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  • Author or Editor: Gerald Edwards x
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Some apple growers place specially designed bags with liners around fruit in the field to produce a unique surface color required by some premium markets. However, heat damage has been observed on `Fuji' apples that were bagged and reached high temperatures in the field. We tested different colored apple bags and their liners to determine the amount of light that is transmitted and whether bag color affected heating of the apples inside. Apple bags and liners were very effective at screening out sunlight; however, the absorbed light substantially warmed the bags and apples inside. No UV-A or B and less than 1% of photosynthetically active radiation (PAR) passed through the outer bag regardless of bag color and the inner liners transmitted ≈9% of the UV-A, 3% of the UV-B, and 30% of the PAR. When ambient air temperatures were only ≈25°C, dark green bags or red or green liners warmed the sun-facing apple surface to ≈43°C, while light green bags warmed to ≈36°C. Wrapping apple bags in aluminum foil to increase bag reflectivity greatly reduced heat buildup and maintained sun-facing fruit surface temperatures only slightly above air temperature (≈27°C). Possible design improvements for apple bags used in hot, sunny climates will be discussed.

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