Soybean Yield Expectations when Planting in July (and possibly August) in Kentucky

 

Carrie Knott, Extension Agronomist-Princeton, University of Kentucky

The 2016 soybean season has quickly become a challenge for much of the state. For soybean fields planted in June, stands were reduced because of the extremely dry conditions across much of the state. Some regions received less than 2” for the entire month of June. These struggling soybean stands were then inundated with significant rain starting over the Fourth of July weekend and not ending until last week. The official precipitation recorded by University of Kentucky Agricultural Weather Center was as much as 10” for parts of the state. However, localized reports of more than 16” occurred. This led to considerable flooding in the state or at a minimum extended periods of saturated soil conditions. As such, many producers are considering replanting soybean fields.

The first question on most minds is “How much yield should I expect from late-planted soybeans?”.

The sugarcane aphid arrived to KY a month earlier in 2016 than in 2015

Raul Villanueva, University of Kentucky Extension Entomologist

Insect description and damage
The invasive sugarcane aphid (SCA) Melanaphis sacchari has arrived to Kentucky almost a month ahead in 2016 compared to 2015 (https://kentuckypestnews.wordpress.com/2016/02/16/sugarcane-aphid-losses-with-sweet-sorghum/). Sugarcane aphids have caused yield losses going from 30% to

Figure 1.  An adult SCA (pink arrow) and first 
instar nymphs (blue arrow) detected on a sweet 
sorghum  field in Trigg County, KY on 07/15/16. 

(Photo credit Raul T. Villanueva)

100% to sorghum grower since 2013 on many states of the US. Sugarcane aphids affected severely grain and sweet sorghum fields last year in GA, SC, MO, and TN and KY. Last Friday (7/15/16), a small numbers of sugarcane aphids were detected in a field of sweet sorghum in Trigg County (Fig. 1). Although the numbers are still low in this field, populations may pick up sooner. So far in the U.S all SCA populations are composed by female individuals. Each female can produce 6 to 12 nymphs per day, and in less than one week they can complete its life cycle. This rapid life cycle can cause quick outbreak of SCA populations.

Corn Disease Update

Dr. Carl A. Bradley, UK Extension Plant Pathologist

Figure 1.  Lesions of northern leaf
blight on a corn leaf
(Photo: Carl Bradley, UK).

With the recent rainfall received in the state, conditions have become more favorable for some foliar corn diseases that are now being observed. UK Plant Pathology interns have been scouting corn fields in western Kentucky for the past few weeks, and they have been observing northern leaf blight, gray leaf spot, common rust, and Diplodia leaf streak. As of July 12, southern rust has not yet been identified by UK Plant Pathology personnel in the state. Below are my thoughts about these diseases and the use of foliar fungicides to manage these diseases.

For more information on Corn Disease in KY see the article on Kentucky Pest New

Precision Ag Data Management Workshop: VI

A Precision Ag Data Management Workshop is scheduled for July 28 and July 29, 2016 at the UK Research and Education Center in Princeton, Kentucky. Dr. Joe Luck at Nebraska is coordinating the workshop. Other speakers include Dr. Mike Sama and Dr. Josh McGrath (both at the University of Kentucky
Topics include crop canopy sensor technologies, converting soil test algorithms to prescriptions, UAV applications in agriculture, setting up on farm research using SMS software, analyzing yield data with as-applied planter data and on-farm research for soil nutrients (P & K)
The workshop is sponsored by the Kentucky Corn Growers, Kentucky Soybean Board and the Kentucky Small Grain Growers Association.
The workshop is scheduled to begin in the afternoon following the Corn, Soybean and Tobacco Field Day.

RSVP to Adam Andrews ( adam@kycorn.org) or 502-974-1121

Flooded Corn and Chance for Survival

Chad Lee, Extension Agronomist, University of Kentucky

Flooded corn, Butler County, KY.
Image taken July 8, 2016
by Greg Drake,
ANR Extension Agent

Reports of flooded corn are coming in from around Kentucky. Corn survival is dependent on the crop stage, the depth of flooding, the duration of flooding and the soil type in the field as well as other factors. The following are some key points to corn survival after flooding.

Complete Submersion: A Short Window

Much of the corn flooded in Kentucky is between tasseling and blister stage (VT to R2). If temperatures were greater than 77 degrees F the likely will not survive 24 hours of complete submersion.  The Kentucky Mesonet reported the July 5, 6 and 7 daily average temperatures near 77 degrees for Butler, Caldwell, Christian Counties and Henderson counties. You still want to inspect the fields, but you may want to call the insurance adjuster as well. Normally, submerged corn is a bad option for silage because of the increased risk for Clostridium bacteria which hurts the fermentation process and increases the risk of botulism toxins.

2016 UK Corn, Soybean & Tobacco Field Day

The 2016 UK Corn, Soybean & Tobacco Field Day will be held Thursday, July 28th at the UK Research and Education Center in Princeton, (1205 Hopkinsville St., Princeton, KY 42445). Registration will begin at 7:00 am (CDT) and the tours will begin at 7:50 am (CDT). The field day will conclude with lunch provided by the Kentucky Soybean Board & the Kentucky Corn Growers Association.

Field Day Topics Will Include:

• Soil Water, Crop & Remote Sensing Measurements for Irrigation Management

How to monitor and when to control the early abundance of thrips on soybeans fields?

Raul Villanueva, Extension Entomologist, University of Kentucky

Insect Description and Damage 
While monitoring an experimental soybean field in Princeton, I have not noticed major insect pest problems during the earlier stages of soybean growth, with the exception of thrips. Thrips are tiny, slender insects (less than 1/16 inch) with characteristic fringed or bristled wings; they have rasping and sucking mouth parts. During feeding, mouth parts scrape the epidermis of the soybean leaf (it can damage flower, bud, or fruit on other plant species) and then suck plant fluids. In addition to these plant feeding thrips, there are beneficial thrip species that prey upon small insects and spider mites.