Integrated Pest Management for Turfgrass


Hello, I’m Alec Kowalewski,
turf grass specialist at Oregon State University. And today, we’re talking about
integrated pest management for turfgrass. In IPM for turf, there are
five cultural practices. From the top down,
these cultural practices are mowing, fertilization,
and irrigation being the primary cultural
practices, as well as cultivation and
pest management being the secondary
cultural practices. So regardless if you are a
homeowner, athletic field manager, or golf
course superintendent, the most time and
money are spent on the primary
cultural practices beginning with mowing,
followed by fertilization, then irrigation with the
least amount of time and money spent on cultivation
and pest management. As time and budget
constraints go into effect, we remove cultural practices
from the bottom up. Removing past management
first, followed by cultivation. Always trying to maintain good
primary cultural practices. The mowing, fertilization,
and irrigation. [MUSIC PLAYING] Mowing, the primary
cultural practice. More time and money
is spent on mowing than any other
cultural practice. And this is the most
important cultural practice when it comes to the
successful turfgrass stand. So we’re gonna cover three tips
today in relation to mowing. These tips are, first,
never cut more than 1/3 of the grass blade
in a single mowing. Secondly, raise
your mowing height and increase your
mowing frequency. And finally, mulch
your grass clippings. Tip one, never mow more
than 1/3 of the grass blade in a single mowing. Very simply put, the 1/3 rule. So mowing more than
1/3 of the grass blade or violating this
1/3 rule is going to cause a number of
detrimental effects. The most noticeable
being scalping. The brown appearance you see
after mowing more than 1/3 of the grass blade. Other detrimental
effects are gonna include depletion
of carbohydrates. The turfgrass
stores its nutrients above ground in the green,
lush growth you see. So when you mow that off, you
rob the plant of its nutrients. It’s also gonna
decrease rooting depth. It’s gonna shock
the plant making it more susceptible to
environmental stresses. Drought stress, heat
stress, and then this is only further amplified by
root feeding insects, which even further compromising
the rooting and stress tolerance of the plant. So as we talk specifically
about the 1/3 rule, we’re gonna take a look
down at this research here at the Lewis brown horticulture
farm at Oregon State University. We see a number of
different heights here. The grass here in front of me
is maintained at a two inch mowing eight. The grass here that
I’m standing on is maintained at a 1/2
inch mowing height. And these are the extreme
ranges for perennial ryegrass. And if I were to suggest
a preferred mowing height, as we’ll
talk about later, higher is better, in my opinion. And as you look at
these different heights, the two inch grass here is gonna
have to be mowed once a week to keep it within that 1/3 rule. Never mowing more
than 1/3 of the grass blade in a single mowing. The grass here that I’m standing
on that’s maintained at a 1/2 of an inch, it’s gonna require
very frequent mowing, maybe two or three times a
week, to prevent it from scalping off or
mowing more than 1/3 of the grass blade
in a single mowing. Tip two in relation
to successful mowing is raising your mowing height
and increasing your mowing frequency. Raising your mowing
height is directly correlated to deeper routing. The higher the grass
is mowed, the deeper the plant roots into the ground. This is illustrated very
well with these two samples. The sample on the left here
is maintained at a two inch height. And you can see very deep
roots down to about a 4 inch depth into the soil. And then, if we compare that
to this sample on the right here, which is maintained
at a 1/10 of an inch, you see rooting depth
down to only about an inch and a half into the soil. Not only will increasing
your mowing height increase your rooting depth,
but it’ll also decrease weed encroachment. So weed seeds fly in from
all over the place existing or surrounding areas, such as
ag fields, unmaintained areas where the weeds are
high in populations. That weed seeds flowed in, and
they land on the turfgrass. And the weeds then make it down
through the grass to the soil surface building
the weed seed bank. And in the low mowed grass
where the weeds make it down to the soil
surface, sunlight can then penetrate down through
the turf canopy, germinating the weeds, allowing
them to establish. And then, as you move over
into higher maintained grass, the grass catches the sunlight
as it comes down, uses it for carbohydrate production,
and prevents the weed seeds from germinating that are
down at the soil surface there at the bottom of
the turfgrass canopy. So as we take a close look
at these two different mowing heights, we see a lot of
annual blue grass encroachment here at the low
maintained mowing height. And then, as we move over
here to the higher maintained mowing height, we see much less
annual blue grass encroachment. And again, that’s a
direct correlation to the mowing height. The higher height being
correlated to the less annual bluegrass encroachment. So the two dominant
grasses in the state of Oregon and
Washington are gonna be perennial ryegrass
along the coast and Kentucky
bluegrass as you move inland across the mountains. Both of these grasses are gonna
do very well at a three inch mowing height. As you take this mowing height
down lower approaching an inch or lower than that, you start
to get more and more weed encroachment, as well as more
and more environmental stresses that the grasses
cannot grow out of. So the second half of tip
two is increasing your mowing frequency. And to illustrate
this point, we’re gonna use the example
of the highway roadside. So the highway is maintained
at a very low mowing height. Probably once a month. And it’s some of the worst
turf you see across this state. This time of year, it becomes
very brown, very thin, tons of weeds in
there, and it’s all related to the low mowing height
and the low mowing frequency. You need to increase
your mowing height and increase your frequency. And the height is also
relative to the frequency. If we go back down
to this grass here, we see the higher
maintained grass at 2 inches needing about
an average mowing of once a week to maintain
it at that height but not violate the 1/3 rule. This is gonna provide a very
healthy grass stand that tolerates a lot of
environmental stresses and is resistant to
weed seed encroachment. Then, as we move over
to the lower cut grass, because of the
low mowing height, this grass is gonna require
very frequent mowing, as much as three times
a week, to prevent you from scalping the grass when
it’s maintained at this height. Again, if we go back to the
grasses used in Washington and Oregon, the dominant
grasses are perennial ryegrass on the coast, and then Kentucky
bluegrass as you move inland. And again, these grasses should
be maintained, in my opinion, around a three inch height. The higher the height
you go, the more stress, environmental
tolerances you’re gonna have from the grass. So weed encroachment associated
with a low mowing height include annual bluegrass, common
dandelion, and crab grass. So tip three for
successful mowing is mulching your grass
clippings by removing the bag from your mower,
and using mulching blades like this double
set of blades here, we can return as much as two
pounds of nitrogen per year into the turfgrass stand,
which is a considerable amount of fertilizer when
we’re trying to achieve annual rates of three to five
pounds of nitrogen, which are suggested for
Kentucky Bluegrass and perennial ryegrass. So by adhering to the 1/3
rule, using a mulching blade like this, we can easily
return a significant amount of organic fertilizer with the
grass clippings to the soil. This area here illustrates the
importance of the 1/3 rule, increasing your mowing height
and increasing your mowing frequency, in relation to
mulching your clippings back into the turfgrass stand. Here, while the mowing
height may be adequate, right around three inches,
the frequency is not. Therefore, we see these
large wind rows accumulating on the surface here. These wind rows
of grass clippings can smother the turf if
they accumulate too much and are very unsightly for
high performance turf grass situations, like athletic
fields or golf courses. And as you look across
the surface here, you see a large number of
broadleaf weeds encroaching into the site. And this is probably associated
with the frequent scalping. The grass is not being
mowed frequently enough. So when it is mowed,
it’s scalping the turf, opening the canopy, and allowing
sunlight to penetrate down to the weed seed bank. So the second of the three
primary cultural practices is fertilization. And the three tips we’ll
discuss today in reference to fertilization
is, first, select a fertilizer designed for turf. Secondly, use a rotary spreader
and not a drop spreader. And finally, the holiday
fertilization plan. So tip one, selecting a
fertilizer for turfgrass. If we come down here and take a
look at this bag of fertilizer here, we see it’s clearly named
or labeled Turf Fertilizer. We have three primary nutrients
being nitrogen, phosphorus, and potassium. So these are the essential
turf grass nutrients with the highest concentration,
the most important nutrient being nitrogen,
followed by potassium. And then, finally, phosphorous. And if we move from this
bag over to the second bag, we now see a product
labeled 23-0-10. And this would be an appropriate
product for homeowners in the state of Washington. There is a ban on fertilizer
containing phosphorus in the state of Washington. And the reason for this
is because products that contain
phosphorus can result in accelerated eutrophication. So as these fertilizers
with phosphorus enter into waterways,
ponds, and lakes, they generate algae blooms. The algae then die, and
microorganisms in the water decompose the algae using
up the oxygen in the water. This, ultimately, results in
the death of the pond system. Animals and other things
requiring oxygen in the water will then die. So the second tip to
successful fertilization is using a rotary spreader
rather than a drop spreader to apply your product. So the problem with
a drop spreader is once we load this fertilizer
spreader with our product, we open the stem here, we make
our application, we close it, and we turn around
for our second pass. We now have to apply
our second pass right over top of
the wheel past we made for the first application
to get even coverage, which is very hard across a large
surface area like this field. The rotary spreader,
on the other hand, when we open this
fertilizer spreader, the product comes out and
hits this propeller here, which throws the product
into a large arc. The majority of the
product lands here in front of the
fertilizer spreader. And as you get further and
further away from the center, the product gets to
lower and lower amounts. Then, we generally use a 10
to 8 foot turnaround period for our second pass as we
come over the surface area to provide a very uniform
coverage over a large surface area. It’s not as important to
be accurate on our overlap. So the third tip to
successful fertilization is the holiday fertility plan. So with this plan, the goal is
to apply three to five pounds of nitrogen per 1,000
feet annually broken up into four applications. So the first
application, which can be made at a rate of a
pound to a pound and a half should be made on Memorial Day. The second application,
which should be applied at a
reduced rate, a half to a pound of nitrogen
per 1,000 feet, should be made on July 4th. The third application
then made again at a reduced rate of a
half to a pound of nitrogen per 1,000 feet on Labor Day. And then, the final application
now at an increased rate at a pound to a pound and
a half on Thanksgiving. The reason we do this
is because cool season grass, such as perennial
ryegrass and Kentucky bluegrass– the dominant grasses
in our part of the world– have a diurnal growth
pattern with heavy growth in the spring and the
fall, very little growth in the summer as heat drought
sets in, and then, again, little growth in the
winter when temperatures are relatively cool. Three weeds that
we’re gonna wrap up with related to low fertility
include white clover, false dandelion, and plantain. So just remember
these four dates. Memorial Day, 4th of July,
Labor Day, and Thanksgiving. [MUSIC PLAYING] The third primary
cultural practice that we’re going to
discuss is irrigation. And the three tips
we’ll be covering are, first, know your
precipitation rates, secondly, adjust your irrigation
rates with the season and, finally, twice as
much is not twice as good. So the first tip is know
your precipitation rates. And more specifically,
what is the depth of water you’re applying in an irrigation
event rather than the time. This can vary substantially
from irrigation head to irrigation head. For instance, a
pop up sprayer can apply a tenth of an
inch of irrigation in as little as 5 minutes
while a rotary sprayer may apply the same amount of
water in as much as 20 minutes. So in this point, we’re gonna
demonstrate an irrigation audit. And you’re gonna
see three steps. The first is placing the catch
cans across the irrigation area that you’re going to audit. Second, run the irrigation
system for a half an hour, 30 minutes. Third, look at the irrigation
depth in the various catch cans, and use that to
develop an average irrigation depth per the 30 minutes. We’re gonna then use that
to develop an irrigation rate targeting 2/10 of
an inch of irrigation. So the reason we’re using
2/10 of an inch of irrigation per event as our
general guide is because a loamy
soil, which is very typical of this part
of the United States, can only hold about .06 inches
of water per inch of soil. Therefore, if we
irrigate 2/10 of an inch, it’s gonna wet the
soil to a 3 inch depth. And if we take a look back to
our turf sample here, remember, this is a very
shallow rooted plant. The maximum rooting
depth is only going to reach a few inches. And the vast
majority of the roots are gonna be in the top three
and four inches of the soil. So other problems associated
with irrigation events greater than 2/10 of an
inch is precipitation rates will often exceed
infiltration rates. Therefore, if you put down more
than 2/10 of an inch of water, the water has a tendency
to run off the surface. And if we exceed 2/10
of an inch and it does happen to
drain into the soil, often, the water will
drain past the root depth, which we previously discussed. Tip two to proper irrigation is
adjusting your irrigation rates with the seasons. In our part of the world,
we have a temperate climate, which has a vast
majority of its rainfall through the fall, winter,
and spring months with a very droughty summer period. Therefore, we need
to adjust our rates to compensate for this summer
heat stress, which is exactly the time when cool season turf,
which is the dominant grass species in our part
of the world, as well, also needs the vast
majority of water. So in the spring
and the fall, we’re gonna target our rates from
0 to 0.75 inches per week, depending on your specific
environment and location. And then, as we move
into the summer months, we’re gonna increase
our rates from an inch to inch and a half. Again, depending on your
particular situation. So if we then
reference back are 2/10 of an inch of
irrigation per event, if we irrigate five times a
week at 2/10 of an itch, that’ll put us at an inch of water
per week, which will get us at the beginning
of our inch to inch and a half rate for the summer. And then, we can adjust
the rates accordingly, if we need to. So the third tip to
successful irrigation is twice as much is
not twice as good. Over irrigation is
gonna result in runoff of nutrients and pesticides
that you’ve applied. Runoff of fertilizers
containing phosphorus are gonna accelerate processes
like eutrophication, which we’ve previously discussed. And over irrigation
is also gonna result in leeching of
nutrients and pesticides through the soil. You’re also wasting water when
you’re creating surface runoff and leeching. So some things associated
with over-irrigation include annual blue grass,
rough blue grass, moss, and crane fly. Here we are at Lauren’s Field
at Oregon State University. And the point of this
visit is to illustrate the importance of frequent
mowing, proper fertilizer, and proper irrigation. So this soccer
field, which is host to the men’s and women’s
soccer team at Oregon State, receives mowing three
to four times a week, fertilization five
to six times a year, heavy applications in the
spring and the fall totaling around 6 pounds of nitrogen
for 1,000 feet per year, and daily irrigation through
the summer heat stress period between a tenth and
2/10 of an inch of irrigation, again, targeting right around
an inch of water a week. And if we just take
a look at this field, we can see the benefits
of proper implementation of these three primary
cultural practices. [MUSIC PLAYING] So now that we have completed
our primary cultural practices– mowing,
fertilization, and irrigation– we’re gonna move into our
secondary cultural practices, which include cultivation
and pest management. So starting with cultivation,
when picking a cultivation method, time, or reason,
there are three objectives that we want to complete. Those objectives are, first,
relieving soil compaction. Secondly, improving
drainage and air movement. And third, reducing
organic matter. So if these three things are
not a problem on your turf area, there’s no reason for you to
core, cultivate, or airify. In reference to that, grasses
that grow stoloniferously, like creeping bank grass
on a putting green, or risominously like
Kentucky bluegrass in the eastern half of
Washington and Oregon are going to require
regular cultivation. Grasses like perennial
ryegrass, however, which are bunch type
grasses, will not need regular core
cultivation or aerification. So again, I’m
reminding you, do you have soil compaction,
organic matter accumulation, or is drainage a factor? Those are the three
things that we should assess before choosing
a cultivation method. So there are all types of
different core cultivation or aerification units
that you can use. In my opinion, Hollow
Tine core cultivation is the most advantageous. So if we look down at this
bottom of this unit here, this is a Hollow
Tine core harvester. So it punches hollow holes into
the soil and removes cores. And the reason I think
this is such a good unit is because it satisfies all
three of those objectives in choosing cultivation. It’s gonna release
soil compaction. It’s gonna improve gas
exchange and drainage. And it’s gonna remove
organic matter that’s accumulated over time. So once we’ve gone through
and run our core cultivator on this area, we need to
either remove these cores from the surface of the grass
or incorporate them back into the soil. We are gonna incorporate
the cores back into the soil using a steel
drag mat or a hand rake. And then, we can remove cores
using a flat end shovel. So once you’ve taken your
drag mat over the surface, if there’s any
remaining material, some choose to run a rotary
mower over top of this. You can either rotary mulch
that back into the ground, or pull it off with a bagger. So once you’ve completed
your core cultivation, harvested your cores, or dragged
them back into the surface or raked them into
the ground, it’s a great time to intercede your
existing turfgrass stand to try and build the turf back up. This is an important
practice, particularly when managing perennial ryegrass. Remember, this is
a bunch type grass, so it does not spread laterally. So it cannot repair
from traffic. Can’t fill in after
areas become bare. So we’re gonna intercede
perennial ryegrass into areas like this. If you’re managing
Kentucky bluegrass I would also suggest
interceding perennial ryegrass into those areas, as well. The reason being
perennial ryegrass will germinate in
seven to 10 days, while the bluegrass takes
21 to 28 days to germinate. When selecting the
seed, you’re gonna apply it with a drop
spreader, and apply it at 8 to 10 pounds per 1,000
feet using the drop spreader. Here we are at the
Trysting Tree Golf Course. And we’re illustrating
the importance of core cultivation or
thatch management using a golf course putting green. The creeping bank grass
on this putting green has a very aggressive,
stoloniferous growth, which will accumulate
thatch in this layer here. This thatch is very closely
related to the disease problems you have on
most golf courses. So the better you can do
at managing this thatch, the less disease you’ll
have on your golf course. This golf course receives
cultivation twice annually, as well as verticutting and
top dressing all summer long, which provides very good
organic matter accumulation control, which relates
to less pesticides when managing the diseases
on the golf course. As we relate cultivation back
to integrated pest management, a weed that is a particular
indicator of a compacted soil is not weed. And finally, let’s review
the cultural practices that we’ve covered so far. We should be mowing at
a relatively high height around 3 inches once
a week at a minimum. We should be fertilizing
four times a year. Twice in the spring. Twice in the fall. We should be irrigating,
particularly during the summer months, around a inch per week
broken up into 2/10 of an inch applications. And we should be cultivating,
as well, particularly in situations when we have
grasses that have rhizomatous or stoloniferous growth
habits, like Kentucky bluegrass or creeping bank grass. So as we finalize this
part of the project, you should remember
we should not revert to pesticides
until we have exhausted proper mowing,
proper fertilization, proper irrigation, and
proper cultivation. It’s only after
we’ve successfully implemented these
cultural practices that we should consider
pesticide applications. [MUSIC PLAYING] For the final part
of this training, we’ll be covering
pest management. The three things we’ll
be highlighting here are, first, the pest triangle. Secondly, pesticide mixing,
loading, and application. And finally, the control
of three different pests. Weeds, diseases, and insects. So first let’s talk
about the pest triangle. The pest triangle, regardless
of the pest you’re managing, a weed, a disease, an insect
has three parts to it. The host, the pest,
and the environment, which is a very important or
critical part to integrated pest management. Here, we see a perfect
example of this. The host is perennial ryegrass. It was seeded as a
pure stand of grass. Then, over time, the
fertility became deficient. So the host is
perennial ryegrass. The environment is a
nutrient deficient soil. And the pest now
is white clover, the weed that does very well
in low fertility situations. Then, if I take a
few steps forward, we see another perfect
example of this pest triangle here, again,
in an area that was seeded as perennial ryegrass. It was nutrient deficient. And now rather than a weed,
we see a disease here. Red thread, an indication
of poor fertility. So here we have two
different pests. A weed, which was white clover. And a disease, red thread,
which are both indicators or pests that do very well in
low fertility environments. So probably the first
solution to the problem here is increasing
the fertility. Regarding pesticide
mixing, loading, and personal
protective equipment, remember to always consult
the pesticide label. The pesticide label
is your reference for all these different things. Mixing, loading, pests
that are properly controlled by the
pesticide, the proper host that the pesticide
can be applied to, and the proper personal
protective equipment for the various products
that you’re applying. So remember, always
consult the label. It’ll make sure that you’re
in compliance with Department of Agriculture regulations. In reference to personal
protective equipment, always consult the label. Some minimal PPE include things
like boots, socks, shoes, long pants, long sleeve
shirt, and gloves. To summarize mixing, loading,
and application of pesticides, in turfgrass
management, products are typically applied
at one to two gallons of water per 1,000 feet. This is very important because
adequate uniform surface coverage will
successfully ensure proper use of your products. To conclude our pest
management section, we’re now gonna focus on the
control of broadleaf weeds. More specifically, white clover
and false dandelion, pathogens being read thread and
necrotic ringspot, and finally, the control of
an insect, European crane fly. So at this point,
we’re going to discuss control of two broad leaf
weeds, the first being false dandelion. False dandelion is a
perennial broadleaf weed with a deep rooted
tap root system. This tap root system
allows the weed to persist well in dry,
droughty, summer stress conditions. This weed is typically
an indication that you have not been
watering your lawn. It’s often one of the
only weeds or plants that stays green in
the unirrigated lawn through the summer. In areas where this weed
is not mowed regularly it produces a large seed stock,
and then a bright yellow flower at the end. So broadleaf herbicides that
we can use for post emergent control of weeds like false
dandelion, common dandelion, and the thistles are three and
four way mixtures containing 2,4-D. 2,4-D is the most
important active ingredient for this group of weeds. This product here, Trimec
Classic, is the first example. So active ingredients in here
are 2,4-D, MCPP, and dicamba. The next product
we’re going to cover is speed zone, which has these
same three active ingredients, as well as carfentrazone, which
is a fourth broadleaf weed herbicide. And the final product
we’ll look at its Q4. So this four way herbicide
mixture includes 2,4-D, dicamba, as well as
quinclorac and carfentrazone. This is a nice product
to include in our list as well because
quinclorac will provide very effective control
of crab grass and lawns that have this weed, as well. So the next broadleaf weed that
we’ll cover is white clover. So here I have an
example of white clover that’s growing in combination
with perennial ryegrass. So this broad leaf weed
is a good indicator that you’re not putting down
enough nitrogen on your turf. It is a lagoom. And like other
lagooms– soybean, for example– it fixes
nitrogen from the atmosphere. So it is very often an indicator
that you’re not putting down adequate amounts of nitrogen.
If I set this sample down and then pick up another
sample of white clover here, we can see the
stoloniferous growth habit of this weed, which allows
it to creep over the surface as it grows perennially. Again, the weed growing with
its stolons across the surface. And then, if we take a
very close look here, we can see some nodules
forming on the roots of the white clover
where the fixed nitrogen from the atmosphere goes. White clover, however, is
often tolerant to 2,4-D, the major active ingredient in
products like Trimac Classic, which we discussed earlier. Other weeds that are tolerant
to 2,4-D include English daisy, black medic, as
well as wild violet. So for control of
this group of weeds, we’re gonna look for
products with triclopyr. An example of such a
product, here is T Zone. T Zone has triangle triclopyr
as the first active ingredient, as well as carfentrazone,
and the ingredients 2,4-D, and dicamba. To summarize our
weed control section, if you apply a herbicide
to take white clover out of your existing
stand of grass and you don’t change your fertility
mowing or irrigation practices, you can expect the white clover
to return to those areas. Remember, after herbicide
applications are made, you need to get the proper
primary cultural practices mowing fertilization
into effect, or weeds will only
return to the areas where they previously existed. At this point in
pest management, we’re going to cover the control
of two different pathogens. Red thread and
necrotic ring spot. First is red thread. So red thread is
a disease that’s very damaging to perennial
ryegrass in low fertility situations. Typically, when we
find this disease, it’s an indicator that we’re
not achieving our recommended rate of nitrogen
per year, which was three to five pounds annually. And it gets the name red thread
because of the mycelium, which gives it this red appearance. The pathogen spreads across
the surface of the leaves. And when it dries
out in the sun, it provides this pinkish,
reddish, hard mycelium on the surface of the leaves. So typically, a control
of this pathogen can be easily provided by
adequate fertilization. And remember, that’s
three to five pounds of nitrogen applied four times. Twice in the spring
and twice in the fall. And this disease also can be
controlled in high priority situations, high
value situations, when the fertilizer has
not been affective with a broad number of contact
or systemic fungicides. The second pathogen
that we’ll cover today is necrotic ring spot. Necrotic ring spot is very
specific to Kentucky bluegrass. The reason being,
Kentucky bluegrass is a rhizomonas grass spreading
laterally underground. These rhizomes develop
organic matter over time. As organic matter
increases, the root borne pathogen
necrotic ring spot will become worse and worse
because the pathogen not only feeds on the turf but also
on the organic matter that accumulates in the soil profile. This pathogen has a very
interesting lifecycle. Initial affections
typically begin in the fall months
and the spring months when the environmental
conditions are wet and cool. However, symptoms are not
visible this time of year. It is very good growing
conditions for grass like Kentucky Bluegrass,
the cool, wet weather. So as the pathogen
infects the turf, we often do not see the symptoms
until we enter into the summer period when heat and
drought affect decrease the health of the turf. The pathogen is not very
active this time of year. However, the grass–
because the root system has been compromised
by the pathogen– succumbs to the summer
heat and drought stress. This is very
important because when we consider fungicide
applications, a fungicide application,
when the symptoms are present during the summer,
will not control the pathogen because the pathogen
infected the turf back in the previous fall
and spring months. We need to make
preventative applications in the spring and the fall
before the symptoms are present. Symptoms of this pathogen
initiate as small, necrotic, brown,
or yellow patches that grow larger and larger. As these patches get larger to
about an 8 inch in diameter, grass will often recover in
the center of these patches. You then have a
necrotic circle or ring with grass outside the ring
and grass inside the ring. We often commonly
refer to this symptom as the frog eye, which is very
typical of necrotic ring spot. In terms of control
of necrotic ring spot, we’re gonna use
cultivation and fungicides. Remember, this disease is
specific to Kentucky bluegrass, which has the aggressive rise
ominous underground growth, which accumulates
organic matter. The pathogen feeds on the
organic matter, as well as the grass. So reducing organic matter
through frequent core cultivation is very important. Cultivating twice a
year can substantially reduce your necrotic ring
spot, infection, and activity. In terms of fungicides, the
two major active ingredients that are going to be
effective on this pathogen include DMI fungicides,
such as propiconazole, which has the common name Banner
Maxx, as well as azoxystrobin, known as Heritage. Another product that is very
effective on this pathogen is headway, which is a mixture
of the active ingredients propicanazole and azoxystrobin. And again, remember
these applications need to be made preventitively
in the spring or fall months, rather than in the summer months
when the symptoms are present. Management of European crane
fly will be the last pest that we discuss. This insect is a
diptera or member of the fly family, which also
includes common crane fly. It is easily identified
by the long, thin legs and the large,
membranous net vein wings that are held out
against the body when the insect is at rest. Turfgrass areas
adjacent to wetlands are very particular
to crane fly habitat. These insects prefer very moist,
wet soils when finding areas to lay their eggs. So typically, grass that is
adjacent or next to ponds, lakes, various wetlands, low
lying areas that drain water, or areas that are
over-irrigated or shady are very typical of
crane fly habitat. So things that we can do
to dry out the soil surface will reduce crane
fly infestations. A general
recommendation is if you have a history of
crane fly infestations, turn your irrigation
system off on Labor Day. This will decrease the
crane fly populations. And it will not be very
detrimental to the turf because during this time
of year, heat is reducing. And the seasonal
rains, typically, are coming into the fall season. So environmental stresses are
not as a concern for turfgrass. So adult European crane
fly emerge from the soil in mid August to October. They quickly find a mate,
reproduce, and then lay eggs. The eggs take about a
two week period to hatch. The larvae then go
through several instar, beginning in the fall,
through the winter, into the summer months. During these instars, we
should be doing our scouting in December and January
about the third instar stage. This is when the larvae
are the most active and will often find the
highest concentration of larva. For scouting, we can use a
square end shovel like this. We’re gonna make a square hole
down to about a three inch depth in the soil. And then, flip over
that piece of soil. We’re looking for concentrations
of 20 to 50 larvae per square feet. The number of larvae that
determine our action threshold is gonna be dependent on
the successful mowing, fertilization, and irrigation. If we’re not doing
these cultural practices successfully, we’ll have
a lower action threshold. Closer to 20 larvae
per square foot where we start to
see thinning turf. If the cultural
practices are maintained at adequate levels–
regular mowing, regular fertilization in
the spring and the fall, and adequate fertilization
in the summer– we’ll have higher
action thresholds of 50 larvae per square feet,
or even greater before we start to see thinning turf. The larvae will complete
their life cycles in the late spring,
early summer months, go into pupation in July,
and then emerge again as adults in mid August. For control of
these insects when we have reached an action
threshold of 20 to 50 or even more larvae, depending
on our cultural practices, we have a number of
different active ingredients that are effective on early,
and then late instar stages. Products effective on early
instar periods of this insect, which, again, would be the
early winter months, include a [? metoclopramide, ?] which is
also known as a product merit. There is some danger associated
with this product in relation to bees. It has been known to kill
bees and does kill bees. However, when we apply it
to a turfgrass situation, the risk is very low because
turf is not a flowering plant. [MUSIC PLAYING] To summarize this training,
let’s review the primary and secondary
cultural practices. The primary cultural practices
were mowing, fertilization, and irrigation. In reference to mowing,
remember a high mowing height around three inches
for perennial, ryegrass, and Kentucky
bluegrass is best. And frequent mowing. At least once a week. In reference to
fertilization, remember, three to five pounds of
nitrogen per 1,000 feet. Two applications made
in the spring months, and two applications
made in the fall months, avoiding applications
in the winter months. In terms of
irrigation, remember, 2/10 of an inch of irrigation
per application is best. It prevents runoff and leeching. During the peak summer months
when it’s very droughty and you have a lot
of heat stress, remember, one to 1 and
1/2 inches of irrigation. If you put down 2/10 of an
inch of irrigation five times a week, that’s
one inch per week. Now the secondary
cultural practices were cultivation
and pest management. Remember, you need
cultivation in situations where you have laterally
spreading grasses, like Kentucky bluegrass
or creeping bank grass. These grasses produce
a lot of thatch, which encourages disease development. Use core cultivation in
the spring and the fall to reduce thatch
and organic matter, as well as compaction, poor
drainage, and air movement into the soil. And the second of the two
secondary cultural practice is pest management. Remember, we’re only relying
on pesticides– whether they’re herbicides, fungicides,
or insecticides– after proper mowing,
fertilization, irrigation, and cultivation have failed
to provide adequate turfgrass stands. When we consider the
various pesticides, remember to get proper
pest identification before selecting a product and
a time to put down that product. [MUSIC PLAYING]

4 thoughts on “Integrated Pest Management for Turfgrass

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