Gardening and Horticulture - disease killing several plants

Something has invaded my in-laws garden. They've lost 2-3 shrubs and several rose bushes.

Whatever it is appears to be coming up through the root system, all of the plants appear to be dying from the inside out, like the life is being sucked out of them.

The evergeen leaves turn yellow in parts, then brown, then curl up and the plant dies.

Any help is appreciated.

Too much water and too little water are present the same types of symptoms. We've had a couple of years of dry summers and then have been plunged into cold winters. Underwatering is usually more of a problem than overwatering. Watering deeply once a week is best, not the frequent light watering that many folks do. Many have reported loss of landscape plants due to recent droughts. Some species are more drought hardy than others. Few species can tolerate wet feet.

A disease that comes through and wipes out multiple species would be unusual. All plants are not susceptible to all pathogens, each pathogen has a host range. It sounds more like too much or too little moisture.

If you could post pictures at www.photobucket.com (http://www.photobucket.com) or other photo site and links here, it would be helpful. Also, some photos showing the lay of land and drainage in the landscape.

Some info on soil type and location would also be helpful. Any idea of chemical spraying going on in the area? Are plants in area where snow melt products were used? Has deck or siding been recently washed with chemicals? Watering habits? Rainfall? Location of plants in landscape?

A false spring that sends plants into spring growth and then a freeze can take a toll on plants. Perhaps a little weather history may be beneficial.

The pix will definitely help. Here we have root nematodes, or grubs that thrive on the root system of plants, and do "suck" the life from the plant. Have you dug around the roots to see any worm activity yet?

Weather has been normal, my father inlaw is an experienced gardener so I am sure he's watering correctly.

I'll dig around the soil for any unusual critters. I saw something online called fire blight that looked close to what I saw (he cut most everything out or down to the stump before I could stop him).

But I would like to address the problem before he replaces the plants.

Parasitic nematodes are microscopic. Your local Cooperative Extension Agent can help with soil root sample and recommended control measures if needed.

http://edis.ifas.ufl.edu/IN469

Good read on environmental conditions: http://www.ct.gov/caes/cwp/view.asp?a=2815&q=376852&pp=12&n=1