SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/517437
FIELD SCIENCE 16 SportsTurf | June 2015 www.sportsturfonline.com nutrient deficiencies. Immobile nutrients will exhibit deficien- cies on the younger leaves because the plant was unable to move them to the new growth. Nitrogen (mobile nutrient). Slowing of vertical growth, general yellowing appears first on the lower leaves. This leads to loss of shoot density, leaf dieback at leaf tips and eventually an overall loss of color with older leaf death and lack of tiller- ing. Ask yourself: Do I have sandy soils? Have I experienced high rainfall or irrigation? Do I have low organic matter? Have I been removing clippings? Or do I have compacted or water- logged soils? Phosphorous (mobile nutrient). Reddish-purple cast appears from the tip of the lower leaf blades, especially in cool weather, dull blue-green color, poor overall growth, slow root growth, often new sod is slow to knit. Ask yourself: Have I experienced cold temperatures? Do I have sandy, low CEC irri- gated soils? Is my soil pH high (7.5-8.5)? Am I growing my turf on infertile or marginal subsoils? Are my soils high in clay? Potassium (mobile nutrient). Yellow-streaking of the lower (older) leaves followed by browning and death of tips and mar- gins, eventually will become completely yellow. Wilts sooner than normal during a drought, poor resistance to disease and cold injury, reduction in turf density. Ask yourself: Have I experienced high rainfall or leaching conditions? Do I have low CEC or acidic (pH<5.5) soils? Have I been removing my clip- pings? Iron (immobile nutrient). Chlorotic between the upper (younger) leaf veins, eventual loss of most chlorophyll. Entire plant may turn white or spindly. Turfgrass stand may appear mottled with some grass exhibiting the symptoms, while others not. Ask yourself: Do I have high soil pH (>7.5)? Do I have excessive thatch or cold, wet soils? Did my soil test high in P? Are we irrigating with reclaimed municipal water that may be high in heavy metals? Magnesium (mobile nutrient). Green or yellow-green stripes in the lower (older), changing to cherry red, older leaves affected first, increased winter injury. Ask yourself: Do I have low pH (<5.5) sandy soils, with high leaching potential? Sulfur (immobile nutrient). General yellowing of younger (upper) leaves, gradual firing starting at leaf tip. Ask yourself: Do I have low CEC soils with low organic matter? Have I received high rainfall? Do I remove clippings? Manganese (immobile nutrient). Chlorosis of younger leaves, yellow green spots on older leaves, withering at tips. Ask yourself: Do I have higher pH soils (>7.0) and have experienced warm, dry weather? Calcium (immobile nutrient). Reddish-brown between veins along younger leaf margins, tips die and curl. Ask yourself: Do I have sandy soils, low in pH (<5.5)? Have I had leaching problems? Boron (immobile nutrient). Slow growth, pale green younger blade tips, bronze tint. Leaves may curl. Ask yourself: Do I have leached, calcareous and sandy soils? Are my soils high in Ca and K? Molybdenum (mobile nutrient). Pale yellow foliage, bleach- ing and withering of the lower (older) leaves. Ask yourself: Do I have acidic and sandy soils? Did my soil test indicate high con- centrations of other micronutrients? Zinc (immobile nutrient). Younger leaves yellow, smaller, grouped together. Some curling on the leaf edges. Ask yourself: Do I have shady conditions and high pH? Do I have high levels of micronutrients? Has it been wet and cool outside? TOXICITY, NOT DEFICIENCY? If not too little, could it be too much? Again, this is where the soil test helps, as well as the overall pattern of appearance of the turf. If it looks burnt, stunted, etc., at least consider that too much of a particular element has been applied. One way to find out would be the plywood test. Cover a portion of the area to be treated with a sheet of plywood, apply your particular nutrient, remove the plywood and wait to see if there is a plant response over the next few days to a week. ■ ST John C. Fech is a horticulturist and certified arborist with University of Nebraska-Lincoln Extension; Brad Jakubowski is an instructor in the Environmental and Earth Sciences Department at Doane College, Lincoln, NE. Example of phosphorus deficiency, courtesy of Dr. Andy McNitt, Penn State.