Winter survival of wheat
Is the crown well protected by soil?
If wheat is planted at the correct depth, about 1.5 to 2 inches deep, and in good contact with the soil, the crown should be well protected by the soil from the effects of cold temperatures. If the wheat seed was planted too shallowly, then the crown will have developed too close to the soil surface and will be more susceptible to winterkill. Also, if the seed was planted into loose soil or into heavy surface residue, the crown could be more exposed and could be susceptible to cold temperatures and desiccation.
Is there any insect or disease damage to the plants?
Plants may die during the winter not from winterkill, but from the direct effects of a fall infestation of Hessian fly. Many people are familiar with the lodging that Hessian fly can cause to wheat in the spring, but fewer recognize the damage that can be caused by fall infestations of Hessian fly. Wheat infested in the fall often remains green until the winter when the infested tillers gradually die. Depending on the stage of wheat when the larvae begin their feeding, individual tillers or whole plants can die. If the infestation occurs before multiple tillers are well established then whole plants can die. If the plants have multiple tillers before the plants are infested then often only individual tillers that are infested by the fly larvae will die.
The key to being able to confirm that the Hessian fly is the cause of the dead tillers is to carefully inspect the dead plants or tillers for Hessian fly larvae or pupae. This can be done by carefully removing the plant from the soil and pulling back the leaf material to expose the base of the plant. By late winter all of the larvae should have pupated and thus the pupae should be easily detected as elongated brown structures pressed against the base of the plant. The pupae are fairly resilient and will remain at the base of the plant well into the spring.
Damage from winter grain mites, brown wheat mites, aphids, and crown and root rot diseases can also weaken wheat plants and make them somewhat more susceptible to injury from cold weather stress or desiccation.
Fall armyworms and army cutworms may have fed on emerging wheat in the previous month (prior to the recent frigid weather, we even found live worms as recently as Dec. 3) leaving bare patches. If the worms were fall armyworms they have died by now. If the worms were army cutworms they will overwinter right there in the soil and continue to feed on wheat plants anytime the temperature is 45 degrees or more from now through about April.
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