Answer: Based on your description I would suspect overwatering to be the cause. The goal in watering is to keep the soil evenly moist, but not sopping wet. In cool weather and in rainy weather, you will not need to water as often as in hot dry weather. Use your finger to check the soil and water only if it is dry. Also, apply a mulch to the area surrounding the tree (keep it several inches away from the trunk) to help keep the soil temperature and moisture more even. Since you have just purchased the tree, I would also suggest that you consult with the nursery where you bought it as to watering and fertilizing recommendations in view of any warranty they may offer.
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