An infection called leaf curl causes curled leaves on emerging rose foliage during the spring. The disease varies in severity from one year to another. The specific pathogen has not been identified as of 2010.
A virus or a virus-like disease causes leaf curl. The pathogen spreads through the plant through the food-transporting system, or the phloem, and infects all parts of the plant. Rose leaf curl most commonly infects antique rose varieties. It also infects other roses such, as hybrid teas, if antique roses are grown nearby.
Leaf curl disease in roses is characterised by downward-curled leaves. Young leaves detach easily from the plant and emerging foliage is undersized and discoloured. Young shoots and canes experience dieback, the bark of mature canes splits and cracks and plants lose vigour. Diseased plants display symptoms during the spring and fall, although they may grow normally during the summer.
Leaf curl infections are controlled by removing and destroying diseased plants and purchasing only virus-free stock. However, since the effects of the disease vary each year, there is no guarantee that new plants will remain disease-free.