There is a large, hard growth on the cane of one of my roses. What is it?
The large, hard growth is probably crown gall. Crown gall is caused by the bacterium Agrobacterium tumefaciens. The bacterial disease can infect roses, grapes, apples, raspberries, willows, euonymus, and many other woody plants. It also affects some herbaceous plants. The bacterium enters through wounds, especially on root and crown tissue. Rough, woody galls develop and interfere with the flow of nutrients and water. Galls may enlarge to an inch or more in diameter. To prevent crown gall, avoid injury to the roots and crown of plants when planting and when doing routine maintenance chores. Eradicating crown gall from infected plants is difficult. In many cases, infected plants should be dug up and destroyed. Also, discard the soil in the area as the crown gall bacterium can survive in the soil for 2 or more years. When replanting, select plants that are resistant to bacterial crown gall.