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Thursday, May 9, 2013

May Wheat Assessments


                Assessing wheat for freeze damage had become a broken record for the last month.  Accumulated head, growing point, and stem damage from almost weekly damaging freezes last month has already forced a good number of intended grain fields into hay, cover, or grazing uses.  Now we should be ready to assess the latest and hopefully final freeze event for the remaining fields.  I expect many more fields over the next few weeks to be swathed or cut for ensilage as additional damage is evaluated and yield potential versus continued irrigation costs are assessed.  There is been a growing concern over next season’s wheat seed availability as a result of the damaging freeze events this spring.  Despite accumulated damage, I still feel there are some decent to good wheat fields in Hale and Swisher County but they are becoming more difficult to find. 

                Fields vary widely from location to location and there is no substitute for checking each field individually and at multiple sites.  Just as an example: This week I found several fields with 80% plus damaged heads and stems from northern Swisher.  Numerous duplicated reports confirming this finding for that area have come in.  Meanwhile, I found one field in the same area with only 30% head damage and moderate yield potential.  I have found and have reports of similar situations across both counties.  The exact circumstances around the reasons for these field differences are too numerous in possibility to mention here and are likely site specific.  Damage can also vary wildly within fields, adding some confusion to the decision process.  Texas A&M AgriLife Extension now has a wheat freeze injury update website / blog to help get producers the latest from the wheat experts.  The link to that site is here.  http://wheatfreezeinjury.tamu.edu

                Evaluating wheat’s potential grain yield and comparing it to hay before wheat is headed out is difficult at best.  For this we are forced to look at the percentage of damaged versus healthy growing points and do the best we can based on experience and field history to get a bushel per acre number and yield potential.  Dr. Calvin Trostle reminds us that, “One economic factor that may sneak up on the average ‘unexpected forage producer’ is the loss of nutrients that will be pulled off a hay field that normally would have gone back into the soil if the field had been utilized for grain.  This could be as high as 40 pounds of nitrogen per acre just for starters.”   

Once wheat heads out it becomes a little easier to evaluate potential grain yield but it remains difficult.  Producers and consultants will need to watch for healthy pollen and grain fill as these fields progress.  Wheat is self-pollenating.  By the time we see any exposed pollen, there should already be notable grain development.  Un-healthy pollen will be a dead giveaway to a very poor yielding grain field.  If a field passes the quick pollen test, evaluating a representative seed sample is the next step.  Sometimes after just a few days post pollination some seeds can be found by feel alone.  But to truly confirm the presence and health of the developing seed we should gently work open the protective seed covering to view the seed.  There can be 0 to 3 seed for each site with multiple sites per head.  Freshly pollenated and healthy seeds will be small but fairly noticeable and fine details can be viewed with a hand-lens.  Un-pollenated or missing seed sites will be absent of seed and can appear much whiter in color.  Freeze damage occurring post pollination will result in an incomplete or shrunken seed. 

Producers that must salvage some wheat seed for next season’s planting might be willing to sacrifice additional water on a moderately damaged and relatively low yielding wheat field.  Determining each field’s realistic yield potential becomes extremely important in these situations.  The sooner this determination can be made the better so as many acres as they need for grain can be set aside from swathing etc. 

Wheat pests seem fairly quiet this week.  Greenbugs and other aphid pests can still be found but look to be under-wraps from applications or the predator / parasitoid complex.  Now is the time to be scouting for fall armyworms (FAW) and cutworms.  I have not seen or heard of any reports of these Lepidopteron pests being a problem so far this season but I urge those producers and consultants staying the course to make wheat grain to remain vigilant in scouting. 

Please call if I can be of assistance.

Blayne

 

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