Question
I have some periwinkles that were growing fine, but all of a sudden, some are yellowing and others are wilting away.  I've read that it could be anything from a fungus in the soil to the Texas heat taking hold of them.  Any ideas?

Answer
Hi Dell,
Thanx for your question.  Sorry it took so long to get back to you.  It sounds like your periwinkles are the victims of a fungal attack.  This could be a botrytis variety or some other varieties that can quickly spread and destroy a planting.  Anti-fungals have been reported to have some effect on the disease but fungal diseases like these are usually soil borne and difficult to get rid of.  Is this a perennial type of periwinkle or the bedding plants?  If it's bedding plants, don't plant any in the same place for a couple years.  If it's the perennial version with the little lavender flowers, try an antifungal on it.  I would first recommend taking a sample to your local county extension and have the horticultural agent look at it.  If you'll give me your county, I'll get you contact information.  I hope this helps.
Tom