Make sure the roots weren't eaten off by voles, there by making them fall over. I found out about the pesky critters when I once leaned against a small dogwood and if fell over. It lifted out of the ground like a stake- no roots. If its not that, and just the canes bending down from the heavy weight of the rain soaked flowers, do as instructed above. You can always add some green staking to support the interior of the plant if it does not have room to sprawl. If the canes stay down like that, you will get lots of growth on all the horizontal canes at each leaf-stem junction. Again, that may or may not be a bad thing depending on how much room you have.

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.

Tree or standard roses can be made without grafting. Select a strong vertical shoot. Prune to 3' or whatever. Dig out the budeyes except for a few at the top. (These are where every leaf is or was attached.) Remove all the other basal shoots at the graft. Install a permanent stake and fasten the standard (trunk) to it. When new shoots appear at the top, pinch out the tips when they are around a foot long to encourage branching. Rip out new basal shoots as they appear. This doesn't work well with all varieties, as in many cases the trunk will wear out after 5+ years and not support vigorous growth. This type of plant is known as a "self-standard."

gobluedjm, "do not plant" is pretty strong wording that I've never seen attributed to this plant, it deserved some follow up, clarification and context. cal-ipc.org doesn't list Catharanthus roseus as invasive, while other lists do. It's reasonable to assume that easy, drought tolerant plants would make such a list. Things like fennel, radish, olive and sweet alyssum are also considered invasive. Invasive isn't the same as "do not plant".