By now, you know that Emerald Ash Borer (EAB) was found in northwest Illinois. Residents throughout the state have been on the lookout for this small (½ inch), metallic-green beetle. EAB has only one host and that is the Ash tree, Fraxinus genus to be specific. In Illinois, the White Ash, Fraxinus americana, and Green Ash, Fraxinus pennsylvanica, are the primary species. Tree owners may be more familiar with a cultivar name. There are many in the trade. Popular cultivars are 'Autumn Blaze,' 'Autumn Purple,' 'Autumn Applause,' 'Marshall's Seedless,' 'Patmore,' or 'Summit.' They are all members of the Fraxinus genus.

Consider Fraxinus as your last name. White Ash (Fraxinus americana) and Green Ash (Fraxinus pennsylvanica) are siblings just as Joe Smith and John Smith are brothers. Nieces and nephews are comparable to cultivars. They are all related. Emerald ash borer attacks only Fraxinus members. Compare it to a fly that could only bite people with the last name of Smith. No one else would be bothered.

Mountain Ash is a small ornamental tree with clusters of red, orange or yellow fruits. It is a member of the Sorbus genus and not susceptible to emerald ash borer attack. Mountain Ash are prone to attack from other types of borers. There is no need to contact the authorities if borer holes are present on a Mountain Ash. Your U of I Extension office can help you identify the pest and provide possible control recommendations.

Both trees have similar looking foliage. Both have compound leaves, which means a single leaf is made up of several leaflets. However, there is a distinct difference to help you identify what type of "Ash" you have. Fraxinus members have opposite buds. Look at the branch and notice if the leaves emerge from the stem directly opposite from each other. Sorbus members have alternate buds meaning they are not directly across from one another along a stem. To help you identify your tree, visit UI Plants at http://wp.nres.uiuc.edu.

So far, EAB has not been found outside the original sighting area in northwest Illinois. As a Master Gardener, you are an important part of the statewide watch-group for EAB. When faced with borer holes on a tree remember, "When is an ash not an ash?"

For more information, check out the Emerald Ash Borer website at www.emeraldashborer.info/index.cfm. You might also want the Michigan State University bulletin, "Distinguishing Ash from other Common Trees," www.emeraldashborer.info/files/E2892Ash.pdf.

June marks the end of asparagus cutting season. Now is the time to think ahead to next year's harvest and take measures to improve and maintain vigor in the planting. From now until the first freeze in the fall, asparagus plants are building and storing reserves, and developing the crown buds that will become the spring shoots of 2008. The degree of sugar and carbohydrate build-up achieved this year influences the quantity and quality of spears next year.

In weakened asparagus beds, spears become small, thin, and spindly. This weakened state is often a result of cutting too long into the summer in previous years and not caring properly for the planting. On a mature, healthy planting, six to eight weeks of cutting is easily tolerated. Low fertility, root and foliage diseases, and insect damage can also weaken the planting and be responsible for poor production. Even though asparagus is winter hardy, severe and sudden drops in temperatures can damage older crowns in shallow plantings. Over time and as plants age, crown depth can decrease as the crowns slowly "creep" upward and become more exposed to sudden soil freezing events.

Reduced spear size is not always related to adverse growing conditions. It is also related to the sex of the plant. Asparagus plants are male and female. Female plants have thinner spears and produce red berries. Male plants also flower but do not fruit, thus expend less energy on reproduction; they develop fewer but thicker spears.

Male plants are preferable, but how can you select for them? With new crowns or seed of older varieties like 'Mary Washington,' usually a mix of male and female plants occurs, but there is no way to tell the sex of the plants until they flower.

Newer "all male" hybrids are now available on the market and are being widely planted. Developed by breeders in New Jersey, the series of asparagus varieties with 'Jersey' in the name are available in most garden catalogs. Varieties that perform well in the Midwest include 'Jersey Knight,' 'Jersey Giant,' 'Jersey Supreme,' and 'Jersey King.' In addition to having larger spears, these hybrids have considerable tolerance to root rotting and foliar rust diseases.

New asparagus beds need several years of growth before abundant, thick spears are produced. Good management of the foliage during the summer and fall months is required, with a focus on providing adequate fertility, managing foliar disease and insect damage, and limiting weed pressure. A well-planted and maintained asparagus bed should be productive for 20 to 30 years or more.

To maintain fertility, apply a surface application of fertilizer after the last cutting is made. Apply well-rotted compost or manure, covering the soil 1 to 2 inches deep in a 2-foot wide area over the row. If manure is not available, apply commercial fertilizer such as 12-12-12 using 1 cup of material for every 10 feet of row. Avoid contact with emerging shoots and stems. When manure is used, cut chemical fertilizer amounts in half. Research has shown that asparagus responds variably to fertilizer applications. If vigorous growth is occurring, a light fertilizer application may be adequate. It may be more efficient to apply some fertilizer in the very early spring before first spear emergence and again after harvest, especially on lighter soil types. Keep in mind that spring- and post-harvest fertilizer application will not improve the current season's crop. Instead, it increases growth and vigor of the tops or 'ferns' from now until fall, improving next year's crop.

Weed control is also essential to maintain vigor. In large plantings, herbicides containing trifluralin (Preen™) can be used to control annual weeds. At one time, salt was commonly used to kill weeds in asparagus. However, prolonged use of salt leads to deterioration of the physical properties of the soil and a reduction in growth; thus, salt is not recommended.

Asparagus beetles and Japanese beetles are common pests. Insecticides such as carbaryl (Sevin™) and malathion (Fertilome Malacide™) can be used for control. Apply when feeding and presence of the beetles is noted.

There are also foliar diseases (rust and leaf spot) that can brown and discolor foliage, reducing the plant's capacity to photosynthesize and build reserves. As noted, the hybrid varieties have some level of resistance. Use a fungicide containing chlorothalonil (Daconil™) at monthly intervals after harvest to help suppress these diseases.

Because hybrid plants are larger, initial spacing at planting can be wider (5- to 6-foot-wide rows, plants 18 to 24 inches apart) than non-hybrid plants. This wider spacing allows more room for the plants and increases air movement in the planting, which helps reduce foliar disease.

Asparagus is an easy crop to grow, needing only minimal maintenance to ensure a successful crop from year to year. Attention to fern care during the summer months will return a plentiful harvest of spears next spring. For more information on asparagus and other vegetable crops, check out the University of Illinois publication, "Vegetable Gardening in the Midwest" or visit the U of I Extension website "Watch your Garden Grow" at: www.urbanext.uiuc.edu/veggies.

Recently, calls have come in about a new Hardiness Zone Map. Some media outlets have reported that Illinois is no longer USDA Plant Hardiness Zones 5 and 6 with an average cold temperature between -10 and -20°F, but rather National Arbor Day Foundation Zone 6 with an average annual cold temperature of 0 to -10°F.

The National Arbor Day Foundation has released their own hardiness zone map that they feel reflects a warmer climate. An article that appears on their website states, "(Their) new map reflects that many areas have become warmer since 1990 when the last USDA hardiness zone map was published. Significant portions of many states have shifted at least one full hardiness zone. For example, much of Illinois, Indiana, and Ohio have shifted from Zone 5 to a warmer Zone 6."

The basis for the USDA Plant Hardiness Zone map is that plants can be classified as either hardy or non-hardy depending on their ability to withstand cold temperatures. The USDA map reflects only average minimum winter temperatures for a given area. It does not take into consideration temperature fluctuations, humidity, or summer temperatures.

The USDA Plant Hardiness Zone Map is recognized throughout the horticultural industry for cold temperature hardiness. Other types of maps have been introduced, including the American Horticultural Society (AHS) Heat zone map and the Sunset Climate Zone map. These maps take into consideration other growing factors besides cold.The AHS Heat Zone map was intended to counterbalance the limitations of the USDA map regarding summer temperature extremes. At temperatures above 86°F (30°C), photosynthesis shuts down in many plants. During the long, hot days of summer, plants may have to rely on stored energy reserves. The plant's ability to tolerate extended periods of heat is the basis for the AHS heat zone map. The United States is divided into zones based on the average number of days per year with temperatures above 86°F.

The Sunset Climate Zone map incorporates the total climate when determining zones across the U.S. This map was created looking at length of growing season, timing and amount of rainfall, winter lows, summer highs, and humidity. Taking all these factors into account, it is yet another tool to help determine the survivability of plant material across the U.S.

As people debate the issue of global warming, the conclusions are varied. By far, the majority of plant references currently in print use the USDA Plant Hardiness Map to identify zones based on cold temperatures. The AHS and Sunset maps have been created to take into consideration other growing conditions and complement the USDA map. The Arbor Day Foundation has started the global warming discussion for the green industry, but zone changes need to be accepted and promoted by all. So until this happens–if it happens–Central Illinois is still USDA Zone 5, and Southern Illinois is still USDA Zone 6.

National Arbor Day Foundation: www.arborday.org/index.cfmUSDA Plant Hardiness Zone Map: www.usna.usda.gov/Hardzone/ushzmap.htmlSunset Climate Zones: www.sunset.com/sunset/garden/article/1,20633,845218,00.html