Question:
What should I do to prevent or correct the problem with the flowers on my Rhododendrons? In the past, they dry up quickly after opening up. Last year, the buds just turned brown. In addition, the foliage looks terrible.Answer:
- The primary causes for Rhododendron blossoms to dry up and turn brown prematurely are insects and fungus. Of the two insets, Thrips, in particular, are the cause.
- Thrips are an insect with both sucking and rasping mouthparts. They attack both the flowers and the foliage of Rhododendrons, Azaleas, Photinias, Viburnum, and other plants. Also, they're a tiny insect, about an eighth of an inch long, very narrow, and black in color. When you shake a damaged flower over a flat, white surface, they're visible to the naked eye.
- The damaged leaves are silvery instead of dark green as the insect strips away the chlorophyll or the green leaf layer. The organic solution is to spray the plant with Horticultural Oil and suffocate any of the exposed insects. You'll have to be very persistent with repeat applications to be successful.
- The non-organic solutions are Bonide Systemic Drench, Bayer Advanced 2 and 1, and All In One Rose Care. The systematics are applied every six weeks. You cover up the damaged leaves by regularly feeding, encouraging the new growth to camouflage the damaged leaves.
- The second cause is a fungal disease called Bud Blast, otherwise known as pycnostysanus.
- It can also occur on Azaleas. The dead give away to this problem because the buds are covered with tiny hairs with a circular structure at the end. Bud Blast is best controlled by good sanitation practices and by spraying with a copper fungicide in February/March.
- Also, the ground around each plant should be cleaned of all dead leaves and other organic debris, along with removing the spent flowers. If you are not sure, I'd suggest you apply a Copper Fungicide now followed up with one of the systemic products in a week, and then feed as necessary.
- I believe the flower and leaf damage is caused by Thrips
Question:
I'd like to know why my Sun Azaleas are so tall and leggy. They flower okay but only at the ends of the long stems. What must I do to make these plants more compact?Answer:
- Sun Azaleas are not a low-growing compact plant. They typically reach a height of four to six feet depending on the variety with the flowers on the end of the branches. Being a leggy grower is a common complaint with Sun Azaleas.
- You can correct this by pruning the plants after flowering to reduce the height by about fifty percent and then feed them with the Azalea, Camellia, and Rhododendron Food to encourage the new growth.
- This doesn't have to be an annual task. They will look a bit ragged for a while, but they do recover. If this is still too tall, you may want to replace them with a different plant.