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Calcium Carbonate Based Products Help Prevent Sun Damage to Fruits and Veggies

Making It Grow! Minute logo

Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow. Although kaolin clay makes a great sunblock for your sensitive vegetables and fruits, many farmers prefer to use a product that’s easier to wash off. Calcium carbonate, the main component of agricultural lime that raises the pH of our soils, is also the main ingredient in several products that act to protect fruits and vegetables from sun scale. Unlike kaolin, which actually blocks the sun’s rays, calcium carbonate sprays form crystals that act like tiny mirrors and reflect the sun’s rays. Kaolin sprays, which coat the leaves and fruits with a white film, reduce photosynthesis to a greater degree than calcium carbonate applications and are much harder to wash off. For farmers, the choice may come down to total costs. Kaolin sprays are cheaper but the extra post-harvest washing may make them more expensive in the long run. 

Amanda McNulty is a Clemson University Extension Horticulture agent and the host of South Carolina ETV’s Making It Grow! gardening program. She studied horticulture at Clemson University as a non-traditional student. “I’m so fortunate that my early attempts at getting a degree got side tracked as I’m a lot better at getting dirty in the garden than practicing diplomacy!” McNulty also studied at South Carolina State University and earned a graduate degree in teaching there.