cottonclouds, what type of shrubs are those that appear to be dying? And where specifically are you located? Lime is a highly unusual suggestion to preserve the health of evergreen shrubs as the vast majority of them will appreciate a similar soil chemistry to that of the rhodies - a slightly it moderately acidic pH. And lime will neutralize that and typically aggravate the situation. I am glad this thread has been resurrected as it presents some misconceptions. Concrete DOES leach lime and the process is ongoing throughout the lifetime of the concrete structure. And lime induced chlorosis is an extremely common issue with broadleaf evergreen plants planted in close proximity to concrete foundation walls, driveways or other structures. So yes, planting acid loving plants close to foundation walls can present issues which affect the plants' growth. Portland cement - one of the primary components of concrete - is primarily (almost 70%) calcium oxide (CaO), also known as quick lime. It is extremely alkaline and extremely caustic. When combined with other ingredients in concrete, most significantly water, CaO forms calcium hydroxide, Ca(OH)2, a fully soluble material known as free lime and what is readily leached out when concrete is exposed to water. And than can be rain water, irrigation water or most simply, ground water. And when free lime is leached out, further chemical reactions in the concrete take place to release more lime for further leaching. The process is ongoing - the more lime that is leached, the more the chemical compounds will disassociate to create more lime. (We can thank my old Concrete Structures engineering class for this esoteric tidbit:-)) How much lime leaching from concrete will affect the plants growing nearby depends on the original soil pH, the plants' tolerance for variation in pH and how and with what they are fertilized. But the effect of lime leaching from concrete on acid loving plants is well documented and established and does not necessarily reduce or disappear with time. In fact, it can get worse over time if not offset by other means of acidification.

Verticillium and fusarium wilt is fairly unusual in rhododendrons. Purdue University considers rhododendrons resistant. Ohio State considers rhododendrons to be typically free of this disease. There are other fungi that cause dieback in rhododendrons. It probably isn't a root rot since that is usually fatal. Dieback is usually caused by f Botryosphaeria Dieback, Phomopsis Dieback, Phytophthora Dieback, or Rhizoctonia Dieback. Botryosphaeria dothidea causes leaves to turn dull green and then brown and roll and droop. Cankers form on branches which may girdle the branch. This is the most common disease of rhododendron in the landscape. A typical symptom of this fungal disease is scattered dying branches on an otherwise healthy plant. Leaves on infected stems turn brown, then droop and roll inward. These leaves often lay flat against the stem and will remain attached. The pathogen can infect all ages of stem tissue through wounds, pruning cuts, and leaf scars. Heat, drought stress, and winter injury can increase disease incidence. Cankers on branches can gradually grow through the wood until the stem becomes girdled. Diseased wood is reddish brown in appearance. Discolored wood viewed in longitudinal cross section often forms a wedge that points toward the center of the stem, and the pith may be darker brown than the surrounding wood. Sanitation and applying a fungicide such as metalaxyl (Subdue) after pruning my provide some control. Plants should be grown in partial shade, with mulch and kept well watered during dry periods. All dying branches should be promptly pruned out in dry weather and all discolored wood should be removed. Plants should also be protected from rough treatment during maintenance activities to prevent unnecessary wounds. Phomopsis rhododendri symptoms vary from leaf spots to chlorosis and then browning of leaves which then wilt. Browning streaks extend down the stem to a wound. Fungicides such as metalaxyl (Subdue) should control an outbreak. Sanitation and applying a fungicide after pruning may provide control. Phytophthora cactorum causes the central vein of a leaf to turn brown and the discoloration extends to the petiole on tender new growth. The infections spreads outward from the midrib tissue and the leaf wilts. Infections are more severe on azaleas. Some varieties of rhododendrons are vulnerable (Chionoides, Catawbiense Album, Nova Zembla) and some are resistant (Roseum Elegans, Scintillation, PJM). Control of the disease is difficult. Since the infection goes from the roots to the tips, when you see the symptoms it is too late. To prevent it, use a raised bed with lots of sphagnum peat moss. Also, keep the mulch back 2 to 3 inches from the stem. Prevention with fungicides and careful control of exposure to high humidity may be practical. Rhizoctonia solani: causes small necrotic spots on leaves, which later become dark brown or black. Defoliation follows severe leaf spotting. The fungus is omnipresent in the soil and appears to be most virulent at high humidity levels. Microscopic examination of roots and crown are the surest diagnosis. Cultural practices to control this disease include improvement of drainage and avoiding excess irrigation. It seems to only be present in irrigated beds such as at nurseries. Nurseries now have a chemical-free way to prevent Rhizoctonia; a hot water treatment. Rhizoctonia Web Blight causes dieback of interior leaves of compact tightly-growing azaleas within irrigated landscape beds. Rhizoctonia web blight is often seen during the warmer, humid summer months. Infection begins in the interior of the plant as the fungus survives in the soil or container rooting medium. Infected leaves develop brown lesions and eventually the entire leaf will brown and separate from the stem. The affected leaves often remain matted together by the fungus´s web-like growth (hyphae) that holds the brown leaves within the canopy. As the temperature cools in the fall, the fungus stops growing and the matted leaves drop from the plant. The disease is only a problem in landscape azaleas that are sprinkler irrigated. Wet foliage and high humidity favor infection. Use drip irrigation or soaker hoses to irrigate landscape beds. Also, remove fallen leaf debris from beneath plants. Fungicides can provide some control but should not be relied upon solely. Apply fungicides at the first sign of disease and continue through the summer months. The Department of Agriculture Research Service has found a prevention. Plant pathologist Warren Copes found placing the cuttings in water at 122 degrees Fahrenheit for 20 minutes is the most effective method to eliminate Rhizoctonia without damaging the plant, thus eliminating the need for fungicide treatment. The pathogen can be eliminated in less time when placed in water at higher temperature, but the risk of damaging the cutting increases. According to Copes, there is still potential for the cuttings to be re-contaminated in other areas of the production process. He is trying to identify which steps pose the most risk for re-contamination, with the goal of maximizing control of this fungal disease with the least amount of effort and expense for producers. Here is a link that might be useful: How to care for rhododendrons

The most likely cause of your problem is a dried out root ball. Pot grown rhododendrons are very prone to this - there are many examples on this forum. The light peat based medium used by the grower is very hard to rewet once it dries out. The problem is made worse if at planting the roots are not cut, raked with a cultivator or otherwise unmatted. The best thing to do is to dig up the plant, tease out the roots - don't be afraid to really do this thoroughly - and soak in a bucket until the root mass is wet. Then replant. If you notice signs of wilting over the summer, water at the base of the plant with a slow trickle for 30 to 60 minutes. Don't soak the whole bed. That just makes it harder for the roots to move out of the original medium and into the soil around it. You may have to use the trickle technique again next year, too.

Drooping like that can be caused by two main causes: too little water, and too much water. :-) Seriously, it's true. Too little water: the surface under the mulch around the stem will feel dry. The plant will perk up in the morning, and wilt in the middle of the day. Newly planted rhododendrons will need water (if there's no rain) in this area every few days, depending on drainage and temps, etc. Flip side: too much water will drown the roots. It can also cause phytophthora root rot (especially in hot temps), which kills the ability of the roots to supply water to the rest of the plant. A well-watered plant that droops over the entire plant almost certainly has phytophthora root rot. At that point, there's no cure. You don't need to water if the soil under the mulch isn't dry, and if it isn't wilted in the morning. (They often wilt during the heat of the day if it's at all dry; this isn't a problem if they're firm by morning.) It also could be unrelated to water. Some other fungal diseases start in the stems/leaves, blocking sap from getting to new growth (which droops), and work their way down. In that case, pruning (with sterilization of pruner between each cut using 1:7 bleach solution!) can save things. See link for pictures. There will be a localized brown discolorization of the branch, often looking withered. One it reached the base, it can cause the entire plant to wilt, though I believe more often it affects mostly newer growth. The 10 plants I got from a good general nursery were infected; I've done a lot of pruning. As mentioned, planting too deep can accentuate problems - rhododendron roots want to be near the surface and get oxygen. Lastly, it could be the exact things recommended above. Unlike many plants, in most cases slitting root balls (even pot-bound ones) of rhododendrons isn't a great idea. A test was done with 5 identical plants; some just planted, some slit, others carefully washed loose for an inch or so, etc. The slit ones did by far the worst when evaluated a year later. If I had to guess, sounds like a fungal disease, but I'd check on how it was planted first. Note: this link will eventually go stale; it's to some temp pictures I uploaded for the rhododendron mailing list. Here is a link that might be useful: Images of fungal branch dieback