Help with unusual problem for knockout rose
Cynthia Harrington
12 days ago
last modified: 12 days ago
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Cynthia Harrington
12 days agoCynthia Harrington
12 days agoRelated Discussions
Please help! Found rose rosette on a sunny knockout
Comments (11)Michaelg, I guess it is possible that a herbcide affected it. My husband put out some weed and feed in another part of the yard and sprayed some Roundup on other parts of the property, not near the roses. He always uses a grounder when he sprays to prevent drift. Also, I live in an agricultural area and although there are no fields adjacent to our property, planes do fly over all the time on the way to and from the ag airports. So there is always a possibility, even if not a probability. After reading more about RRD I think I am safe in that there is a lot of this red growth and RRD develops slowly. Also, there have been no documented outbreaks of it in Louisiana. I will keep watching and thanks so much for your help! I am glad that someone suggested posting pictures!...See MoreDouble knockout roses doing poorly Help!
Comments (6)Hi again, There are a couple of possible issues here. Spraying anything in warm, dry weather has the potential to burn foliage. Be sure to DEEP water the day before spraying anything or giving any sort of drench. Spray in the early morning or evening when the day is coolest. Spraying Neem or other 'organic' insecticides can also burn foliage in hot weather because they contain oils. Your roses will have aphids every spring. I promise! Spring = aphids. Aphids are best controlled by squishing (very satisfying to the gardener) or blasting with a strong stream of water from a garden hose (more effective). Treating aphids with insecticide is a mistake, it sets your roses up for infestation by spider mites and spider mites are MUCH more difficult to kill. Aphid damage is cosmetic, they don't really harm your bushes. Since you've already used pesticide, relax, you won't automatically have spider mites but for heaven's sake don't use any more pesticide on your roses. I'm thinking that you used fungicide because yellowing leaves with spots sounds like blackspot. In central Texas you won't see BS on Knockout roses. Maybe some wimpy rose like Iceberg or Lagerfeld would BS in Texas but not Knockout. Your humidity level is too low and your summers are too hot. I think your roses defoliated due to spray burn. How can you best help your poor naked roses? Water, water, water. Your roses should be deep watered twice a week to grow & bloom nicely. Any week that you receive two inches of rain, don't water. If it rains less than two inches a week in summer, water. If it rains less than an inch a week in fall, water. Water, water, water. You have several chemical products formulated for roses in your garage and your Knockouts don't need them. Go to the garden center and buy a hybrid tea rose so you have a rose to nurture. You sound like a very nice person and you truly want to care for your roses but Knockout only needs water....See Moreknockout rose problem
Comments (12)Never apply insecticide unless a particular pest that has serious consequences has been identified. You are stressing the plants unnecessarily with chemicals that can burn leaves. The symptom of Sevin poisoning would be bronzing and dead brown spots on the leaves. However, I doubt that is the problem. Let me repeat my point that, if you plant Western-grown roses in Florida sand, they will decline after 2-3 years from root-knot nematodes. If you dig such a plant for inspection, the roots will be sparse and lumpy, Choose Florida-grown roses on nematode-resistant Fortuniana rootstock. If that is not the problem, it is probably insufficient water or nutrition. In sandy soil during summer, pants need water every three days and over an inch (about 6 gallons) per week. I strongly disagree with the advice not to fertilize in summer. When I gardened in Central Florida, we fed roses every 4-6 weeks year around. Malcolm Manners is a professor of horticulture in Lakeland and a world expert on roses. He feeds twice as much in summer as in winter because the rainy season leaches nutrients from the sandy soil. He uses Osmocote-for-Florida every 3 months plus organic ferts and lime. Let me ask again if the yellowish leaves have green veins. You should get a soil test through the county extension agent....See MoreDouble knockout roses got disease, need help
Comments (6)I did live in the burbs in Houston for almost a decade, and if I see your gardening area correctly, the rose is planted right next to a cement slab. (And the weepholes in the brick wall in back of the rose?) The problem is, or at least may be, that the slab may be affecting the pH of the soil. And that pH may be affecting nutrient uptake by your roses. (Also there may be some chemical treatments done to the perimeter of your house before you moved in. First, call the Texas County extension agent and ask him or her about getting a soil test for that specific soil (forget about any suggestions that you should take samples from all over your yard, that's for grass growers). Also ask that the test check for nutrients in the soil....See MoreMoses, Pittsburgh, W. PA., zone 5/6, USA
12 days agolast modified: 12 days agorosecanadian
12 days agomad_gallica (z5 Eastern NY)
12 days agoCynthia Harrington
12 days ago
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