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).

June Article for Kentucky Gardening:
Tips from UK Extension--This thing called Drought.

Are we in a drought? That's what the weather anchor at the local news station said. He said something about the Palmer index for Central Kentucky being -3.33 which puts us in the severe category, and he indicated that we need around eight inches of rainfall just to bring us back to normal. But wait, we had almost an inch of rain last week. My plants are doing great. The city hasn't told me which days I can water and which days I can't. We're not in a drought, are we? I'm confused. I don't even know which way to spell the word, is it drought or drouth? Let's dive deeper into this drought subject an see if any sense can be made of it.

To the layman, drought usually signifies a negative departure from normal rainfall that adversely affects the welfare of people, plants or animals. When most weather professionals talk about drought, they speak of the Palmer Drought Severity Index, or just Palmer Index. The index was developed by W. C. Palmer in 1965, and is used to measure the overall departure from normal in water balance for a particular region. The index uses several inputs including precipitation, temperature, soil moisture, and other factors, to determine drought severity. The more negative the index value, the more severe the drought. The Palmer Index looks at the long-term status of drought, therefore, a short wet period in the midst of a severe or extreme drought may have little effect on the index value. Many states use the Palmer Index as part of their decision making process for drought contingency plans.

Another popular measure of drought severity is the Crop Moisture Index, or CMI. The CMI uses inputs of precipitation and temperature to estimate short-term soil moisture conditions as they affect crop production. Therefore, the CMI tends to be of greater use to farmers than the Palmer Index, but the CMI does not give an accurate overall evaluation of drought conditions. The CMI fluctuates more rapidly than the Palmer Index due to changing meteorological conditions. For example, a significant rainfall event during drought may result in a change in the CMI to indicate adequate soil moisture for crop development, while the Palmer Index remains relatively unchanged. So how should a homeowner evaluate these indices? They are probably of little value as an indication of when to water in the landscape. A good method to use is what I call the calendar method of water management in the landscape. Good water management in the landscape during times of plenty is the best preparation you can make for times of drought.

During the growing season, most plants in the landscape will grow well with about one inch of rainfall each week. I have a small rain gage in my yard and record on the calendar when there is precipitation. I do not record a rainfall of less than one-quarter inch since little of this moisture will make its way into the soil. If my calendar indicates rains are averaging around one inch a week, I do not water. If the rainfall amounts drop and my plants appear wilted, I water. Also, if I measure a heavy rain, say one and a half inches last week but only a quarter of an inch this week, I will usually wait a little longer before I water. The timing of watering is the key to conserving water in the landscape and preparing your plants for a time of drought.

Most people tend to water in the evening either after they get home from work or during/after the dinner hour. While this may be an ideal time for the homeowner, it may not be the best situation for their landscape plants. Plants watered late in the day will generally have wet foliage into the evening hours and the chances of the foliage drying after sunset are reduced since temperatures usually fall and the relatively humidity rises during this time. Why all this fuss about wet foliage? The longer a plant's foliage stays wet, the greater the chances for disease. Therefore the best time to water is in the morning before the heat of the day. Less water will also be lost to evaporation in the morning meaning that more of the water that is applied will make its way into the soil. Also think about the frequency of watering. A plant's depth of rooting will affect the frequency and volume of water that should be applied. Frequent shallow watering, such as that provided by sprinkling plants every few days, will promote a root system that is shallow. Such plants are very susceptible to periods of even mild drought such as a lack of water during the home owner's week-long vacation, not to mention periods of more extreme drought. Less frequent but thorough watering is best.

Another water conservation practice is the use of mulch. A mulched bed will lose less water to evaporation for several reasons. The mulch is a physical barrier to evaporation from the soil surface, the mulch shades the soil and reduces soil temperatures thus decreasing evaporation, and the mulch reduces growth of weeds that would compete with your landscape plants for water. Mulches also slow down the force of water moving across the soil surface and thereby increase the likelihood that water will percolate into the soil rather than being carried away by run off. The type of mulch one uses is not as important as that the mulch be applied properly. Apply mulch only to a depth of about 2 or 3 inches. Deeper may smoother plants or cause disease problems.

Finally, what are we to do during a severe drought when water may not be available for the landscape? When possible, only high quality water should be applied to plants in the home landscape, 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. The presence of soaps is generally less of a problem, 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.