Maize chlorotic mottle and maize dwarf mosaic viruses; effect of single and double inoculations on symptomatology and yield.
Three maize hybrids (A619 X A632, B73 X FR16 and Mo17 X B73) were planted in replicated blocks and spray-inoculated at the 3-, 7- and 14-leaf stages. Inocula consisted of maize chlorotic mottle virus, maize dwarf mosaic virus str. A and a combination of the two. Single virus infections caused systemic mottle or mosaic leaf patterns and reduced grain yields. Symptoms on all hybrids inoculated with the combination, at 3- and/or 7-leaf stages, consisted of a systemic chlorotic mottle, tissue necrosis beginning at leaf margins and progressing to the midvein, stunting and premature death of plants. Chlorosis and necrosis of terminal leaves developed in plants at the 14-leaf stage inoculated with MCMV and MCMV + MDMV-A. In general, early virus infections significantly reduced maize yields; losses were heaviest on plants receiving the virus combination.