| dc.description.abstract | Sorghum (Sorghum bicolor [L.] Moench) production in many areas of the world
is reduced due to damage caused by sorghum midge (Stenodiplosis sorghicola). There
are several methods of control to reduce losses due to sorghum midge, which include
cultural practices, biological control, chemical control and resistant cultivars. The best
long-term solution for sorghum midge control is the use of genetic resistance in cultivars
and hybrids. Recently, sorghum midge resistant hybrids have been developed by several
sorghum breeding programs, but there is limited information about agronomic
performance relative to planting dates compared to susceptible standards. Thus, the
objectives of this research project are: (1) to evaluate the value of sorghum midge
resistant sorghum hybrids in the USA production system, (2) to confirm the presence of
sorghum midge insect resistance in sorghum hybrids, and (3) to determine whether the
resistance in eighteen sorghum hybrids is stable across two environments in Texas where
sorghum midge is a damaging pest. Sorghum hybrids with different levels of resistance
to sorghum midge were evaluated at College Station and Corpus Christi, Texas in 2003
and 2004, using two different planting dates and the presence or absence of an insecticide treatment. Agronomic data, sorghum midge incidence ratings and number of
adult midges, were determined for all entries. All entries designated as resistant did
have some resistance compared to susceptible checks. Across all hybrids, grain yield
was higher in sorghum with normal planting dates compared to late planting. Under
midge pressure resistant hybrids performed better than susceptible hybrids, but lacking
midge pressure the susceptible hybrids were higher performing. The use of midge
resistant hybrids in commercial production is only warranted when producers are
reasonably sure that midge will be a problem. Otherwise, they should continue to plant
early using traditional hybrids. | en |
