Barton County

Field Scouting Report for May 25

Tornado Debris, Bacteria and Army Worms Show up in
Southwest Missouri Corn and Wheat Fields

The biggest surprise in area wheat and corn fields this week was debris from the Joplin tornado according to Tim Schnakenberg, an agronomy specialist with University of Missouri Extension.  “I scouted corn and wheat fields in Dade and Barton counties this week,” said Schnakenberg. “It was sobering because I found debris like miscellaneous papers, a utility bill, a canceled check, cards, a photo and building materials from Joplin.”

The fields were also saturated from recent rains and the corn was in need of sunshine and heat.  Much of the corn had been replanted and the older corn was small and undeveloped for its age.  Corn ranged from just spiking (VE) to about the V5 stage. 

“Color of the leaves was surprisingly good for the amount of rainfall we have had.  Leaves of the older corn still showed some signs of the hail from a week or two ago,” said Schnakenberg.

The most obvious issue found on older stage corn was whitish oval spots on the leaves.  These spots had no margin, indicating that it is possibly bacteria called Holcus leaf spot.   This occurs occasionally following a hail storm or strong wind storm that brings in the bacteria for infection. 

“This condition is considered to be fairly benign to the plant since it does not produce fruiting structures in the lesions following infection.  For this reason it is believed that the plant should outgrow the problem with time once growing conditions improve,” said Schnakenberg.

ARMY WORMS
Insect activity appears to be minimal, although reports of more significant feeding have come from areas in Stone and Barry counties. Signs of true armyworm feeding were found this week but nothing significant in number.  “This can change quickly with warmer, dryer growing conditions, so farmers should continue watching the crop for this development,” said Schnakenberg.

The threshold for treatment of true armyworms in small corn is when 25 percent or more of the plants are being damaged.  The true armyworms that Schnakenberg found were still small but this can change quickly with warmer weather.  Growers should scout for armyworm activity including leaf feeding higher in the canopy and clipped heads as harvest gets closer.

The threshold for treatment of armyworms is when four or more half-grown or larger worms are seen per square foot and before two to three percent of the heads are cut from the stems.  “Scouting is most successfully achieved at dusk or dawn since they do most of their feeding at night.  They often remain in the plant debris during the day,” said Schnakenberg.

WHEAT FIELDS
Wheat fields were developing slowly and are at the watery ripe kernel stage of development.  The crop will very quickly be in the milk stage.

“The most pronounced symptoms found in many fields were the purple and yellow flag leaves that were due to the Barley Yellow Dwarf virus.   This virus was most likely infected by aphids last fall,” said Schnakenberg.

“Highly productive fields should be scouted in the late fall for aphid activity.  Treatment at key times may help to prevent this virus infection.  There is nothing that can be done to the crop at this stage,” said Schnakenberg.

Some fields showed infection from loose smut, showing the signs of black sooty mold on the heads.  Seed treatment at planting can guard against some of this infection.

“Diseases were developing rapidly due to recent weather conditions but it is past the time to treat for these problems.  The primary disease noted was Septoria leaf blotch which was at least half way up the canopy in some fields,” said Schnakenberg.

Fields that had been treated with a fungicide were in better shape. For example, in the treated fields, Schnakenberg said he saw little disease symptoms in the head as well as no Fusarium head scab. 

“As in the corn, little insect activity was seen and very little feeding was going on in the wheat fields this week,” said Schnakenberg.

For more information on this scouting report or to learn how you can receive it by telephone each week, contact the MU Extension Center in Barton County at (417) 682-3579.  These weekly field crop scouting reports are sponsored by MU Extension in Barton County and the Barton County Soil and Water Conservation District.

Click here for PDF file                                                Audio report --  http://tinyurl.com/3o4WZ5X

New Replant Tables

Field Scouting Report for May 17

Hail Damage in Corn Fields Main Concern this Week

Fields south of Lockwood and north of Lamar were scouted on May 16 by Jill Hankins, Barton County agronomy assistant, and Ed Browning, natural resource engineering specialist with University of Missouri Extension.  Both found hail damage in the corn fields.

“If corn has been emerged for three-plus weeks and is at or near the seventh leaf stage, it is most susceptible to hail damage because the growing point is above ground,” said Browning. “Corn can withstand a large amount of defoliation.”

If the corn leaves are 100 percent defoliated, it will only result in a 9 percent yield loss.  The stem is the most important part of the plant that needs to be protected from hail.

“So if the stem is not damaged, your corn does not need to be replanted.  Some insects and diseases were seen but not at harmful levels,” said Browning.

The wheat had barley yellow dwarf virus on the leaves but harmful insects were not found at damaging levels.

“Wheat is also far enough along that aphids are no longer of concern. The upper part of some wheat heads had blanks from the hail, but not many heads were damaged,” said Browning.

For more information on this scouting report or to learn how you can receive it by telephone each week, contact the MU Extension Center in Barton County at (417) 682-3579.  These weekly field crop scouting reports are sponsored by MU Extension in Barton County and the Barton County Soil and Water Conservation District.

Click here for PDF file                                                Audio report --  http://tinyurl.com/4xuz2oo

Hail damage on corn

                                   Hail damage to wheat                      Hail damage to wheat kernel

          Aphid eggs                                                   Barley Yellow Dwarf virus

Disease on corn leaf

Leaf Defoliation and Yield Loss Information:
Assessing Hail Damage to Corn
Assessing Hail Injury in Corn
Assessing Hail and Freeze Damage to Field Corn and Sorghum

Field Scouting Report for May 11

Wheat Diseases Fade as Temperatures Rise;
Scouting for Black Cutworms Still Needed in Corn Fields

Wheat fields near Lamar were scouted on May 9 and according to Jay Chism, agronomy specialist, University of Missouri Extension, wheat in those fields were in the flowering stage and diseases were fading as the temperatures rise.

“It is important to remember to read the fungicide label if you want to spray because it could be off label now.  I saw a few aphids but wheat is now at the stage that aphids are no longer a concern.  No armyworms or other harmful insects were seen,” said Chism.

Some corn fields scouted were in the fourth and fifth leaf stage. Cutworm damage is no longer a concern for plants at that stage.  However, fields that are not that far along and need to be individually scouted for black cutworms. 

“I saw a little phosphorus deficiency likely due to the rain. I also saw a small amount of insect feeding, possibly brown stinkbug, pictures have been sent off to confirm,” said Chism. “Some fields are being re-planted but individual scouting needs to be done is order to see the individual population of the field.”

For more information on this scouting report or to learn how you can receive it by telephone each week, contact the MU Extension Center in Barton County at (417) 682-3579.  These weekly field crop scouting reports are sponsored by MU Extension in Barton County and the Barton County Soil and Water Conservation District.

Click here for PDF file                                                Audio report --  http://tinyurl.com/63bdfdt

Insects feeding

Corn and Soybean Replanting article

Field Scouting Report for May 4

Various Viruses Showing up in Area Wheat Fields;
Just Remember Fungicides are not Effective Against Viruses

Wheat and corn fields northwest of Lamar and in northern Jasper County are showing signs of various foliar diseases but no worm damage yet according to Jay Chism, agronomy specialist, University of Missouri Extension.

   

Other viruses