Aquatic insects in rice
In rice fields, many insects are
aquatic and obtain oxygen by absorbing
this dissolved gas directly from
the water through their integument, by surfacing and taking
a bubble of air with them underwater or by trapping air
among fine hairs on the undersides of their abdomens.
Speaking of aquatic insects, I am frequently asked by
farmers and crop consultants about egg masses found on
leaves of rice under flood. The eggs in these masses are
brown/grey/black/green/white (depending on age), elongate
and spindle-shaped. A single mass can have many
overlapping eggs somewhat resembling a sugarcane borer
Not to worry about your rice crop; these masses are eggs
of biting deer flies! Female flies need mammal blood, such
as humans and cattle, to produce eggs, which are laid on rice
foliage. Eggs hatch, and the worm-like larvae fall to the water below
and begin their aquatic existence. The larvae are dark-colored, flattened,
leathery and feed on detritus – so they do not pose a threat to
our rice crop.
Another aquatic insect I am asked about is the immature dragonfly,
which is an excellent hunter. It has retractable/extendable mouthparts
that help it capture all kinds of aquatic invertebrates and even
small fish. Before it transforms to an adult dragonfly, the immature insect climbs up above the water surface on a rice culm. The adult then
escapes from the immature exoskeleton leaving behind the white
cast skin of the immature clinging to the culm.
In addition, you have probably observed swarms of “gnats” in the
shape of an inverted pyramid hovering above stagnant bodies of
water (in drain ditches, for instance) in the early spring. Usually you
will see these swarms at dusk. The swarms are composed of adults of
rice seed midges – small flies whose larval stages can be damaging to water-seeded rice. The larvae feed on germinating
rice seed underwater. To minimize
rice seed midge injury, employ a pinpoint
instead of a continuous flood, pre-sprout seed,
plant as soon as possible after flooding and
possibly increase seeding rate.
We have many good rice insect pest management
tools, including seed treatments containing
an array of active ingredients and
foliar-applied insecticides representing different
classes of insecticides. If you have
insect questions, contact your state
research/Extension scientists – or you can
always contact me: (409) 658-2186 or
Good luck this field season!
When I got into this business, management
of the rice water weevil was limited to
two practices: Apply carbofuran (Furadan)
or drain the field. Managing rice stink bugs
has not changed in terms of techniques;
however, the materials at our disposal have changed.
Today we can control the rice water weevil preventatively by
treating seeds with Dermacor X-100, CruiserMaxx or Nipsit
INSIDE insecticides. All three are effective against the rice water
weevil. In addition to controlling the rice water weevil, Dermacor
controls or suppresses the Mexican rice borer, sugarcane borer, rice
stalk borer and fall armyworm. CruiserMaxx and Nipsit INSIDE
pick up Colaspis beetles, chinch bugs and thrips. CruiserMaxx also
includes a fungicide package to control seedling diseases. A mixture
of Dermacor with either of the other insecticides will widen
the spectrum of insect control, but labels must be consulted and followed
carefully, or control will be compromised.
Nipsit INSIDE and CruiserMaxx can only be used on dryseeded
rice. Dermacor can be used on water-seeded rice in areas
where the Mexican rice borer is of concern. Dermacor-treated
seed cannot be soaked; it must be dry seed. All of the seed treatments
must be applied by certified seed treaters.
If seed treatments are not used, the next line of defense are the
foliar insecticides, which, until this year, were all pyrethroids
(Declare, Fastac, Karate, Mustang Max and Prolex). Belay is a new
foliar (neonicotinoid) insecticide. It is used in the same manner as
the others in that treatment is recommended when rice water weevils
or leaf scarring is found and water is present in the field. Trebon
is a granular insecticide applied at about the same timing
and is of a similar chemistry to the pyrethroids.
Given the complaints about pecky rice in years when stink bug
pressure is heavy, I am fairly confident that our current threshold
values for rice stink bug are correct, but we will see what Dr.
Mike Stout’s research results provide. This will be the last year for
use of methyl parathion. Methyl parathion cannot be sold after
Aug. 31, 2013, and cannot be used after Dec. 31, 2013.
Another change on managing rice stink bug for Louisiana is the
discontinuance of recommending malathion. Studies by Dr. Stout
have confirmed what we have seen in the field for the past few
years: Malathion does not control rice stink bugs anymore. Tenchu
insecticide, a neonicotinoid, has been granted a full federal label
for use to control rice stink bug in Louisiana in 2013.
All of this information is available through your local county
Don’t cut rates
As we begin to finalize plans for rice
acreage in the coming weeks, it’s important to
look back at what we did last year. I have
had more than one discussion with farmers
about certain fields performing poorly last
season with no particular reason why.
Upon further discussion, it was revealed
that these poor-yielding fields were planted to
soybean the previous season and treated with
Prefix or Flexstar. These products, along with
several others, have a 10-month plant-back
restriction for rice. Simply put, be conscious
of the previous year’s herbicide program
when rotating into rice.
According to Dr. Bob Scott, Extension
weed scientist, it will be important to focus on
utilizing multiple modes of action in Clearfield
rice. We cannot afford to depend solely
upon a single mode of action (MOA) for weed
control. (For example, Newpath and Beyond
are the same MOA).
Begin with a burndown application, if
needed, followed by a pre-emergence application
(e.g. Command + Facet). Remember
that it may be necessary to flush to activate
pre-emergence herbicide applications.
Please keep in mind that we are beginning
to have problems with barnyardgrass in rice.
Populations of this weed have been found to
be resistant to propanil, Facet, Command
(limited) and ALS (i.e. Newpath, Beyond,
Regiment, Grasp). Barnyardgrass could
become “the pigweed of rice.” Resistance to
Prowl, Bolero and RiceStar/Clincher has not
been found, but it is becoming increasingly
important to protect these remaining modes of
action as no new herbicides are coming any
We saw a decrease in the percent of acreage
planted to Clearfield rice in 2012. In terms
of managing our available weed control
options, both Dr. Scott and I view this as a
step in the right direction. Given instances of
ALS-resistant barnyardgrass, we must limit
ourselves to using Clearfield technology only
where we need it, when we need it.
If ALS-resistant barnyardgrass were to
develop in a field where you need this technology
for red rice control, how long can you
justify continued use of this technology when
you will need additional herbicides to control
My guess is not long.
Early season insect control in rice continues
to improve as we now have three insecticide
seed treatment options available for 2013.
Growers have the option of having their seed
treated with CruiserMaxx Rice, Nipsit
INSIDE or Dermacor X-100.
Grape colaspis is typically the most worrisome
of early season insect pests in rice.
CruiserMaxx Rice and Nipsit INSIDE both
provide excellent control of this pest.
If rice water weevil is typically your greatest
problem, Dermacor X-100 may be your
best bet. However, all three of these products
have activity on both grape colaspis and rice
water weevil. Ultimately, choose the one that
fits your insect problems and your budget.
Choose the one offered at the lowest price,
but don’t cut the rate.
Keep in mind when evaluating price that
CruiserMaxx Rice contains both an insecticide
and a fungicide, while Nipsit INSIDE and
Dermacor X-100 are insecticides only.
Final reminders: For early season weed
control, don’t get behind to start the season.
Flush in a pre-emergence herbicide and use
multiple modes of action. Don’t wait until
weeds are large before spraying.
For early season insect control, ensure your
seed is treated properly with good seed
coverage and don’t cut rates.
ID specific problems
Missouri producers are telling us that their
attention is on selection of varieties, early control
of resistant and other weeds along with
early insect and disease control.
We confirmed the value of flushing early and often in 2012 for herbicide
activation, which resulted in good early weed control. Due
to the drought, we were forced to flush early and often for rice seed
germination. With conventional and Clearfield rice, we recommend
starting clean with tillage or a burndown, followed with a pre/delayed
pre, early post herbicide program.
We estimate that Missouri farmers plant about 50 percent Clearfield
technology. We suggest matching technology and mode of action
to your specific weed problems. And, plan and pay attention to not
only what your neighbor is planting in the field next to yours but to
all applicators in the area throughout the season. My work on drift and
misapplications tells me how complicated it is, so that’s why I’m
emphasizing to plan carefully now.
For early insect control, we are following the insecticide seed
treatment recommendations of entomologist Dr. Gus Lorenz, University
of Arkansas Division of Agriculture. Due to the low seeding
rates and cost of seed, it’s very important to control seedling diseases
and insects. The best way to get seedlings off to a healthy start
is seed treatments matched to your insect and disease situation.
Missouri producers ended the 2012 season with a good-yielding rice
crop. For 2013, we suggest they identify their specific problems for
each field, study their options for solutions and build a plan to match
the technology to get positive results. We recommend enlisting the
help of a consultant, your retailer and university personnel. I know it’s
not simple. That’s why God made a farmer.
that are too common
Tadpole shrimp (TPS), Triops longicaudatus,
is a crustacean and a common problem of
seedling rice in California. Most fossils are
rare, but species in this group are often referred
to as “living fossils” because their morphology has remained
unchanged for over 180 million years. Tadpole shrimp feed on germinating
rice seeds, killing them and reducing the stand. Their digging
during egg laying and foraging
can uproot young seedlings, which
float and accumulate to the sides of
the basin, especially downwind.
Additionally, TPS digging muddies
the water, reducing sunlight penetration,
which in turn reduces
seedling growth. TPS do not pose a threat to rice seedlings once they
are rooted and emerge through the water. At this time, seedlings are
large enough not to be affected.
Copper sulfate has been the primary control method for TPS and
algae from the 1990s until recent years. Research has shown that
rice straw can bind up to 75 percent of a copper treatment, making it
less available in the water. Since 2001, air quality regulations limit the
amount of straw California growers can burn, and this has increased
the straw residue present in fields. Pyrethroids, registered for rice
water weevil, are now the best chemical management tool, although
the application timing for TPS is earlier than for rice water weevil.
Cultural control, including minimizing the time from the start of
flooding to getting a stand established, is the best management tool.
Quickly flooding fields, seeding with well-prepared seed, flying on
seed as soon as possible after flooding, optimal water depths, etc.
are also important factors. This allows the rice seedling to root and
establish before the TPS can hatch and obtain the most damaging
stage. In monitoring for this pest, look for muddy water in the absence
of significant wind, a high number of floating seedlings, the floating
caste skins from the TPS molts, etc. Let’s hope for great weather
during this season’s rice seeding so we can fend off this “prehistoric”
creature. Even though it hasn’t changed for 180 million years,
TPS still competes very efficiently with us for rice stands.