One aspect of rose growing that has changed in recent times is the access to chemical sprays to control a multitude of problems. In most cases the sprays used are very safe to plants but occasionally problems are encountered. The following are the most common spray needs and problems.
Gyphosate – Roundup, No Grow etc.
This spray is used to kill weeds around the garden. It is most damaging on soft new growth and when used in a rose garden extreme care should be taken to avoid any contact with new growth. Only use in a rose garden should be in winter when roses are dormant or with a guard around the plant or spray nozzle. Most spray damage problems occur when using the same container for another spray purpose with a little of this chemical left in the container. New growth of the rose appear wispy with little length to the shoot. Sprayed plants should be cut back severely and given time to recover. A sprayed plant has a good chance of survival but it will take 12 months to recover properly.
Dycambre – Weed and Feed
Weed and feed style products are popular to remove small weeds in a lawn whilst feeding the lawn. Extreme care must be taken while using these products as they are selective herbicides and target broad leaf plants – which roses are. Avoid any spraying near rose bushes as consequences can be quite severe. If sprayed in error cut back plants severely and feed and water well.
Non Chemical weed sprays
Just in the last few years a number of weed killers have emerged on the market which claim to kill weeds yet are safe for humans and animals. These sprays do work to a degree and are worth considering if health concerns are a major factor.
Tests we have conducted do show the spray burns growth however some repeat spraying is needed to control some that have not been affected. These sprays are useful around woody plants for they are contact sprays and do not seem to affect the woody aspect of established plants such as roses.
As usual try a small application in an area of less concern if uncertain how the spray may affect established plants.
After pruning in July it is good practise to spray the plants with two products to help control problems in spring. Copper Oxy Chloride, Lime Sulphur or Boudreaux sprays can be used in winter after pruning when the temperature is less than 25 degrees to control fungal attacks when new growth appears in spring. A second spray of Winter Oil, Pest Oil or Eco Oil is used to coat insect eggs (mainly aphid) and kill them.
In the rose garden there are times when spraying for Black Spot, Mildew and Rust must occur. Spraying with a spray containing Triforine or Macozeb + will control these fungal problems. For more complete information see our fact sheet on these problems.
By far the most common insect that may need to be controlled is rose Aphids. These pests occur in plague proportions in spring and can damage flowers in their immature state. Some control must take place but we never spray chemicals to control Aphids. Soapy sprays, Eco Oils, Pest Oils or just a jet from a hose can all reduce the numbers enough to let natural predators control remaining insects.
Spraying of roses should only occur minimally and when the problems are really bad. Care of the gardener must be assured and reading instructions is always the first step prior to any use. Safety equipment should be used even in low toxicity chemicals and cleaning of the sprayer after use vital to avoid cross contamination. If many roses consider having 1 sprayer for just herbicides and another for other applications.