. If you are using drip irrigation, you should have a minimum of 2, preferably 3 or 4 drippers per rose bush. Roses in pots (especially clay pots) typically need to be watered more often than roses planted in the ground. You don’t want the soil to be soggy, but you also don’t want it to get totally dry between waterings.

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Symptom
Leaves are dull or feel sandy and are falling off in the summer.
Dianosis
Spider mites. If you look closely, you will see tiny webs in the leaf axils. The best control is to spray the undersides of your leaves with a sharp spray of water every couple of days. Morning is the best time to do this. A miticide can be used, but since spider mites reproduce so quickly, the miticide needs to be reapplied frequently as new generations hatch.

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Symptom
Holes on the tops of pruned canes.
Dianosis
Cane borers. These are bugs that "drill" holes into the canes to lay their eggs. Best prevention is to seal your canes with carpenter's glue after pruning your roses or cutting blooms.

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Symptom
Half circles cut out of leaves.
Dianosis
Leaf Cutter Bees. These are tiny bees that are cutting pieces of leaves to line their nests for their eggs. There is no known prevention.