What to do about rose pests?

Roses suffer from few pests and of the pests which might like roses, they are not specific to rose plants.

The most common and problematic pest is Greenfly, one of the most widespread insect pests affecting many different crops and garden plants from potatoes to wheat, to roses. The good thing is that they are pretty easy to control and mostly appear at certain times of the year.

It is all about the lifecycle of the humble aphid (the collective name for greenfly, blackfly, and lots of different coloured “greenfly” that will trouble roses).

They overwinter as eggs, laid in the autumn on the woody stems of your rose plant, usually at the top of stems – the eggs are pretty tiny, round and black in colour, but, can be spotted with a hand lens or similar.

They hatch in spring, and the amazing thing is that they are all females, which in turn give birth to live offspring which are also all females so that is why the population explodes so quickly and you will see stems smothered with aphids. The young aphids moult several times as they grow, the telltale white cast skins can be seen sticking to the plant stems.    

We normally see this in April, but it depends on the temperatures we get in spring.

Later generations are born with wings, these migrate from the host plant, and are carried by the wind over huge distances, depending on the strength of the wind as they are weak flyers – every year the U.K. has times when we get huge arrivals from the continent (Europe).

So aphids can appear “overnight” on rose plants, and that is why we need to be on the lookout for them.

There are some interesting things about aphids, they are sap feeders, pushing their mouthparts (a fine tube called a stylus) into the veins of the plants, this sap is pushed through the insect which in turn is exuded as honey dew – a weak sugary liquid which is loved by ants which rather than killing and eating the aphids “milk” them and take it back to their nests to feed their young.

I am sure everyone has at some time parked their car under trees to find it covered with sticky liquid- the honey dew – especially under sycamore trees.

So, if you see a procession of ants crawling up stems of roses there may well be colonies of aphids up near the growing point/ flower buds where the young soft growth makes feeding easier and more bountiful.    

The cycle continues with adults returning to lay their eggs in the autumn.  

How to control it? 

Pruning in the early spring will remove a lot of eggs before hatching – but some will survive to hatch. Natural predators such as hoverflies and ladybirds / wasps can eat a lot of aphids, but they are usually playing catch up and may not get on top of the problem. Sprays are readily available and effective – some of which are a mix of fungicide and aphicide (e.g. Rose Clear Ultra) so can be used both to eliminate the aphid and give protection against mildew and blackspot.

Many of our customers do not like the idea of using sprays in the garden, that is down to personal choice, but we would say that if used sensitively and at the right times sprays need not be viewed as indiscriminate destroyers of the ecosystem.

Other none chemical treatments are widely used for example soaps which attack the waxy cuticle (skin) of the aphid causing it to dry out and perish, it’s best to apply these with a garden sprayer (small one litre sprayers are available at most garden centres and are perfectly good) which gives a more targeted approach preventing over spraying.

Other Pests: The only other things we see are caterpillar damage ( usually early in spring caused by winter moth) and leaf cutter bees will occasionally remove pieces of leaf leaving unmistakable scalloped edges to the leaf, we don’t consider these as serious problems and leave them alone as any damage is usually random and short lived.

Four legged Pests: Rabbits will nibble young stems if they are short of more tasty alternatives and deer can be a much bigger problem. Some of our customers have real deer problems, but this is rarely seen in more urban environments.

Overall, while pests like greenfly pose a common challenge for rose enthusiasts, a combination of preventive measures, natural predators, and selective use of sprays or soaps can effectively manage these nuisances without causing significant harm to the overall ecosystem.

Back to blog