Table of Contents
Deer love the top shoots, buds and foliage
Leaving ragged stems and bare branches as they go. They are particularly attracted to new planting out of sheer inquisitiveness. Deer tend to graze at night so it is difficult to frighten them off. They are more of a pest when foraging elsewhere is reduced; when berries or fruit harvests are low, or during winter. The main miscreants are muntjac and/or roe deer. The latter are larger. Strategies to deal with deer include fencing and thick, thorny hedges which make pretty effective barriers but take time to grow. Gates should be deer-proof too. And having a ditch beyond the fence or hedge adds immeasurably to its effectiveness. Temporarily netting around a newly planted rose with bamboo canes and ordinary fruit netting gives the rose time to become woody and less tempting. Other options include aluminium ammonium sulphate spray but you need to keep on applying it to be effective. Some people put human hair in muslin bags around the garden to deter badgers and deer but there are no guarantees with this method – maybe it depends on the hair. Lion and tiger droppings have had mixed reviews so perhaps the most reliable deterrent is to have a dog in the garden at night, or in a kennel, so that the deer can smell and hear them.
Rabbits munch at young rose canes
You can tell whether it’s a deer or a rabbit because rabbits tend to use their sharp incisors to leave a clean cut lower down the plant. Rabbit proofing is the only answer – a less arduous and expensive task than deer proofing – usually involving lengths of chicken wire and canes to protect the plant while young. Eventually as the plant becomes woodier and older, rabbits will content themselves with more digestible meals.
Aphids AKA blackfly, greenfly, whitefly
Roses are a favourite food for these tiny, sap-sucking insects around March to August. You will spot tiny green or pink insects just covering the buds, foliage and very tips of the shoots of roses, each sucking away at the sap and draining the life from your plant. If you see them winged you know you have more of a problem because they have been forced to grow wings to escape their overcrowded conditions and so they need to find another victim. Another giveaway for aphid infestation is their white sloughed off skins, like a touch of dandruff on your rosebuds. In addition, aphids charmingly excrete a sticky substance known as honeydew which is obvious to the touch. This stickiness of course then attracts black, sooty moulds to compound the problem and further weaken your rose. What to do? Rather revoltingly, but most efficiently, you should don your gloves and squish any aphids you see before they have really got munching. Don’t forget to check on the underside of leaves too. It would be lovely to be able to rely on natural predators like lacewing and hoverfly larvae as well as ladybirds but it is an unusual year if their numbers are sufficiently large as early in the year as required to cope with a serious infestation. Allowing plants like Queen Anne’s lace, Yarrow or Dandelion that attract lacewings and ladybirds into your garden is still a worthwhile tactic although you may still end up resorting to chemical sprays. These sprays vary in their effectiveness and environmental credentials. With persistence, spraying roses with organic sprays like natural pyrethrum or just frequent squirts of horticultural soap can certainly help. A severe attack may need something more brutal but there is an environmental cost as many of these sprays are harmful to vital pollinating insects like bees as well as aphid predators. Whatever you use, apply it in the early evening when the wind is still, most pollinating insects have done their work.
Brown scale insects cause similar problems to aphids
These little brown scale bugs laying their eggs and the little nymphs are out and about and sucking sap in early July, when they can be zapped in the same way as aphids.
If you are aware that there has been a problem with brown scale in the summer it is worth using the organic Vitax winter tree wash on the affected plant to try to remove the overwintering nymphs while the plant is dormant. This is a pretty good cure all as it also kills aphid eggs.
Cats and dog toilet is bad for roses
They tend to leave thorny roses alone, but regular toilet use is bad, especially for newly planted roses.
Fungal diseases
Blackspot Fungus
Diplocarpon rosae is the most common and debilitating fungus.
Similar to but less aggressive than blackspot is rose rust. Here you will spot vivid orange pustules on the surface of the rose leaf and possibly some distortion of the rose stem. The pustules develop into orange dusty patches that can then be spread by the wind and you may encounter some early leaf drop. The dusty patches then become black and are able to spend the winter dormant on a trellis or rose stems ready to power up again into the orange pustules for the cycle to begin again. While this all looks unattractive, it has little long term effect on the rose, especially if you manage to cut out any infected branches and leaves.
Powdery mildew however occupies the number two fungal disease position. You will see white, powdery growth on the stalks leading up to the flower, on upper and lower leaf surfaces, the calyces and stems. The mildew can be so bad that buds then do not develop into flowers. Apart from being unsightly mildew greatly weakens any plant it attacks. Powdery mildew occurs when the roots have been deprived of water and when there is little air circulation amongst the stems and foliage so that the spores collect in one place and can settle on the rose. Preventative measures include watering plants well, especially if it has been very dry, and then mulching the soil to keep in the moisture. Feed your roses so that they produce robust growth but avoid feeding high nitrogen fertilisers which promote green sappy growth, an ideal target for fungal disease, especially later in the season. Trying to maintain a through draught through the rose will really help: redistribute the stems so that they do not cross and cut back other plants that grow too close to the rose. Mildew particularly affects climbing roses which grow tight up to a wall preventing airflow and because it is often dry in the lee of a wall so that the roots dry out. Special attention has to be made for roses in this situation. Cut out any badly affected shoots or branches as soon as you seem them and burn them. Fungicides can be used sparingly but will need to be wheeled out several times over a summer. If used once in spring and once in autumn, you can aim to clear the disease in buds where it might otherwise have overwintered or be about to do so and then spread to other parts of the plant. There are dual purpose spray products on the market that combine nutrients to boost the rose while coating it with surfactants that prevent mildew, and stop aphids or scale insects from moving about and feeding and so gaining traction. Relatively new, they are yet to be proven but do not contain pesticides and are natural products. SB Plant invigorator and Ecofective Plant Defender are two examples and are less heavy hitting than most synthetic combined fungicide and insecticides.
Downy mildew is less easy to spot than powdery because there may be few signs on the leaf bar a little discolouration before it turns yellow and then falls prematurely. Downy mildew affects many types of plant and each suffers with its own version caused by prolonged leaf wetness which is when the spores establish themselves. There are no fungicide treatments so if you suspect that you have a case, remove and dispose of any diseased leaves, and if necessary dig up and destroy really badly affected roses. To prevent downy mildew, water roses in the morning if you need to so that leaves can dry out before the cool and damp of night, and avoid planting densely around the rose. The secondary spores can remain dormant in the soil for a long time so if you have had a bad bout of downy mildew and have been forced to remove your rose, do not replant in the same soil – this can lead to rose replant disease.
Just as sometimes daffodils come up and do not flower, so a rose can produce a perfectly normal flower stem but it does not then produce a terminal flower bud making the rose somewhat pointless. For some reason, the energy of the plant is diverted away from producing flowers, known as Rose Blindness. The cause is unclear, but is probably to do with unusual weather conditions. It usually only affects modern roses like Hybrid Teas. The remedy is to cut back the stem by half to a bud and hope that it then produces flowers when it regrows. Alternatively when pruning in the winter, remove some of the old stems right at the base of the plant in the expectation that new shoots will be more productive.
Rose leaf rolling sawfly sounds a little like a Country and Western song but is in fact a rather vexing insect that chooses rose leaves as the hatching location for its eggs and at the same time injects the leaf with a chemical that causes the leaf to curl or roll up. Once rolled, the area of leaf exposed to the sun decreases compromising photosynthesis. The subsequent larvae then chomp through the leaf. Sawflies flourish if the weather is hot when they lay their eggs which is between the end of April and early summer. With a light infestation just pick off any affected leaves so that the larvae do not have a chance to feed on them. A serious case can be more debilitating because it could be more detrimental to the rose removing a large quantity of infected leaves than for the rose to suffer the ravages of the larvae. There is little that one can do in terms of chemical control either. If sawfly have been at your roses, in winter it is worth scouting around and disturbing the soil in the hopes of unearthing some larvae – which the birds will have in a flash but you have to be careful not to damage the roots. This disease is often mistakenly attributed to weed-killer damage, so do check for larvae if you see the characteristic rolled up leaves.
Dieback is a common affliction in roses and can occur at any time of year for a variety of reasons. The most obvious example is when the pruned tips of stems go brown and die and this then proceeds further back down the stem. Often this is due to poor pruning technique or, if you see it on young shoots in spring as a result of frost damage. Sometimes black fungal bodies also become apparent on the damaged stems and can cause cankers that spread into the rest of the healthy plant. It is also possible for dieback to affect a whole plant. This is caused by stress from unpromising weather or because the rose was not planted properly. So always make sure that your roses are planted well with their roots evenly spread out in good soil. Avoid sites that are prone to dryness or to becoming waterlogged. Feed your roses with a proper rose fertiliser in spring. Then follow pruning instructions faithfully to prevent further dieback. While these considerations will help, the immediate cure is simply to prune below the dieback to healthy white pith and hope that you have managed to remove the stressing factor
While this long list of possible ailments may feel daunting, roses are, in the main, made of tough stuff and will survive most of the above especially if cosseted and fed. And of course they bring a loveliness and glamour to your garden that few other flowers achieve. So, to finish in positive fashion we are going to run through some ideas about using roses to best advantage in your garden.