JenREES 7-8-18


Crop Update:  A few diseases started showing up the past few weeks in various portions of eastern and south central Nebraska.  Phytophthora root rot in soybean is perhaps the

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Phytophthora root and stem rot in soybean. Notice wilted plant with leaves hanging on turning yellow/brown.  Also notice characteristic brown lesion from base of plant up a good six inches on this plant.  This affected plant is surrounded by healthy plants.

most common in both areas.  We normally think of this disease as seedling damping off and death; however, it can also affect plants later in the season.  What surprised me was how much we are seeing it this year in higher ground and sidehills instead of the typical lower ground we often see it on.  Dr. Loren Giesler, Extension Soybean Pathologist said that in situations where we’ve had dry conditions followed by heavy rains (as we have this year), especially on clayey or soils prone to compaction, Phytophthora can also affect plants.  He has a few videos along with additional information at the following website:  https://go.unl.edu/tdfh.  Symptoms characteristic at these growth stages include wilting of plants during the day with leaves eventually turning yellow-brown-gray and remaining on the plants.  Also, look for a brown stem lesion that goes from the soil line upward about 4-6″.  Some of these plants are also snapping off at the soil line. For those experiencing Phytophthora this year, future management includes:

  • Using resistant varieties including a combination of good partial resistance and an Rps gene. Partial resistance alone will not be as effective during early growth stages or under high disease pressure.
  • Cultural practices include anything that can improve soil drainage and compaction.
  • Seed treatment fungicides containing mefenoxam or metalaxyl should be used and you may need to consider a higher rate of them.

Regarding corn diseases, bacterial leaf streak (BLS) has greatly increased on more

bacterial leaf streak

Bacterial Leaf Streak (BLS) in corn.  Lesions are elongated and skinny staying between the leaf veins, similar to gray leaf spot (gls).  However, leaf margins are wavy and diagnostics under the microscope show the presence of bacterial streaming from the leaf veins.  With gray leaf spot, there will be the presence of fungal spores.  Thus, the importance of correct diagnosis when considering fungicide applications.

susceptible hybrids since rain events.  Early lesions can look very similar to gray leaf spot, so it’s important to correctly identify the two.  The margins of BLS are wavy vs. those of gray leaf spot are more blunt.  Both can have yellow margins when backlit by the sun.  Fungicides are not effective against BLS and hybrids do vary in their tolerance to this disease.  It’s important to scout fields as we may see an increase in fungal diseases due to the humidity, leaf wetness, and recent rain events.  Southern rust has taken awhile to develop in the southern U.S., which is somewhat unusual, yet many states have been in drought this year too.  As of July 5th, southern rust has been confirmed in Georgia with one suspected sample in a Missouri county.  You can watch the map at: http://ext.ipipe.org/ and follow @corndisease on Twitter for the latest on corn disease findings in the U.S.

Trees:  With numerous wind storms, the following resource has a lot of great information regarding pruning storm damaged trees correctly and questions to ask tree care services regarding tree pruning:  https://go.unl.edu/94fm.

Agronomy Youth Field Day:  All youth ages 9-18 years old are invited to the 3rd Annual Agronomy Youth Field Day. Youth will have exciting educational experiences while discovering Science & Agronomy/ Irrigation / Mechanized Agricultural careers for producing Nebraska crops! The field day will be held Wednesday, August 8 from 9 a.m.-3 p.m. at Nebraska College of Technical Agriculture Educational Center in Curtis, NE.

Hands-on activities (for all age levels) will focus on pest management, equipment technology, crop growth, soil management, precision farming & center-pivot irrigation technology. Several Nebraska Extension Cropping & Water Systems and 4-H Youth Development Educators along with Nebraska College of Technical Agriculture in Curtis Agronomy / Ag Mechanics Department professors will be sharing the researched based information with the students.

Participants will gain important life skills while discovering the science behind producing Nebraska crops. The six-hour field day is a great opportunity for ALL the youth to learn more about the agronomy industry and increase their basic understanding of science, ag literacy, a technology & STEM while exploring careers. Parents/Adults are welcome and lunch will be provided.

Reserve your spot today by registering online at:  https://go.unl.edu/agronomyyouthfieldday  by August 3, 2018. For more information (or if trouble with registration) contact Nebraska Extension Frontier County at 308-367-4424 or email 4-H Educator Kathy Burr at kathy.burr@unl.edu.

About jenreesources

I'm the Crops and Water Extension Educator for York and Seward counties in Nebraska with a focus in irrigated crop production and plant pathology.

Posted on July 8, 2018, in Crop Updates, Diseases, JenREES Columns and tagged , , . Bookmark the permalink. Leave a comment.

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