A study on the effectiveness of using Bt sweet corn for managing CEW was conducted between 1996 and 2016 in Maryland.4  The non-Bt hybrids showed average ear damage levels of 82.4%, and that level was constant over the 20 years of the study. In the eastern United States, corn earworm does not normally overwinter successfully in the northern states. The performance of selected Bt corn hybrids/technologies against corn earworm was evaluated at the Delta Research and Extension Center (Washington County), Stoneville, MS. For Bt sweet corn 5 Dively, G., Venugopal, P., Bean, D., Whalen, J., Holmstrom, K., Kuhar, T., Doughty, B., Patton, T., Cissel, W., and Hutchison, W. 2018. Plots planted to Dekalb DKC6697 (VT Double Pro) or Pioneer P1319VYHR (Optimum Leptra) had fewer large larvae compared to plots planted to either of the non-Bt hybrids (Dekalb DKC 6694 or Pioneer P1319R). Larval counts are presented as the number of larvae per ear. There were no differences among hybrids/Bt technologies observed for yield.1. Plots were harvested on 8 Sep when grain moisture was ca. Websites verified 10-1-2019. Decreased susceptibility of corn earworm to Cry toxins in Bt sweet corn was confirmed a couple of years ago and these are the same Cry toxins expressed in field corn. Transgenic corn, Zea mays L., hybrids expressing insecticidal proteins from Bacillus thuringiensis (Bt) and non-Bt near isolines were sampled for injury from Helicoverpa zea (Boddie) in North and South Carolina from 2012 to 2017. Regional pest suppression associated with widespread Bt maize adoption benefits vegetable growers. Farmers use Bt corn as an alternative to insecticide application. It is a migratory pest, migrating from the southern and southeastern U.S. every summer. For additional agronomic information, please contact your local seed representative. One of the most popular methods of controlling cotton bollworm/corn earworm is the use of transgenic Bt … Thus, areas have overwintering, both ov… Damaged kernels are presented as number of damaged kernels per ear. For this reason, there still is a 20% structured refuge requirement for Bt corn with no option for the RIB strategy in the southern U.S. which faces high H. zea population pressure and additional selection from Bt cotton. Plots planted to Dekalb DKC6697 (VT Double Pro), Pioneer P1319YHR (Optimum Intrasect), or Pioneer P1319VYHR (Optimum Leptra) had fewer medium corn earworm per ear than plots planted to Pioneer P1319HR (Herculex). New research from the University of Maryland indicates that corn earworm, also known as tomato fruitworm, has developed resistance to the Cry1 Bt toxins present in some sweet corn hybrids. BAYER GROUP DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE. Plots planted to Pioneer P1319HR (Herculex) or Pioneer P1319YHR (optimum Intrasect) had more small corn earworm larvae per ear than those planted to Dekalb DKC6694 (non-Bt). At the R3 growth stage, plots planted to Pioneer P1319VYHR (Optimum Leptra) had fewer small larvae compared to plots planted to any of the other hybrids/technologies (Table 1). 2014, Reay-Jones and Reisig 2014, B ibb et al. Bt sweet corn still needs to be monitored and in some situations may need to be sprayed to prevent infestation with corn earworm. Journal of Invertebrate Pathology 163:11-20. A total of 7,260 ears were sampled, with an average kernel injury from H. zea feeding of 1.22 ± 0.02 (SEM) cm2. The “Handy Bt Trait Table for US Corn Production” makes it simple to determine the Bt toxins in any commercialized corn. The hybrids containing only the Cry1Ab gene showed the greatest level of change with 6.3% ear damage in 1996 and 85.1% ear damage in 2016. The variety known as Bt sweet corn has been genetically engineered to kill certain caterpillars, including corn ear rooms. 7 Venugopal, P. and Dively, G. 2017 Climate change, transgenic corn adoption and field-evolved resistance in corn earworm. These hybrids should still be effective for controlling European corn borer, and many of the Bt hybrids also have some form of herbicide tolerance, which will still be effective. First and second generation caterpillars attack the whorl stage while the later generations are largely found in corn ears. Extoxnet. Sweet corn planted in late April and early May and produced with insecticide applications for corn earworm can sometimes escape damage. Plot size was four rows (40 in centers) by 40 ft. Hybrids/Bt technologies were replicated four times in an RCB design. BT-based insecticides kill corn earworm larvae if the larvae ingest spray residues. dOptimum Leptra express the Cry1F, Cry1Ab, and Vip3A proteins. In 2019, reports of higher numbers of corn earworms observed feeding on Bt field corn, are raising concerns for potential decreased susceptibility to Bt … Iowa’s corn is more vulnerable to infestation of the second flight, arriving in late July. In 2019, reports of higher numbers of corn earworms observed feeding on Bt field corn, are raising concerns for potential decreased susceptibility to Bt … Decreased susceptibility of corn earworm to Cry toxins in Bt sweet corn was confirmed a couple of years ago and these are the same Cry toxins expressed in field corn. Lower moth count action thresholds and more frequent insecticide applications may be needed to obtain acceptable levels of control on Bt hybrids than were needed in the past.

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