Rose Plant Pests

Leaf Feeders

• Some pests of roses feed specifically on the leaves of roses, while others feed on many parts of the plants. The larvae of sawflies eat rose leaves, leaving the veins of the leaves intact. The larvae of bristly roseslug -- another species of sawfly -- and curled rose sawfly chew holes in the leaves of roses. Sawflies can be knocked from your roses with a spray of water or picked off by hand. Horticultural oil and insecticidal soap are effective against immature sawflies.

Flower Feeders

• Japanese beetles feed on both the flowers and foliage of roses. These beetles may be the easiest leaf-eating pest to spot because they feed during the day, they are large beetles, and they have a striking, shiny metallic appearance. You can remove the beetles by hand, exclude them through the use of netting, or control large populations through the use of traps. The Clemson Cooperative Extension warns that you should place traps at least 50 feet from your roses, as there is a danger that the traps may attract beetles to their location.

Sap Feeders

• Aphids and mites pierce rose foliage to draw sap from the plants. While this feeding doesn't usually harm plants, large numbers of feeding aphids can affect the plants' ability to grow and produce blooms, and the wounds can allow microorganisms entry points into plant tissues. Both of these pests may be handled using similar methods: by encouraging the proliferation of their natural enemies, such as parasitic wasps, lady beetles and green lacewings; directing a spray of water onto affected plants to dislodge the pests; or by applying insecticidal soap to treat the plants.

Root Feeders

• Nematodes are soil-borne roundworms; root knot nematodes feed on the roots of roses. The roots become damaged by this feeding and form galls that disrupt the function of the vascular system. You may not see the galls as they are below ground, but you may notice your plants lack flowers or appear to have a nutritional deficiency. The University of Florida IFAS Extension notes that you must send a soil sample to a nematode assay lab to diagnose a nematode problem and identify the nematode involved. The extension recommends you purchase roses grafted onto the nematode-resistant rootstock Rosa "Fortuniana" if nematodes are a problem in your area.