Zinc is an essential micronutrient that is required by plants for growth, development, and defense against diseases and pests. In cotton, zinc plays a critical role in various physiological and biochemical processes that are necessary for high-quality yield and fiber strength. However, zinc deficiency in cotton is a widespread problem in many parts of the world, including the United States.
Zinc deficiency symptoms in cotton plants usually appear on younger leaves as white or yellow spots, interveinal chlorosis, and stunted growth. In severe cases, the entire plant may become stunted, and the leaves may fall off. Zinc deficiency can significantly reduce cotton yields and fiber quality, leading to economic losses for farmers.
Fortunately, there are several ways to control zinc deficiency in cotton. The first step is to test the soil to determine the zinc status and adjust the soil pH to the recommended level (6.0-7.5). Soil testing can also help in identifying the appropriate rates of zinc fertilizers needed to correct the deficiency. Zinc fertilizers can be applied as foliar sprays, seed treatments, or soil applications.
Foliar sprays are an effective way to supply zinc to plants, especially in the early vegetative stage when the roots are unable to absorb adequate amounts of zinc. Foliar sprays should be applied in the morning or late evening to avoid leaf burning and should not be mixed with other fertilizers, pesticides, or herbicides.
Seed treatments are another effective method to control zinc deficiency in cotton. Zinc can be coated on seed or applied as a seed treatment using commercial formulations. Seed treatments ensure that the young cotton plants have access to sufficient zinc during early growth, reducing the risk of deficiency.
Soil applications of zinc fertilizers can also be useful in controlling zinc deficiency in cotton. Zinc can be applied as a broadcast application or in the furrow during planting. However, soil applications of zinc fertilizers can be less effective than foliar sprays or seed treatments, especially in soils with high levels of phosphorus.
In conclusion, controlling zinc deficiency in cotton is crucial for achieving high yields and fiber quality. Soil testing, adjusting soil pH, and applying zinc fertilizers as seed treatments, foliar sprays, or soil applications are effective ways to correct zinc deficiency in cotton. Farmers should also take measures to prevent soil erosion and maintain soil organic matter to improve the availability of zinc to cotton plants.