Wheat has broken dormancy across much of Indiana. Plant growth in the southern one-third of the state is now sufficient to permit field evaluations of the condition of the crop.
To help understand what has happened and is happening to the wheat plant, lets recap the growing season to date. Most of the wheat in Indiana was planted into very dry soils which resulted in slow emergence of the plants. Coupled with the slow emergence was a cooler than normal late October and November. The net result was a small plant with less development than would occur in a normal year. In addition to the fall and early winter stresses, temperatures the first week of February dropped well below zero with little snow cover, resulting in death of most of the exposed leaf tissue. In early March, the wheat started to come out of dormancy and was subjected to single digit temperatures a short time later. The early March episode resulted in death of the new green tissue further weakening the plant. Additionally, some fields heaved badly.
Now that wheat has broken dormancy, many fields have significantly reduced stands. The degree of injury and death varies widely from field to field and within a field. A number of factors may have contributed to this variability. No attempt will be made to explain all of these factors but they include one of more of the following: variety, soil type, date of planting, depth of planting, available moisture at time of planting, slope of the field, type and amount of residue, and possibly others. The var ieties with poor winter hardiness are all significantly damaged in southern Indiana, with some fields suffering nearly 100% plant death.
Some fields began to show some new green color recently, then suddenly a number of the plants died. This was most likely caused by rhizoctonia. Normally this organism is considered to be a weak pathogen but, when the wheat plant is severely weakened, as it is this year, rhizoctonia can be devastating.
In southern Indiana, now is the time to evaluate wheat fields to determine the number of live plants per square foot, an estimate of the number of good tillers per plant, and the resulting number of heads per square foot. Once the number of heads is estimated, the number is multiplied by 1.6 to give an estimated yield in bushels per acre. If a field has an average of 15 plants per square foot and a potential of 2 heads per plant, this give 30 heads per square foot. When multiplied by 1.6, the potential yield is 48 bushels per acre assuming normal growing conditions from the present to harvest.
A decision on keeping or abandoning the field will vary from farm to farm depending on the potential for the production of double-crop soybeans. If double-cropping is possible, then a lower potential yield is acceptable when compared with only a wheat crop.
If a field of wheat is kept with a poor stand, weed pressures could be greater. This will most likely require a herbicide application. However, DO NOT apply a herbicide until you decide to keep the crop, because of plant-back restrictions. Additionally, the plants will tend to be shorter than normal and will most likely mature 5 to 7 days later than normal.
One positive from all the cold temperature and dead plant tissue is the fact that leaf diseases will be less of a problem this year. Little or no infection of Barley Yellow Dwarf occurred last fall because of aphid inactivity.
It is still too early to determine the condition of the wheat crop in central and northern Indiana. Next week should permit an opportunity to evaluate the central Indiana crop with northern Indiana the following week.
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The Corn Growers Guidebook , a WWW resource for corn management systems in Indiana and the eastern CornBelt.
Purdue University Agronomy Extension WWW Home Page.
Purdue Agronomy On-Line! , Purdue's Agronomy Department WWW Home Page.