MAY 1965 A Publication on Turf Management by the United States Golf Association FLOOD DAMAGE IN OREGON The 11th green at lllahe Hills Country Club, Salem, Ore., lies in ruin after severe flooding of the Willamette River last December. See story page 12. Published by the United States Golf Association Copr. 1965 by United States Golf Association. Permission to reproduce articles or material in the USGA GREEN SECTION RECORD is granted to publishers of newspapers and periodicals (unless specifically noted otherwise), provided credit is given the USGA and copyright protection is afforded. To reprint material in other media, written permission must be obtained from the USGA. In any case, neither articles nor other material may be copied or used for any advertising, promotion or commercial purposes. VOL. 3, No. 1 May 1965 Effects of Phenoxy Herbicides on Turfgrasses By Lloyd M. Callahan and Ralph E. Engel 1 Potassium—Neglected Nutrient........................................ By Dr. H. E. Hampton 6 Flood Damage in Oregon ....... 12 Turf Twisters ....................................................................................................... Back Cover Published six times a year in January, March, May, July, September and November by the UNITED STATES GOLF ASSOCIATION, 40 East 38th ST., NEW YORK, N. Y. 10016. Subscription: $2 a year. Single copies: 35£. Subscriptions and address changes should be sent to the above address. Articles, photo­ graphs, and correspondence relevant to published material should be addressed to: United States Golf Association Green Section, Texas A&M University, College Station, Texas. Second class postage paid at Rutherford, N. J. Office of Publication: 315 Railroad Avenue, East Rutherford, N. J. Editor: Dr. Marvin H. Ferguson Managing Editor: Don Weiss THE GREEN SECTION OF THE UNITED STATES GOLF ASSOCIATION Green Section Committee CHAIRMAN: Henry H. Russell, P.O. Box 57-697, Miami, Fla. 33157. DISTRICT CHAIRMEN: Northeastern: John P. English, Williamstown, Mass.; Mid-Atlantic: Martin F. McCarthy, Chevy Chase, Md.; Southeastern: El­ bert S. Jemison, Jr., Birmingham, Ala.; Mid­ Western: Charles N. Eckstein, Chicago, HL; South­ western: L. A. Stemmons, Jr., Dallas, Texas; Pacific Northwest: Edward A. Dunn, Seattle, Wash.; California: Lynn A. Smith, Pasadena, Calif. Rocky Mountain: J. W. Richardson, Magna, Utah. Green Section Agronomists and Offices EASTERN REGION Northeastern Office: P. O. Box 1237 Highland Park, N. J. Alexander M. Radko, Director, Eastern Region Holman M. Griffin, Northeastern Agronomist Raymond E. Harman, Northeastern Agronomist Lee Record, Northeastern Agronomist Southeastern Office: P.O. Box 4213, Campus Station, Athens, Ga. James B. Moncrief, Southeastern Agronomist USGA OFFICERS AND PRESIDENT: Clarence W. Benedict, White Plains, N. Y. VICE-PRESIDENTS: Wm. Ward Foshay, New York, N. Y. Hord W. Hardin, St. Louis, Mo. SECRETARY: Philip H. Strubing, Philadelphia. TREASURER: Robert K. Howse, Wichita, Kan. EXECUTIVE COMMITTEE: The above officers and: Fred Brand, Jr., Pittsburgh, Pa.; Robert F. Dwyer, Portland, Ore. ; Edward L. Emerson, Bos- USGA HEADQUARTERS: “Golf House”, 40 MID-CONTINENT REGION Southwestern Office: Texas A&M University, College Station, Texas Dr. Marvin H. Ferguson, Director, Mid-Continent Region and National Research Coordinator Mid-Western Office: Room 221, LaSalle Hotel, James L. Holmes, Mid-Western Agronomist Chicago 2, Ill. WESTERN REGION Western Office: P.O. Box 567, Garden Grove, Calif. William H. Bengeyfield, Director, Western Region EXECUTIVE COMMITTEE ton, Mass.; C. McD. England, Huntington, W. Va. ; Edwin R. Foley, San Francisco; J. W. McLean, Los Angeles, Calif., Eugene S. Pul­ liam, Indianapolis, Ind.; Henry H. Russell, Miami, Fla. ; Charles P. Stevenson, Buffalo, N. Y.; Morrison Waud, Chicago, Ill. GENERAL COUNSEL: Lynford Lardner, Jr., Milwaukee, Wis. EXECUTIVE DIRECTOR: Joseph C. Dey, Jr. ASSISTANT DIRECTOR: P. J. Boatwright, Jr. East 38th Street, New York, N. Y. 10016 The Effects of Phenoxy Herbicides on the Physiology and Survival of Turfgrasses By Lloyd M. Callahan, Assistant Professor, The University of Tennessee, and Ralph E. Engel, Turf Specialist, Rutgers Injury to sensitive turfgrasses by some of the more prominent herbi­ cides has received considerable interest in recent years. Two such susceptible species are Colonial bentgrass (Agros- tis tenuis} and creeping bentgrass (Agrostis palustris}. These species are especially sensitive to the phenoxy herbicide 2-(2, 4, 5-trichlorophenoxy) propionic acid (silvex). Furthermore, silvex is gaining increased acceptance in turf weed control. Bentgrasses growing in cooler habi­ tats may exhibit a fair degree of toler­ ance to herbicidal rates of silvex. How­ ever, silvex treated bentgrasses grow­ ing under high temperatures are often fatally injured. Since bentgrasses are becoming more widely used in golf greens and fairways throughout warm­ er regions, it has become necessary to re-evaluate weed control programs which include the use of silvex or other phenoxy herbicides. To exclude silvex would be a waste of scientific achievement since this herbicide is safe on most turfgrasses and gives excellent control of many broadleaf weeds normally tolerant to most other phenoxy compounds. In just what form phenoxy herbi­ cidal injury manifests itself in turf­ grasses has received little attention in past years. A common belief is that injury occurs simply as foliage burn which, in severe cases, results in plant death. Recent investigations have re­ vealed that phenoxy herbicides may cause disturbances to internal plant functions which greatly weaken a plant. This type of injury often goes unnoticed but may destroy na­ tural plant tolerances to environmental stresses and predators which eventu­ ally receive the blame if the plant dies. Certain highly susceptible turf species have tolerated phenoxy treat­ ments at particular times of the year. This suggests that naturally occurring environmental conditions may exist which allow sensitive turfgrasses to be safely treated with weed control rates of silvex. With these interests in mind, studies were conducted using several rates of silvex to determine its effects on the physiology, morphology, and anatomy of Colonial and creeping bentgrasses growing under various environmental influences. A primary consideration was to determine if there is a time of the year in which herbicidal rates of silvex can be applied with little danger of injury to bentgrasses. A special ef­ fort was made to explain the type, ex­ tent, and form of tissue disorders in­ duced in the roots of phenoxy treated turfgrasses. Comparisons were made also between the effects of silvex on turfgrasses with those of 2, 4-dich- lorophenoxyacetic acid (2, 4-D) and 4- (2, 4-dichlorophenoxy) butyric acid (4-(2, 4-DB) ). Influence of Environmental Factors on the Effects of Silvex on Bentgrass Seasonal temperature responses: MAY, 1965 1 Silvex treatments of %, 1, iy2 or 3- pounds active per acre applied during early- to mid-spring on a mature Co­ lonial bentgrass turf in northern New Jersey caused no serious injury. These spring treatments still provided good broadleaf weed control. Applications during this time appear to be safer after the grass has started its flush of new growth and is growing rapidly. Often foliage showing little or no response to treatment give no indica­ tion of the severe injury occurring to the roots. Occasional reductions in root length, density, food reserves, and dry matter accumulation may oc­ cur from most any weed control rate of silvex applied during the spring. Fortunately, this injury appears to reach less critical proportions when bentgrass is growing under cool tem­ peratures and short photoperiods from early- to mid-spring. However, treatments of 1-pound or more per acre applied during late spring may cause moderate to severe injury to bentgrass. If temperatures increase after sil­ vex applications, injury to top and root growth of bentgrass tends to in­ crease. Treatments during warm weather and summer are generally undesirable, especially if bentgrass is in an active stage of growth. The obvious responses of foliage to silvex during high temperatures and long photoperiods, especially under droughty conditions, appear suddenly as leaf burn. This type of injury which resembles contact chemical burning may result in reducing the amount of phenoxy absorbed by the plant. Such environmental stresses reduce plant activity and result in plants that are less receptive to up­ take and translocation of phenoxys. However, contact injury to weakened bentgrass growing under hot, dry con­ ditions offers greater possibility for kill of the plant. The crowns of the plants are highly vulnerable to chem­ ical contact which under high tem­ peratures cause fatal disruption of these tissues and ultimately plant death. In general, treatments applied dur­ ing late summer and early fall ap­ pear to have very severe and even fatal effects on bentgrass. Treatments during mid- to late-fall are more risky than assumed previously. The explanation for this appears to be herbicidal interference with build-up of food reserves in preparation for winter dormancy. Effects of silvex rates: Under high temperatures silvex treatments of 1 and Impounds active per acre gen­ erally cause the most severe reduc­ tion of root growth and appear to be most detrimental. The 3-pound rate does not always give as much kill; it tends to cause more contact burning and give less total effect. Under cool temperatures bentgrass appears to be injured the most from treatments of 1% and 3-pounds per acre. Influence of pH: Untreated bent­ grass plants grown in nutrient solu­ tions of pH 4.8 appeared to grow bet­ ter than those in cultures at pH 7.0. However, with plants receiving silvex treatments injury was greater at the low pH. Effects of moisture level: Bentgrass conditioned to low available moisture appears to tolerate detrimental rates of silvex better than when growing under higher moisture levels. How­ ever, when moisture is depleted silvex treatments tend to hasten bentgrass desiccation. Effects of Phenoxy Herbicides on Four Turf Species Turfgrasses treated at several ages of seedling growth with 2, 4-D, silvex 2 USGA GREEN SECTION RECORD and 4-(2, 4-DB) showed greater toler­ ance with increasing age. Seedlings of Colonial bentgrass, Merion Kentucky bluegrass, creeping red fescue, and common bermudagrass treated at 8, 10, 14 and 18 weeks of age with the three phenoxy herbicides usually showed foliage injury. Generally, in­ jury correlated with the rate of phe­ noxy application and with the type of root and shoot growth of the species. Seedling responses at 6-weeks of age: At 6-weeks bentgrass seedlings were fatally injured and bluegrass was severely injured by all rates of the three phenoxy herbicides. The rapidly developing fescue and ber­ mudagrass seedlings showed severe injury only from the rates of 1-pound and higher. Seedling responses at 10-weeks of age: Bentgrass was severely injured from 1, iy2 and 3-pounds of 2, 4-D and 4-(2, 4-DB) and fatally injured from all rates of silvex. The 1-pound rate of 2, 4-D and silvex and 1, iy2 and 3-pounds of 4-(2, 4-DB) caused very severe or fatal injury to blue­ grass. Fescue continued to exhibit considerable tolerance being severely injured only from the 1-pound rate. Bermudagrass showed a fair overall degree of tolerance; it was severely injured from the 1-pound rate and higher, particularly from silvex. Seedling responses at 14-weeks of Fig. 1. Root and shoot growth of Colonial bentgrass, Merion Kentucky bluegrass, creeping red fescue, and common bermudagrass at 18-weeks of age 20 days after treatment with silvex. Figures under each plant indicate pounds per acre. MAY, 1965 3 age: Although 14-week-old seedlings of bentgrass and bluegrass were still highly sensitive to silvex, they showed considerable tolerance to 2, 4-D and 4-(2, 4-DB). Fescue and bermudagrass declined rapidly in general suscepti­ bility. The higher phenoxy rates of 1 through 3-pounds per acre still caused moderately severe injury. Seedling responses at 18-weeks of age: Bentgrass and bluegrass showed good tolerance at 18-weeks of age, especially to 2, 4-D and 4-(2, 4-DB) (Fig. 1). Although fescue declined in growth rate it still exhibited very good tolerance to the three phenoxys. Bermudagrass seedlings continued to grow rapidly and gain tolerance. General seedling response: Blue­ grass seedlings usually showed more tolerance to the phenoxys than did bentgrass at corresponding ages. Fes­ cue generally appeared less suscept­ ible to phenoxy injury at the four ages of seedling growth than did ber­ mudagrass. However, both exhibited much greater tolerance than either bentgrass or bluegrass seedlings. Silvex injury was usually more severe than 2, 4-D. Generally 4-(2, 4- DB) caused mild injury. The 1-pound rate generally caused more severe plant injury than higher rates. This suggests that lower concentrations may be absorbed and translocated be­ fore foliage burn prevents further chemical uptake. Higher concentra­ tions usually cause rapid burning of foliage which greatly reduces the amount of chemical absorbed. Phenoxy Induced Tissue Abnormalities Untreated root tip: Normal root cells in an untreated root tip of Co­ lonial bentgrass (Fig. 2) may appear well defined, orderly and uniformly arranged. Various stelar elements (photo A and B) such as the peri­ cycle (the cylinder of cells in the outer stelar region exhibiting a nu­ cleus), the xylem, and phloem gen­ erally lack prominence. Typical meristematic cells can be seen to rapidly differentiate into column type rows of rectangular shaped epidermal and cortical cells (photo C and D). The general absence of lateral roots and root hairs is also typical of this region. Silvex affected root tip: Those who have observed for the first time the microscopic effects that a phenoxy herbicide may have on the roots of a turfgrass are often astounded (Fig. 3). This is understandable since these tissue abnormalities are not normally visible to the naked eye. Tissue ab­ normalities induced in bentgrass roots were observed as contributing to the death of the plant. These tissue dis­ PUTTING GREEN CONSTRUCTION ASSISTANCE Greens constructed according to procedures outlined by the USGA Green Section must have a seedbed that conforms to a rather narrow specified range of physical qualities. The tests for determining the mix­ ture of your materials which will most nearly meet these requirements are available through the Green Section. Cost of the analysis is $109. Con­ tact any Green Section office for further details. (See inside front cover). 4 USGA GREEN SECTION RECORD orders and cellular disruptions ap­ pear to obstruct normal nutrient pass­ age through conductive tissues and actually destroy the function of many cells. Accelerated and prolific forma­ tions of roots, root hairs, and cells could also occur at the expense of food reserves. Abnormal formations of roots and root hairs are highly prevalent in the region of the root tip following a phenoxy treatment. Some cortical cells may swell to at least 24 times the size of corresponding normal cells. The pericycle cells, as well as their nu­ cleus, often become very large and prominent (photo B). Lateral root for­ mations (photo C) may occur abnor­ mally close to the root tip. Massed pro­ liferations of the pericycle (photo D) and massed lateral root formations (photo E), with accompanying swollen cortical cells, are often conspicuous. These massed lateral root formations are usually more prevalent in the region where the pericycle is prolif­ erating. Similar tissue abnormalities were Fig. 2. A median longitudinal section of the apical 2000 microns of a normal Colonial bentgrass root. (Camera lucida drawing as 100X and photomicrographs as 1290X). Fig. 3. A median longitudinal section of the apical 2000 microns of a silvex affected Colonial bentgrass root. (Camera lucida at 100X, photomicrographs A. C, D, E at 300X and B at K90X). MAY, 1965 5 observed to be produced by 2, 4-D, silvex, and 4-(2, 4-DB) in Colonial and creeping bentgrasses, Merion Kentucky bluegrass, creeping red fescue, and common bermudagrass. to plant diseases. Any of these factors offer a great threat to the survival of the plant particularly when accom­ panied by medium to high tempera­ tures. SUMMARY The effects of phenoxy herbicides on turfgrasses may be limitation of root system, depletion of root food re­ serves and actual tissue disruptions which result in either plant death or making the roots readily accessible Safety of sensitive turf species to phenoxy herbicides may be increased by using lower concentrations applied during cooler growing seasons. The safest period for treating bentgrass appears to be from early- to mid­ spring. Potassium - Neglected Nutrient By Dr. H. E. Hampton" Potassium is one of the several chemical elements which are es­ sential for plant growth; it is needed in rather large amounts by plants, especially the grasses. All growing portions of plants, both tops and roots, are rich in the ele­ ment. Potassium seems especially abundant in the cells of new roots and young leaves. It is one of the more mobile nutrient elements and is ap­ parently withdrawn from older tissues of the plant and transferred to regions of new growth. As plants approach maturity, it has been found that po­ tassium can be translocated into the soil. Of all the major nutrients, potas­ sium seems to be the only one that does not become a constituent of plant compounds. Its primary role seems to be that of a catalyst — a substance which accelerates a chemical reaction or enables it to go on but does not enter into the products of the re­ action. An Australian researcher working with perennial ryegrass found that potassium occurs entirely as soluble, ionic potassium in cell sap and protoplasm. Other workers have found the potassium contained in plants to be readily soluble in water. It appears that if the potas­ sium in plants is combined at all with the protoplasm, it is easily dissociated from it. The loss of the plant’s power to syn­ thesize carbohydrate in the absence of potassium has been reported in several papers. It seems that potas­ sium is essential for the process of photosynthesis in which sugars are manufactured. Potassium has been found essential for the condensation of the simple sugars into more com­ plex carboydrates such as starches and the celluloses and for the forma­ tion of lignin, the principal compound of woody plants. Several workers have reported evidence that potassium is necessary for the translocation of the carbohydrates from one part of the plant to another. Lignin Content The lignin contained in plants con­ tributes to the strength of stems and ★Professor, Soil and Crop Sciences, Texas Acf:M University; summer staff member, USGA. Green Section. 6 USGA GREEN SECTION RECORD also the leaves. It has been reported that potassium significantly affects the lignin content of plant parts. The highest lignin content was found in plants of the grass family when the plants were supplied with medium amounts of potassium. Both deficient and excessive supplies resulted in lower lignin contents. Potassium is considered to play a role in the synthesis of plant pro­ teins. It is believed by a number of authors to be essential for the manu­ facture of the protein in plant cells. A deficiency of potassium has been found to result in significantly higher amounts of both amino nitrogen and nitrate nitrogen in the cell sap at the expense of protein. Several studies have shown rather conclusively that an adequate potas­ sium supply is necessary for normal development of the growing apexes of plants, especially the grasses. Not only will the above-ground parts show abnormal growth but root growth and extension is curtailed as well. But what has been said about the role of potassium is just so much “book learning” to the golf course superintendent. What he wants to know is how potassium affects the turf on a golf course. It has been said many times, and often not so humorously, that it would be a much easier job to grow grass on a golf course if it were not for the golfers. This is simply another way of saying that foot traffic and cart traf­ fic and swinging golf clubs are hard on turf. We pointed out earlier the essential nature of potassium on the formation of complex carbohydrates and lignins and it was stated further that these compounds, especially lig­ nin, contribute strength to stems and leaves. Turf plants deficient in potas­ sium are soft and lush, the leaves are lacking in turgor, and the blades are neither erect enough nor stiff enough to present a desirable putting sur­ face. The leaves are easily bruised by traffic. The correct ratio of potassium to other nutrients, particularly nitro­ gen, will do much to harden and stif­ fen the turf. The “Health Nutrient” Potassium has been referred to as the “health nutrient.” It is generally accepted that potassium - deficient plants are more subject to certain diseases. The regular clipping of turf, especially on putting greens, prevents the plant from maturing and thereby increases the susceptibility of the plants to disease. Several studies have indicated that leaf spot diseases of turfgrasses. Helminthosporium spp. TURF BOOK AVAILABLE The book “Turf Management,” a popular educational printing of all matters pertaining to turf, is available at $10.95 per copy from the USGA, 40 East 38th Street, New York, N. Y. 10016; the USGA Green Section Re­ gional Offices; the McGraw-Hill Book Co., 330 West 42nd Street, New York, N. Y. 10036, or at local bookstores. “Turf Management” is a complete and authoritative book written by Professor H. Burton Musser and sponsored by the USGA. The author is Professor Emeritus of Agronomy at Pennsylvania State University. MAY, 1965 7 especially, are more prevalent when the supply of potassium is limited. Other diseases of turf may be simi­ larly affected by potassium. The influ­ ence is due in part to the soft, easily- crushed leaves of potassium-deficient plants which enable the pathogens to gain entrance, and in part to the con­ centration of sugars and nitrates in the leaves which makes more favor­ able media for the development of the organisms. This does not mean that applications of potassium consti­ tute a specific cure for diseases. If it is found, however, that a disease persists in spite of regular use of fungicides, it would be wise to check the potassium status of the soil. Any practice which will promote the vigor of the plants will help combat disease. Both phosphorus and potassium fertilization have been reported to in­ crease the winter-hardiness of turf­ grasses. The effect has been attri­ buted to the increased concentration of dissolved substances, largely sol­ uble carbohydrates, in the cell sap. The fact that potassium increases the reserve of stored carbohydrates in the roots is thought also to make peren­ nials more cold tolerant. In an experiment conducted at Iowa State, it was found that Ken­ tucky bluegrass which was supplied relatively low nitrogen and phos­ phorus and high potassium withstood hot weather better than bluegrass sup­ plied with either high nitrogen, phos­ phorus, and potassium or high nitro­ gen and phosphorus and low potas­ sium. The practice of applying nitrogen alone during the summer months is likely to induce a nitrogen to potas­ sium imbalance resulting in greater heat damage to the turf. Many super­ intendents wisely make a practice of reducing the amount of nitrogen ap­ plied during the hot months to about half the amount they apply during the same period of time in the cooler spring months. Some withold nitrogen entirely during the hot months, especially on bent greens. If adequate potassium has been applied in the fall and spring, a summer application of potassium fertilizer may not be needed. In case a shortage of potas­ sium becomes apparent, however, it might be wise to apply a light appli­ cation of potassium fertilizer in the hot months. Turf Density A common problem in the manage­ ment of turfgrasses is the mainten­ ance of a good stand, often referred to as turf density. Although much of the loss in density is due to winter- killing, injuries associated with high temperatures and the weakening of turf by disease also cause many plants to die. Potassium deficiencies aggra­ vate all of the above. The growth and extension of roots which are promoted by potassium are particularly import­ ant in keeping a cover of healthy, vig­ orous turf. The importance of potas­ sium in helping to maintain the den­ sity of turf should be emphasized but the need for potassium fertilization is often overlooked. Potassium occurs in several forms in the soil. By far the greatest por­ tion of it is present as a constituent of the minerals and the organic mat­ ter composing the solid portion of the soil. Only a relatively small portion of the potassium occurs in soluble, avail­ able forms. Potassium is taken up through the roots of plants as the po­ tassium ion which occurs in the soil solution and also attracted to the clay particles. Either of these can be ab­ sorbed by plants. Plant species vary considerably in their potassium needs. A review of the 8 USGA GREEN SECTION RECORD literature seems to indicate that the potassium requirements of turf grasses are intermediate to high as compared to plants as a whole. At least the turf grasses are generally benefited by potassium fertilization. Some soils are well supplied with natural potassium whereas many others are deficient. Sands and sandy loams are nearly all naturally lack­ ing in potassium. The finer-textured soils usually but not always contain a good supply of the nutrient. Inasmuch as fairways and tees are usually constructed of the soil occur­ ring locally, potassium may be lack­ ing or in adequate supply depending upon the nature of the soil. The soil mixture used to construct putting greens contains more sand and potas­ sium deficiencies commonly occur. This is especially true if the putting greens have been constructed accord­ ing to USGA Green Section specifica­ tions. The potassium problem under putting greens is aggravated by the practice of removing the grass clip­ pings. The removal results in accelerated exhaustion of several plant nutrients including potassium unless the nutri­ ents are regularly replaced. It has been shown that the removal of large amounts of herbage can reduce po­ tassium from an apparently high to a low level in one season bringing about problems associated with potassium deficiency. Much has been written about “nu­ trient balance,” which is to say that an over-supply of one nutrient will bring about deficiencies of one or more other nutrients. Large applica­ tions of lime, for example, have been known to induce shortages of phos­ phorus and potassium and often mag­ nesium. The trend toward the use of nitrogen fertilizers alone on nitrogen and phosphorus fertilizers has re­ sulted in deficiencies of potassium. On the other hand, too much potas­ sium may induce deficiencies of cal­ cium and magnesium. Signs of Deficiencies Deficiencies of potassium may be indicated in several ways. The specific symptom depends upon the species or possibly the group of plants and to an extent upon the available supply of other nutrient elements. Signs of po­ tassium starvation are often seen as premature dying of the leaves when nitrogen and phosphorus fertilizers are applied in high amounts relative to the potassium. When nitrogen and potassium are simultaneously in short supply, the plants tend to be stunted, their leaves small and somewhat ash- gray in color. Premature death often occurs, starting at the tips and along the margins of the leaves. Large sup­ plies of nitrogen relative to potassium, on the other hand, result in the de­ velopment of large leaves which are watery and lush. Actually clear-cut visible symptoms of potassium de­ ficiency in turf grasses are not com­ mon. The growth and health of turf­ grasses may be impaired due to a po­ tassium shortage although there are no visible signs. The result is an over­ all loss of vigor in the plants. The in­ sidious nature of “hidden hunger,” especially that induced by a shortage of potassium, has been mentioned by several writers. Soil and tissue tests are helpful tools in the diagnosis of plant needs. By chemical techniques we hope to ascertain the “hidden hunger” that is not visibly evident. Recommended pro­ cedures for soil and tissue analyses are not entirely infallible, however, and interpretations of test results are not easy. This is particularly true in the case of potassium. For example, MAY, 1965 9 many people have full confidence in plant tissue tests for potassium al­ though it is known that in nitrogen deficient plants potassium may ac­ cumulate whereas with adequate ni­ trogen potassium may be utilized so rapidly that it appears deficient. By the foregoing statements it is not intended to imply that soil or tissue testing are not helpful tools. They must be conducted and inter­ preted by a well-trained, experienced person, however, who knows or has been informed of past treatments and plant behavior. At several of the Land Grant Universities the personnel con­ cerned with soil and tissue testing are cooperating closely with the turf specialists. Most golf course superintendents use liberal amounts of nitrogen fertil­ izer. Many make applications of phos­ phorus and potassium alone or with nitrogen once or perhaps twice a year. On some courses, only nitrogen and phosphorus are applied. There is evid­ ence that enough phosphorus fertil­ izers are being used on most courses to satisfy the needs of the turf. There is about as much evidence to indicate that the amount of potassium which is being applied does not adequately supply the grass plants throughout the year. Either an insufficient amount of potassium fertilizer is being put on or the amount being applied could be better distributed through the year. Such a statement may be made be­ cause plants are known to take up more potassium then they need if the soil supply is high in potassium and a fall or winter application of potas­ sium can be exhausted before summer. The variations in soil characteris­ tics and the differences in plant species mean that there is no such thing as a balanced fertilizer. Amounts of N, P, and K which seem adequate or “balanced” for a certain turfgrass on one soil are likely to prove inadequate on another soil or for the desirable growth of another turfgrass. The need for better balance between nitrogen and potassium is currently receiving more attention. Relative amounts of nitrogen and potassium which appear to result in the produc­ tion of desirable turf in the cooler spring months usually do not work out so well in the hot months. This is not to say that nitrogen is not needed dur­ ing the summer; it does appear, how­ ever, that more potassium in relation to the nitrogen is needed during sum­ mer especially on bermuda greens. Muriate of Potash Potassium is most commonly ap­ plied as muriate of potash. In areas such as Florida or the Pacific North­ west where sulfur is often deficient sulfate of potash is recommended. There has been little evidence of a shortage of sulfur in the soils of the Southwest. A few other potassium ma­ terials are used in parts of the country where such materials are cheaper than muriate of potash. At the present time nearly all of the muriate of potash fertilizer used in the Southwest is mined near Carlsbad, N.M. Most of the mixed fertilizers on the market contain potassium as well as nitrogen and phosphorus although a few contain only nitrogen and phos­ phorus. All of our fertilizers having ratios of 1-1-1, 2-1-1, 3-1-2 and the like contain potassium. They are called complete fertilizers. The amount of potassium in a fertil­ izer is expressed as per cent potas­ sium oxide, usually referred to as pot­ ash. None of our potassium fertilizer materials or mixed goods actually con­ tains potassium oxide. Any potassium compound in the fertilizer which is 10 USGA GREEN SECTION RECORD soluble in water is determined chem­ ically and calculated as per cent K2O (potassium oxide). It is not necessary that any potassium oxide be present in the fertilizer. In muriate of potash, the most common potassium material, most of the potassium occurs as the chloride but there may be a very small amount of potassium sulfate present. Both the chloride or the sulfate forms of potassium are suitable as sources of potassium. Fertilizer recommendations are us­ ually given in pounds of plant food per acre although recommendations for lawns, putting greens and other small-sized areas are often given in pounds per 1,000 square feet. A recom­ mendation of 120-80-80, for example, calls for sufficient fertilizer to supply nitrogen equivalent to 120 pounds of N, to supply phosphorus equivalent to 80 pounds of P2O5, and to supply potassium equivalent to 80 pounds of K2O per acre. The fertilizer recom­ mendation is taken to mean the an­ nual amount unless otherwise stated and all of the plant food may not be put out in one application. In order to convert a recommenda­ tion in pounds per acre to pounds per 1,000 square feet, one simply needs to divide each number of the former by 43. To the nearest whole number then, the recommendation of 120-80-80 would become 3-2-2 pounds of N, P2O5 and K2O respectively per 1,000 square feet. This means that an amount of fertilizer equivalent to 3 pounds of N, 2 pounds of P2O5, and 2 pounds of K2O should be applied to each 1,000 square feet. The amount of potassium which will produce healthy, vigorous turf de­ pends upon several factors or condi­ tions. It is not possible to give a specific amount which will fit all soils and all turfgrasses. Recommen­ dations have ranged from one to as much as four pounds of equivalent K2O per 1,000 square feet annually. Frequently all of the potassium is ap­ plied in the fall or sometimes all is applied in the spring. Some superin­ tendents apply part of the potassium in the fall and the remainder in the spring. Most commonly all of the phos­ phorus and a part of the nitrogen are applied with the potassium. Applying Potassium Although recommendations based on sound soil tests are more reliable, the following may be helpful in ar­ riving at the amounts of potassium to apply: 1. Pounds of equivalent K2O annually per 1,000 square feet on fairways and tees— a. Clay or clay loam soils 1 pound b. Loams or silt loams ........ 1 pound c. Sands and sand loams 2 pounds 2. Pounds of equivalent K2O annually per 1,000 square feet on putting greens— a. Sands and sandy loams 3 pounds b. Putting green mixture* 3 pounds For best results it appears that the annual amount should be split into fall and spring applications. The fall and spring applications should include all of the phosphorus and a part of the nitrogen in addition to the potas­ sium. In other words, a fertilizer hav­ ing a ratio 1-1-1, 2-1-1, or 3-1-2 is a good choice. Inasmuch as nitrogen fertilizer is usually applied regularly on the putting greens throughout the year, a high nitrogen to low potassium balance may develop resulting in greater heat damage to the turf. In this connection it is wise to consider reducing nitrogen slightly and in­ creasing potassium a bit during the summer months. Applications of about ■According to specifications recommended by the USGA. Green Section. MAY, 1965 11 % pound of equivalent K2O per 1,000 square feet should be ample unless the amount of nitrogen being used is exceptionally high. Inasmuch as recommendations are nearly always given in pounds or equivalent K2O, it is necessary to be able to calculate the amount of potas­ sium fertilizer or mixed fertilizer needed to attain the recommenda­ tion. Suppose it is desired to apply one pound of equivalent K2O per 1,000 square feet using a 12-4-8 fertilizer. The amount of the 12-4-8 fertilizer needed would be calculated as fol­ lows : The equivalent percentage of K2O in the mixed fertilizer is 8%, therefore each 100 pounds of the fertilizer contains 8 pounds of equivalent K2O. Since one pound is 1/8 of 8 pounds, 1/8 of 100 pounds is 12.5 pounds, the amount of the 12-4-8 fertilizer which should be applied to 1,000 square feet. Such an amount of 12-4-8 would supply also iy2 pounds of equivalent N and % pound of equivalent P2O5. Soluble salt crystals which cling to the foliage cause the injury called burning. Pelleted fertilizers are less likely to cause burning than crystal­ line or powdered materials. It is well to keep in mind that potassium fer­ tilizer materials like nitrogen mater­ ials have a salt effect and will burn the turf if not applied properly. Po­ tassium materials can be applied dry but to prevent burning the turf must be sprinkled immediately to wash the fertilizer off the tops. Muriate of pot­ ash can be dissolved in water and ap­ plied as a solution. It should be borne in mind also that uniform distribu­ tion of fertilizers is essential. Potassium has been aptly called the neglected nutrient. Its effect on the growth and appearance of grass is not as pronounced as that of nitrogen, therefore a deficiency of potassium is not so evident and is often overlooked. From experimental evidence, we are certain that proper attention to po­ tassium fertilization is essential for a healthy, vigorous turf. Flood Damage in Oregon The photographs on the next page and the front cover show some of the damage suffered by the Illahe Hills Country Club course in Salem, Ore­ gon, from flooding of the Willamette River during Christmas week, 1964. Two greens were totally destroyed and although reconstruction is now under­ way at least seven months and a con­ siderable expenditure will be needed before complete recovery is achieved. The 11th green (see front cover) is situated in a bend of the river and was under 10 feet of moving water at the crest of the flood. It seems apparent that most of the damage to the green was caused by swift moving logs or trees as they floated down the stream and across the green. They tore through the sod, exposed the soil be­ low and allowed the erosion process to begin. To guard against future severe damage from flooding, the Club is considering elevating the green by several additional feet and having the elevation taper off to the upstream side. Also under consideration is the use of pilings on the upstream side to divert the flow around the green and to prevent debris from passing over it during flood stage. 12 USGA GREEN SECTION RECORD USGA GREEN SECTION RECORD 40 East 38th Street, New York, N. Y. 10016 TURF TWISTERS ACID SOILS Question: In recent issues of a New Zealand turf publication, the virtues of acid soils have been described. What does the Green Sec­ tion think about this? (Missouri) Answer: There is not a simple answer to the question. Two fairly well established facts should be kept in mind. First, grasses will tol­ erate a rather wide range of conditions with respect to acidity and alkalinity, provided all of the necessary nutrients are supplied in adequate amounts. Secondly, a soil which is near neutral or just slightly acid in reaction will favor the availability of most plant nu­ trients. Therefore, we normally suggest that soils be maintained at somewhere near the neutral point. The theory of acidifying soil has enjoyed some favor in the United States in past years. It is believed that clover and some other weeds are easier to control if soils are acid and that grasses will continue to thrive. While this is probably true, we have taken the position that it is preferable to control weeds by other methods and to maintain as good conditions for nutrient availability as is pos­ sible. LEAD ARSENATE Question: Is there any value in using arsenate of lead on putting greens? (California) Answer: It has been demonstrated many times that arsenate of lead is both a good insecticide for controlling soil inhabiting insects and an effective control of Poa annua and crabgrass. Its effectiveness as an herbicidal agent is modified however by the phosphorus content of the soil. Apparently high levels of phosphorus cause lead arsen­ ate to be less effective and consequently much larger quantities must be used under such conditions.