Annuals - Periwinkle (Vinca)
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  (December) For the last three years, we have had beautiful periwinkles bordering our sun room. However, this year, something went wrong. We planted as usual, but gradually one by one, the flowers and leaves were gone with only the stems left. We replanted again, and the same thing happened. The plants came from different nurseries. The only difference in this situation was, we extended two small bird feeders to the sunroom wall so we could enjoy watching the birds while we ate. They were truly squirrel proof, but the squirrels would eat the remains on the ground. We have a big feeder in the middle of the yard where the squirrels again ate on the ground, but the grass and flowers remained healthy. We have a sprinkling system and they were fertilized the same as other years. Do you know what could have happened.

  Several possibilities occur to me. One is that periwinkles do suffer from a disease called stem canker. It is more common, if they are under frequent overhead water from a sprinkler system. The plants will start to "melt" with them dying back. If you look closely on the stem, there is a small sunken lesion, and the plant is dead from that point up, but is ok beneath it. Another possibility is that if you are feeding the birds sunflower seeds, the droppings from those can have a detrimental effect on some underlying plants. And thirdly, the squirrels may be feeding on them. Did you try planting some other plant in this location? If they also had problems, I would suspect squirrels.

  We have a flower bed that we change each season. In the fall, we plant pansies and tulips. In the spring, we plant vinca, blue salvia, lantana and artemesia. This summer the vinca has turned brown and looked very wilted. We were advised that vinca can develop a fungus, especially if you continue to use it in one area. The soil may be infected also. Are you familiar with this problem? Should we not use vinca for a season? Or, should we use a fungicide? (Little Rock)

  Annual vinca has been plagued with a stem canker disease, (phytophthora stem and branch rot) for several years. It seems to be much worse with overhead watering, particularly from sprinkler systems. It starts out as a sunken lesion on the stem, or the foliage gets water soaked and the disease spreads to the stem. This fungus is favored by moist conditions. It resides in the soil, but does not affect the root system. Splashing water sprinkles soil particles on the foliage, which then infects the plant. Crowded plants and overhead irrigation can assist in the spread of the disease. Annual vinca, or periwinkle is a great plant for a dry, arid environment. Water management can help prevent the disease. If you can’t cut back on the moisture, plant a different plant. Fungicide sprays would help manage the disease, but are not a recommended practice, due to the frequency of application.

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