Dutch Elm Disease - Ophiostoma

Vascular Wilts

A culture of Ophiostoma growing on agar in a petri dish. A few pieces of elm wood are also on the plate.

A culture of Ophiostoma growing on agar in a petri dish. A few pieces of elm wood are also on the plate.

Sporothrix stage. Conidiophores producing conidia. 

Sporothrix stage. Conidiophores producing conidia. 

Synnemata on elm bark as viewed with a hand lens.

Synnemata on elm bark as viewed with a hand lens.

Another view of elm wood with synnemata. Conidia collect on the top of each synnema in a sticky droplet.

Another view of elm wood with synnemata. Conidia collect on the top of each synnema in a sticky droplet.

Microscopic view of the top of a synnema showing a flair of conidiophores that would produce the conidia.

Microscopic view of the top of a synnema showing a flair of conidiophores that would produce the conidia.

Another view of the top of the synemma showing many conidiophores producing very small conidia. The conidia accumulate in a sticky droplet on the synemma.

Another view of the top of the synemma showing many conidiophores producing very small conidia. The conidia accumulate in a sticky droplet on the synemma.

A and B strains coming together will result in perithecia forming on the elm wood.

A and B strains coming together will result in perithecia forming on the elm wood.

Perithecia have a bulbous base and long neck. Ascospores accumulate on the tip in a sticky matrix.

Perithecia have a bulbous base and long neck. Ascospores accumulate on the tip in a sticky matrix.

A perithecium as seen through the microscope with the spore mass oozing out.

A perithecium as seen through the microscope with the spore mass oozing out.