I have much vinca minor (dwarf periwinkle) planted about 20 years ago as ground cover in my yard. Some is in full sun, some is in part sun/part shade. Some small areas of the vinca (3-4 feet in diameter) in several places in the yard have begun the most recent two Springs looking yellow/pale green, not deep green like the rest of the gardens. Neither have they flowered. A couple of the small yellow/pale green areas e thinned, and some of the plants died. The veins in the leaves of the unhealthy plants are green, but the leaves are yellow/pale green. They have remained thus all summer. They don't turn brown and dry and die. I have treated with fertilizer and snail bait, but neither has had any effect on the unhealthy looking plants. Are these plants deficient in some nutrient? Healthy plants I planted in the bare areas had a hard time establishing but did eventually and have not paled. What should I do? I don't want the problem to spread. The periwinkle has added a great texture to the yard.



From the symptoms you are describing it sounds like your Vinca has iron chlorosis.  This is a problem that some ornamental plants have with accessing the iron in the soil because of our typically high pH levels.    Treating for this condition can be challenging and often the best control method is to use plants that are iron efficient.  Below I have included a link to a fact sheet about iron chlorosis that contains more information on the condition as well as treatment options and recommendations. 



Posted on 1 Oct 2008

Heidi Wayman
Horticulture Intern, Salt Lake County

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