Today managing your corn crop requires knowledge of the different growth stages of the corn plant. Growth stage identification is critical for scouting and proper timing of fertilizer and pesticide applications. Throughout the growing season I will discuss the various corn growth stages and management issue at each stage.
VT – Tasseling
- Approximately 1250 Growing Degree Days (GDD’s)
- Tasseling and kernel fertilization are arguably two of the more critical stages.
The VT stage occurs when the last branch of the tassel is completely visible, extended outward, and not held in by the upper leaves. The plant is nearly at its full height. Most hybrids grown in the Corn Belt will have a total of 19 to 20 leaves prior to tassel. VT begins about 2 to 3 days before silk emergence.
Although the tassel is an easy structure to identify for staging purposes, the occurrence of pollen shed is more important. The shedding of pollen is a determining factor in whether or not silks become pollinated and potential kernels fertilized.
All branches of the tassel may not be fully extended above the upper leaves before the anthers on the main branch start shedding pollen. Also, silks will often be visible before the tassel is fully extended above the upper leaves; if this occurs the plant should be defined as Rl despite VT not technically occurring first. The interval between VT and R1 can fluctuate considerably depending on the hybrid and the environment. Drought stress lengthens this interval. The plant is extremely vulnerable to hail from VT through silking (R1)
The length of the pollination window differs based on whether it is for the whole field or for an individual plant. Plants within a field do not all begin or end pollen shed at the same time due to plant variability. Most fields will have pollen shed occurring for seven or more days. However, the greatest production of pollen from that field exists for a shorter time period of approximately four days. An individual plant at peak pollen production can release .5 million or more pollen grains per day.
Management/Scouting: Scout for Insects: Corn Earworm, Corn Rootworm, European Corn Borer and Japanese Beetles and Western Bean Cutworm. Diseases: Eyespot, Gray Leaf Spot, Norther Leaf Blight, Southern Leaf Blight and Tar Spot