Maize chlorotic mottle virus (MCMV) is not widespread in the United States; it has been reported in Nebraska, Kansas, and Hawaii. Symptoms are fine chlorotic yellow streaks developing in the youngest leaves about 10 days after inoculation. The streaks then coalesce to form chlorotic mottling, which is then followed by leaf necrosis, epinasty, stunting, and plant death. The natural vectors of this virus are Diabrotica spp. adults and larvae and thrips. Experimental vectors include a few other Chrysomelid beetles as well. Hosts of the disease include corn, wheat, barley, rye, sorghum, and many grass species. This virus is very often found in mixed infections with maize dwarf mosaic virus or wheat streak mosaic virus. In combination, the viruses cause corn lethal necrosis, a disease name that is self-explanatory. |
It is probably fairly obvious where I am headed now. We commonly do have maize dwarf mosaic virus (MDMV) transmitted by aphids in the state. As discussed earlier in this year in the Bulletin, corn is a host to wheat streak mosaic virus (WSMV), although not affected by it. Wheat curl mites from infested wheat fields move into the corn, and the virus is maintained there. So, we have several but not all pieces of the puzzle present for corn lethal necrosis. Definitely something to keep in mind.
Hopefully no new virus diseases will make their way into the state. The right questions were asked, though, when a high population of a suspected virus vector was found infesting several fields of seedling corn. That was good scouting and troubleshooting.--Suzanne Bissonnette