Pest and Disease Control of Roses
Introduction – What is IPC and its Methods
For those that have followed My blog on
general pest & disease control Will remember that I use the IPC method on all plants especially roses. So you will just need to skip this paragraph until you get to the one you that you know. For those that are new . I will briefly explain what IPC is before going on to the Pest and Disease section .
Briefly I P C stands for :-
- Identify – By Identifying the pest or disease you can then isolate it and treat it without harming any other insects or predators that are beneficial to the plant
- Prevention –
Prevention is better than cure
If you followed the guide lines that i told you. You are less more than likely to get infected by a blight or pest but like the common cold no matter how much we keep healthy we still get it. so is very much like plants
in their case they will become less sickly if we observed their requirement from the off set as I have pin pointed in the first blog
Control or Monitor methods – And finally Control With the pest or Disease on rose isolated we can begin the applying the safe practise of control whether its Chemical or Organic or mechanical
The 6 main pest & Diseases
& How to treat them
The main 6 pest & Diseases of roses are :-
- Black Fly
- White Fly
- Black Spot
There are others pest like the leaf cutting bee thrips &saw flies but those are the main six
These are caterpillar-like larvae, which feed on the leaves of your roses in the spring. They are about 1 ¼ inch long and are light green, some with black spots. If you get on top of this pest right away, you should be able to control them by simply hand-picking them. Look for them on the undersides of the leaves.
These you just simply remove and incinerate as the caterpillar is well protected
Up close and personal these critter look quite menacing a little like caterpillars but in a large abundance
Leaf Cutting bees
Thrips are tiny, slender, dark brown or black, sucking insects that damage and destroy opening rose buds turning them brown and leaving them only partially opened. They also feed on the upper surface of the leaf. They can be difficult to see outdoors. If you think that your rose may have thrips, take a cutting inside and shake it over white paper to see if any fall out. Look for a brownish black insect with a narrow body up to 1/16 inch long. They thrive in hot, dry conditions. Regularly watering your roses and spraying with an insecticide or simply cutting off the affected rose or leaf should do the job
I have already been mentioned in detail along with white fly in the following blog
As you can see from this picture these pest can be easily Identified & tend to swarm in colonies attacking anything that is green and sappy whether it your green beans or bedding plants to roses that have been over feed with high nitrogen fertilizer to produce sappy growth .
The best way to prevent your roses being attacked by these pest is to carefully check your feeding of roses.
As I said above these and other pest like aphids like green sappy growth for their piecing and sucking mouth parts
Feeding this way causes problems for the plant: aphids can transmit plant viruses, and the sticky honeydew they exude can attract sooty moulds to grow
As in the case of lime trees every where
Good hygiene too don’t compost any infected plants in winter as the females lays its eggs in the autumn on plants to feed its nurseries and ounce the eggs has hatched in spring they fly off on to much better food supply and the circle begins.
So by either bagging up infected plants or burning them you are at least cutting down on the numbers in your garden . But since they can fly doesn’t really guarantee you that you are free them
So we go to the next Section
Control or Management
There are 3 methods of control
By this mean good hygiene and feeding regime as I said above also to encourage their natural predators into the garden like Ladybirds lacewings even small birds feed on the insects now and again
Click to tweet how you can attract more predators into your garden
Spraying with tar oil or winter washes tends to work well in winter when the female lays it eggs
2. Biological Control
is comparatively expensive, but effective – if you can create the right conditions. The main problem being that there will be a time lag between being able to source the biological control of Blackfly. Together with this, there will need to be enough Blackfly for the biological predators to act upon.
However ongoing research according to this article here published in 2005
This discovery has applications for pest management – the aphid sucrase enzyme could be a suitable target for specific inhibitors that would abolish its dual role in osmoregulation and carbon nutrition of the aphid.
that these pest can be controlled by spraying or other methods not yet mentioned,
Current research is focussing on determining the mechanism – it’s possible that an anti-microbial with the symbiotic bacteria as the primary target may have evolved in certain plants.
As I already have gone into detail about the use of chemical as a method of culture I wont go into detail here but only to stress the dangers
As you can see from the picture that Mildew can be easily recognised by its powdery white effect on leafs and stems . In fact Mildews a fungal Disease rather like BlackSpot but cause its feeds on moisture on the plant leaves it easily remedied by following the procedure
If you seen any signs on your roses whether on the leaves or buds its best to prune them out to avoid the spores from spreading any further.
Good hygiene again is important – keep the center clear of branches in the spring to allow air flow through and around the plant
Try avoid watering from above or in between the branches water from the bellow ,
Avoid watering in them evening go for in the morning where if you have splashed the leaves the water has a chance to dry off
Plant rose far enough part so they can spread out
As you can see from these two examples that rose rust can be easily recognised by its orange flex on leaves and buds
And like Powdery Mildew its a fungal disease on the roses but less severe. That occurs from the beginning of spring right up to summer should the environmental conditions be right for the spores to spread
6 Cultural Methods of controlling rust
- Good Hygiene as always –
- remove infected leaves and incinerate to prevent the spores from spreading like Black Spot spores lay dormant in the on the soil surface until they are either splashed up by the rain or watering from above or carried up by insects especially ants . So clearing the ground of debris around the plant is a must.
- Pruning – By leaving the center clean and cutting out crossing branches improves the air circulation around the plant thus reducing the breeding grounds for the spores to live by drying out the leaves and buds.
- Weeding – By clearing any weeds around the plant esp oxalis that get infected by rust you are reducing the risk of it spreading to the roses
- Improve the soil structure of the soil by forking over the ground in spring to improve drainage
- Avoid watering from above always water from the base of the plant
- Avoid working on rose beds when its wet as you can spread the spores by simply walking around .
When you see the first signs of rust spray the entire rose bush with a copper formulated compound examples can be found here until the bush is cleared giving it a good drench.
Always go by the rules i have mentioned for proper chemical Management
There are many new ‘organic formulations’ on the market you could try if you are organically minded one is the
Vitax 2 in 1 pest and disease control spray Yet I haven’t had the chance to test it out yet.
But Vitax is reputable firm that specialize in Rose Care products
Finally I come to most dreaded killer of all roses,
Black Spot – as You can see by this image this too easily recognized by it instinctive black splotches that are actually spores . The thin white threads are in the roses stem. hence once you see it its pretty much that there is no real cure for it except to either live with it or destroy the bush all together.
In cases of My many Clients they rather live with it until it dies completely
So what can be done to prevent it
- As I mentioned at the very start of the Blogs on roses That when planting a new rows always make sure the rose gets a good start
- Mulching around the roses in spring with sterilized compost like Cocopeat or peat based formulations This will stop any fungal spores that i mentioned above from splashing up and infecting younger shoots
- Pruning out any dead diseased or dying branches and incinerating it ( Do not compost them
- Improve the air circulation around & inside the bush by cleaning out any inward pointing branches
- Don’t plant roses close together as one rose can spread the disease to another and this too allows air to circulate
- Water from the base only