This tip was provided by:
Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101, firstname.lastname@example.org
Recent High Plains Grain Sorghum Replanting
Starting the last week of June there was widespread storm damage on cotton and grains in the Texas High Plains, and a lot of cotton was lost. Numerous calls from producers noted the dilemma some felt about planting grain sorghum primarily due to sugarcane aphid concerns. Fortunately, among those that replanted to grain sorghum, finding a purported SCA-tolerant hybrid was a priority (glad you asked!), grain prices are up (some central South Plains, or Lubbock area, pricing now sets grain sorghum bu/A pricing = Dec17 corn), and many producers ultimately recognized that replanting grain sorghum was the right thing to do. Those growers that put two sugarcane aphid sprays in their budget probably overdid the expenses (though growers in the NW South Plains from last year have major damage fresh on their minds).
Be sure to review the SCA management guidelines outlined in the June 8 Sorghum Tip (have you watched the nine short videos yet?—now is a good time).
If you have late-planted grain sorghum or have replanted the crop…
Dicamba in Grain Sorghum
Dicamba (most commonly as Banvel or Clarity, but in many generics) along with 2,4-D have almost become anathema to many grain sorghum growers. Past experience of damaging the crop due to injury of twisting, rolled leaves, leaning, etc. that growers don’t like the appearance of and, yes, actual injury to the all-important growing point which can lead to significant loss of grain yield (blasting of heads). A grower in Lubbock Co. calling on Wednesday looking for quick options to control small pigweed (Palmer ameranth or carelessweed) assured me he knew full well the potential injury from dicamba.
But many of the errors of dicamba and 2,4-D injury can be attributed to diverging from the label. I have written before in Sorghum Tips the connection between the label timing of dicamba (and 2,4-D) applications and growing point differentiation, i.e. once grain sorghum is past about the 5-leaf stage (actually probably 6-leaf stage) or 8” tall, dicamba must move to drop nozzles or hooded sprayers, and all applications completed by 15” tall. This stage of growth at 5 & 6 leaf is before the head starts to form. After that, head injury may occur with over-the-top sprays, but you won’t know until the head emerges and begins to flower (or not). Otherwise, dicamba at 3-5 leaf stage (label recommendation) is still a good broadleaf weed control option, especially in the face of herbicide tolerant weeds. You know this if you are a cotton farmer in the Texas High Plains as over 60% of the cotton planted this year is some type of dicamba-tolerant (Extend) variety.
Furthermore, since there is so much dicamba-tolerant cotton in the area, the risk of off-target drift is reduced. The above farmer noted there was no non-dicamba cotton within at least 1.75 miles of the field he called about spraying dicamba on grain sorghum. Also, consider whether some of the physical drift minimization technology (spray tips, etc.) developed and recommended for use in dicamba and 2,4-D tolerant cotton might help you manage any dicamba and 2,4-D use in your grain sorghum.