Researching Maintenance

Tree fertilization I am looking for a soil-injectable fertilizer with an analysis of around 10-30-20. Do you know of any? Most soil-injectable fertilizers have nitrogen ratios that I think are too high for mature trees.-South Carolina

I asked Dr. Tom Smiley, a researcher with Bartlett Tree Research, about this and he suggested the following:

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First of all, it's the rate of applied nitrogen more than the product's analysis that is important. Regardless of the fertilizer's analysis, you can vary the rate to deliver the desired amount of nitrogen. However, you should have a laboratory perform a foliar or soil analysis to determine nitrogen needs. The other nutrients are important too, of course, and like nitrogen, you should determine the need for them with an analysis.

Smiley notes that in the absence of laboratory results, many experts recommend using a 3-1-1 or 3-1-2 ratio. This is the recommendation of the new ANSI A300 guidelines (due to be published this year), which also suggest using 2 to 4 pounds of slow-release nitrogen per 1,000 square feet, distributed uniformly between the trunk and the dripline, with a maximum rate of 6 pounds of nitrogen per year. Use of quick-release nitrogen is discouraged "except when the objectives of fertilization cannot be met with slow-release fertilizer."

The A300 guidelines also make an important point: "...ratios should be adjusted based on local knowledge, age and condition of the plant, soil and environmental conditions." As this implies, there is no substitute for hands-on site familiarity. Still, you're just making educated guesses about nitrogen needs without an actual laboratory analysis. In lieu of that, the A300 recommendations are a reasonable estimate of nitrogen needs for mature healthy trees.

Gypsum Is gypsum used on greens and fairways? What are the benefits and pitfalls of applying gypsum? Does it substitute for some other practice?-Address unknown (via the internet)

Gypsum is used on golf-course turf-both greens and fairways-which is different from saying that you should use it on golf-course turf. Certain soil conditions call for gypsum. Otherwise, little need exists for gypsum that is not satisfied by more common materials.

Dr. Peter Landschoot, a turfgrass soil specialist at the Pennsylvania State University, explains that in the Northeast the only well-founded reason for using gypsum is as a calcium supplement when, for some reason, you don't wish to use lime (which also is a calcium source). Landschoot notes that the need for calcium nutrition is itself somewhat controversial, but assuming that you want to add calcium, gypsum is one way to do it. It is cheap and safe.

A persistent myth is that gypsum alleviates compaction. Landschoot states unequivocally that this is not the case. This misunderstanding may stem from the fact that gypsum is useful for displacing sodium in sodic soils. Sodium causes soil particles to disperse, hence destroying soil structure. However, this isn't really an issue in the Northeast or any other regions where rainfall is high enough to naturally leach the sodium out of the soil. Rather, compacted soils in such areas tend to result from the usual factors such as traffic and high clay content. Gypsum won't influence these things, so it can't substitute for practices that relieve compaction such as aeration.

Gypsum also isn't a suitable material for pH management because it is essentially neutral in this regard. Lime, of course, will raise pH (in addition to adding calcium), while sulfur and ammonium sulfate are good products for lowering pH.

So why would you use gypsum? As already noted, gypsum is an excellent source of calcium. Plus, sodic soils definitely benefit from gypsum. Sodic soils are common in the Southwest and other areas with sparse rainfall. A soil test will easily detect whether your site needs such remediation. Otherwise, according to Landschoot, it's difficult to justify applying gypsum to your turf.

What's a plant worth? Please advise me of any resource literature for the evaluation or assessment of damaged landscape materials and plants. For example, is there a standard formula to gauge the value of a mature tree or shrub?-Address unknown (via the internet)

Estimating the value of damaged trees and ornamentals is not always a simple task. The Guide for Plant Appraisers is a manual that describes in detail methods for appraising dead or damaged plant specimens. The National Arborist Association Inc. (NAA) offers this publication for $40 to NAA members and $45 to non-members. You can call the NAA at (800) 733-2622 to obtain a copy.

To estimate costs for structures and various "hardscape" features, you go through the same basic exercises you would for estimating any project. Kerr's Cost Data for Landscape Construction (Van Nostrand Reinhold, New York, N.Y.) is one popular guide. Another is Means Landscape Estimating (R.S. Means Co. Inc., Kingston, Mass.). Both are available in many bookstores.

>From the U.S. Department of Agriculture's Agricultural Research Service (ARS) comes the latest new bermudagrass variety: TifEagle. ARS researchers and their cohorts at the University of Georgia have been testing the new variety on numerous golf courses across the United States and have found that TifEagle can tolerate mowing heights slightly lower than 0.125 inch-comparable to the new generation of bentgrasses.

TifEagle originated in 1988 from an induced mutation. After several years of development and testing at 24 U.S. golf courses, TifEagle has been licensed to several U.S. turf growers, some of which should have limited supplies available this year.

The researchers note that TifEagle exceeds TifDwarf in overall quality, color and overseeded-turf quality at heights ranging down to 0.125 inch. In fact, TifEagle has tolerated twice-daily mowing at 0.10 inch without loss of stand density (though 0.156 inch is recommended for periods of extended stress). Further, TifEagle produces far fewer seed heads than TifDwarf or Tifgreen-virtually none under typical growing conditions-and doesn't appear to have any unusual pest or disease problems.

Does TifEagle have any drawbacks? Yes. It forms significantly more thatch than TifDwarf. For that reason, only courses that can supply the necessary thatch management should consider TifEagle. Without such intense management, TifEagle produces a spongy, inferior putting surface. At a minimum, this variety needs topdressing and verticutting every 2 weeks, 3 to 5 aerations per year and severe verticutting once a year.

Because of its tendency to form thatch and the low mowing it requires, TifEagle is a greens-only variety. However, for courses with the necessary resources, it can produce putting surfaces with the speed and quality that modern golfers expect.

In May 1997, Grounds Maintenance published an article by Stephen Cockerham of the University of California about managing kikuyugrass as turf. This prompted a response from Joe Finger, a Texas turfgrass consultant, warning of the problems a turf manager could expect with kikuyugrass, particularly in areas of higher rainfall. Here is another take on kikuyugrass from Richard Cooley of Agrotera (McMinnville, Ore.), representing Arizona Kikuyu Growers.

According to Cooley, several factors should prevent us from dismissing kikuyugrass as valueless: *Research conducted by Dr. Jeff Klingenberg and supervised by the Arizona Department of Agriculture has found that practical control of kikuyugrass is possible with cultivation and herbicide (glyphosate) applications, demonstrating that the grass ('Whittet' forage-type kikuyu) can be grown for seed production without risking uncontrollable spread. As a result, Arizona has removed kikuyugrass from its noxious weed list. *Andrew Storrie, an Australian agronomist, notes that in Australia, where kikuyu has long been used for forage and erosion control, "kikuyu is easily controlled with the tools of modern agriculture and is unlikely to achieve a major weed status." * Dr. Albert E. Carlson, president and director of research for Arizona Plant Breeders, plans to release an experimental turf-type kikuyugrass, AZ-1, in the near future. AZ-1 "is a much denser turf with smaller stolon development compared to 'Whittet' and the much coarser African plants introduced into California in the 1920s." *Kikuyugrass stays green later in fall and winter than other warm-season turfgrasses. Therefore, using kikuyugrass as turf could reduce the need for winter overseeding.

Regarding the problems that California turf managers report with kikuyugrass, Cooley notes that the kikuyugrass brought into California in the 1920s (and which has been extremely invasive) originated in East Africa. Since then, breeding efforts have resulted in both forage and turf types of kikuyugrass that are "vastly different" from the original African type. Therefore, states Cooley, generalizing about kikuyugrass based on the invasive types found in California (which are descendents of the East African introductions) is unfair.

Although kikuyugrass is a federally listed noxious weed, not every state lists it as such. Hawaii, in particular, uses kikuyugrass extensively. However, due in part to federal restrictions, no good domestic source of kikuyugrass seed exists. Therefore, users in Hawaii must import much of the seed they use from Australia. Arizona growers hope to develop an alternate source of seed for this controversial grass.

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