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Description:
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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 . |