Baute Bug Blog

I’m getting quite a few calls about slugs taking out soybean plantings not once but sometimes twice in the same field.  It has been an ideal spring for slugs with all of this wet cool weather.   And last fall was wet too, which helped all those slugs lay eggs and survive in these problem fields. 

Unfortunately there is not a lot that can be done (affordably anyway) as a rescue treatment.  Only 1 in 4 growers who try the UAN 28% solution, sprayed 3 nights in a row, find it to work.   Especially in a season when it continues to rain or experience heavy dews in the early mornings that can wash off the salt on the slugs.  And Sluggo bait is too expensive to apply on field crops, unless used in very small problem areas and must be applied around May 24 to knock the population down when they first start up.

The only effective and affordable method of control is tillage.  Removing the crop residue will get rid of the habitat that the slugs are hiding out in, being protected from the sun and heat.  Till these problem fields in the fall since the slugs that are present in the fall are the same ones that will be a problem again next spring in that same field.  Go back into these fall tilled fields in the spring and place shingles or small blocks of wood down on the soil surface.  Check under the boards in the early mornings to see if slugs are hanging out.  If slugs are easily found, then more tillage may be needed and potentially the use of the Sluggo bait in the problem areas of the field.

The good news is that once the weather does turn a bit more dry and warm, the crop should be able to grow faster than the slugs can feed and the problem will be behind you shortly.  At least until next spring

Have a fantastic Canada Day Everyone!

We are starting to see natural enemies moving into the soybean fields to feed on the aphids there.  Ladybugs and syrphid fly larvae are the most evident but there have been a few fungal mummies starting to show up too, thanks to this moist week.  This cooler weather will slow down the aphids doubling rate a bit and help the natural enemies catch up.   Hopefully with this combination we will safely arrive in the R1 stage of soybeans before aphid numbers build up to concerning levels.  Once R1 is reached, we can follow the well proven threshold of “250 aphids per plant and increasing, when found on 80% of the plants during R1 to R5 stages.

Syrphid fly larvae feeding on soybean aphids

Traps were just going up last week but already both Michigan and Ohio have caught their first WBC moth of the season.  Traps also went up last week in Ontario and our trap participants will be sending in their results this week.  We will be updating our trap captures each week via maps. 

Ontario WBC Trap Maps will be available at:  http://www.cornpest.ca/default/index.cfm/wbc-trap-network/ 

Michigan is also reporting their trap captures via maps, available at: http://www.msuent.com/insect_info_by_crop/Corn/

I’ve had a few calls come in this week about this issue.  Some reps are starting to find about 15 - 30 aphids per plant and want to know if they should  tankmix some insecticide in with the herbicide since they have to spray the weeds this week anyway, in hopes of getting ahead of the aphid infestation.

Straight up this is not a good idea for several reasons.  Though we do not have thresholds yet for the V stage soybeans, the bit of experience I have had with it indicated that you can cause the aphid populations to flare back up beyond  the R stage threshold of 250 per plant within 10 days after spraying because the natural enemies that were trying to establish in the field were nuked too.  And other factors come into play as to whether you see any yield advantage to spraying this early, including weather as one of the biggest factors.  If the crop becomes stressed from lack of rain after an application then there could been some yield protection from spraying within the V stages, though if the field is that stressed, it does start to flower by the time it reaches V4.  Then the R stage thresholds would apply.   But if the field gets some rain, then the aphid population is not as big of a stress to the crop.  The R stages do tend to be the more vulnerable stages when it comes to stressful situations like soybean aphids.  And finally, herbicide sprayer set up (lower water volumes and large droplet size) is not appropriate for insecticide application which requires high water volume, higher pressure and smaller droplets to obtain good control. 

So right now, let’s stick to the current threshold of 250 aphids per plant and increasing on 80% of the plants in the growth stages of R1 to R5.  Anything outside of those stages is unknown and fairly risky to spray.

That said, we are running some trials this year to answer this question once and for all so that we have more experience under our belt as far as V-stage soybeans and soybean aphids go.  If you are finding a consistent population within your field (ie..30 or more aphids per plant on 80% of the plants) give me a call. 

Enjoy the heat! 

Young trifoliate infested with soybean aphids

We are starting to scout our soybean sites for 2009.  Our weekly scouting results are available on the IPM PIPE Network at:  http://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=All%20Legumes/Kudzu&pest=soybean_aphid

We will be updating these maps weekly and will include any key observations and recommendations within the commentary for both soybean aphids and bean leaf beetles.  To see the Ontario commentary, you need to zoom in to the province of Ontario by either using the “magnifying glass with the + sign” button to highlight or crop to our province or click on the button next to this one (the magnifying glass on the word STATE) to get a drop down menu that has Ontario within the list of states and provinces.  Select Ontario and the map will zoom in.  If the commentary still does not show up, zoom into the province a little more until it does.

Similar maps will also be going up on the OSG website starting next week.   A new addition will be our Bean leaf beetle weekly scouting maps that will also be included on the OSG website.