Baute Bug Blog

More reports of WBC damage are coming in.  Here is an updated list of sites with damage and or larvae found in Ontario:

Chatham- Kent (Dover Centre, Bothwell)

Lambton (Petrolia)

Middlesex (Wardsville, Appin, Glencoe)

Elgin (Rodney)

Huron (Blyth, Clinton, Exeter, Dashwood, Holmesville, Belgrave)

Bruce (Walkerton, Kincardine)

Simcoe (Alliston, Barrie, Stayner)

Durham (Kinsale, Lindsay, Brooklin)

Victoria (Dunsford)

Peterborough (Millbrook)

Dundas (Chesterville)

I will be attending a meeting this week with my US counterparts where we will be discussing what each state/province has observed with regards to WBC and soybean aphids.  I will give an update next week on any new information from the meeting.

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)

Lambton (Petrolia)

Middlesex (Wardsville, Appin)

Elgin (Rodney)

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/

There are a few guys out there thinking that with the cooler nights, SOYBEAN APHIDS will be leaving their fields so they don’t need to spray those fields that recently reached threshold.  If aphids are staying at threshold levels 3 or 4 days after the initial assessment, you still need to spray.  Only those fields that are dropping in numbers or have reached into the R6 stage and are no where close to threshold can be considered safe from having to be sprayed for aphids.  The cool night temps do not guarantee the aphids will leave to look for buckthorn yet.  Triggers from plant quality may also determine whether they stay or go elsewhere.

HOWEVER other insects are starting to be a problem.  IP and seed fields need tending to still.  BEAN LEAF BEETLE adults are showing up in high numbers at a few of our sites in both Lambton and Elgin Counties.  Fields in other counties could also be at risk.  Scout fields to determine beetle presence and look at pods for feeding.  I like to pluck about 50 pods randomly in the field, grabbing pods from the top 3rd of the plant without taking the smallest/youngest ones.  If 10% of the pods collected (or in this case 5 pods) have feeding scars and holes on the surface, AND the beetles are still active in the field, a spray is required in IP or seed fields if the crop is not reached the middle of R6.  Preharvest intervals come into play if you get any deeper into the R6 stage of soys.  Look for clipped pods on the ground as well as this should also be included in your assessment.  If significant clipping is taking place and beetles are still active in the field, spray is required.

STINK BUGS  have also made an appearance at threshold levels in a field in Chatham Kent.  Very high numbers were reported by Joe Tomecek  and after some discussion it was obvious the field needed to be sprayed.  Again, only IP and seed soybean fields are at risk, as stink bugs impact quality by piercing the soybean pod, scaring the seed itself.  Control may be warranted in IP food grade and seed soybeans if an average of one stink bug per foot of row or 0.2 bugs per sweep are found during the late R5/early R6 stage of soybeans.

We visited the Newbury WBC site last week and it was concerning to see so many plants infested with WBC larvae.  There were no external entry holes from the outside of the ear which could fool those who think the ears are clean.  Pay extra attention to those ears that are slightly opened at the ear tip (husk not tightly closed) and if the silks look thinned.  Once ears are peeled open, look for signs of frass (larvae excrement).  Neighbouring plants are also likely to have larvae too.

 More reports were coming in late last week from reps who were out checking their trials and finding WBC.  So far, WBC larvae have been found in corn in Dover Center (by Shawn Winter of Maizex) and near Strathroy (by Nick Stokman).  Also, Joe Tomecek reported finding WBC in dry beans near Kent Bridge.

Please keep checking fields and sending me your damage reports.   There is nothing we can do this year about this injury (and none so far have been at economic levels) but the more damage sitings we know of this year, the more knowledge we gain about the distribution and impact of this pest in Ontario.  It will also inform us of any potential overwintering sites and potential problem regions for next year.

My summer students are going to be frustrated when they find this out, especially with all of the scouting they have done looking for WBC egg masses and larvae and finding nothing to show for it.  But today Adam Pfeffer of Monsanto brought in the first WBC larvae found here in Ontario.  The larvae was from a corn field in Rodney Ontario.  This tells us that there are probably other sites with some larvae  in them as well, so I do encourage you to be out scouting your fields too.  Larvae would most likely be in the ear of the corn.  But we are also still catching moths in our traps so some egg laying could still be taking place.

Purdue University put a WBC scouting video within their newsletter this week which helps explain how to look for larvae in the corn ear:  http://extension.entm.purdue.edu/pestcrop/2009/issue21/index.html

And Ron Hammond from Ohio State University put together a video from our trip to visit Chris DiFonzo from Michigan State University in one of her heavily infested corn field last year: http://www.youtube.com/watch?v=u5EsPWySxEI

If you do find ear feeding, larvae or egg masses, please let me know!

I have had a few calls from some reps and growers who have been amazed and delighted and some who have been frustrated and frazzled this week.  But I’m in it with you, believe me.  Soybean aphids seem to be very active right now, developing winged generations and have been moving from one field to another for the last two to three weeks.  I have had sites that were approaching 200 or more and then the very next week there were barely 20 per plant with a lot more natural enemies present too.   In part this drop is due to the natural enemies that are moving in to make the kill.  But a stronger influence could be the cooler temps we are starting to experience at night and the desire of the aphids to keep finding later planted fields to finish off in before heading to buckthorn.  We tend to still see aphids active in fields until at least the second week of September but this year is a bit of a guessing game.  On one hand, the soybean growth stages are behind and have quite a few more weeks to go before maturity, on the other, the temps are starting to make it feel like fall already.

Either way, it does mean that it really pays off for you to at least hold off a couple days before spraying at threshold just to make sure that the aphids are truly there to stay.  If you are lucky like some, they may decide to leave and the ones that are left can easily be taken care of by the natural enemies.

Patience is key when it comes to these aphids.

Some counties in Michigan have been given the recommendation to spray their dry beans due to the high moth counts and observations of pod feeding at some locations.  Montcalm County (central Michigan) in particular is at the highest risk with some trap sites capturing over 400-500 moths in the last few weeks.  Isabella, Gratiot and Mecosta counties are also considered at risk.  Current Michigan WBC Trap Map:  http://www.msuent.com/files/WBCmapAug15.pdf

Thankfully Ontario has not yet experienced these kind of levels yet.  Current Ontario WBC Trap Map: http://www.cornpest.ca/?LinkServID=848D2ECA-188B-3AFA-083F4B11E7B95388&showMeta=0

Only one trap site near Appin has accumulated more than 50 moths so far in Ontario.  Others have been ranging from no catches to about 30 moths so far.  We have been scouting for egg masses and feeding damage at most sites that have captured moths but have not found anything yet in corn or dry beans.  However, given what Michigan is dealing with this year, I don’t think we have many more growing seasons to go before we are see levels high enough that management will be needed in at least some fields.

I have been getting more calls this week with people wanting to spray the aphids just to take care of them..even if they are not at threshold.  Most realize that the natural enemies are going to get killed but they also assume 100% kill of the aphids and struggle to understand how the aphids can build back up so quickly in that same field. 

The problem is, you don’t get 100% kill of the aphids.  Even if you get 90% control, which is pretty good control, that leaves 10% of the aphids surviving on the plant.  They are baby making machines and can build up their numbers back up to threshold in no time…especially now that you killed their natural enemies too, which are not baby making machines and take about 2-3 weeks to recover.  Unfortunately the natural enemies need to find mates, produce eggs again, wait for about a week before hatching, then be larvae for another week or two (and hopefully the larvae feed on aphids) before finally becoming the hungry adults.  Aphids are different.  They are born pregnant and don’t need to mate.  They pop out hungry nymphs that can suck on the plants  immediately, just like the adults.

Here is a simplistic example to help get this point across.  Let’s say a field is sprayed when there is only 100 aphids per plant.  If you got 90% kill, that would leave 10 aphids per plant left surviving, and not many natural enemies left to eat these 10 aphids per plant.  Aphids can double their population in 1.5 to 2 days, depending on the temperature.  So if you started at day 0 with 10 aphids per plant, Day 2 would have 20, Day 4 would have 40, Day 6 would have 80, Day 8 would have 160 and Day 10 would have 360 aphids per plant.  You’d essentially be back up above threshold in less than two weeks time..not saving you any money or time for your effort in spraying too early.

At least wait until you are confident that the aphid population is rising above 250 aphids per plant.  That is truly the only way to know whether the natural enemies are not doing their job and that a spray is finally necessary. 

Spraying before the threshold, grinds all of your biological control to a complete halt, when they may have actually been the ones making a difference.   Otherwise, wouldn’t every single soybean field in Ontario need to be sprayed every single year?

A recent summer migration of soybean aphids in Ontario has resulted in many new fields having a fair number of aphids in them now.  Fields that were scouted a week or two ago and were found to have very few aphids could now be closer to threshold than you think.  Scouting is advised.  Scout Cruiser treated fields too as we are starting to see some of these fields also nearing threshold now.

Admittedly some people got lucky.  Some of the fields that were infested earlier this year and were rising in numbers are the ones that the aphids developed wings in and left so they may have dropped in numbers and no longer need to be sprayed.  But again, scouting is advised to determine which fields this migration has impacted, good or bad.

Recent soybean aphid scouting maps for Ontario can be found at: http://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=All%20Legumes/Kudzu&pest=soybean_aphid 

This weeks map will also go up on the OSG site later tomorrow (Friday Aug 7th) at: http://www.soybean.on.ca/aphids.php

Good luck!

SPIDERMITES: I have a sneaking suspicion that spidermites are making their way into those fields that haven’t had rain in a while.  We have had situations in the past where not only have they popped up in soybeans and were being disregarded as “drought stress” symptoms but also in seed corn, especially around or just after wheat has been harvested in the area.  Be particularly careful in watching those fields that may have had a pyrethroid used recently for any other insect issues.  Pyrethroids do not work on spidermites and can actually cause mite populations to flare up.  For more info on spidermites and scouting, refer to: http://www.omafra.gov.on.ca/english/crops/pub811/13soybean.htm#spider

SOYBEAN APHIDS:  As suspected, some fields are noticing a drastic decline in numbers, while others have seen a drastic increase.  A significant soybean aphid flight took place this week (as captured by our suction traps) and some winged aphids left the early planted fields they started in this summer and have moved to later planted fields either nearby or in other regions entirely.  But we also may have received aphids from neighbouring states and provinces so fields should be checked soon to figure out if you were one of the lucky ones or not. 

 WESTERN BEAN CUTWORM:  We experienced an increase in moth captures this week, indicating that this is a good time to start scouting for egg masses, especially at trap locations that have been catching moths into the double digits.  Since corn is still barely tasseling, the moths will prefer to lay their eggs in corn still.  Trap capture maps for this week are at:  http://www.cornpest.ca/default/index.cfm/wbc-trap-network/weekly-maps-of-wbc-trap-catches/

Information on how to scout for egg masses and larval activity can be found at: http://www.cornpest.ca/?LinkServID=3FD7CC42-65B8-8CF0-A092D60341F09626&showMeta=0   Make sure to click on the speaker notes at the top left of each slide for more detailed information.

Also here is an infosheet on WBC in corn:  http://www.cornpest.ca/?LinkServID=D23DD4EE-188B-3AFA-0809F13CA830D6F4&showMeta=0

Have a Fantastic Long Weekend Everyone!