Bolls are the part of a plant that hold and protect the seed. They are most commonly found on cotton and flax plants. Bolls can be damaged by bugs or rot, making the plant unable to reproduce or unsuitable for harvest.
The word "boll" comes from the Dutch word bolle, which means "round object." Bolls generally are round or mostly round with a taper at one end. They usually are firm to the touch and are similar in color to the rest of the plant.
The purpose of bolls is to protect seeds until the plant is ready to reproduce. In addition to seeds, bolls often house soft fibers. It is these fibers that are harvested from cotton and flax plants to make fabric. This is a labor-intensive and time-consuming process.
Like all farmers, farmers who grow cotton and flax want to keep their plants as healthy as possible. Two major threats face every farmer of cotton and flax: bugs and rot. Both can affect the bolls of plants if proper precautions are not taken.
The boll weevil is a small beetle that can range in color from yellow to black. These bugs pose a double threat to plants. Adult boll weevils eat cotton seedlings and flower buds, and female boll weevils lay their eggs in the bases of cotton bolls. A single egg is laid in each boll. When the egg hatches, the larvae stay in the boll for a week or two, eating it from the inside out.
Cotton plants that have been infested by boll weevils produce little to no usable cotton fiber. Boll weevil infestations can be controlled using pesticides. Scientists have studied the possibility of breeding cotton plants that are genetically resistant to boll weevils.
The other major threat to healthy bolls is rot. Cotton bolls can rot if there is too much moisture in the soil. Excess moisture can be caused by too much rainfall, over irrigation and overgrowth. When plants are too close together, they create thick canopies that keep moisture from escaping. This can happen when too much nitrogen is added to the soil.
The best way to prevent boll rot is to plan plantings well. Leaving plenty of space between plants and staying within recommended nitrogen fertilizer guidelines allows moisture to evaporate. Fungicides also help keep bolls from rotting, but studies have shown that their use is not a cost-effective method of preventing boll rot.