Why Are My Rose Leaves Curling?

Aphids and greenfly

Rose aphids (primarily Macrosiphum rosae) build up rapidly on young shoot tips and flower buds from April to June. Feeding causes the young, tender leaves to distort, curl, and pucker. Heavily infested shoot tips may be entirely twisted and cupped with the tip appearing stunted. The pale green to pink-green aphids are visible to the naked eye on the undersides of curled leaves and on shoot tips.

What to do

• Tolerate for a few days to allow natural predators (ladybirds, lacewing larvae, parasitic wasps) to colonise; physically squash colonies with fingers or knock off with a jet of water from a hose, repeating every few days through the April to June peak period; if chemical control is needed, apply insecticidal soap or pyrethrin-based products in the morning or evening away from open flowers; avoid neonicotinoid products near flowering plants.

Rose leaf rolling sawfly

Blennocampa phyllocolpa is the cause of the distinctive, very precise, tight, cigar-shaped rolling of individual rose leaflets in May and June. The adult female releases a chemical that locks the leaflet in a rolled position before laying eggs inside. The rolling is very characteristic: neat, cylindrical, not unrolling when pressed. The overall health of the rose is not significantly harmed.

What to do

• Pick off the rolled leaflets by hand and squeeze them firmly to kill the larvae inside, or dispose of them in general waste (not compost); repeat regularly through May and June; no spray is effective once rolling has occurred as the roll protects the larvae inside; this is primarily cosmetic damage and the rose bush is not significantly harmed; hand removal is the most practical control for UK gardeners.

Drought stress

Rose leaves on recently planted roses, container roses, or roses in thin sandy or chalky soil in a hot, exposed position may curl inward from drought stress in dry UK summers from July to September. Drought-stressed rose leaves curl inward without the distortion and puckering of aphid damage and without the very precise cylindrical rolling of sawfly damage. Leaves may also appear pale, dull, and limp, with premature leaf drop and reduced flowering in severe cases.

What to do

• Water thoroughly and regularly during dry periods from July to September; apply a thick mulch (7 to 10 cm) of well-rotted compost or bark chippings around the base to retain soil moisture and suppress weeds; water deeply and infrequently (every seven to ten days in dry weather) rather than little and often, to encourage deep root development; container roses dry out very rapidly in summer and may need watering daily in hot weather.

Herbicide damage

Herbicide exposure from spray drift, contaminated soil, or aminopyralid-contaminated compost or manure can cause cupped, downward-curling, distorted, or strap-like (excessively narrow) rose leaves. New growth produced after the herbicide exposure may be particularly distorted. No aphids or sawfly are visible. Distinguishing feature: strap-like, downward-cupped, or abnormally shiny leaves from aminopyralid or phenoxy herbicide damage.

What to do

• Remove and dispose of the most severely damaged leaves; the rose usually produces normal healthy new growth once the herbicide effect has been metabolised; avoid using compost or manure that may be contaminated with aminopyralid (test suspect compost by growing tomatoes in it; tomatoes are very sensitive to aminopyralid and show clear strap-leaf symptoms quickly if contamination is present); identify and eliminate the herbicide source to prevent reoccurrence.

Frequently asked questions

Why are my rose leaves curling?

Rose leaves curl most commonly because of aphids and greenfly (pale green to pink-green aphid colonies visible on undersides of curled puckered shoot tip leaves and on flower buds; April to June peak; tolerate for natural predators; squash by hand or knock off with water jet; insecticidal soap or pyrethrin if chemical control needed), rose leaf rolling sawfly (very distinctive very precise tight cigar-shaped rolling of individual leaflets in May to June; no insects visible on the rolls; pick off rolled leaflets and squeeze or dispose of in general waste; cosmetic damage only; does not significantly harm overall rose health), drought stress (inward curling without distortion or precise cylindrical rolling; pale dull limp leaves; premature leaf drop; water thoroughly and regularly in dry periods; thick mulch; deep infrequent watering), or herbicide damage (cupped downward-curling distorted strap-like leaves; no insects visible; usually resolves as herbicide metabolised; test suspect compost with tomatoes for aminopyralid contamination).

What is rose leaf rolling sawfly and how do I control it?

Blennocampa phyllocolpa: overwinters in soil as a pupa; adult emerges in May to June; tiny (4 to 5 mm long) black wasp-like insect; female crawls to individual rose leaflets; releases a chemical causing the leaflet to roll and lock tightly in cylindrical form; lays eggs inside the rolled leaflet; larvae feed on inside surface of rolled leaflet; larvae drop to soil to pupate when feeding complete; one generation per year. The damage: very tight neat cylindrical cigar-like rolls of individual leaflets that do not unroll when pressed; green turning pale or yellowish inside; multiple leaflets on same leaf may be rolled; cosmetic damage only; no lasting damage to overall rose health or flowering. Control: hand removal is most practical; pick off rolled leaflets and squeeze firmly to kill larvae inside; dispose of in general waste not compost; no insecticide spray is effective once rolling has occurred; contact insecticides applied before rolling begins in April to early May may discourage adult females but timing is difficult.

How do I treat aphids on roses in the UK?

Identifying aphid damage: clusters of small pale green to pink-green soft-bodied insects on undersides of young curled puckered shoot tip leaves and on flower buds; sticky honeydew; possible black sooty mould; stunted bent shoot tips. Non-chemical: tolerate briefly to allow natural predators (ladybirds, lacewing larvae, parasitic wasps, hoverfly larvae) to find the colony; physically squash or rub colonies off with fingers or knock off with a jet of water from a hose; repeat every few days during April to June peak. Chemical: insecticidal soap or pyrethrin-based products if needed; apply morning or evening away from open flowers; repeat every 7 to 10 days; neonicotinoids now restricted or banned for many outdoor uses in the UK. Resistant varieties: modern shrub roses and English (David Austin) roses often somewhat less severely attacked than older hybrid tea cultivars.

Can herbicide damage cause rose leaves to curl?

Yes. How herbicide reaches roses: spray drift from neighbouring weedkiller application; contaminated soil from previous herbicide treatment; aminopyralid residues in treated manure or compost (persistent; passes through treated silage to cattle manure to garden compost; a significant documented problem in the UK); lawn weedkiller products containing selective broadleaf herbicide applied near the rose. Symptoms: leaves cupped downward; distorted; strap-like (excessively narrow and elongated); leaf surface may appear unnaturally shiny or waxy; veins stand out prominently; symptoms confined to new growth produced after exposure; older leaves at time of exposure relatively normal. Distinguishing from aphid and sawfly damage: no tight cylindrical single-leaflet rolling; no aphid colonies visible; strap-leaf and downward cupping particularly suggestive of broadleaf or hormone-type herbicide (2,4-D, mecoprop-P, dicamba from lawn weedkillers; or aminopyralid from contaminated compost). Recovery: normal healthy new growth once herbicide metabolised; test suspect compost by growing tomatoes in it before using on roses.