Answer: There are two reasons for peony buds to turn brown and dry up. One is a fungal disease called botrytis and the other is due to insect feeding. You'll want to take several of the dried up flower buds off the plant and open them up to see if you can find evidence of feeding. Flower thrips (Franliniella ritici) are extremely tiny, narrow-bodied insects and only 1/20 inch long. Young thrips are lemon yellow. Adults are light brown with orange undersides. Thrips hide deep inside peony flowers and are almost impossible to see on plants without using a magnifying glass. If you suspect that a flower has thrips, pick a damaged flower and shake it over a clean sheet of white paper. If thrips are present, they will drop onto the paper and will look like dark specks. These pests injure only peony flowers (which explains why my stems and leaves look wonderful) and their feeding can ruin the flowers. You can: Destroy infested buds and flowers. Use insecticidal soap, following directions. Keep plants adequately watered and mulched to keep soil moist but not soggy. Apply loose, organic mulch to attract beneficial spiders. Attract other beneficial insects by planting nectar and pollen plants, such as alyssum, yarrow, and scabiosa. Purchase lacewings and beneficial nematodes from mail-order suppliers, and release these beneficials in the garden. Hope this information is helpful!
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