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This squash problem isThis squash problem is probably blossom end rot. It won't spread but indicates a lack of calcium in the developing fruit. You may have soil that is too acidic. The pH of acidic soils can be raised by adding lime, but this should only be done if soil test results indicate it is needed. To change pH, lime should be tilled into the soil 6” to 8” deep 2 to 3 months before planting (or as much lead time as possible) to change the nature of your soil. A little sprinkling of lime won't do much once they have the rot.

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