Farm News, IA
07-20-07
Scouting crops
Tracy Burger, Agronomy Sales Specialist and Dave Olson, rural Otho, scout
Olson’s bean field for aphids.
The critical corn growing period is upon the state and agronomists say now is the
time to scout fields.
“Pests have not been a large problem,” said Joel DeJong, Extension Field
Agronomist. “There has been the occasional field infested with corn room worm
beetle with evidence of the silk clipping.”
According to DeJong, some evidence of soybean aphids is also visable, yet the
largest concern among farmers is the lack of rain.
“Dickinson County started out a little more wet than many farmers would have
liked,” said Paul Kassel, Extension Field Agronomist. “Now the fields are dry
and farmers are needing rain before corn yields suffer.”
According to a number of Iowa State University Extension Field Agronomists,
crop conditions and the pests found in the crops varies per county and area of
the state.
Webster county
Leaf diseases are becoming more evident in corn, according to Tracy Burger
Agronomy Sales Specialist for NEW Coop. Diseases that have been found
include Gray Leaf Spot, some Eyespot as well as some Southern or Common
Rust.
Both Western and Northern Corn Rootworm Beetles have also been present in
corn and producers should be on the look out for clipped silks.
In soybeans, Burger said they’ve already been scouting for aphids and as well as
the first generation of Bean Leaf Beetles, and Spider Mites could be another pest
that could cause some problems as well.
Burger said Webster County is in some definite need of rain and has been seeing
more stress for corn on those corn-on-corn acres.
The soybeans he didn’t believe were doing too badly, as they tend to handle
drought better than corn, however the plants seem to be shorter than most years
and a rain would definitely help.
Cherokee county
According to Joel DeJong, crops field specialist for Cherokee County, the corn is
still pollinating and producers should be scouting their corn fields for the Western
Cutworm beetle that may be clipping silks in those later pollinated fields.
Now is the time to be watching for aphids in soybean fields.
“You better be scouting all of your soybean fields to see where your aphid
populations are at,” said DeJong.
Crops in Cherokee County are marginal on water, DeJong said, particularly the
western part of the county. The eastern part of the county received some rain in
early July and fields are beginning to show some stress.
Pocahontas county
Jim Day, agronomy department manager for Pro-Coop in Pocahontas said most
of the fungicide being applied to corn will have been applied by now and the corn
is getting past the point for any pest spraying, however, producers should still be
on the lookout for corn borers laying egg masses under the leaves.
In soybeans, producers should be on the lookout for Bean Leaf Beetles as well
as aphids. Spider Mites could also become a problem, Day said if the weather
remains dry. The last application of Roundup is also being applied, he added with
timing becoming the real impact for the herbicide to work.
The early planted maturities, Day said should all be pollinated.
“It is real critical right now for moisture for the kernel fill,” Day said. However the
stands are looking excellent.
Soybeans, he said aren’t seeing the stress as much as corn is, as soybeans are
typically made in August and not in July so rains will be more important in August
for that crop. Soybeans in Pocahontas County are now reaching the R1 up to R2
stage.
Humboldt county
John Eveland, Humboldt County Extension Education Director said it is time to
be on the look for the Western Bean Cutworm moth and egg masses they have
laid on the upper leaves of the corn stalk.
In soybeans, it is time to start scouting for Aphids and continue to scout for
awhile. Also it’s time to be on the look for Bean Leaf Beetles.
Weed control in soybeans is also wrapping up and some fungicide has been
applied to corn, Eveland said as some producers throughout the county are
trying that this year on a trial bases.
It is getting crucial for some rain, Eveland said, as plants that are in light soil
areas are really hurting.
Soybeans have been flowering for sometime, Eveland said and they are in need
of rain as well, especially those planted in lighter soils.
Calhoun county
The big pest to be scouting for in Calhoun County is the Western Bean Cutworm.
According to Mark Licht, Iowa State University Extension Crops Field
Specialist, egg masses and some larvae should be evident. There has also
been some corn rootworm feeding to be on the lookout for as well.
A few aphids have been spotted in the soybeans, Licht said, but so far
populations have been low. It is also time to be scouting for the first generation of
Bean Leaf Beetles. Very rarely does this generation cause any damage, however
these will tell us how the second generation will be, which is what producers will
be most concerned about.
A quick moving thunderstorm in southwest Calhoun County in early July caused
some significant root lodging and some minimal greensnap in corn, Licht said,
and conditions are very dry and rain is needed to help with the pollination.
“We definitely need more rain, we’re going to start noticing that stress more as
temperatures rise,” said Licht.
In soybeans, he said he is not noticing as much stress, however there has been
some coupling of leaves due to the lack of moisture, but they have a couple of
more weeks before drought is an issue for them.
Sac county
Mark Licht, Iowa State University Extension Crops Field Specialist said to be on
the lookout for the Western Bean Cutworm in corn where egg masses on leaves
and some larvae around the silk and the tassel have been found.
Scouting for aphids in soybeans as well as Bean Leaf Beetles should be being
done now although aphid populations have been low.
Sac County is seeing some dry conditions, Licht said. The cooler weather last
week helped out a little as did the shot of rain from back in early July. With
temperatures rising again, stress will become more evident as it is harder for the
plants to recover when it is this hot, Licht said.
Buena Vista county
Mike Kaskey, Agronomist CSR for Ag Partners LLC said they have been busy
performing root digs for rootworm damage in corn and the time has come to start
to become aware of any leaf diseases that may cause problems.
Aphid scouting he said will continue as those levels are rising and the secondary
issue right now they are keeping a heads up on is Spider Mites.
The conditions in Buena Vista County are definitely dry, Kaskey said with the
west half receiving just a slight bit more moisture than the east half of the county.
The early planted corn, he said is tasseled and seems to be holding its own,
while the later planted corn crop looks like it will struggle through pollination.
The soybeans are doing ok, Kaskey said, however they are showing a little
trouble developing a canopy and the narrow row planted beans definitely look
better than the wide row planted beans for that reason.
Story/Polk counties
Rhonda Birchmier has been in the fields scouting for aphids, using the speed
scouting method where she samples 11 plants in a field, checking for a threshold
of 40 aphids. Once she hits 40 in a field, she stops counting and considers that
an infested plant. “We’re starting to have outbreaks of soybean aphids and it
varies from hardly any to over the threshold,î” she said. “I imagine some people
will begin spraying soon if it doesn’t rain where we’re located.”î In Birchmier’s
area, they didn’t receive any rain earlier in the week or last week. She said that
moisture levels are “quite a bit” shortî with 75 percent of the corn having
pollinated and doing ’’quite well.î But, if they don’t receive substantial amounts of
rain soon, the corn will begin nosing back. There also has been quite a bit of
rootworm pressure with the insecticides doing well.
Boone county
The heat is really hurting crops in Craig Heineman’s area and the lack of rainfall
is worsening conditions, Heineman said. “I am hearing about some aphid activity
out there and I haven’t seen enough to spray, but I’ve heard some people have,î”
he said. The corn was beginning to curl on Monday with the 90-plus degree
temperatures.
Hamilton county
According to Dan Thompson, Pioneer agronomist, he’s seeing very dry
conditions with little to no measurable rain since the first week of June. The dry
weather during this critical pollination period might decrease corn yields.
Soybeans also are showing slight signs of stress with some spraying for aphids.
Polk/Dallas counties
In these two counties, corn is ranging in size from starting to silk R-2 to starting to
tassel V-T for a majority of the corn. The later planted corn is slower to develop
and rain is needed now for the corn, since this is a critical time for corn to have
adequate moisture, Aaron Saeugling said. Fungicide applications are being
made to some area corn and soybean fields with airplanes. Soybeans are
generally full flower R-2 in most cases. They are starting to close the rows in
narrow rows. Scouting is being done for the western bean cutworm with some
moth captures and aphids are being found in low numbers. When scouting,
Saeugling recommended looking for aphids on at least a weekly basis, as well as
checking for second generation bean leaf beetles.
“For corn, now is the time to look for disease development and begin to look for
corn rootworm beetles on corn as it begins to silk,î” said Aaron Saeugling, ISU
Extension field specialist.
Plymouth and Woodbury counties
Plymouth and Woodbury Counties have a good percentage of acres that area
very dry, and the week of July 15 was a real challenge for pollination. “Corn is
curling every day on most acres, particularly in the eastern part of both
counties,Ӕ said Joel DeJong, a field agronomist for Iowa State University
(ISU) Extension in northwest Iowa. “Some neighborhoods have totaled less than
an inch of rain since May 3. Others received a half inch on July15, so the
variation is quite wide.î”
Local crop scouts are watching for soybean aphids. The insects can be found in
area fields, but the numbers are low. Scouts are also watching corn silks to
determine if rootworm beetles are clipping silks too short for pollination to occur.
Bean leaf beetles are emerging, but numbers remain low. In alfalfa, potato
leafhoppers have been a continuous pest.
Greene, Carroll, Crawford and Ida counties
Crops are progressing well in Greene, Carroll, Crawford and Ida Counties,
although the area is dry.
“I think we’re in the same boat for most of this area,”î said Mark Licht, an Iowa
State University Extension field agronomist in west-central Iowa. Cooler
temperatures during the week of July 8 helped, and some small isolated areas
recently received a small drink of rain (generally less than half an inch),
accompanied by hail and high winds.
The corn is at the tassel to silking growth stage and some of the earliest planted
may be starting to blister. Pollination can be hurt by dry weather and hot
temperatures, causing poor synchronization of pollen shed with silking. “A good
rule to go by is if leaves are able to unroll and regain turgidity overnight,
pollination should occur just fine, since the majority of pollen shed occurs from 5
a.m. to 10 a.m.,Ӕ Licht said.
Soybeans are in the full bloom to beginning pod growth stage. For both corn and
soybeans, foliar diseases appear to be minimal at this point. Insects such as
western bean cutworm, soybean aphids and first-generation bean leaf beetles
are present but are currently well below thresholds.
Aphid populations still are averaging one to three aphids per plant with few
individual plants having more than 50. The economic threshold is reached when
250 aphids per plant are present with populations increasing.
As for bean leaf beetles, Licht has been about two beetles per foot of row with
less than five percent plant defoliation. In the blooming to pod-fill stages, the
economic threshold is greater than 15 percent defoliation. Thresholds are also
reached when 10 percent of pods are damaged and there are 10 or more beetles
per foot of row.
Western bean cutworm moths have been reported just north of Sac City, where
flights peaked on July 9 with 112 moths. Egg laying will decrease with decreasing
moths flying, although there is the possibility of secondary moth flights. Economic
thresholds are reached when eight percent of the plants have egg masses,
and/or young larvae are in the whorl.
“Scouting for all insects should continue to determine severity as we move into
critical reproductive growth stages,Ӕ Licht said.
Alfalfa, hay and pastures are looking pretty dismal due to cold injury and wet feet
in April and the hot, dry conditions of July. They will perk up with cooler
temperatures and rain, Licht added.
Kossuth, Hancock, Cerro Gordo, Franklin and Hardin counties
According to Tim Rogers of the North Iowa Cooperative serving Cerro Gordo and
surrounding counties, they have been monitoring soybean aphids and are seeing
an increase. Some customers have begun preventative spraying. Rogers sees
spraying for aphids in coming weeks a “good possibility.”
Other pests he is watching now includes bean leaf beetles and on alfalfa he is
monitoring potato leaf hoppers.
Wright county
Soybean aphids were Larry Harrah’s first concern. Harrah, of Harrah’s Ag
Service in Dows, said right now they are at a low threshold and the next two
weeks will be key weeks for numbers. High temperatures will slow down
population. Harrah has been catching 50 Western bean cutworm moths per night
and recommends spraying non Herculex corn.
Bean leaf beetles are the next problem and according to Harrah, the next two
weeks will be critical for them. Harrah said it would be wise to spray for both BLB
and aphids at the same time. Root worm larva is also showing up and it is a
situation that should be monitored.