Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2012
Publication Date: N/A
Interpretive Summary: not required
Technical Abstract: Our goal is to develop new sweet sorghum germplasm lines and new hybrids can be used as biofuel feedstocks for the southern coastal plain region. After previous comprehensive examination of both agronomic traits and resistance to biotic stresses (i.e., insects and diseases), insect and disease resistance in a subset of germplasm lines and experimental hybrids in the sweet sorghum breeding program were evaluated in 2011 and 2012. Thirty three inbred lines and 48 hybrids were evaluated for insect resistance in 2011, and 100 experimental hybrids were evaluated for insect and disease resistance in 2012. The damage by whorl-feeding fall armyworm [Spodoptera frugiperda (J.E. Smith)] and piercing-sucking aphids [i.e., corn leaf aphid, Rhopalosiphum maidis (Fitch), and the greenbug, Schizaphis graminum (Rondani)] was rated using visual rating scales. The fall armyworm damage was rated based on a scale of 1-9 (1 = least damage and 9 = completely defoliated), the aphid damage was rated as 1-3 (1 = no aphid or damage, and 3 = both aphid colony and leaf chlorosis observed). For foliar anthracnose (Colletotrichum spp.) rating, a scale of 1-5 were used for leaf necrosis (1 = no necrosis, 5 = 80% of the leaves with necrosis). Fall armyworm and aphid damage ratings were significantly different among the 33 germplasm lines, but the fall armyworm damage ratings were not correlated to aphid damage ratings on the inbreds in 2011. In contrast, the fall armyworm and aphid damage ratings were not significantly different among the hybrids in either 2011 or 2012. The ratings of anthracnose infection on the 100 experimental hybrids were not different in 2012. The difference in insect resistance between inbreds and hybrids and possible genetic basis of the phenomenon will be discussed.