Baute Bug Blog

If you can believe it, we have not reached WBC peak moth flight yet!  Trap counts continue to climb and some participants are having a hard time counting them all.  During this intense period, I do recommend that our trap participants check their traps more than once a week, simply to keep on top of the numbers you are catching.  The longer the moths stay in the traps and rub up against each other before dying, the more they lose their scales on their wings and make identification difficult.  Checking them more frequently means you see them when they are fresh and easier to ID.

So now what?  Well, this means we are still at risk of peak egg laying.  My crew has been running out to high trap count sites to look for eggs in fields but have not had much success outside of the original hot spot areas of Bothwell and south of Tillsonburg.  Does this mean that no other fields outside of these two areas have egg laying going on?  No.  It just means that the moths are more spread out now and scattered in ideal fields across the various counties catching moths in significant numbers.  We certainly can’t scout every field in the area of a trap site so it is up to you to be looking too.   Though the Bothwell and Tilsonburg locations were extreme with egg infestations ranging from 9 to 80% of the plants, other fields have got to be close to the 5% threshold too in other counties.  Scout late planted corn fields first that have not reached full pollen shed yet.  As long as you can feel a tassel in the whorl of the plant, the larvae can survive on it.  So target young fields first and move up from there.  Other host crops are also going to be at risk now as more corn fields starting to get beyond the more ideal egg laying stages.

Let us know too if you do find fields near or above threshold.  We want to make sure we document other locations of concern besides the heavy hot spots of Bothwell and Tillsonburg.  Even if it’s not until closer to harvest when damaged ears are spotted, we want to capture that information too.

Once we have all the data compiled from this week’s trap reports, I will make a graph comparing this year’s catch to the last two years just to show you how much higher our numbers are this year.  So..more to come tomorrow.

Some scouts are starting to notice tiny WBC  larvae that have hatched that crawling in the whorl or making their way down to the ear of the plants.  To help you know whether they are WBC larvae, here are some photos.  You can click on them to enlarge them.

They start out with spots along their bodies (spots have tiny short hairs coming out of them).  You will need a handlens to really see the spots.

Newly hatched WBC Larvae (T. Baute, OMAFRA)

Closeup of newly hatched WBC larvae (Photo Credit: Chris DiFonzo, MSU)

Within a few days they start to develop stripes.

2nd or 3rd instar WBC larva (Photo Credit: T. Baute, OMAFRA)

To know for sure that they are WBC, watch how the way.  The itch their way along a leaf like an inchworm.  Click on video to see how they crawl.

I’ve been getting asked this a lot over the last few weeks so I thought I had better finally write a quick blog on it.  What is this insect?  It’s a red-headed flea beetle.  Very common in soybeans but even more abundant this year, showing up in other crops too.  Defoliation in corn is not a concern and in soybeans, just follow the defoliation thresholds already established.  I highly doubt populations will get high enough to need to spray in soybeans but in certain fields where dry conditions persist, defoliation may reach threshold.  For thresholds and defoliation charts, see the OMAFRA Pub 811, Agronomy Guide for Field Crops or click here.

Trap counts sent in to the network this week from last week’s moth catches indicate that moth flight increased dramatically.  And from tweets on Twitter and emails coming in from participants, even higher numbers are being caught this week in some traps.  So we haven’t quite reached peak moth flight yet here in Ontario.  The top counties that caught the most moths last week were Lambton (93/trap), Haldimand/Norfolk (88/trap) and Chatham-Kent (63/trap).  I’ve summarized the results for the top 9 counties so far this year in a graph below:

Top 9 County Trap Catches So Far

What does this mean?  We still have more scouting to do.  With moth counts still increasing, egg laying is also still on the rise.  Hot spot areas like Bothwell will start to be less ideal for the moths to lay eggs, as the corn starts to advance into full tassel/pollen shed.  Other counties with high trap counts and younger corn are at risk.  Though I suggest everyone scout their corn fields at least once or twice these next few weeks, even if trap counts are not that high.  Some of the original sites we found the most eggs in this year had very low trap counts initially.  Focus scouting efforts to corn fields that have plants with at least a tassel developing in the whorl of the plant to those fields with the tassel fully emerged but not fully shedding yet.  These are the fields that seem to be the most attractive for the moths.  And if fields have variable plant heights, we also noticed that there tends to be a higher concentration of eggs on what some tease about as “Baute” height corn.  No offense to my family members who are taller than me but those who have seen me know that I am a little vertically challenged.  So scout shorter corn in a field first before moving deep in.

Since peak flight has not happened yet, dry bean scouting is not quite necessary yet.  Most of the crop is still just starting to flower and develop pods.  Ideal management timing is when pod feeding can be easily found, which typically takes place 10 to 20 days after peak flight.

The official announcement came through today.  Coragen Insecticide is now also approved for use in dry beans and other legumes (except soybeans) for WBC control in Canada through the URMULE system.   Rate is 250 to 375 mL/ha.  Use a minimum of 100L/ha of water for ground app.  1 day PHI.  Click link to see revised label: Coragen CG6 except soybeans E Label 2011.’

WBC management recommendations for dry beans will come later this week once we can determine if we have hit or are close to peak moth flight.