UACES Facebook Diseases


(October 2007)

QuestionMy rose bush has black spots on the leaves and they turn yellow and fall off. I have sprayed it with disease spray from the gardening center but it hasn’t helped. Now it has almost no leaves and looks like it could die. It usually blooms a lot in the spring and summer, but this year it only bloomed in the spring and has been pitiful ever since. I have had it for about 10 years and don’t want to lose it. What can I do? Also there was an ant bed underneath it (small black ants and we sprayed them, could they have damaged the plant?

AnswerYour rose bush has the classic rose fungus disease called black spot. This was a great season for diseases of all types, but if you have a susceptible variety, you typically have the disease every year in Arkansas. Spraying after you see the disease is usually a futile attempt at control. The key is to start your spray schedule in advance of the disease—soon after the plant kicks into growth in the spring. Sprays every week to three weeks—depending on what product you use, will be necessary throughout the season. Black spot can weaken a rose bush, and if it occurs year after year, it can weaken it enough for it to die, but it should come back strong next spring with proper pruning, spraying and fertilization. I don’t think the ant spray had any effect.

(July 2006)

QuestionWe have a brick mailbox with a rounded top. I have 3 climbing rose bushes that I want to climb over the top of the mailbox. I got busy last fall and did not prune them. We had a lot of roses this year, but there weren’t a lot of leaves. The roses have finished blooming and they are scarce as far as the leaves go. The leaves that are there look green with no spots. After they started blooming this year, I fed the bushes and also applied the Bayer liquid for roses. At this time, I have several limbs with little or no leaves that are going all over the place. There are a lot of thorns. Any suggestions of how to train these climbing roses to climb over the mailbox? Should I go ahead and prune them now? I was just not sure, because if I keep pruning them, they will never be long enough to climb the mailbox.

AnswerClimbing roses can bloom all summer or only once in the spring--it depends on the variety. Many people are uncertain as to when to prune so they just don't and the plants get gangly and less thrifty. Allow climbers to bloom in the spring and then do your pruning. Normally we like to take out one to three older canes and take out the thin, weak wood. Taking out an old cane now is not going to hurt but recovery will be slower since it is hot and dry. The goal is to have a variety of aged canes with foliage from the ground up. Mailmen are often not fond of a lot of landscaping around the mailbox, as bees can compete with mail delivery. Have some type of trellis for them to grow on, prune annually after the first flush of blooms in the spring, fertilize monthly, water as needed and control black spot when it is needed and your roses should do well.

(July 2007)

QuestionMy running rose is losing all of its leaves. It bloomed very well earlier this year, but looks awful now. Can you tell me what the problem is? The plant is only about two years old.

AnswerThe common fungal disease black spot, has defoliated many roses this growing season. This disease attacks a variety of roses, from bush types to climbers. The disease starts off with small black spots on the leaves, which over time yellow and fall off. If you grow a variety that is susceptible to the disease, the key is to spray in the spring after they begin growing with a fungicide such as Daconil, Funginex, Immunox or Bayer All in one Rose spray. Regular spray schedules are needed all season long following the label directions. At this point, starting a spray program would be futile. Trying to control a disease that has become firmly entrenched is fighting a losing battle. Prevention is key. For now, I would water when dry, lightly fertilize and hope for a better year next year.

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