According to the latest U.S. Drought Monitor, the western half of the United States is experiencing various levels of drought.
Nebraska is not excluded from this as we are currently facing abnormally dry or moderate drought stress across the region. For many producers in this part of the state, irrigation is a necessity to help mitigate any potential drought concerns. However, irrigation adds additional costs to crop production and there’s still a concern about drought stress on dryland corners and non-irrigated fields.
As corn and soybeans are in the mid- to late-reproductive stages, a question that might be on producer’s minds is, how are drought conditions at this point going to impact my yield and bottom line?
Many corn fields in the area are in the late milk/dough stages (late R3/R4) but we are seeing quite a few reaching beginning dent (nearing R5). With the exception of late planted fields, most soybeans range from beginning seed (R5) to full seed (R6).
While some fields may have received scattered showers over the past couple weeks, others are dry and might be exhibiting drought stress. On dryland fields, pivot corners, and field edges, we are starting to see leaves turn yellow or brown.
While lower leaves drying down might appear normal late in the growing season, some plants might have leaves in the upper canopy drying down too, leaving only green leaves in the middle of the canopy. Since most grain fill comes from sunlight capture and photosynthesis in the upper third canopy, early leaf senescence can be concerning for grain fill and yield potential. This greatly depends though on the hybrid, environmental conditions and how early in the season leaf death occurs.
Another thing to consider is if early leaf dry down is caused by drought and heat stress alone, or if there are other confounding variables that are hastening this process. Late season diseases like anthracnose top die-back or insect pressure could also increase leaf dry down and impact standability as the season progresses.
In soybeans, late season drought stress can be detrimental on yields as they aren’t able to complete seed or pod fill as efficiently as anticipated. If sufficient water isn’t available, seed size will be smaller, resulting in fewer seeds/pound and less overall yield in bushels/acre.
Spider mites have also been an issue this year as it has been very hot and dry. Their activity tends to increase if insecticides were applied earlier that reduced natural predators.
In fields that were not sprayed, and especially on borders, we are starting to see plants exhibit a gray-green color with yellow speckling on leaf surfaces, indicating heavy infestations.
Combined with drought and heat stress, these areas are starting to lose leaves and at this point, yield loss is likely to occur.
Source - https://theindependent.com
