Drought swept across many key corn- and soybean-growing states this season.
And with drought comes yield and grain quality concerns. Here’s what you need to know about what drought does in corn, and what you should expect at harvest. Stay tuned for a soybean update later this week.
First, think back, when did drought conditions actually hit your farm? Knowing this will give you a better idea of the potential yield impact. As you can imagine, prolonged drought that starts in the early season can be incredibly damaging. However, even short-term drought during key development times, such as pollination, can be devastating.
Here’s a look at corn yield loss and effects at various stages, according to Iowa State University Extension (ISU):
- At vegetative stages, drought can cause one to three percent of yield loss per day.
- Look for shorter plants with less leaf area. When drought is combined with heat stress, the plant moves through vegetative development faster. Stress from V6 to V8 impacts kernel rows and stress at V8 to V17 can result in fewer kernels per row.
- At pollination, drought stress can result in two to five percent lost per day.
- If drought hits seven to 10 days before silking, silks development can be delayed. Drought stress during tasseling through silking delays silks, reduces silk elongation and can impede embryo development. High temperatures can make silks desiccate and not be receptive to pollen. Ultimately, drought and heat stress at pollination results in fewer kernels per ear.
- During grain fill, drought means declines: at milk three to six percent, dough three to five percent, dent two to four percent and after physiological maturity no more yield can be lost from drought.
- Stress at this time can cause premature leaf tissue death, shorter grain fill periods, lodging, fewer kernels from abortion and light kernel weights. Kernel abortion typically occurs withing two weeks of pollination and starts at the tip of the ear. If drought continues through milk it results in more kernel loss and lightweight kernels. In late grain fill the plant matures and dies rapidly.
“Corn leaf rolling is the primary symptom of drought. Greying of leaf tissue will occur under extremely severe conditions. The earlier leaf rolling occurs in the day or the longer the duration of leaf rolling the greater the stress the crop is under. Yield loss estimates are assumed when drought stress occurs for four consecutive days or more,” according to ISU.
