Rose Pests And Prevention

Roses suffer from few pests, and of the ones that do like roses, none are 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, and sadly roses too. The good thing is that they are pretty easy to control and mostly appear at certain times of the year.

It's all about the lifecycle of the humble aphid. 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 are all females which give birth to live offspring (also all females) so their population explodes 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. This is dependant on the strength of the wind as they are weak flyers, but every year the UK has times when we get huge arrivals from 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, so rather than killing and eating the aphids, ants "milk" them and take the honey dew back to their nests to feed their young.

Everyone has at some time parked their car under trees to find it covered with sticky liquid, the honey dew, especially under sycamore trees.

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.

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

Control

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 moths) 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.