i just lived thru 2 years of drought ... you dont mention heat ... nor whether the slope faces the sun ...

and why are you presuming there is sufficient water???? watering slopes can be very hard ... especially if relying on lawn sprinklers ...

where are you.. whats the soil type ... whats behind the hill ... maybe a pic??? .. how bad was your winter???? .. and what fert are you throwing around??? .. and is the hill downwind of lawn spraying????

i would bet the black spots is irrelevant.. in that something is attacking already stressed plants .... so we have to figure out the stressor .. the cause .... rather than treating the effect ...

ken

In addition to what Ken mentioned, are you near a road where salt spray may reach the bed ? Can you give us a clear close up photo of the stems and leaves ?

This post was edited by geosankie on Fri, Apr 4, 14 at 11:38

Thank you both. Will try to get a photo posted.What puzzles me is that , until 2 years ago, the vinca was robust .It has been there 30 years or more and nothing has really changed in the environment.

The "sunny bank" statement causes me some concern - Vinca minor is shade lover. Too much sun is definitely a stressful situation (per several university websites: "declines and becomes chlorotic when improperly placed in full sun").

Any stressor can have cumulative effects over time. Vinca is prone to a stem and leaf blight that can kill off large patches. It is typically attributed to excessive watering/moisture or poor drainage but a weakened plant may fall prone under less severe conditions.

Vinca minor loves sun.

You need to hold the people at your local Extension office to a higher standard. Do you know if you talked to an actual Extension professional or just one of the volunteers? Did you visit in person or make a phone call?

Tell your agent, not the volunteer, that you wish to send samples to Plant Disease Clinic, available to all citizens of Va. for very little cost. This clinic is part of the Department of Plant Pathology, Physiology, and Weed Science and exists as part of the Va. Tech outreach.

When I was there, all samples were expected to be sent by the local extension offices. It's their responsibility to provide you with the information needed to collect, prepare, and package a proper sample for testing. They used to provide boxes and bags for this purpose. At the very least, you should be given a sheet of instructions. Your samples will probably require soil and tissue and will require some careful handling.

Your job will be to follow the instructions carefully, then return samples to the extension office for shipping.

Remember....bypass the "master gardener" volunteers and deal directly with an agent. Of course, the clinic can be contacted by phone or email, but they prefer to go through the local extension office.

P.S. I just visited the website of the Plant Disease Clinic and you can find forms and instructions right there! That's pretty handy! Type PPWS plant disease clinic into Google or other search engine and it will take you directly to the main page. From there, you can click on the Extension and Outreach category for everything you need to know about collecting samples.

Sorry that I can't include a clickable link from my Kindle, but it truly is as easy to find as I said. PPWS plant disease clinic

This post was edited by rhizo_1 on Tue, Apr 8, 14 at 8:20