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Use Growth Stages as Guide for Corn Silage Harvest

July 1, 2020



Mid-July might seem like an unusual time to start prepping for corn silage harvest, but it is the perfect time to consider corn silage harvest timing based on when the plants tassel. Variable spring weather can mean an extended corn planting season for some producers, so the range for corn silage harvest can vary considerably. Research done at Michigan State University compared short-season and late-season hybrids planted at successive planting dates to determine the effect of planting date on corn growth. In general, late planted corn required fewer growing degree days (GDD) to complete vegetative and grain fill stages than early planted corn.


To assist growers in their plans for silage harvest, knowing the tassel (silk) date can predict when a field will be ready. Silk dates (R1) occur when corn plants are at maximum or near maximum height and have maximum vegetative dry matter.


The silking period is the most sensitive period for the crop. Silks on the ear must be present while pollen shed occurs for successful pollination and fertilization. Producers can use the day of silking as the start of the reproduction process and a guide for when to harvest. When the corn plant reaches the half-milk line, approximately 42 to 47 days after silking, plants will normally have 40 percent moisture and 97 percent of their total dry weight.


Joe Lauer, University of Wisconsin forage agronomist, has the following guidelines to use for predicting corn silage harvest date:

  1. Note hybrid maturity and planting date of fields intended for silage.

  2. Note tasseling (silking) date. − Kernels will be at 50 percent kernel milk (R5.5) about 42 to 47 days after silking.

  3. After the milk line moves, use kernel milk triggers to time corn silage harvest. − Use a dry down rate of 0.5 percent per day to predict date when field will be ready for the storage structure.

  4. Do a final check prior to chopping.

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