Extension Update by Jenny Rees

Reminder of the Seward and York County Fairs this week! August also brings the season of field days! Soybean Management Field Days will be held next week at various locations in the State from Aug. 10 to Aug. 13. The closest to this part of the State is Aug. 12^th near Rising City at the Bart & Geoff Ruth Farm. More info. at: enrec.unl.edu/soydays.

Corn Update: I realize this week’s column shares lots of problems seen in the field last week. My goal is always to increase awareness, but sometimes it feels ‘heavy’ hearing about the problems. Grateful we’ve had few problems overall this season till now! The high humidity has allowed non-irrigated crops to hang on and crops in general to not use as much water as anticipated for crops at this stage. In general, fungal disease is still low in fields. I’m starting to see baby lesions that will most likely become gray leaf spot around mid-canopy, so that will be something to watch in coming weeks. Spidermites have also been flaring above the ear in some fields, particularly non-irrigated.

For our area of the State, southern rust has been confirmed in Adams, Nuckolls, Thayer, Gage, Saline, Clay, and Fillmore counties. There are probable samples at time of writing this for Seward and Jefferson counties (https://corn.ipmpipe.org/southerncornrust/). In all the samples, incidence and severity were very low. Many are being found around waist-high in the canopy. Three samples I confirmed last week were from fields that had already been sprayed and the pustules were found mid-canopy. This happens every year, regardless of the residual applied in the first application. I know a couple farmers who have paid a little extra to have the aerial applicator increase gallonage from 2 gal/ac to 3 gal/ac. They felt that aided in coverage a little further into the canopy. For those with chemigation certification, I also know several growers who chemigate their insecticide and/or fungicide effectively, which allows for better plant coverage into the canopy (as long as pivot doesn’t have drop nozzles below canopy).

I really enjoy observing what occurs with plants, yet I honestly don’t know anyone who wishes to see abnormal corn ears, especially after wind events such as July 9. I feel it’s important to observe and document what occurs on these plants that bent and didn’t break. The goal is awareness to know what type of ear development exists so there’s not such a surprise at harvest if yields are off, and to be aware when working with your crop insurance agent. There’s unfortunately some ugly looking ears out there. Some similar stress events occurred this year comparable to 2016, minus the drop in temperature prior to the wind event. I’m not seeing anything yet to the level like what we saw in 2016, which is encouraging. What I’m seeing ranges from row abortion above where the ear stress occurred to torpedo and banana shaped ears to pinched areas on ears including various forms of ‘barbells’. Finding greater damage in fields where the plants were within a week of tasseling when the wind event occurred. It also appears like those fields that were 2 weeks or more from tasseling at the time of the wind event aren’t as impacted. For growers that had plants that blew down or leaned and then righted themselves but didn’t break, it’s wise that you and/or your agronomist are checking ear development on them. Each field can be unique depending on stage of development the particular hybrid was in at the time of the wind event. Pictures of what is being observed are at jenreesources.com.

Soybean Update: Received a number of calls regarding poor-looking patches in soybean fields this week. Drought stress is showing up in non-irrigated fields. Be checking those areas for spidermites as well. If they’re present, I tend to find them towards the edge of the patch between the impacted area and what appears to be healthier beans. White mold in soybeans is something that’s becoming more common in counties such as Butler. It can have patterns such as several plants in a row impacted and/or a patchy area in the field. The plants will have a white cottony fungal growth on them and eventually the stem (upon splitting) has black fungal structures that look like mouse droppings in them.

Sudden death syndrome (SDS) and/or brown stem rot are also showing up in small patches of fields where the leaves have a chlorotic/necrotic look between the veins. The humidity has allowed the blue/gray fungal growth characteristic of SDS on the rotted taproots to be observed even mid-day. If you split the stem and the pith is brown, the culprit is most likely brown stem rot; if it’s not but the taproot is rotted and you can easily pull it from the soil, it’s probably SDS. Plants can sometimes have both diseases. All of these are soil-borne fungal diseases and there’s no control measures for this time of year. It would be wise to pull 0-8” soil samples to check for soybean cyst nematode in areas of fields you’re finding SDS and brown stem rot in. Dectes (soybean) stem borer tunneling can be confusing when determining dectes vs. brown stem rot. At this time of year, I don’t typically see dectes moving far (more than 1-2″ either direction) from the initial point of hatching near the petiole. This is in comparison to brown stem rot which would have browning of pith from soil line. Dectes also will not kill plants (just create conditions for lodging and breaking off near harvest). This is because the vascular bundles of soybeans are found on the outside edge and not in the center of the stem. Thus, death of plants this time of year are due to another cause.