Common rose pests, diseases and disorders

Watch on Flower buds and soft new shoots

Rose aphids, or greenfly, cluster in dense pink or green colonies where buds meet the stem and along soft new shoots. They breed fastest in spring on soft growth from heavily fed plants. They leave sticky honeydew that blackens with sooty mould, and a heavy colony can make buds open poorly. Run finger and thumb up an infested shoot to clear it quickly. Leaving a few early aphids can also support ladybirds and hoverflies.

Watch on Older canes and stems, worst on neglected bushes

Scale insects appear as small brown or whitish domes fixed to older canes and stems, often on the shady side near the base. Rose scale can form white crusts along neglected canes. It stays in place when pushed with a fingernail. Soft scales leave honeydew that blackens with sooty mould, while armoured rose scale leaves nothing sticky and can still weaken the cane. Scrape them off, or prune out a cane crusted along its length. Scale is worst on congested, shaded bushes left dry at the root.

Watch on Leaves, worst under glass or against a hot wall

Red spider mite makes rose leaves finely speckled, then dull, bronze, dry and likely to drop. It breeds fastest in hot dry air, so roses against sunny walls or under glass suffer most. Fine webbing over the shoot tips means a heavy attack. Tap a shoot over white paper and watch for moving specks. Wash the leaf undersides with water and keep the plant watered. Outdoors, rain and predators usually keep it in check.

Watch on Petals, flower buds and young leaves

Thrips rasp rose petals and young leaves, leaving silvery flecking with tiny black dots of excrement. Buds may open unevenly or fail to open at all. Pale roses show the petal streaking most clearly. New leaves damaged while still furled emerge puckered and scarred. Deadhead spent blooms where thrips breed, hang a blue sticky trap to check for them, and shower the plant. An established rose can grow through light damage once numbers are reduced.

Watch on The newest leaves and shoot tips

Capsid bugs feed on the youngest rose leaves and shoot tips. The damage shows only after the leaf expands, as small ragged holes with brown rims in puckered, uneven foliage. The fast green bug has usually gone by then, so you may not find it on the plant. Buds may open one-sided or fail. The holes can look serious, but they usually do little harm to an established rose. On most roses, leave it alone.

Watch on Leaves and green shoots

Sawfly larvae damage rose leaves in three main ways. Rose slug sawfly grazes the surface off, leaving a lace of veins that dries brown. Leaf-rolling sawfly makes the leaflets curl tightly downward into tubes. The large rose sawfly eats whole leaves and cuts rows of slits into green stems to lay eggs, splitting the shoot along the line. Count the fleshy prolegs to tell sawfly larvae from caterpillars, since caterpillar treatments do not work on them. Pick the larvae off, or cut out stems that carry a line of laying slits.

Watch on Leaves, buds and shoot tips

Several caterpillars chew rose leaves, and the winter moth is the one that matters. Its looping green caterpillars hatch with the buds and eat the developing leaves and flower buds, spinning two leaves together at a shoot tip. Others leave ragged holes with dark frass pellets below, which separates them from the clean scallops of a leaf-cutter bee. Count the prolegs to tell a caterpillar from a sawfly larva. Pick them off by hand, and put grease bands on standard rose stems to stop the flightless winter moth females climbing up to lay.

Watch on Whole shoots, and bark on young plants

Deer tear rose shoots off and leave a ragged, frayed end because they have no upper incisors. They can graze well above head height. Rabbits cut lower shoots cleanly at a sharp angle and usually work below about 50 cm. Both can strip a bush to bare stems, and rabbits may gnaw bark from the base of a young rose over winter, which can ring and kill it. Check the cut and the height to identify the animal. A suitable fence is the only reliable protection.

Watch on Roots of container roses, and leaf margins

Vine weevil troubles roses grown in pots. The plump white legless grubs eat the roots through autumn and winter, so a container rose that was healthy collapses in spring and lifts out with almost no root left. The dull black adults notch neat semicircles from leaf margins at night, which warns that eggs are going into the compost. Knock a new pot out to check the compost before buying, water on nematodes while it is still warm, and grow vulnerable roses in the open ground where predators reach the grubs.

Watch on Leaves of most garden roses

Rose black spot can strip a bush bare by late summer. It makes rounded purple-black blotches with ragged edges on the upper leaf, and the leaf yellows around them and falls. The disease usually works up from the base. A badly affected bush may be half bare in high summer. Small dark blotches on young stems carry it through winter, and it also overwinters on fallen leaves. Clear fallen leaves, water at the roots and choose a resistant variety.

Watch on Leaf undersides and, in spring, whole shoots

Rose rust shows as raised orange pustules on leaf undersides, with pale yellow spots on the upper surface directly above. The powder rubs off on a finger. Leaves yellow and drop from the base upward. In spring the fungus can swell and distort whole shoots, coating them in bright orange spores. Remove those shoots at the base. Rust needs the leaf wet for hours, so it builds in still, crowded, damp plantings. Space the bushes and clear every fallen leaf.

Watch on Young leaves, shoots and flower buds

Rose powdery mildew coats young leaves, shoots and buds in a white powdery film. The growing tip often distorts and turns slightly purple before the coating shows. Buds may open badly or not at all. Unlike most rose diseases, it worsens when the roots are dry and the air is humid, so roses in dry soil at the foot of a wall are often affected first. Water the roots well, mulch to hold moisture, and give the bush room so air moves through it. The coating wipes off, which separates it from black spot.

Watch on Leaves, in cool wet spells

Rose downy mildew is less common than black spot but moves much faster, sometimes stripping a bush in days in cool wet weather. It makes angular purplish or dark red blotches on the upper leaf, bounded by the veins, sometimes with faint greyish growth beneath. The leaves drop quickly. It appears in wet spring or autumn weather, and under glass on cutting-raised plants. Improve airflow, avoid wetting the foliage, and clear infected leaves. It will not rub off, which tells it from powdery mildew.

Watch on Flower buds and open blooms

Grey mould, or botrytis, rots rose buds and open blooms in cool damp weather, coating them in a fuzzy grey-brown growth that puffs a cloud of spores when touched. Buds may go brown and fail to open, a fault sometimes called balling, and petals rot from the edges. It establishes on a dead or damaged petal first, then pushes into sound tissue, so it is worst in a wet spell and on crowded, poorly ventilated plants. Remove faded blooms and damaged tissue, improve the airflow, and cut cleanly without leaving snags.

Watch on Leaves of an infected plant

Rose mosaic shows as yellow mottling, wavy line patterns, rings or oak-leaf markings on the leaves, usually on a few canes rather than the whole plant. It does not improve with feeding or watering. An infected rose may be a little less vigorous and flower less freely, though many carry it for years and still grow well. It spreads through grafting and propagation rather than from plant to plant in the garden, so there is no garden spread to stop and no spray to use. Buy from a supplier who uses clean stock, and never propagate from a marked plant.

Watch on Roots and stem base of the whole plant

Honey fungus kills roses from the roots, and roses are among the shrubs it infects readily. A bush declines or collapses over a few weeks, with smaller paler leaves and dieback in the stems. It may flower unusually heavily the year before it dies. Confirm it by paring a flap of bark from the base below soil level and looking for a sheet of creamy white growth that smells strongly of mushroom, with black bootlace strands in the soil. Dig out the dead plant and as much root as you can.

Watch on Leaves, in a pattern that follows the veins

A rose short of a nutrient yellows in a pattern that follows the veins, and the position on the plant helps identify the shortage. Magnesium shortage leaves the oldest leaves yellow between green veins, often with red margins, and often follows heavy feeding. Iron shortage turns the newest leaves almost white with a fine green net, usually where the soil is alkaline or the water is hard. Most yellowing comes from roots that cannot take up nutrients already in the soil, so check drainage and pH before feeding, and work in organic matter each year.

Watch on New leaves and shoot tips

Roses are sensitive to hormone weedkillers, and a small amount can distort them. New leaves come out narrow, twisted or thread-like, with the blade barely formed. Shoot tips cup and spiral, while older lower leaves stay normal. The weedkiller may arrive as drift from lawn treatment, in clippings from a treated lawn, or in manure carrying aminopyralid residue. The pattern helps identify it, because it affects susceptible plants in one area rather than one isolated plant. Keep weedkillers and treated clippings well away from roses.

Watch on Soft new shoots and young leaves

A late frost can blacken soft new rose growth overnight, leaving shoots and young leaves limp while sheltered parts of the same plant remain untouched. The damage arrives in one night and does not spread, which separates it from disease. New growth is soft and vulnerable, so a mild spell that starts growth early makes a following frost worse. Leave blackened growth in place as insulation until hard frosts have passed, then cut back to a live bud.

Watch on The stem base and roots of tall bushes

Wind rock loosens a tall or leggy rose in the ground until a funnel-shaped hole opens in the soil around the stem base. The rocking tears fine feeding roots, slows growth, and lets rain collect against the collar through winter, where collar rot and other root diseases can start. Cut a leggy bush back by about half in autumn to reduce the top growth the wind catches. Then firm the soil back and fill the hollow so water cannot stand in it. Do the main pruning in spring.