Our next speaker today is Krista Hamilton.
Krista is an entomologist with the Plant Industry Bureau
at DATCP.
She has directed and continues to direct
an exceptionally-productive state-wide
pest-insect survey program.
She's been doing that for the last 17 years.
Hard to believe 'cause I think I remember
pretty well when she started.
She's the primary author of the Pest Bulletin,
which if you guys are not receiving it,
I would encourage you to make sure
that you go to her web site and sign up for it.
It's a very informative insect entomology piece
that she puts out during the summer months
when insects are active.
Krista's originally from Wausau, Wisconsin.
She now lives in La Crosse.
She holds a bachelor's and a master's degree
from the University of Wisconsin in entomology.
Please welcome Krista Hamilton.
(applause)
- Thank you.
Thank you very much.
So this morning we'll be taking a look at
the results of Datcp's insect surveys from last season
and what they can tell us about potential
crop-pest pressure in 2016.
Most of the surveys are ones that
the department has conducted for a long time.
Our European Corn Borer Survey, for example,
is nearly three-quarters of a century old.
Our rootworm surveys started back in the early 1970s.
So my point in telling you this is that we have
extensive data sets on these insects.
And when we compare 2015's results
to those long-term records, it's apparent
that levels of all but one of these pests
are exceptionally low, and in some cases historcially low,
so you'll be seeing some low numbers
in the next 20 minutes or so.
To begin, I just wanna take a minute to provide
some background on the Wisconsin Pest Survey Program.
So we're the group that's responsible for
the survey results you'll be seeing.
We've been around 100 years,
tracking pest populations and documenting
growing-season trends through our surveys.
One of the main points of this work is just simply
to help Wisconsin growers anticipate pest problems
so that they can take measures to avoid losses.
Another important objective of the work
is exotic pest detection.
So we conduct surveys to detect new or exotic pests
as they show up in the state.
Some of our survey work also supports the process
of export certification by confirming
presence or absence of certain regulated pests.
So those are the main objectives of our work.
We sample thousands of fields across the state each summer
and we cover all the major agronomic crops
as well as specialty crops, so everything from
wheat and corn to apples and grapes.
And in addition to our own surveys we also receive
information from networks of cooperators around the state
who send us insect counts on a regular basis.
And I think most of you are probably familiar with that.
Some of you are our cooperators or have been at one point.
And the help of our cooperators
is really vital to our program.
So in short, we collect a lot of information
through the program each year
and we've been around a long time.
Here's where we publish our survey results.
This is the Wisconsin Pest Bulletin.
It's our weekly newsletter.
It's published each Thursday from April through August
during the growing season.
And it's a compilation of topics.
It includes things like insect growing-degree days,
alerts to new pest finds,
and a diversity of observations from
our surveyors and from growers around the state
on different pests.
If you're not a subscriber,
please go to our Web site and sign up.
I know that a lot of consultants consider this
a really useful and timely resource.
So these are the insects that we'll be focusing on today.
We'll start with our corn-pest surveys
and then I'll conclude with just some brief notes
on a newly-established pest in the state,
the brown marmorated stink bug.
So we'll get started with the result
of the European Corn Borer Survey.
As I mentioned, this is the oldest of all of our surveys.
It dates back to 1942,
when the corn borer was still an exotic pest,
brand new to the state.
The survey objective has always been the same.
We're sampling corn fields in September and October
to determine the size of the fall population
of corn-borer larvae.
So these larvae will overwinter in cornstalks,
much like you see at the stage here.
They'll pupate in spring and then begin emerging
as moths in May and June.
So that fall population is really our best predictor
of the size of the spring moth flight.
And in years when corn-borer populations fluctuated
a lot more than they do now,
this was really a key predictive survey.
At this point you know the corn-borer population
has collapsed in the last 15 years or so.
So I think what our survey helps to document at this point
is just really a continued low population trend.
So this map shows the 229 sites that were surveyed
for corn borers last fall.
What you'll notice immediately are a lot of black circles.
So these circles are negative sites
where we found no larvae
or no signs of corn-borer infestation:
things like broken stalks or tunneling in the stalks.
That was 86% of our survey sites.
The green circles represent sites where we found
0.01 to 0.5 borers per plant,
so low counts that are less than half of threshold.
The yellow circles are where we found moderate counts
in the range of 0.51 to 0.99 borers per plant.
And then the one orange circle
you can see over in Winnebago County
is the only site where we found an economic population
above one borers per plant.
The 2015 state average was just 0.02 larvae per plant.
That's two caterpillars per 100 cornstalks.
It's the lowest average we've documented
in the history of Wisconsin Corn Borer Surveys.
What should be obvious is just corn borer
was very very scarce again in 2015.
When we look at the district averages,
I think what you'll see right away are just a lot of zeros.
Again, these numbers are really low.
All of our nine districts had averages
of 0.04 borer per plant or lower,
so four larvae per 100 stalks.
These are low numbers.
We did see some increases in five of the nine districts,
but these were very minor insignificant increases.
And I'll just say it again, these are some
of the lowest averages that we've seen in 74 years.
So for 2016,
what those results suggest is that
populations are still historically low.
I don't think they're likely to change anytime soon.
To date there's been no evidence of corn borer resistance
to BT or any BT trait.
So that's good news.
I think that extremely-low larval population
that we saw in fall should produce
a really small flight of moths next spring,
and in a small subsequent first generation of larvae.
So a favorable forecast for 2016.
Next up is the corn rootworm beetle.
So this survey takes place from mid to late August,
and it's timed to coincide with peak beetle emergence.
So we go out into the cornfields
once 50% or more of the population has emerged.
And the idea is that we're surveying cornfields
to get a snapshot of beetle populations,
which in turn are a predictor of larval root damage
potential in next season's corn.
So the reasoning is that high beetle numbers
would lead to high egg populations in the soil
that hatch in the spring and then become
damaging larval populations.
So it's just a way to forecast
the risk of root damage from year to year
and to evaluate beetle pressure.
The 2015 Rootworm Survey found a state average
of 0.6 beetles per plant.
That's an increase from 2014's very low average
of 0.4 beetles per plant;
yet it's still below both that 10-year average
and the threshold.
If you look at the map, again, the black circles
are negative sites where we found no beetles;
the green circles are sites where we found
low counts of 0.1 to 0.4 beetles per plant;
the yellow circles are where we found moderate counts:
0.5 to 0.7 beetles per plant;
and then orange circles are, again, the economic populations
above 0.8 beetles per plant.
And remember that what's considered the threshold
is 0.75 beetles per plant
or about seven to eight beetles per 10 plants.
25% of our sites had economic counts last year.
That was an increase from 2014 from 16%.
But again, that was a really low-beetle year.
So 25% is about average.
It's what we often see.
So when we look at the district averages,
I think it's more clear where those increases occurred.
The first thing I would point out is just that
populations increased in the eastern two-thirds
of the state, so these six crop districts.
Of those six districts, the largest increases
were in the south-central area and in the east-central area
where those average counts rose from
0.3 to 0.8 beetles per plant, so they more than doubled.
We also saw moderate increases in the Southeast,
Central, and North-Central Districts.
By contrast, in the western part of the state
we saw decreases in all three districts.
Except I would point out that in the southwest
this average of 0.8 beetles per plant
is still considered high.
So what this suggests is that
rootworm pressure in 2016
should be greatest along those southern
three tiers of districts, so that's no surprise,
but also in the east-central area.
And then when we look at the rest of the state,
rootworm pressure is really pretty low,
those averages are quite low.
So again, the higher numbers that we saw last season
do suggest we'll see increased rootworm pressure in 2016,
but not statewide.
There's definitely some key areas
where we're expecting higher numbers of beetles
and potentially root damage;
and that would be those southern three districts
and the east-central area.
And Brian Jensen's gonna be up next
talking about rootworm resistance management recommendations
so I'm just gonna keep my notes here brief.
I think the three key things to remember about rootworms
and their management is that
crop rotation is still an effective management strategy
and it's the simplest one,
it's I think one that everybody
should consider; especially if you're seeing
rootworm problems.
Also, rotating traits is really important.
Avoid using the same trait or the same product
year after year; otherwise you're selecting for resistance.
And then lastly, scouting is just so critical.
It's not that hard to do.
It takes once or twice going out in late August
or September.
And there's really no substitute for knowing
what pressure is like in those fields,
scouting is imperative.
So now we'll move on to the result
of the Western Bean Cutworm Survey.
The western bean cutworm, as you probably know,
is a pest of corn and dry beans.
And it first started becoming more prevalent
in the state about 13 or 14 years ago.
We began monitoring the adult flight,
and there's just one flight per year,
back in 2005,
and we've seen some really I think dramatic change
in the last 11 years.
So our survey consisted of 96 traps.
So each one of these circles represents a pheromone trap.
And in those traps, during our 10-week monitoring period,
which was from mid-June to mid-August,
we caught a total of 644 moths, or seven per trap.
That was an increase from 2014's very low count,
but very very low in comparison to the survey record
documented back in 2010.
In looking at the map, there's a lot of green circles.
Most of our traps caught fewer than 25 moths
during this 10-week monitoring period,
so really low numbers.
The highest trap count was just 112 moths
at a site in Columbia County.
So although the annual flight was larger than 2014's flight,
it was still comparatively small.
These are low numbers.
Here we have the last six years of survey results.
And the bold orange number at the top of the maps
represents the state total moth count for the year,
so that's the cumulative count.
So from 2005 to 2010 the trend that we were seeing
was an almost doubling of that count every year.
And then the number peaked in 2010 at almost 11,000 moths.
Since then, you can see that populations
have declined dramatically;
in fact, they've really plummeted in the last three years.
So we've now seen three years in a row
of really low western bean cutworm moth counts.
And I think this is encouraging news for 2016.
Just six years ago it looked like this thing
could potentially be a really serious threat
to corn production in the state,
potentially replacing corn borer
as one of our major caterpillar threats.
And now it seems like it's probably only
going to be a sporadic pest, at least for now.
Nevertheless I think it's still important
if you are in the central area of the state
where we tend to see higher populations,
or if you work with clients who've had
issues with this pest, think it's still important
to scout for those egg masses and small larvae
as soon as corn reaches the late boil stage.
And then the last reminder is just to know
your BT hybrid and how it should perform.
They don't all perform equally well against this pest.
Some perform only moderately well;
some have no effectiveness.
So just make sure that if you have a BT trait
that's supposed to have efficacy against this pest
that it's doing what it should.
All right, so that completes our corn pest surveys,
so I'll talk just a few minutes about soybean aphid.
Our surveys for soybean aphid begin
just as soon after soybeans emerge in spring.
And typically we see our first aphids
around the first week of June.
This year it was June first.
We then wait usually four to six weeks
for aphids to colonize more fields
and for populations to increase,
and then we go in and sample in two intervals,
usually the first from mid to late July
and then the second in August.
And the idea is that we want to see
how those populations change over the course
of two to three weeks and we really wanna be
in those fields as population densities are peaking.
We wanna know what those numbers look like.
And sometimes if we only survey those fields once,
we kind of miss that window.
Here's what numbers looked like in July.
So we surveyed 108 fields,
this was during the last week of the month and into August,
and found a state average of only 15 aphids per plant,
so that's very low.
85% of our sites had fewer than 25 aphids per plant.
There were just four that had moderate averages
of 101 to 249 aphids per plant,
and no sites with economic populations above
the 250-aphid-per-plant threshold.
So what we found was that aphids colonized fields
very slowly last season and populations grew very gradually
and really remained low throughout July.
When we resampled those same fields in August
we found slightly higher densities.
That state average density increased to 35 aphids per plant,
so it doubled, but it's still a very low average.
We had a handful of sites that had moderate populations
in that range of 101 to 249 aphids per plant.
Just one site had an economic population.
So what these results suggest is that
most soybean fields did not develop high populations
last year and most did not require treatment,
although there were definitely definitely exceptions.
So I think we could call 2015 probably
a low to moderate aphid year.
For 2016, the aphid outlook is a little bit uncertain.
I think we never know quite what to expect
of the soybean aphid.
If it follows this every-other-year cycle
with populations being lower in even-numbered years
then we're potentially looking at lower densities.
Another factor that we should consider
are those multicolored Asian lady beetles
that were everywhere last fall.
So remember, these things are the number-one aphid predator,
and last fall's numbers were really some of
the highest in a long time.
So all those beetles, while they were sort of
a short-term nuisance, could have
a longer-term benefit in terms of lowering
aphid numbers for 2016.
And then lastly I just want to make you aware
that the brown marmorated stink bug
is now considered established in Wisconsin.
I know most of you are probably familiar with this pest.
It's been on our radar for about a decade.
This is another exotic Asian insect
that's invaded the state.
It was first confirmed in Wisconsin back in 2010.
And I guess in the five years following,
from 2010 to 2014, there were 18 confirmed reports.
Last year there were 35 confirmed reports;
so almost double the number
in the previous five years combined.
Most of those cases were in Dane County in the Madison area.
Some of the reports were also from Brown County
and Milwaukee County.
So what we think, or feel certain about,
is that it's established in Dane County,
possibly in the southeast or eastern areas
of the state as well.
I think what's important to know is that
the trend with this stinkbug is that
it tends to start causing crop damage
or moving into crops three to five years
after that initial detection.
So what that means is we could potentially
start seeing this thing in crops next year;
especially after this mild winter.
Soybeans and sweetcorn are both considered high-risk crops.
So this map just shows the current status of the stinkbug.
It's been detected in 42 states and two Canadian provinces.
It's considered a fall nuisance pest in 17 states.
And it's considered a severe agricultural pest
in nine states, so all those red mid-Atlantic states
that you see.
So I think it's just a matter of time
before we become a yellow state and then a red state,
so I think it's really important
to be on the lookout for this insect.
And as PJ just mentioned in his talk,
it's critical if you think you see this thing,
take a sample and get it to the Insect Diagnostic Lab
at UW because that's really the only way we can confirm
whether or not it's indeed the brown marmorated stinkbug.
And then I would also point you
to that StopBMSB.org web site.
All these states that have serious problems with this pest
are doing a lot of great research,
and so there's a lot of good information
on how to manage this thing in field crops.
So please take a look at that Web site.
It might give you some good ideas
on what to do about this thing
if it does show up next season.
So that completes our review of the 2015 Insect Surveys.
I think with the exception of maybe the corn rootworm beetle
and this new stinkbug it's a pretty favorable forecast
for 2016.
We're looking at some really low insect populations
heading into the next season.
Just a reminder, please sign up for the bulletin
if you haven't already done that.
And then I just wanna say thank you so much
to everybody who contributed their time
and their energy to this program last year;
especially during the busiest time of the season.
The survey results that you've just seen
are really made possible by the people
who have helped out our program,
so thank you very much.
(applause)