JenREES 5-20-18


Crop Update:  So grateful for rain and truly hope those who wanted and needed rain received it!  An update to soil moisture profile as of 5/17/18 can be found at http://jenreesources.com.

A number of crop issues surfaced this week.  One being root burn and wilted-looking corn seedlings from anhydrous ammonia applications with the dry winter/spring we’ve had thus far.  Anhydrous ammonia can expand in soils 2.5-3” in all directions and potentially more in dry soils.  Pivots were running to help with that and hopefully rain events will help non-irrigated fields that were suffering in this way.  Another problem observed in some non-irrigated corn fields has been fomesafen carryover injury from products such as Flexstar, Reflex, Prefix, etc.  These products have a 10 month planting window back to corn which is fine in most years, but dry conditions didn’t allow for the herbicide to break down in all situations from applications last June.  This active ingredient is in Group 14 (PPO inhibitors) and the injury from this particular active ingredient is unique in that it causes yellow/brown striping of the veins themselves instead of interveinal chlorosis/necrosis.  Seedlings most affected right now are found on field edges or wherever there was overlap of application.  Hopefully corn should grow out of this injury in time.  Herbicide carryover may be a something to watch for in soybean as well from other active ingredients.  We also saw regrowth occurring on plants affected by wind/dust/debris damage but there are situations where replanting will be needed on endrows, etc.  Roger Elmore has a photo gallery explaining regrowth in this week’s CropWatch at http://cropwatch.unl.edu.

Another situation that surprised me this year was finding seed corn maggot damage in

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Seed corn maggot feeding on soybean seed.  No insecticide was included in the seed treatment.

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Seed corn maggot affecting soybean seedlings by feeding on cotyledons and hypocotyls.  The brown grain-like structure in the bottom of the picture is a seed corn maggot that is pupating.  These seeds did not have an insecticide in the seed treatment.

soybean.  At first I was puzzled as the beans were clearly treated but then learned the beans didn’t have an insecticide added to the seed treatment.  In scouting a number of fields, I’ve actually seen quite a bit of seed corn maggot damage, particularly in tilled fields and those with manure applied or those with cover crops that were green or where termination included tillage.  I’ve also been surprised how many have told me they don’t use an insecticide seed treatment on early planted beans.  We didn’t have any research in our early soybean planting studies without insecticide + fungicide seed treatment so we just automatically recommend both.  Unfortunately this year we’re seeing what can happen without it with higher insect pressure in some fields.  For seedlings with the insecticide seed treatment, I’m seeing light scarring on the cotyledons and hypocotyls but no maggot penetration.  In fields without the seed treatment, I’m actually seeing penetration of the cotyledons and hypocotyls.  The good news is that most of the maggots were also pupated, pupating or will be soon.  But it is something to watch for, particularly in fields that have been tilled and especially if manure was applied or they were tilled and had a cover crop on them.  They are not as attracted to no-till fields.  Regarding stands, from my experience with soybean pops and stand loss due to crusting, hail, herbicide injury, etc., I keep stands of 60,000 plants/acre or more.  It really stinks to talk about replanting anything right now with guys still trying to finish planting.  If you choose to replant soybeans, consider proving it to yourself by planting strips and leaving strips.  If you’re interested in that, I’d be happy to work with you.  You can learn more about seed corn maggots here:  https://crops.extension.iastate.edu/cropnews/2016/04/look-seedcorn-maggot-corn-and-soybean.

Wheat in the area ranges from boot to flowering.  A couple of wheat fields I know of

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Wheat field cut at boot stage for hay.

were taken for hay.  For those still considering silage, check out the CropWatch article this week where Todd Whitney shares data on wheatlage (wheat silage):  https://go.unl.edu/qkbr.  The rainfall will greatly help our wheat right now.  And, rainfall at heading to flowering makes me think about the potential for Fusarium Head Blight (scab).  The wheat scab prediction monitor http://www.wheatscab.psu.edu/ is predicting medium to high risk for scab in Nebraska for the next 48-72 hours.  Some years I feel the model is delayed in prediction, but I still feel it’s a good tool and resource.  Scab is caused by Fusarium graminearum and is favored by warm (70-80°F temps), humidity, and rain events before and during flowering.  Once wheat begins flowering (Feekes 10.5.1), many foliar wheat fungicides are off-label.  In fact, recent research presented at the 2017 Fusarium Head Blight meetings shows that in general, strobilurin products can actually increase the presence of deoxynivalenol (DON) in wheat if applied at full heading (Feekes 10 or 10.5).  Thus, your better fungicide options for preventing scab are Caramba and Prosaro and these products can also kill any fungal diseases present on leaves (such as powdery mildew, tan spot, and rust).  These products aren’t 100% for scab prevention due to the variation of heading and flowering that occurs in so many fields.  Better efficacy is obtained with more uniform plants which begins at seeding time.  So I would recommend watching the growth stage in your fields, the weather, and the prediction tool regarding if you feel you need to treat any fields this year to prevent scab.  Research has shown best efficacy to be obtained when at least 50% of the plants are at 1/3 flowering.  Flowering begins with yellow anther sacs in the middle of the head with flowering continuing throughout the head from there.  Once the pollen is released, the anther sacs turn white.

LBNRD Open House Public Hearing:  The Little Blue Natural Resources District (LBNRD) is hosting a public hearing on May 29th from 6:30-9:00 p.m. at the Davenport Community Center in Davenport, NE.  The purpose of the hearing is to provide information and receive testimony on proposed amendments to Groundwater Management Rules and Regulations.  The hearing will be an open house format allowing individuals to ask questions of the NRD staff, look at exhibits, and offer testimony.  The proposed rule changes and additional information can be found on the LBNRD website at:  http://www.littlebluenrd.org/.  Please contact the NRD with any questions at (402) 364-2145.


Not part of my news column: on a more positive note after mentioning all the crop problems, the lilacs in general were beautiful and smelled amazing!!!

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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 May 20, 2018, in Crop Updates, JenREES Columns and tagged , , , , , , . Bookmark the permalink. Leave a comment.

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