A Summer on the Detasseling Crew
1Lorenzo Hakimi, who is 13, spent his first summer job on a detasseling crew in a seed-corn field outside his town in Iowa. The field, the people and the numbers here are made up, but they are based on real farm studies. On the first morning, crew leader Annika Brandvold explained what the crew was doing and why.
2A corn plant has two kinds of flowers. The tassel at the very top holds the male flowers, which release pollen. The ear, lower on the stalk, holds the female flowers. Each future kernel on the ear is joined to its own long thread, called a silk, that grows out of the tip of the husk. Silks are covered with fine, sticky hairs. Corn flowers have no petals, no nectar and no scent. A tassel sheds millions of tiny, light pollen grains over about a week, and the wind carries them. Most grains settle within a few dozen meters of the plant.
3In this field, four rows of one corn variety, the seed rows, alternate with one row of a second variety, the pollen row. Rows are about 0.75 m apart. The crew pulls the tassels off every plant in the seed rows before they shed pollen, so that the seeds on those plants are a cross between the two varieties.
4Plant scientist Dr. Ingrid Mwale tagged ears on plants in the seed rows to show the crew how kernels form. She bagged the ears in Groups B, C and D before their silks appeared and treated them in different ways (Table 1). In the table, “shedding ended” means the day the pollen rows stopped shedding pollen. She also tagged ears on tasselless seed-row plants in a strip running away from the field's last pollen row (Table 2).
5Wildflowers and milkweed grow along the field's edges. A female monarch butterfly lays eggs one at a time, gluing each to a leaf, and may lay several hundred in her life. Before laying, she often lands on a leaf and drums on it with her front feet, which have taste receptors. Monarch caterpillars eat milkweed leaves and no other plants. A newly hatched caterpillar is about 2 mm long and chews soft, young leaves more easily than tough, older ones. Milkweed mowed in June grows back as young plants with soft leaves and no flowers, while unmowed plants are tall, older and in flower. In July, Lorenzo helped Dr. Mwale search 40 plants of each kind along one edge for eggs (Table 3).