Symptoms characteristic of viral infection are showing up on the winter wheat crop in several areas of the state. Matt Montgomery, of Sangamon/Menard Extension Unit, reports many area fields showing the yellowing typically associated with infection by barley yellow dwarf virus (BYDV). |
Wheat leaves symptomatic of BYDV infection. (Photo courtesy of Matt Montgomery.)
He notes, as well, that he isn't seeing many aphids. Aphids are responsible for spreading BYDV. If the affected fields test positive for BYD infection and few or no aphids are found, this suggests that aphids transmitted the virus to the plants last fall.
Although aphids can and do transmit the virus in the spring, fall infection by BYDV presents a more serious situation for the plant. Typically, fall infection results in discolored, somewhat stunted, plants and blasted or poorly filled heads. As you are scouting, you will note that on plants infected with BYDV the older leaves typically begin to die back from the tip and may feel somewhat leathery, while the new leaves begin to discolor. Robert Bellm, of Edwardsville Extension Center, was out scouting wheat with Omar Koester, of Monroe Extension Unit, and they also reported viral symptoms of yellowing and flecking in several fields. I'll paraphrase Robert's comments, because he correctly indicated that "the symptoms we were seeing could have been caused by any number of viruses that pathologists have a million acronyms for." Very true. Keep in mind that a true diagnosis of BYDV or any of our other viral diseases cannot be made in the field but must be sent to a laboratory for specific testing. For more information on symptomatology and testing for common viral diseases of winter wheat in Illinois, refer to issue no. 3 of this year's Bulletin.--Suzanne Bissonnette