List of pests and diseases of roses

Insects that affect roses are often considered pests.

• Aphids (greenfly) (order Hemiptera family Aphididae) Macrosiphum rosae – Likely to be found on new shoots and buds, aphids are soft bodied insects 1–2 mm long. Often green but occasionally light brown, and sometimes with wings, they may cover (in a colony) the complete growing tip of the plant. Aphids are most active in spring and summer and multiply at a prodigious rate feeding on the sap of the plant by piercing the plant cells via a proboscis. In large quantities they may seriously retard the growth of the plant and ruin buds. They are particularly damaging to the new shoots with subsequent damage to the emerging leaves which become malformed with much the same appearance as leaf-curl in peaches.[3]
• Two-spotted mite (spider-mites or red spider mite) (order Acari: family Tetranychidae) Tetranychus urticae – Previously known as red-spider mite these arachnids prefer the underside of leaves and are difficult to see with an unaided eye. Evidence of their presence is silvering of leaves where the mites have destroyed individual leaf cells. Fine webbing and eggs on the undersides of leaves is further evidence of the presence of Tetranychus urticae.
• Thrips (order Thysanoptera) – Thrips are slim-winged insects 1 mm in length, resembling fine slivers of wood or rice. Preferring light-coloured blooms and often appearing in plague numbers, flowers are often left looking scarred, warped, and lustreless.[4]
• Rose slugs (rose sawflies) – Sawflies are non-stinging wasps (Hymenoptera) in the suborder Symphyta, not flies (Diptera). They lay eggs in plant leaves or stems with a saw-like ovipositor. There are three species that commonly cause damage to wild or cultivated roses:[5] The bristly roseslug (Cladius difformis) is found in Europe, Siberia, and many areas of North America. The larva is pale green, up to 16 millimetres (0.6 in) long, and covered with hairlike bristles all over its body. It looks like a caterpillar but that term, strictly speaking, only applies to the larvae of moths and butterflies. It skeletonising the underside of leaves, with several generations per year. The European roseslug (Endelomyia aethiops) is found in North America and Europe. The larvae is more slug like (but not slimy), up to 13 millimetres (0.5 in), and skeletonises the upper surface of leaves with only one generation per year.[5] The curled roseslug (Allantus cinctus) larva is pastel green on the back, marked on the thorax and abdomen with white dots, and up to 19 millimetres (0.7 in) long. It frequently coils up like a snake. After skeletonising entire leaves except the main veins, it pupates in the pith of canes, with up to two generations per year in North America.
• Caterpillars (order Lepidoptera) (See also List of Lepidoptera that feed on roses) – The (tortrix) moth Lozotaenia forsterana is a prominent pest of roses. The caterpillars are green, up to 15 mm long, and can be found boring into buds or within curled leaves. When disturbed the caterpillars move swiftly, dropping to the ground on a fine thread. Damage is chewn leaves and flowers and buds with "shot holes".
• Curculio beetles (family Curculionidae)
• Japanese beetles (Popillia japonica) – This species, introduced to North America in 1912, is now an endemic pest in the eastern United States. Adult beetles emerge from the ground in early summer and join into swarms for four to six weeks, devouring blooms and skeletonising foliage on roses and many other garden plants. Japanese beetles can be partially controlled, albeit slowly, by spreading milky spore bacillus on the lawn areas where the larvae live. The popular pheromone-baited traps may do more harm than good by attracting beetles from a wide area.
• Scale insects (order Hemiptera)

Cottony cushion scale (order Hemiptera: family Coccoidea) Icerya purchasi – This scale infests twigs and branches. The mature female is oval in shape, reddish brown with black hairs, 5 mm long. When mature the insect remains stationary and produces an egg sac in grooves, by extrusion, in the body which encases hundreds of red eggs. The insect causes little damage but produces copious honeydew (frass) that can cause damaging sooty mould.

California red scale (order Hemiptera: family Coccoidea) Aonidiella aurantii – A hard scale, orange to orange pink, the female covering being less than 1.5 mm across. Often in plague numbers this scale infests upper surfaces of foliage causing yellowing, leaf fall, and twig and branch dieback. Serious infestations can cause plant death.

Rose scale (order Hemiptera: family Coccoidea) Aulacaspis rosae – Mainly found on the stems and branches of the plant, lack of control will allow the pest to spread to flower stalks and petioles. At this point the plant would be stunted, spindly and with a white, flaky crust of scales on the bark. Female Aulacaspis rosae may live for one year and may lay 80 eggs each with several overlapping generations living within millimetres of the original parent.[4]

• Leaf cutting bee (order Hymenoptera: family Megachilidae) Megachile species – Leafcutter bees are 6–16 mm long and mostly black with bands of light-coloured hair. They chew pieces from the edges of leaves. The pieces are regular in shape, circular or oval. Damage is not often significant.
• Nematodes (eelworms) (order Tylenchida: family Heteroderidae)

Root-knot nematode Meloidogyne species – symptoms of Meloidogyne infestation in roses is stunting, slow growth, pale green leaves and wilting in mild weather.[2]

• Rose chafer (order Coleoptera: family Scarabaeidae) Macrodactylus subspinosus – The rose chafer is common to North America, and emerges in late May to mid June. These beetles form aggregations and feed upon foliage, buds, flowers, and fruit of roses and other ornamentals.[6][7]
• Metallic flea-beetles (order Coleoptera: family Chrysomelidae) Altica species – The small, shiny and metallic Altica beetles have thickened hindlegs adapted to jumping, similar to fleas. The insects are 3 mm long and chew holes of irregular shapes in young leaves and buds. As the leaves enlarge so do the holes.

Hoar frost on Rosa sp.

• Frost will destroy fresh growth causing stems and leaves to wilt, turn black and fall away from the plant. Timing pruning to promote growth after the threat of frost is a means to avoid frost damage.
• Salinity will present in roses as limp and light brown leaves with dry leaf margins. Soil may require testing to determine salinity levels. Symptoms will present if salinity is greater than 1200 parts per million.[27]
• Herbicide damage – Overspray or soil leaching of herbicidal sprays can present with several symptoms:

Prolonged exposure to overspray of glyphosate will cause yellow leaves and new leaves will be small and elongated. Hormone weed sprays (e.g. 2,4-D and 2,4,5-T) may cause grotesque new growth with thin twisted leaves and distorted buds. Plants may die in severe cases. Pre-emergent herbicides contacting the plants' root system via the soil will cause yellowing foliage. Effects of soil borne herbicide may take several years to clear.[1]

Bare-root roses: Plant in late autumn at leaf fall, and from late winter to early spring, before growth resumes. Avoid planting in the middle of winter when the ground is frozen.

Containerised and container-grown roses: Plant all year round, provided the ground is neither frozen, nor very dry.

• Common Names of Diseases, The American Phytopathological Society