Copper was identified as an essential plant nutrient in 1931 and is classified as a micronutrient since it is required in very small amounts in the plant. It is used throughout the plant in a variety of processes, including chlorophyll (photosynthesis) production, cell wall and stalk strength (lodging resistance), nodulation and nitrogen fixation in pulses, and various enzymatic functions.
Copper is especially important in cereals since a deficiency will cause poor pollination and seed set in these crops. It is important for cell wall strength throughout the plant, including the reproductive structures. The anther of the flower houses the pollen grains which will pollinate the flower. Copper is required to keep the walls of the anther strong. If the plant is copper deficient and the wall of the anther is not rigid, it will not open properly to release the pollen grains to the flower. When copper is deficient pollination is reduced, which reduces the number of flowers that will produce kernels. It also causes the flowers to remain open longer as they wait to be pollinated. This extended period of time where the flowers remain open will give diseases, such as fusarium head blight and ergot, the opportunity to infect the flowers.
In cereals, deficient plants will start to exhibit symptoms during stem elongation. These symptoms include limp leaves, slight chlorosis (turning the leaves pale green or yellow in colour), and a combination of leaf curling, withering, and necrosis (tissue death) most often called pigtailing. Severe deficiencies will cause poor head emergence from the boot (resulting in twisted or misshapen heads) and reduced seed set seen as small, shriveled kernels.
Figure 1. Typical pigtailing in wheat caused by copper deficiency.
So how do you know if you have sufficient levels of copper for cereal production? Start by soil testing. A composite soil test will give an indication of the copper levels across a given field. A qualified agronomist will explain the relationships and interactions that happen in the soil with other nutrients and soil characteristics as well as give a recommendation whether or not copper fertilizer should be applied. Copper can be applied in both dry and liquid fertilizer situations. Our iFARM precision grid soil sampling program will provide a map of where exactly the high and levels are located in the field.
If you see copper deficiency symptoms in the field and think your crop may be deficient, it is recommended that you have your crop tissue tested. A tissue test will confirm your suspicions and provide you with the concentrations of nutrients in your crop. Once you have confirmed the deficiency, a foliar product can be applied to alleviate the deficiency to some extent. However, it is important to remember that by the time a deficiency has been confirmed in a plant, yield has already been lost. By soil testing and scouting your crop, you can start proactively addressing the deficiency and prepare to prevent it from occurring in the future.
If you have any questions about soil testing, tissue testing, or copper-based products, feel free to talk to your local Cavalier Agrow agronomist.
Written By: Melanie Hawrysh