Ceratocystis Ulmi on elm hyphae in vessels. Dutch elm disease was first found in the United States in Ohio in 1930. It has now spread throughout North America and has destroyed over half the elm trees in the northern United Sates. The disease has been reported in all states except the desert Southwest. Trees infected with Dutch elm disease usually develop brown streaks in the sapwood of wilting branches. Cross sections of infected branches will show brown streaks in the outer wood in spring; in summer they will show a single ring of brown dots in the wood.