canker of apple fruit

例句：

1. 1. The farmer's canker had spread to the roots of the trees.
   农民的坏疽已经蔓延到树木的根部。
2. 2. The patient was diagnosed with a serious canker on his leg.
   患者被诊断出腿上有严重的坏疽。
3. 3. The disease is caused by a virus that attacks the cells in the canker.
   这种疾病是由一种病毒引起的，这种病毒攻击细胞中的坏疽。