University of Missouri Extension

Barton County

April 2011 Crop Scouting Reports

Field Scouting Report for April 27

Cooler temperatures and wet conditions slow growth in Southwest Missouri

Wheat fields were scouted Monday and Tuesday in Barton County by Jay Chism, MU Extension Agronomist and Jill Hankins, Barton County agronomy assistant. Field conditions are obviously extremely wet and growth continues to be somewhat slow. Heads are beginning to emerge in some fields. The rate at which a field moves from the boot stage to flowering can be influenced by temperature. At warmer temperatures the crop can move quickly through growth stages. At cooler temperature, the crop may move very slowly from boot to flowering.

According to Laura Sweets, University of Missouri Crop Pathologist, frequent light rains, high humidity, extended periods of overcast weather and moisture that stays in the canopy will favor the increase of diseases including Fusarium head blight or scab.

Calls have been received asking about fungicide applications. As far as foliar fungal diseases we have only seen isolated areas where infections are occurring. This is probably due to the dry weather in Texas that reduces inoculums that reduces the number of spores that are carried to SW Missouri.

If growers are considering fungicide applications be sure to scout fields to monitor the stage of growth of your crop. It is important to remember that once the main head is fully emerged, flowering will follow quickly. To help suppress Fusarium head scab, fungicides must be applied at the beginning of flowering. Be sure to read fungicide labels carefully as nearly all products will have a pre-harvest interval.

For more information on this scouting report or 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/3cr8ms6

Field Scouting Report for April 20

Aphids, cutworms and Nitrogen deficiencies Spotted

Jill Hankins, Barton County agronomy assistant scouted wheat fields Monday April 18 north of Lamar. The wheat was in stem elongation stage with the second node detectable. Hankins saw some nitrogen deficiencies in low lying spots, likely due to rain. A small amount of tan spot on the lower leaves were spotted, but not enough to cause concern.

Hankins also noticed up to 10 bird cherry oat aphids per linear foot. Economic thresholds for bird cherry oat aphid are 12-25 per linear foot. Bird cherry oat aphids are close to economic threshold levels and fields should be scouted to determine if a pesticide needs to be applied. I also counted up to 14 English grain aphids per tiller in many spots. Economic thresholds for English grain aphids are 100 per tiller. Warrior is the most effective insecticide for aphid control, according to state entomologist specialist Wayne Bailey.

Pat Miller, the Vernon County agronomist, recently counted an intensive capture of black cutworms. This count triggered a predicted cutting date for corn for April 27. A cut date is an estimated date of when damage may be seen in the field. Three week control for Black cutworm can be provided with Warrior, or any pyrethroid. Note that pyrethroid does not perform well in cold weather.

For a complete list of black cutworm control, please see our website, where a chart will be posted.

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

Black Cutworm control chart (pdf)

Aphids on wheat Tan spot on wheat

Nitrogen deficiency Nitrogen deficiency

Field Scouting Report for April 13

Aphids in Scouted Wheat Fields at Threshold Populations

Aphids were showing up in bigger numbers this week in the wheat fields scouted west of Golden City. The fields were scouted by Tim Schnakenberg, an agronomy specialist with University of Missouri Extension and Jill Hankins, an agronomy assistant with MU Extension.

According to Schnakenberg, bird cherry oat aphids were counted at threshold populations, which are 12 to 25 aphids per linear foot, in the lusher and thicker wheat in the beginning flag leaf stage.

Dr. Wayne Bailey, a professor of entomology at MU, says insecticides are economical to apply to avoid yield loss. “Looking at past trials, Dr. Bailey says Warrior has been shown to have the best results. Be sure to follow the instructions and rates label when applying these pesticides,” said Schnakenberg.

English grain aphids were also seen, but were not at threshold populations.

Septoria leaf blight was spotted on a few leaves, but not enough to cause concern. “It is identified on the upper leaves by yellow patches that run parallel to the leaf and small black specks within the discoloration,” said Schnakenberg.

Nitrogen deficiencies were seen in all the fields and is most likely due to the large amounts of rain that have been received in low lying spots in the fields.

“Some weeds were spotted but the wheat is thick enough to shade them out, so herbicides are unnecessary,” said Schnakenberg.

Click here for PDF file Audio report -- http://tinyurl.com/698rde5

Aphids on wheat Bird cherry oak aphids

Field Scouting Report for April 4

Multiple Foliage Virus Diseases Found

Jill Hankins, agronomy assistant, scouted wheat fields with Jay Chism, an agronomy specialist with University of Missouri Extension in Barton County fields in southwest Missouri this week and found multiple foliage virus diseases.

Hankins scouted wheat fields with Jay Chism southwest of Lamar on Monday April 4^th and observed multiple viral diseases.

Laura Sweets, in Columbia, indicated that many types of wheat viruses have already been confirmed, including barley yellow dwarf virus spread by bird-cherry oat aphids. Virus tends to be more prevalent in lower, wetter areas of a field. They are most pronounced in temperatures 46-54 F and tend to fade as air temperatures increase above those temperatures. Warmer temperatures later in the season slow disease development. *It is important to remember that virus diseases cannot be controlled with a fungicide application.

Very few aphids were observed in the fields; the highest count was 14 aphids in 1 linear foot. Threshold populations for aphids in wheat fields are 50 aphids per 1 linear foot. Not enough were scouted to warrant concern yet. Aphids are common, but rarely require control.

Dr. Wayne Bailey, in Columbia has received calls from southwest Missouri about populations of cowpea aphids being 60% above threshold in alfalfa. Looking at past trials, Dr. Bailey feels Warrior and Dimethoate were the top performing insecticides. Be sure to follow the instructions and rates label when applying pesticides.

Pat Miller, MU Extension agronomist in Vernon County, recently counted an intensive capture of cutworms. This count triggered a predicted cutting date for corn for April 27. A cut date is an estimated date of when damage may be seen in the field.

Intensive captures were not seen in Barton County, but insects can easily be brought into the area.

For more information on this report, please refer to our website or contact the MU Extension Center in Barton County at (417) 682-3579.

Click here for PDF file Audio report -- http://tinyurl.com/3fb29p

Foliage virus diseases on wheat