I am cultivating artichokes 2 years now and this year I noticed that in some of them the leaves turned yellow and they stopped growing. I opened some roots and saw in every root a black hole. I am not sure if it is pest or disease.
Artichokes are relatively pest-free and easy to grow. However, they can be subject to crown rot and verticillium wilt. Here is a description of crown rot in artichokes from the University of California. “Plants with bacterial crown rot may be stunted. During periods of high temperatures the leaves may wilt. In advanced stages of the disease, plants may collapse entirely. New leaves in the center of plants may fail to expand, becoming brown and dry. Crown and tap root tissues become soft, rotted, and turn brown or black. Infected crowns are readily identified after cutting because blackened tissue can be seen in the cross section of the stem. After cutting, infected plants may regrow more slowly than healthy plants.” There is apparently no control for this disease. Do not plant artichokes in the same location again to prevent future infection.