Rick Durham, Consumer Horticulture Extension Specialist, University of Kentucky
 

Watch for fire blight on apples and pears.

This appears to be a particularly bad year for fire blight. Fire blight is a bacterial disease that is devastating to susceptible apples, pears, crabapples and certain ornamental pears, especially 'Aristocrat.' The disease is often spread from tree to tree by bees as they pollinate flowers in the spring. From the flower, the bacteria move down the stem and spread into surrounding leaf tissue. As this happens, the terminal portion of the plant dies and is very noticeable in the otherwise green canopy of the tree. This is where the disease gets its name because the infected branches look as if they have been scorched with fire. Such diseased branches should be removed as soon as possible to prevent the bacteria from spreading further down the stem. If the disease is caught early, only the first leaf or so below the flowers may show symptoms. In this case the small affected branches can be easily broken out of the tree by hand. However, since the bacteria move in advance of tissue damage, diseased branches showing more advanced disease symptoms should be cut 6-8 inches below the lowest sign of infection. It is also wise to disinfect pruners between cuts by coating them with a solution of either 10% bleach or 70% ethanol. This will prevent the spread of disease to newly pruned areas.
 

When your Colorado Blue Spruce is green.

Colorado Blue Spruce, Picea pungens, is a tall, slow-growing evergreen tree. The needles range in color from gray-green to blue-green with the young growth usually a silvery blue, hence the common name. Certain cultivars have been selected that retain more of their blue color throughout the growing season. At a nursery, consumers will encounter one of two types of Colorado Blue Spruce, either named cultivars that likely have been propagated by grafting, or seedlings. There are many named cultivars available. Some of the more common and desirable cultivars include 'Hoopsii,' 'Moerheim,' 'Fat Albert,' and 'Thompsenii.' These have all been selected for enhanced blue color in the needles and usually have more compact growth. 'Fat Albert' in particular has a short, broad growth habit. When seedlings are purchased, they usually have needle coloration similar to the wild species-grey-green to blue-green and only intensely blue as new growth is produced. Trees grown from seedlings may be quite attractive but the needles usually do not retain their blue color into the growing season. Trees of named cultivars will command a higher price (but worth it in my opinion) and less expensive trees (e.g., magazine and newspaper adds) are almost always seedlings. So if you have a not-so-blue spruce, blame it on the tree's genetics. Adding lime to sweeten the soil will do nothing to affect the tree's needle color. A word of warning-a specimen tree of Colorado Blue Spruce is very attractive, but often the tree's size and color overwhelm the rest of the landscape.
 

Using 'gray' water in the landscape.

When possible, only high quality water should be applied to plants in the home landscape. Municipal water supplies in Kentucky are of sufficient quality to be used for landscape irrigation, however, with the rising incidence of water restrictions in urban areas often coupled with drought conditions, some people are reclaiming bath water or other water such as that used for washing clothes and dishes, and applying this 'gray' water to their landscape plants. One should exercise caution when using 'gray' or reclaimed water. Water that contains detergents or bleach should not be applied to plants because of the adverse effects these chemicals have on soil chemistry or root growth. This means that dishwater and water used for washing clothes should be avoided. Rinse water collected from these washes may be acceptable if the level of detergent or bleach is minimal. Soaps are less damaging to plants and soils so bath water would usually be suitable for irrigation purposes. Alternating irrigation with gray water and clean water will reduce any long-term adverse affects of the gray water since the suspect chemicals are readily leached from the soil. For sources of clean water, consider keeping a container handy to catch water from the tap as you are waiting for it to become hot. This could be used for watering houseplant or spot watering plants outdoors.
 

Soil Organic Matter.

As gardeners, we often place an emphasis on plants in our landscape. However, there is something under foot that is equal to, if not more important than the plants. Of course I'm talking about the soil. Soil is classified according to its texture, or how much sand, silt, or clay it contains. Each of these contribute desirable properties to the soil and apart from a major renovation, we usually have to accept and work with the soil texture that we have. One other ingredient, however, can drastically improve the quality of soil and that is organic matter or humus. The presence of organic matter helps to aggregate soil particles and thus improve drainage and aeration and lessen compaction. In sandy soils, organic matter works like a sponge to absorb and retain needed moisture for plant growth. As organic matter decomposes in the soil it releases nutrients necessary for plant growth. Another benefit of organic matter is that it buffers and stabilizes the soil pH. So where does organic matter or humus come from? The level of organic matter in the soil is not constant and it must be replenished periodically. In nature, organic matter is continually being added to the soil in the form of dead plant and animal matter. In our well-tended landscapes, this is rarely the case with the exception of those who use a mulching mower to allow chopped grass clippings to remain in the turf where they decompose to humus. If you feel your soil would benefit from the addition of organic matter (and it most likely woul), here are some sources that are generally available: peat moss, manures (dried or composted), bark- or wood-based mulches, leaf mold, straw, and composted materials of all types including leaves, prunings, grass clipping, non-meat kitchen waste and saw dust. (This article was taken in part from information provided by the National Garden Bureau (www.ngb.org).