Sorry…It’s been a few weeks since my last blog but I finally went on holidays. I’m back and want to give you an update. While away, more reports were coming in of western bean cutworm damage being found in Ontario. Others are asking how to scout for the damage this fall so that they can determine if they have WBC. So here is an update:
Counties (nearest town) reporting larvae and/or damage in 2009 include:
Chatham- Kent (Dover Centre)
Middlesex (Wardsville, Appin)
Huron (Blyth, Clinton)
Simcoe (Alliston, Barrie)
Eastern Ontario – Dundas (Chesterville)
Anyone who finds damage/larvae in their field, please report it to me either via this blog or through email so that I can continue to keep track.
How to scout for WBC damage this fall: WBC damage will not necessarily be in one specific area of the field. Wander through the field looking for any signs of frass at the ear tips. Look for any signs of external entry holes from the sides of the husk, though WBC do not always enter from the side of the ear. Signs of bird damage can also indicate that there was something in the ear that the bird went after. Though bird damage does not confirm that WBC was in the ear. The birds could be going after picnic beetles, corn borer or corn rootworm adults too. I have also had the odd hybrid that didn’t have a tightly closed husk at the ear tip and when there were signs of less silk or there was frass on the silk, I’d open that husk to investigate. Otherwise, just peel back random husks throughout the field if no external signs of damage exist. Once you have found an ear with damage and or larvae, investigate the plants around that one. Check in that row and the plants in the rows directly adjacent to the initial plant with damage. Odds are there will be more. These larvae spread from their original egg masses and can crawl 12 feet down the row and 10 feet across. So many neighbouring plants can be infested by just one eggmass.
If a WBC larvae is not present in the ear that has damage, we can not fully confirm that the damage was caused by WBC as it could also have been from ECB or corn earworm..though WBC does tend to be the most destructive feeder.
Here is a scouting video through Purdue University that helps explain what I’ve talked about: http://extension.entm.purdue.edu/pestcrop/2009/issue21/index.html#westernWhat do you do if you find damage? First, report the location of the damage to me. Then keep an eye on the quality of this site before harvest. If ear rot starts to set in because of the damage caused by WBC, plan to harvest this field as early as possible. Additional precautions/actions that should be taken to reduce the impact of ear rot can be found in the Agronomy Guide, OMAFRA Publication 811 at: http://www.omafra.gov.on.ca/english/crops/pub811/14corn.htm
That is all the bad news I have for today 🙂
Pictures are also available in my previous blogs and on the WBC Trap Network website at: http://www.cornpest.ca/default/index.cfm/wbc-trap-network/trapping-workshop/