Test evaluation for resistance can beconsidered valid if hopper population is uniformly distributed at a high level across the screening box or field. For field screening, a minimum of the following hopper density on susceptible check is necessary. Extreme signs are wilting to death of plants. Infested areas in the field may be patchy. Partial to pronounced yellowing and increasing severity of stunting.
Extreme signs are wilting and death of plants.
Infested areas in the filed may be patchy. Incidence of dead plants could be considered for final evaluation. Percentage of susceptible check should be recorded. For Diopsis spp., it is not necessary to estimate whiteheads since infestation occurs usually at growth stages 2-4. Stem dissections from 10 hills of susceptible checks are necessry at maximum tillering, panicle initiation and late ripening, in order to identify SB species and to assess more accurately the actual incidence of stem damage.