Research Update

Unbiased information Where can I get unbiased information about turf and ornamental cultivars and susceptibilities?-Florida

The most consistently unbiased information you are likely to find regarding specific cultivars will be through your local university, including Cooperative Extension offices. Extension offices often provide variety lists appropriate for your region, based on recommendations of local experts and trials.

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For example, many campuses participate in All-America Selections trials, which evaluate new cultivar releases by rating their performance in specific locations. These results are available to interested parties and the trial gardens often are open for viewing. Many universities conduct National Turfgrass Evaluation Program (NTEP) trials as well. These evaluations examine turfgrass performance in certain regions and under specific maintenance regimes. Other university programs conduct their own trials independent of any industry organization. However, in all such cases, the point of the trials is to provide unbiased information about turfgrasses and ornamentals, including identification of poor performers and specific susceptibilities as well as superior selections.

One of the best aspects of the information that local universities and extension offices provide is that it is region-specific. Innumerable horticultural reference books are available, most of them containing good information. However, out of necessity, they often are rather general in how they address species and cultivars. They simply can't address the cultural needs and performance characteristics of specific varieties in all the possible conditions where they might grow. Further, they often don't contain information about the latest variety releases. Thus, while reference books are indispensable tools, they cannot substitute for real-life trials conducted under local conditions.

Of course, the time-honored method of consulting with your peers to see what works for them has always been an effective strategy.

Online MSDSs Is there a web site that provides MSDSs?-Address unknown (via the internet)

No "master list" of all MSDSs (material safety data sheets) exists that you can access over the internet. However, many organizations, especially universities, make MSDS databases-usually industry-specific-available to interested parties. Commercial MSDS search services also are available (for a fee, of course). One site I've found useful is from the University of Minnesota at Duluth. Go to http://www.d.umn.edu/~mlabyad/MSDS.html and you'll find links to a variety of sites with MSDS databases. This is just one-performing an internet search should yield many useful resources related to MSDSs.

If you are looking for MSDSs for pesticides specifically, try the corporate websites of manufacturers (or distributors, where applicable). Not all such company sites provide MSDSs on-line, but some do and it's certain that more will do so in the near future.

Another possibility is C&P Press's web site, which you can access at www.bluebooktor.com. Parts of the site are free, and parts require a subscription. However, this site offers many labels and MSDSs.

Although the internet is potentially the ideal tool for making information such as MSDSs available, not all companies are taking advantage of it yet. Until they do, remember that they are required to supply MSDSs for the products they sell to anyone requesting them, even if they do so the "old-fashioned way" with paper copies.

Pre-emergent timing When should I apply pre-emergence herbicides to turf, rockscapes and landscape beds in the desert Southwest?-Adress unknown (via the internet)

The timing for pre-emergents in the Southwest depends on a variety of factors, including the type of site, the cultural regime you use and in what part of the Southwest you reside.

In landscape plantings without supplemental irrigation, rainfall dictates when weeds will grow. According to University of Arizona extension weed specialist Bill McCloskey, this typically means the winter months, so pre-emergent applications should occur in late fall-usually October or November, depending on the region. McCloskey also notes that some parts of the Southwest receive monsoonal rain in July and August, so a June application may be necessary to combat summer annuals such as pigweeds and other heat-loving species. Conversely, other desert areas receive virtually no summer moisture and, therefore, need no summer herbicide application.

Irrigated landscapes can have weed problems year round. Nevertheless, winter annuals still tend to start germinating when days become shorter and cooler, and summer annuals still grow in the warmer parts of the year. Therefore, your timing may not really vary that much. However, the supplemental moisture may make weeds more persistent or bring them on during the summer in areas that, absent irrigation, would not experience summer weed problems.

Turf is more complicated because the weed problems you encounter there depend so much on the type of turfgrass and how you maintain it. If you overseed turf in the fall, your options for pre-emergence control are limited, although post-emergence control of broadleaf weeds still should be relatively easy. If you don't overseed, weed control-pre- and post-emergence-is much easier, especially in dormant warm-season turf. Regardless, health, vigorous turf is quite competitive easier and may not have serious weed problems even though you irrigate it.

Because pre-emergents need incorporation to become active in the soil, McCloskey emphasizes that application timing relative to precipitation is important. Obviously, when irrigation is available, you can apply the half-inch or more of water necessary for herbicide activation. However, if you rely on natural rainfall for incorporation, you must try to time the application to precede rainfall as closely as possible-not always an easy thing to do in arid regions. McCloskey points out that although some herbicides are more photosensitive than others, pre-emergents cannot remain exposed to sunlight indefinitely without degrading. Read product labels for specific information on this topic.

Fertilizer use is a favorite target of environmentalists. Fertilizer use on turf is a particularly inviting target, which is not surprising considering environmentalists' traditional disdain for golf courses. However, many fertilizer opponents may not know (or care to admit) that unfertilized turf actually can release more nutrients through runoff than fertilized turf. That is the conclusion (consistent with other research) of a series of studies by Dr. Wayne Kussow at the University of Wisconsin. In his work, Kussow compared turf plots receiving fertilizer with unfertilized swards. He found greater runoff in the unfertilized plots, resulting in more movement of nitrogen and phosphorus.

The reason? Thicker turf slows surface movement of water and sediment, increasing the time available for water to infiltrate into soil and allowing sediments to settle out. This decreases off-site movement of nutrients, both dissolved (such as nitrogen) and sediment-borne (such as phosphorus). Unfertilized-and therefore thinner-turf, by contrast, allows more and faster runoff, allowing more dissolved and sediment-borne nutrients to leave the turf. Bare ground is most susceptible to such runoff.

Kussow used a variety of synthetic-nitrogen carriers (including urea, coated ureas, IBDU and methylene urea) as well as a natural-organic source (Milorganite) but found no significant differences among them. Further, he found that nearly all of the runoff and nutrient transport occurred when the soil was frozen (a factor not nearly as significant for most turf managers as it is in Wisconsin).

At least some of the phosphorus-the nutrient most implicated in surface-water problems-in any runoff comes from airborne particles that settle out of the atmosphere. Because you can do little to eliminate that, the best way to reduce phosphorus movement is to reduce surface runoff. Maintaining thick turf is one of the best ways to do that. Thin, un- or under-fertilized turf may result in more movement of phosphorus, not less.

In our May issue, we published a question and answer in Researching Maintenance regarding the use of gypsum on golf-course turf. Essentially, it stated that few reasons exist for using gypsum on turf, at least in non-arid regions. Garn Wallace, executive director of Wallace Laboratories (El Segundo, Calif.), responded, citing numerous benefits to soil deriving from gypsum.

Among them are several effects relating to high-pH and sodic soils, conditions that are common in the western and southwestern United States. For example, gypsum can lower pH in sodic soils (even though it mostly has neutral effects in non-alkaline soils). Gypsum also is an essential tool for improving sodic soils by displacing sodium with calcium, allowing the sodium to combine with sulfate and leach from the root zone. Further, it may provide some protection for plants against sodium toxicity. These are some of the reasons why gypsum, applied to soil or in irrigation water, aids in the use of reclaimed municipal wastewater, which tends to be high in dissolved salts.

Considering these factors, it is fair to point out that gypsum can be an important soil-management tool, particularly in arid regions where sodic soils are relatively common and where effluent is a more frequently used source of irrigation water. However, because many of gypsum's benefits apply to specific soil conditions, be sure to conduct a soil analysis before deciding to apply gypsum (or any other material) to your turf.

Questions are selected on the basis of current or general interest. Unfortunately, we are unable to respond to letters individually.

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