-"era "'v . f v g” 75K; - n A W“» ibw Dxc@¢b§ , UQO + 9 1 L" U‘ ‘j 4' '14"! i Sweetclover in T exas OALLAv 541w». or . “we: uPScOMB $0M . aomfll\ PCYYEP CAQSCW 69A‘ WNEELE" DIOR YB gr» 5mm nancr. “m” l OONLU lc°"'""‘°5' ' I smouc l pinata l gnsvno _ Sms '9 an-sooal wzu. °:‘LQ L ‘ as. __ I _ Jitnnocum “u. gAUB MALE lamb vomzv covnt \‘"'\*‘wn.ana- l \ romo can ""°"'“. l \__ —\ "' l I l . - u.“ ‘ g ‘ ‘ o F N u ‘ “an - . N , gq “can z COOKE GRAYS I l "' U] ' r-‘K-(“QAN p-qficiLtY LIJBBOCI 5BV WCKENJ KING KNOX BAYL _ . g no‘ _ no‘ a I | i ‘ vs , l‘ ' ' l I'll 5 . u: s “Dub what“ "not... vow“ . “c, “,5; “mo... cow» ‘nu-n new. - as u Ton _ l ' Fl» . cm» o“ . ' n11 - mic ‘ fin n“ “.n'°~ - fl wooo , uvsuul - WALL ____ 7i u I SMACIEL- u; "L0 .PARKEI nmunv -ou.:.n$ 6,143 lglISCH BZM.&$CUPRY _ r-snzn 40mg; m” To ‘cum; Y[flliv. 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ITLSCOSA _ “M18- J V Znvf-Ll ""0 l 1 . . . 6O 5D ' z _ 1 *' 3| r ant-u.- — u SILLC .'“ l uv:\ a“ *1‘ w‘ X IIULLEN o“ _ l. ‘T G - - " w,“ l: 340K515 ' g ntsawf -. _ ~""‘_ Qsnoons xzmznv was J - s i 1 EIWLAC; NIQA.CQ l“ CN- E; an ‘a Areas of adaptation oi sweetclover in Texas. Area I—not g lly recommended. Area II—biennial white, biennial yellow. annual white (Hubam): Area II-N—spring planted: Area II-S-may be tall planted. Area III-annual white, annual yellow. Area IV-not recommended except under irrigation. - ‘#mmMm@fl TEXAS AGRICULTURAL EXPERIMENT STATION R. D. LEWIS. Dmscron. COLLEGE STATION. TEXAS DIGEST Sweetclover was among the first legumes tested by the Texas Agricultural Experiment Stati Four species, two biennials and two annuals, are now grown in Texas. The important varietiesam these species are Madrid, Evergreen, Hubam and annual yellow-flowered sweetclover. The cover - ture shows the areas of adaptation. Biennial sweetclover was found to be well adapted on the limestone soils in the State before 19 Agricultural research workers recognized its value as a soil-conditioning crop and recommended it i this purpose. Research at the Angleton station in 1915 showed that it was necessary to inocu sweetclover. Studies were conducted at Chillicothe to determine the most effective date of planti rate of seeding, row width and the influence of seed scarification on forage yields. Good yields w obtained from plantings ma.de from January 1 to April 1. Better stand survival was obtained at C A icothe when sweetclover was seeded in 32-inch rows than when close-sown in 8-inch rows. ' Since sweetclover seed are small, 260,000 to 350,000 per pound, they should be planted one- inch deep on a firm clod-free seedbed. Location within the State determines whether sweetclover sho be spring or fall-seeded. It may be planted alone or with small grains. At least 40 pounds of phi phoric acid (P205) per acre usually are necessary for good results. Soils should be tested to det mine the kinds and amounts of fertilizer for sweetclover. Band application of phosphate fertil” has proved superior to broadcasting. I Sweetclover is a good pasture crop and provides abundant grazing. Because of its character’ bitter taste, the first reaction of cattle to sweetclover may be unfavorable, but they graze sweetclo readily when they become accustomed to it. On sweetclover-oat pasture at Temple, steers gained much as 2.1 pounds per day. The quality of the forage, as measured by protein and phosphorus tent, is excellent. Sweetclover grows well with perennial grasses, especially Johnsongrass. 5 grown with oats, it is one of the best pasture combinations. Sweetclover makes good hay and si Spoiled sweetclover hay or silage contains dicoumarol which injures the fine capillaries and redu, the clotting power of the blood of animals. Such spoiled hay or silage should not be fed to livest‘ Sweetclover adds nitrogen to the soil, makes soil more friable, thereby increasing aeration, offers protective cover for the land. Crops following sweetclover normally produce more than cr grown continuously on the same land. i Maximum soil benefits have been obtained from sweetclover by harvesting a seed crop and ret r ing all the residue to the soil. On many farms, the production and sale of sweetclover seed are pa enterprises. Sweetclover planted in pure stands and managed for seed production gives highest ‘a yields. Experiments show that pollinating insects are necessary for good seed production. Cutting =i windrowing the sweetclover plants when two-thirds of the seeds have turned brown, allowing them dry in windrow and then combining, is the most satisfactory method of harvesting the seed. " Although a number of insects attack sweetclover, there is only one at present that is specifici sweetclover. This is the sweetclover root borer, for which there is no known control. Amongfithemg important diseases of sweetclover are cotton root rot, blackstem and anthracnose, for which there no known controls. a ACKNOWLEDGMENTS Much of the research reported in this bulletin was conducted at the various substations. Sp recognition is given to J . Roy Quinby and J . C. Stephens of the Chillicothe station for the early rese g on seeding sweetclover. The early work of Paul B. Dunkle (deceased) at the Denton station _1 been a major factor in the wide distribution and use of Madrid sweetclover in North-central Te The Blackland station at Temple also has contributed much information through grazing studies sweetclover and small grain. ~ The section on Diseases of Sweetclover was contributed by Marvin H. Whitehead, formerly - fessor, Department of Plant Physiology and Pathology. i ' l I J TCLOVER IS MORE WIDELY ADAPTED IN TEXAS any other cultivated legume. Where sweet- I grows well, the roots penetrate the soil, g it up so that water intake is rapid. The ‘cal condition of the soil is improved and nd is easierto till. When sweetclover roots ell nodulated, large amounts of atmospheric en are fixed and are available for succeed- ,~ ops. It is a good pasture and hay crop. '- farms make a good business of the sale of Sweetclover was among the first legumes p: by the Texas Agricultural Experiment Sta- ,_ The performance of Melilotus alba, a bien- white-flowered sweetclover, is reported in jtin 34 of the Texas Station, published in f (3). At McKinney, spring-planted M. alba i to a height of 4 feet by August 1. In Oc- ,_ , the taproots were 18 to 24 inches long with _meter at the crown of one-half to three- hs inch. At College Station, M. alba, plant- April 20, 1894, grew to a height of 15 to ches by midsummer. In summarizing this the authors stated that “it is prized as a vating crop for enriching worn lands” and is fof the most promising spring-planted clovers. 1 Texas Station bulletin (14), published in , sweetclover was recommended as “a restor- e crop on poor loams and lime land,” and the ors stated that “sWeetclover thrives on lime hes and dry prairies where many crops fail.” l: from farmers, given in a Texas Station etin in 1901 (5), show the wide adaptation of tclover: Waco—“planted on fertile sand, it splendidly and kept down all weed growth”; lin—-“grew 3 to 5 feet tall, roots very large could not be pulled up; stood drouth very . ”; Harris county- “planted on heavy black A1 l. SPECIES AND VARIETIES OF SWEETCLOVER ADAPTED TO TEXAS 1.... on names Species Varieties ~ 'al white- Melilotus alba Evergreen wered Spanish " Common white ~ ‘al yellow- Melilotus Madrid wered otticinalis Common yellow ual white- Melilotus alba Hubam wered annua Floranna dual yellow- Melilotus indica Annual yellow-flow- wered ered (Sour) or (M. indica) Sweetclover In T exas R. C. POTTS, Professor Department of Agronomy clay, stood 90 days without rain, lived through dry season and made some growth.” DESCRIPTION OF SPECIES There are several known species of sweet- clover, but only four are important to the Texas farmer. Table 1 gives the species and varieties of sweetclover adapted to Texas. The sweetclover plant is erect with slender, somewhat angular stems which become woody at maturity. The central stem often is not conspic- uous as 5 to 10 stems may come from the crown of the plant. Stems on biennial sweetclover may reach a height of 4 feet the first season, While the second year they will be tallerand more vig- orous. Figure 1 shows some characteristics of the sweetclover plant. The leaves are trifoliate and the leaflets are borne on a petiole about the length of the leaves. The leaflets are one-half to three- fourths inch in length, broadly oblong, rounded CONTENTS Page Digest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . .. 2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 Description of Species . . . . . . . . . . . . . . . . . . . . . . . . 3 Biennial White Sweetclover . . . . . . . . . . . . . . . . . 5 Biennial Yellow Sweetclover . . . . . . . . . . . . . . . . 5 Annual White-flowered Sweetclover . . . . . . . . . 5 Annual Yellow-flowered Sweetclover. . . . . . . . 5 Early Tests with Sweetclover . . . . . . . . . . . . . . . . . . 6 Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 Planting Sweetclover . . . . . . . . . . . . . . . . . . . . . . . . . 8 Sweetclover for Pasture . . . . . . . . . . . . . . . . . . . . 9 Sweetclover for Hay . . . . . . . . . . . . . . . . . . . . . . . .10 Sweetclover tor Silage . . . . . . . . . . . . . . . . . . . . . .10 Sweetclover in the Cropping System . . . . . . . . .11 Seed Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Diseases of Sweetclover . . . . . . . . . . . . . . . . . . . . .14 Southern Anthracnose . . . . . . . . . . . . . . . . . . . . .14 Cotton Root Rot . . . . . . . . . . . . . . . . . . . . . . . . . ..15 Charcoal Rot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Spring Blackstem . . . . . . . . . . . . . . . . . . . . . . . . . .15 Summer Blackstem . . . . . . . . . . . . . . . . . . . . . . . .15 Leaf Spot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 (p. IV V Stigma (B) Style (C) Ovary (D) Anther (E) Stamen (F) United stamens. III. Mature ovary (A) Pod (B) Calyx. y Figure I. Sweetclover plant. I. Single floret (A) Standard (B) Wings (C) Keel (D) Calyx. II. Sexual parts (I Flowering branch. V. Leaf showing (A) Stipules. d notched at the tip and serrated 0n the mar- s. The stipules, small leaf-like bracts at the A e 0f the leaf petiole, are one of the basic means distinguishing sweetclovers from alfalfa and 3 ain other legumes. The flowers are small and are borne in slen- i racemes. The calyx is green, smooth or slight- pubescent, and the calyx teeth are short and rly equal. The corolla is made up of two wing als, a keel and a standard petal. The standard larger than the wings. The wings have nar- ;~ claws at the base and are somewhat longer n the keel petal. There are 10 stamens, 9 are ted at the base and 1 is on a single filament. stamens produce fertile anthers but do not elop at the same time, thus pollen may be shed E hina given flower for several days. The num- i of ovules that develop per flower vary from ,to.four, one being the most common. It is erally accepted that sweetclover is cross pol- ted but seedmay be produced by self-pollina- I 5 The pod is indehiscent, short, one-eighth to ee-sixteenths inch in length and wrinkled. The I are covered with a thin cuticle which is not A eable to water. The number of seed per nd varies from 260,000 to 350,000, depending the species. . Sweetclover has a taproot system. Its ex- t and vigor varies with-the species. The root item of the biennial sweetclover enlarges 'tly the first year, storing large amounts of ohydrates for use during the second grow- season. As the first-year plants become old- the upper part of the root system becomes 'y. Dormant buds develop at the crown of plant. In the early spring of the second year, k dormant buds develop into the second year’s wth. The root system of the annual types is vigorous and reaches full development at the e of flowering. 11- 'al White Sweetclover . This species, Mellilotu-s alba, is distinguished its biennial habit of growth and white flowers. hough several varieties have been developed, rgreen shows the most promise for Texas con- ons. Developed by the Ohio Experiment Sta- , it was released in 1924. It is tall-growing, - maturing and higher in forage production n other varieties. The flowering period occurs - a period of 6 to 8 weeks, therefore, it is pos- e to obtain only a small amount of seed at any time. This characteristic has made seed ex- ive and difficult to obtain. For these rea- _, Evergreen has not been generally planted in S, ' I Spanish, a variety introduced from Spain in 0, shows some promise in Texas. It has vigor- , growth, is leafy, upright and of medium ht and maturity. - White-flowered biennial types of unknown 7 'n are sometimes grown, and the seed are sold r the name of common white. Biennial Yellow Sweetclover This species, M elilotus officinalis, has a simi- lar growth habit to the white biennial, the main difference being its yellow flowers. Minor differ- ences are that white sweetclover may reach a height of 6 to 8 feet but the yellow rarely exceeds 4 to 5 feet; the variety Madrid is finer-stemmed with more leaves than common white. Taproots are well developed, but branch more than the white biennial form. The stems of the first season’s growth are inclined to be decumbent. Madrid, the most important variety, was introduced in 1910 by the U. S. Department of Agriculture from the Madrid Botanical Gardens of Madrid, Spain. Its vegetative characteristics are similar to the bien- nial white-flowered types. Early and uniform rip- ening of seed make this variety the best of the yel- low-flowered varieties for seed production. It has finer stems and more leaves than other varieties of sweetclover. It has good seedling vigor and is able to compete with weeds. It is more depend- able in the drier areas than common white be- cause it is 2 weeks earlier in flowering, thus es- caping the midsummer drouth. Common yellow consists of types of unknown origin grown for a number of years in the Great Plains States. It is lower-growing and more pros- trate with less leaf surface than the white-flow- ered types. Because of its ability to withstand adverse soil and climatic conditions, common yel- low often is planted in the Great Plains region. No attempt has been made in Texas to isolate varieties from the common yellow. In general, yield and performance of common has been infer- ior to the Madrid variety. Annual White-flowered Sweetclover Among. the annual white-flowered sweet- clovers, Hubam, M elilotus alba annua, is the most important in Texas. It was selected in Iowa from seed obtained in Alabama in 1916. It grows from 3 to 7 feet tall and has a good taproot system. It makes all its growth in one season, usually pro- ducing one main stem from which many branches arise and these are terminated by flowers. Hu- bam may be planted in the spring or fall in areas II-S and III, front cover, but should be spring- planted in area II-N. On soils where cotton root rot is a problem, Hubam fits into a cropping sys- tem better than the biennials. Although subject to cotton root rot, Hubam usually matures be- fore the disease can kill the plants. Floranna is a variety of annual white-flow- ered sweetclover released by the Florida Agricul- tural Experiment Station in the fall of 1951. Pre- liminary tests show that from College Station southward, it produces more forage than Hubam, is about 2 weeks earlier and makes more rapid regrowth after being grazed. Elsewhere in the State, it has shown no superiority. Annual Yellow-flowered Sweetclover species, M elilotus indica, is sometimes called sour clover. It is the only sweetclover that 5 Figure 2. Biennial white-flowered sweetclover. will grow on a soil low in lime. Annual yellow seldom reaches a height of more than 3 feet and the root system is Weaker and shallower than the other sweetclovers. This species is the most rapid growing and the earliest maturing among the sweetclovers. It usually is not winter-hardy north of an east-west line through Robertson, Madison, Trinity and Bell counties. Annual yellow sweet- clover has escaped from cultivation and is found growing along roadsides, wasteland and in pas- tures throughout South Texas. EARLY TESTS WITH SWEETCLOVER Tests were conducted with sweetclover by many of the substations soon after they were es- tablished (1, 4, 7, 9, 10, 19). In 1915, the Angle- ton station determined that it was necessary to inoculate sweetclover for good growth. Figure 2 shows a field of biennial sweetclover on the Den- ton station in 1917. Early work at Denton com- pared seeding rates in 30-inch rows (Table 2). In 1918, broadcast plantings of sweetclover at Den- ton were reduced as much as 40 percent by drouth; no'killing was observed in clover planted in 30-inch rows. Figure 3. A comparison of the growth of Hubam clover receiving phosphorus with no phosphorus at the Temple station. 6 Picture taken Iune 23, 1917 at the Denton station. S The Chillicothe station initiated tests in to determine the influence of planting date, wi of rows and scarified versus unhulled seed“? yield, along with a variety test. Table 3 sum p izes the results of date-of-planting and scarif tion experiments. Good yields were obtained f A all dates of planting from January 1 to Apr’), From these tests it was determined that unhu seed gave better results than hulled seed wt planted in December and January. The stay superintendent in reporting on these experim, stated, “the advantage of unhulled seed . that several stands of unhulled seed will ‘ quently emerge and a stand may be obtained i ter one emergence has been killed by freezi p The Chillicothe results show that sweetclo seed planted after February 1 should be scarifi Table 4 shows that on the average there ' no difference in forage yield from sweetcl planted in 32-inch and 8-inch rows at Chillico However, differences occurred among plan dates within years. Where weeds are a probl row plantings may be cultivated to control th ADAPTATION Many variety tests with sweetclover hi been conducted in Texas. Varieties released 3. experiment stations, the USDA and private i; ducers have been tested under various envip mental conditions. Varieties and species ada to different areas of the State are given in 1. Results of sweetclover yield tests at sev locations are shown in Table 5. " The general a r of adaptation of these varieties are given on p 1% front cover. TABLE 2. INFLUENCE OF RATE OF SEEDING BIE SWEETCLOVER IN SO-INCH ROWS ON YIEL. AIR-DRY FORAGE. DENTON f Rate of seeding’ Yield, pounds per acre pounds per acre First year Second year I Tot; a ssso zsoo also? s 2.480 2910 e450 a 2920 e170 eoal 3. POUNDS PER ACRE OF AIR-DRY FORAGE FROM BIENNIAL SWEETCLOVER PLANTED ON DIFFERENT DATES. ; CHILLICOTHE f Date harvested .‘ Scarified seed Unhulled seed ted Nov. 26. 1929 I May 28. 1930 | Total Nov. 26, 1929 May 28. 1930 Total ‘r 28 0 0 4,500 9,820 14.320 -28 2.480 3,860 6,340 6,120 6.900 13,020 ‘I 9 3,300 5,880 9,280 4.940 7,800 12.740 -29 3,940 6.060 10.000 4.380 6.920 11,300 1-29 3,280 5.720 9,000 3.460 6.000 9,460 29 2,780 5.520 8,300 6.200 9.440 * 9 2.360 5,370 7,730 . —— i -29 3.640 6.440 10.180 p 2,380 5,700 8.080 Q29 2,500 6,140 8,640 2,220 5,000 7.220 _. -29 3,040 6,760 9.800 2.860 6,780 9,640 29 2,580 _ 8,540 11,120 1,780 5.080 6.860 j Dec. 2, 1931 Iune 23, 1932 Dec. 2, 1931 Iune 23, 1932 i - " 2,500 5,760 8.260 2,680 5.980 8,660 2,320 5,840 8,160 2,540 6.640 9.180 2.980 7.940 10,920 2.300 6,300 8.600 2.680 8,060 10.740 2,640 7.940 10.580 2.560 7,420 9,980 2,380 7.680 10,060 7 2,720 8,540 11,260 2,500 7.920 10.420 ‘I 31 2.320 7,060 9,380 2.340 7,020 9.360 31 2.600 8,200 10.800 1.500 6.460 7.960 -31 2.460 7.720 10.180 2.540 11,160 13.700 p 1 2,100 8,460 10,560 1,600 6.560 8,160 31 1.940 6,980 8.920 1,480 6.820 8,300 _31 2.240 9,840 12,080 820 5,080 _ 5.900 i -31 Lgég ___. 1.120 1,120 4 1 , , I 1 3,980 3,980 4,0001 4.000 = .31 4,300 4.300 3.4001 3,400 V: 31 3,940 3,940 3.2001 3,200 ' 1 1,580 1.580 5001 500 ;i Oct. 28, 1933 Iune 24. 1934 Oct. 28, 1933 Iune 24, 1934 I 3 960 1,920 2,880 1,140 2,380 3,520 . 3 1.020 2.080 3,100 1,120 2.320 3,440 _ 3 1.180 2.600 3,780 1.180 2.460 3,640 l 33 1,120 2,260 3,380 1,140 2.420 3,560 " 3 840 3.280 4,120 1,620 2,720 4.340 nts bloomed in spring of 1932. "area I. d. a II. CHILLICOTHE, 1929-321 . Because of poor internal drainage in the soil, pH and a deficiency of phosphorus and pot- , sweetclovers generally are not recommended Sweetclover will grow on some soils this area if lime and proper fertilizers are ap- The sweetclovers, both the annual Hubam -» the biennial varieties, are well adapted to In much of the region, phosphorus is F only fertilizer needed. Figure 3 shows the in- fluence of phosphorus on the growth of sweet- clover in area II. The soil should be tested to determine the fertilizer needs for sweetclover. In the western part of area II, the tight, hard soils are too drouthy for growing sweetclover. Its growth is limited in this area to sandy soils, creek and river bottoms and land under irrigation. As water becomes a limiting factor, seeding in reg- ular width rows with some cultivation is recom- mended. LE 4. POUNDS PER ACRE OF AIR-DRY FORAGE FROM TWO DIFFERENT ROW SPACINGS OF BIENNIAL SWEETCLOVER, _ Date harvested 32-inch rows 8-inch rows Nov. 29. 1929 | May 29. 1990 | 13191 Nov. 29. 1929 | May 29. 1990 i T9191 9.120 9.900 19.020 9.990 5.990 9.990 4.990 9.990 11.240 2.990 5.540 9.400 9.240 9.200 9.440 2.440 5.700 9.140 2.990 5.700 9.090 2.990 5.020 7.990 4.090 9.420 10.190 2.910 5.590 9.470 Dec. 2. 1991 Iune 29. 1992 r9191 Dec. 2. 1991 Iune 29, 1992 T9191 2.900 9.900 9.900 2.920 7.200 ' 9.920 2.990 7.990 10.090 2.990 7.920 10.490 2.940 7.020 9.990 2.440 7.290 10.720 1.500 9.490 7.990 2.940 7.940 10.290 1.490 9.920 7.900 1.900 10.990 12.190 2.000 9.990 9.990 2.970 9.120 10.990 ulled M. albu planted. TABLE 5. YIELDS OF SWEETCLOVER VARIETIES AT VARIOUS LOCATIONS Madrid yellow Common white Evergreen Common yellow Location First Second First Second First First Second Hubam Yea!‘ Yeflr year year year year year Iowa Park 3,993 Dentonl 3.160 3.100 2.980 2.940 2,420 Chillicothe? 2.190 2.670 2.980 5.360 1.060 2.170 Angleton 5.040 6.710 3.2003 College Station. Brazos Valley Lab. 7.5904 3,3404 5,4394 Raymondville 1.440 870 2,240 San Benito 3.040 1.260 4.070 Winter Haven 4.410 Beaumont4 3.780 3.760 Temple 3.6804 4.1704 1 5-year average. 2 2-year average. 3 8-year average. 4 3-year average. In area III, sweetclover is fall-planted. In the Western part of the area, planting of sweet- clover is hazardous. However, there is less evap- oration from the soil during the fall and winter and more water is available for use by the plant. If good soil moisture is present when the seed germinate, a crop may be expected on the more productive soils. In the eastern half of area III, on calcareous soils, the annual sweetclovers will make abundant growth, provided phosphate is ap- plied according to the needs of the soil. Acid soils require applications of lime for best results for all varieties except M. indica. In area III, usually the biennial sweetclovers do not live through the summer. Hubam makes earlier and more rapid growth, but the biennials extend later into the summer. Drouth and dis- eases, or a combination of the two, usually kill most of the biennial plants by August. When planted in the early fall, many plants bloom in June but produce few seed. Moisture is the limiting factor for sweet- clover growth in the western part of the State, area IV. Sweetclover will grow in years when moisture is above average. In area IV, sweet- clover should be planted in regular width rows to take advantage of all moisture. In general, sweet- clover is not recommended for this area. Figure 4. Rear view oi drill used for planting small grain and sweetclover in one operation. PLANTING SWEETCLOVER Because of the small size, sweetclover should not be planted more than three-fourth an inch deep. Best stands are obtained when a. seed are planted one-fourth to one-half inch on a firm, clod-free seedbed. Seeding rates a ommended are influenced by climate, row wi companion crop and use that is to be made of clover. In regular width, 36 to 42-inch r0, plant 2 to 3 pounds per acre; in 14 to 16-i rows, 4 to 5 pounds; overseeded on small gra 8 to 10 pounds; and drilled alone 12 to 15 pou Sweetclover often is interplanted with the small grains. In areas II-S and III, front , er, the sweetclovers may be seeded in the fall the same time winter small grains are plan Several methods have been used successf a Where grain drills withsmall seed attachm are available, the down spout from the small box may be attached to the rear of the disk l; and the seed allowed to fall behind the disk =, then covered with the chain drag. Figure 4 sh the equipment used in planting sweetclover in t, manner and Figure 5 shows the stand obtain In area II-N, sweetclover normally is seeded February or March. However, the biennial sw Figure 5. F all-seeded oats and sweetclover w above a band of phosphate fertilizer. u .5 7 . k. l‘ 6. INI-‘LUENCE OF PHOSPHATE AND PHOSPHATE PLACEMENT ON GROWTH AND NITROGEN AND PHOSPHATE A CONTENT OF EVERGREEN SWEETCLOVER TOPS AND ROOTS. TEMPLE " D - . l 4319 plant prgflllfigitgii Nrtrogen Phosphorus lent part II’ Pounds per acre ‘Y, I Pounds per acre ‘Z, I Pounds per acre Tops 1930 2.4 47.0 0.12 2.4 51*. 111.12 Tops 0000 2.5 91.0 0.15 5.1 d2 Tops 4750 2.5 117.0 0.18 8.5 k 11.10153 1000 2.0 05.0 0.00 1.0 111112 11.15153 2000 2.1 40.0 0.15 0.2 A - 2 Roots3 2520 2.2 55.0 0.20 5.1 lsted 116 days after planting. rs may be planted in late summer 0r early Mnder irrigation. The yield 0f spring-seeded tlover in fall-seeded small grain often is 10W 1:- of the competition offered by the small 1 and the subsequent dry weather after small is are harvested. If a good stand survives, h may be expected during the fall and spring the biennial types. TIn planting sweetclover on calcareous soils, T results have been obtained when the phos- s was placed in bands 2 inches below the g Table 6 shows that banding 60 pounds of gphorus acid per acre produced 4,750 pounds ps and 2,520 pounds of roots on a dry-mat- asis per acre, whereas the broadcast applica- produced 3,680 pounds of tops and 2,030 ds of roots per acre. The forage and tops 1 the banded application contained 172 pounds itrogen and 13.6 pounds of phosphorus in farison with broadcast production of 134 ds of nitrogen and 8.9 pounds of phosphorus D In the 20 to 25-inch rainfall area, sweet- er should be planted in pure stands on a firm bedin regular width rows and cultivated to irol weeds. Y The use of sweetclover with small grains ted in the regular manner is limited to areas more than 30 inches annual rainfall. When tclover is to be used with small grain in areas 5 to 30 inches rainfall, the small grain should lanted in wider rows, 14 to 42 inches. Fig- 6 shows Madrid sweetclover planted in reg- i Width rows with oats in the fall at Beeville. ; clover was still green in May, after the oats e matured. This mixture was grazed during winter and spring. It often is possible to obtain volunteer stands he sweetclovers if they are allowed to produce ed crop. In area III, stands of Hubam and 11a] yellow have been maintained for several rs in a perennial grass stand such as Johnson- s. Tetclover for Pasture Sweetclover is a good pasture crop and with per management will furnish abundant graz- i for some time. Frequently cattle will not sweetclover well when it is grown with a QSixty pounds of phosphoric acid per acre. 3Root obtained from 0-l8-inch depth. small grain as long as the small grain furnishes abundant grazing; but as they become accustomed to the sweetclover they usually will make good use of it. Figure 7 shows cattle grazing Hubam clover. After they become accustomed to its char- acteristic bitter taste, they relish it. Young sweetclover is high in moisture and protein. Mature cows utilize the early growth of sweetclover better than young stock. When graz- ing new growth of sweetclover, young stock fre- quently do not obtain enough dry matter to meet requirements for fast gains, but mature cows with greater stomach capacity do well. For proper utilization, sweetclover should be kept to a uni- form height of 8 to 12 inches. Longtime cattle-grazing studies at Temple show that oats and sweetclover will average 127 days of grazing with a variation from 80 days during dry years to 160 days in favorable years. Steers have gained from 1.3 to 2.1 pounds per day during the grazing season. Steer gains per acre have been 168 to 304 pounds, with an aver- age acre gain of 218 pounds (16). Table 7 shows the phosphoric acid, protein and lime content of sweetclover harvested in South Texas in the prebloom stage. The protein content is above 20 percent in all cases and the Figure 6. Sweetclover planted in alternate rows with oats. phosphorus content is high. In these tests, irri- gation did not influence the quality of the forage but did influence the yield. The biennial sweet- clovers were higher in protein than the annuals but were lower in total yield (17). Good results have been obtained by seeding small grain and sweetclover in an established stand of Johnsongrass. A good practice is to graze this combination during the winter and spring, then remove the livestock to allow the J ohnsongrass and annual sweetclover to mature. Such management also gives the first-year bien- nials a chance to build up root reserves. After the sweetclover and J ohnsongrass mature, the pasture may be grazed as needed. Once a good seed crop has been produced, it will not be neces- sary to plant the sweetclover the following year. With first-year biennial sweetclover, a small grain may be seeded in the fall, Figure 8. If the ground is packed, it may be necessary to use a deep-furrow drill or special planting equipment for placing the small grain seed 2 inches in the soil. A ‘regular seedbed for seeding small grains may be prepared for annual sweetclover in com- bination with small grain. Sweetclover for Hay Sweetclover makes good hay in areas where it can be cured properly, Figure 9. Annual sweet- clover should be harvested when the first blooms appear. If cut too early, the moisture content is so high that the hay is difficult to cure. If cut- ting is delayed until full bloom, there may be a great loss of leaves and the hay will be coarse and stemmy. TABLE 7. POUNDS OF HAY AND PROTEIN PRODUCED PER ACRE, AND THE AVERAGE PERCENT LIME, PHOSPH, ACID AND PROTEIN IN SWEETCLOVER FORAGE AT TWO LOCATIONS, WITH IRRIGATION ,. » i. Figure 7. Cattle grazing sweetclover. First-year hay crops from spring-seeded ennial sweetclover should be harvested in summer or early fall after the plants have up root reserves. Biennial sweetclovers that fall-planted may be harvested more than onc is possible to graze until April 15 and get a, crop in late June when weather conditions more favorable for hay making. Second- sweetclover should be cut in the early bloom s If a high stubble is left, it is possible to ob two cuttings for hay or one cutting for hay a seed crop. ~ Harvesting of sweetclover for hay should done when conditions are favorable for cu Q Improper curing may result in spoilage. Sp. sweetclover hay contains a substance called‘ coumarol which injures the fine capillaries reduces the clotting power of the blood and7 animals may bleed to death from slight W0 i or internal hemorrhages. Hay containing di » marol does not always show signs of spoilage. observing the animals being fed sweetclover 3i the bleeding disease usually can be detected l. the animals taken off such hay in time to pre losses. As a precautionary measure, it is not to feed cows a full diet of sweetclover hay ing. Sweetclover for Silage Sweetclover for silage is equivalent to 0 legumes when the crop is harvested at the p t? stage of growth. Spring growth of sweetcl may be used more economically as silage that hay because of the difficulty of curing hay in} Hay . . . "/0 "/0 phos- ‘X, Po vane“! Locahon 1:215:38, lime phoric acid protein pro! Hubam Raymondville 233g .10 21.62 1 ~= San Benito - I .69 21.21 l Annual yellow Raymondville 2160 1.88 .69 21.40 A San Benito 2110 2.30 .63 21.56 Madrid Raymondville .70 24.20 ll San Benito . .69 23.17 ‘Q Evergreen Raymondville 3140 3.17 .74 24.72 7 i“ San Benito 2210 3.00 .76 24.46 10 before or a short time after calving or deh g‘. Since prebloom sweetclover has a high ture content, the crop should be allowed to slightly before ensiling. When sweetclover e is to be used for silage, 80 to 100 pounds l olasses or 150 to 200 pounds of ground corn I ld be added for each ton of green material. pats or barley are growing with the sweet- 'er, the mixture should be cut when the grain a the dough stage and no preservative will be pssary; in most cases this mixture need not ilted. Because of the possibility of dicou- Fol being formed, it is especially important 7 sweetclover be firmly packed as it goes in iisilo. The same precautions should be observ- feeding sweetclover silage as in feeding hay. ietclover in the Cropping System weetclovers are excellent soil-improving f; By their proper use, a farmer can go a p: Way toward maintaining the productivity of =soil. There are many ways that sweetclover be fitted into a cropping system. Sweet- may be made to pay its way by using it §grazing, hay, silage or seed. Best results for improvement may be obtained by returning t of the residue to the soil. Maximum bene- .may be obtained from sweetclover by har- Flilng a seed crop and returning all the residue e soil. I In an experiment at Temple, Table 6, Ever- n sweetclover harvested 116 days after seed- contained 117 pounds of nitrogen in the tops 55 pounds in the roots, or a total of 172 g ds of nitrogen per acre. The nitrogen con- i of sweetclover tops on a dry-matter basis I prior to blooming is 2.5 to 3.0 percent (8). k roots of sweetclover contain about 2 percent Yogen. A yield of 3 tons of tops and roots is pmon where sweetclover is adapted. With the fption of annual yellow. sweetclover has a ,1 root system and will improve the physical ition of soils. It improves the friability of soil and makes it easier to work. Good root ietration permits a greater and faster absorp- . of water and roots also improve aeration i drainage. Sweetclovers provide a protective er for the land against runoff and reduce soil es. The effects of growing sweetclover in rota- } with other crops have been determined by Texas Station at several locations. On allu- Brazos Valley soil, corn following 1 year of 1 rid sweetclover produced an average yield of ,ushels. At the same time, corn following . produced only 35 bushels (15). In this test, f the sweetclover residue was returned to the , Figure 10. At the Denton station, contin- A); corn produced an average of 35 bushels per i; while corn following Hubam clover for seed uced 41 bushels, Figure 11. At Denton, in . sweetclover produced adequate nitrogen for I following it on the same land. Yields from f4 receiving 60 pounds of nitrogen were 30 els, as compared with 29 bushels for corn fol- Figure 8. Oats in second-year Madrid sweetclover. lowing sweetclover (13). A comparison of the yield and quality of continuous corn with corn following Madrid clover is given in Figure 12. The yield of continuous cotton compared with cot- ton following sweetclover at two locations is shown in Figure 13. The use of sweetclover in the rotation materially I increased cotton yields (2). Sweetclover also can be grown for a cash crop. Hubam grown for seed in the rotation at Temple averaged 352 pounds of seed per acre (6). The rotation ‘where the Hubam was used for hay and green manure averaged 3,240 pounds of hay per acre. Studies were conducted at the Temple sta- tion on the control of cotton root rot by the use of sweetclover, Figure 14. In summarizing this work the authors state: “Delay and marked re- duction in cotton root rot and the highest yield of cotton were found in the plots in which Hubam had been grown to maturity the previous year.” Hubam clover usually matures in the early sum- mer before cotton root rot becomes severe, there- fore, the benefits from a soil-improving stand- point have already been obtained ( 11). Sweetclover may be seeded with small grains. If the sweetclover makes enough growth to_ 1n- terfere with combining of the small gram, 1t 1s Figure 9. Cutting Hubam clover ior hay. ll Bushels per acre 30 1 40 l I l Contin- Annual Fall Madrid uous yellow Hubam Madrid Madrid corn corn corn corn corn Figure l0. Influence of sweetclover on subsequent yields of corn at the Brazos River Valley Laboratory near College Station. a Q _.. t~ 0 CZ Lf\ o H u U i i 8 O -—1 o. *1‘ " Ill III g _-. ‘J a: R -- o H ii Contin- Hubam Hubam for Madrid for uous for seed green manure green manure corn corn corn corn Figure ll. A comparison of continuous corn with corn lollowing 1 year of sweetclover at Denton. Average of 2 years, 1950-51. _ j a 12 necessary to cut and windrow the crop to .p the sweetclover and small grain to dry be combining. After the small grains have c, harvested, the second growth of sweetclover i, be used for grazing, hay or seed. Biennial s clover will not produce seed the first year j only hay or grazing may be obtained. " I Using sweetclover as a mixture with t; grains in the cropping system offers the ‘a possible means of soil maintenance on a s ~ term basis. Subsurface tillage should be the small grain-sweetclover stubble in prepay a seedbed for cotton or corn to follow. As f; as the Hubam has completed growth in the s” mer, if cotton is to follow, the land should bef ed and kept free of Weeds that might harbor i root-rot organism. If the biennial sweetclo are to be used as annuals in the rotation ahea cotton, the land should be tilled in late Jul ‘i early August. If corn is to follow, the bien clovers may be allowed to grow until the re time for seedbed preparation for corn. SEED PRODUCTION Sweetclover seed production in Texas 1950-53 averaged 11,060,000 pounds annuf Most of it was produced in the Blackland Grand Prairie regions. Harvested yields pa aged 150 to 300 pounds of seed per acre. Only about 60 percent of the sweetcl seed produced by the plant is harvested. Wea hazards, which cause shattering, and impr harvesting methods account for most of the l, Seed production often is the by-product of a ing program. Livestock sometimes are a110, to remain on the sweetclover too long in spring and they graze the clover too closely highest seed production. Proper grazing i agement will aid in obtaining a better ha a Sweetclover sometimes grows too rank for £ efficient harvesting if the plants are not gri or clipped. The highest yields of seed are obtained ~' the sweetclover is planted on good soil that . Figure 12. A comparison oi the yield and qua “=1 continuous corn with that oi corn following Madrid clot; the Temple station. - . ' _ ‘~4- wn»; " " f”. ' "= . "fr." ~. I . -n pa: acre ""' D L i; "'- Hubam for Contin- Hubam Contin- Hubam hay-green uous for seed uous for seed manure cotton cotton cotton cotton cotton Iowa Park Temple Figure l3. A comparison of the yield oi continuous 3 with cotton following l year of Hubam clover. t» properly fertilized. In areas of above 30 es rainfall, sweetclover for seed usually is ted broadcast or close drilled. In lower rain- 291638, it should be planted in regular width is for best seed production. When seeding dcast or with a drill, plant 12 to 15 pounds ' acre; in regular width rows, plant 2 to 3 ds per acre. Hubam is the most important sweetclover llseed production in Texas. In areas III and , it usually is seeded between October 1 and November 15, and in area II-N, in February or March. A smooth, firm seedbed is needed and the seed should not be covered more than one-half inch deep. Hubam should be inoculated at the time of planting. For best results, it usually is necessary to apply fertilizer. The soil should be tested to determine the kind and amount of fer- tilizer to use. Where phosphorus alone is ap- plied, banding 2 inches below the seed gives best results. When Hubam makes good growth it should be clipped or grazed in the winter to re- move the excessive vegetative growth. The clover should not be grazed or clipped lower than 6 in- ches. For maximum seed yields, cattle should be removed and plants not clipped for at least 70 days before the normal time Hubam matures. Recent experiments show the necessity of pollinating insects for good seed production. Where all bees were excluded, seed yields were only 16 pounds per acre, but when the area was left open to natural pollinating insects, seed yields were 130 pounds. When the bees were caged in, the yield was 157 pounds per acre. Sweetclover flowers wilt soon after pollination. A field of sweetclover in bloom that has flower stalks with many fresh open blossoms indicates an inade- quate number of pollinating insects present (18). Harvesting of Hubam seed begins during June in South Texas and continues through Au- gust in North Texas. The two general methods of harvesting Hu- bam clover in Texas are windrowing before threshing and combining the standing crop. In the windrowing operation, the plants are cut when about two-thirds of the seed have turned brown. Figure 15 shows Hubam being cut and windrowed with a converted grain binder. The operations necessary to change a grain binder to permit windrowing are relatively simple. The binder attachment and the bundle carrier should be removed and the binder deck covered with smooth sheet iron. A factory-made platform - “a; - iliigure 14. Influence of Hubam clover is cr 2-year rotation on cotton root rot. Right, continuous cotton. Left, cotton ‘ng Hubam. 13 Figure 15. Windrowing Hubam clover with a converted grain binder. swather also may be used for Windrowing. Other methods of Windrowing may be used but there is greater loss from shattering. The clover should be cut 12 to 18 inches high. In thick stands, the stubble holds the cut material off the ground and allows more rapid drying. When possible, Windrowing should be done early in the morning or at night when the stems are tough and there is enough moisture present to prevent shattering. The width of the swath should not exceed the width of the combine by more than 2 feet. It usually takes 4 or 5 sunny days to dry the clover for best combining. Figure 16 shows Hubam clover being combined that was windrowed with a converted grain binder. Combining the standing plants is the second method used. To eliminate as many green stems and seed as possible, most of the pods and seed should be dead ripe, therefore, there always is a loss from shattering. Seed comblned from the windrow may be sacked and stored but seed har- vested from standing plants contain green pods and stems and should be dried before storing. Figure l6. Combining seed from a windrow oi sweetclover. 14 Standard grain-drying equipment may be provided the temperatures are held below 130 The seed also may be spread 4 to 6 inches d1 on wooden floors and stirred at 3 or 4-hour tervals until dry. '5 Chemical drying through defoliants red the moisture content of the standing sweetclo Satisfactory results have been obtained from , use of several drying materials. One pint of, nitro in 10 gallons of diesel fuel can be used approximately half the seed pods are brown. C bining normally should follow within 3 days The production and harvesting of annual I low sweetclover is essentially the. same as i Hubam. This species can be harvested with , loss by direct combining than can Hubam. i the time the plant matures, most of the have fallen off. In area III, oats and annual i low sweetclover sometimes are grown as a I ture and sweetclover seed may be separated f , the oat seed in the process of cleaning the oa Madrid, being a biennial sweetclover, ; quires different management for seed product, Madrid seed are not produced commerciall .1 area III. Spring-planted Madrid in area II duces a seed crop the second year some ahead of Hubam. Under most conditions, i not advisable to graze second-year Madrid in early spring if maximum seed yields are desi‘ Evergreen, a white-flowered biennial clover, is well adapted to Texas growing cot tions but has low seed yields. This variety q duces flowers over a long period of time an no one time is there a heavy seed set. Clippin grazing the plants in the spring forces a unif! growth, whichsets seed more uniformly. Texas conditions, however, yields of more t 100 pounds of seed per acre are seldom obtai; The same procedures discussed for harvi ing Hubam should be followed with biennials. ' ceptable yields of sweetclovers have been obtafl when seeded with small grains. DISEASES OF SWEETCLOVER Sweetclover may become infected with or more severe diseases such as seedling damp, off, ‘anthracnose, cotton root rot, charcoal spring blackstem, summer blackstemrand spots. This group of diseases is difficult to con q The cost of protective fungicidal sprays, d» and fumigants is too great to permit their eral use, therefore, control must be accompli by seed treatment, crop sanitation, rotation I‘ the development of disease-resistant or dis escaping varieties. i Southern Anthracnose Anthracnose, Colletotrichum trifoliz", f ently is severe on clovers, alfalfa and lespe Light to dark-brown, elongated, sunken i with scattered, short, dark-brown bristles of” * g s occur on the crown and lower stems. Kill- and browning of the foliage results when the completely encircle the stem. on Root Rot “Sweetclover, used as a green manure crop, i tively controls cotton root rot, Phymato- um omnivorum. However, it will be infected killed when the crop is grown during the i» er in root-rot-infected areas. The presence p, e disease is shown by the development of spots in the field. In local areas, the plants and turn brown with the dead leaves remain- ttached to the plant. Symptoms of root rot vident below the soil surface. Brownish-yel- ropy-like strands of the fungus appear on urface of the rotted roots and, upon cutting section of the root, brown streaks through inner portion of the root and crown can be Rotation with corn, oats or some other p; crop, or plowing under of large green ma- p crops are the only economical means of con- oal Rot This disease, Botryodiplodia phaseoli, is dif- t to control because of the wide variety of ; it will attack. It occurs as a rot on the and lower stems of legumes and grass crops. erous small black bodies of the fungus de- i in and on the rotted tissues of the clover. disease is most severe during hot, dry sea- l The main economical control is by irriga- g Blackstem This disease, Ascochyta caulicola, causes ed and distorted stems. The blighted areas e stem are not black but tan or brownish . The common name of the disease is deriv- rom the symptoms which occur on alfalfa e the stem is blackened. Black spore-carry- odies of the fungus develop over the blighted . Under severe conditions the entire plant die. in er Blackstem § Summer blackstem, Cercospora zebrina, freq- y occurs with the spring blackstem during g. summer and becomes severe during mid- I er, resulting in extensive killing. The spots be scattered or the entire stem may be af- i The reddish-brown, sunken spots later a ashy-gray from the abundant development _ores of the organism. The blackstem or- ms are seed-borne and live overwinter on tems. p Spot Leaf spot, Stagonospora meliloti, generally a minor importance, appearing in significant rtions only in early spring and late fall. VF: results from the dropping of the infec- Figure 17. A biennial sweetclover plant showing the “sweetclover root borer." ted leaves. The leaf spot is circular to angular, pale buff with light brown margins and with numerous spore-carrying bodies of the fungus in the central portion of the lesion. INSECTS A new insect pest was discovered in 1950 on biennial sweetclover near Denton. The insect is commonly known as the “sweetclover root borer,” Walshia amorphellia. The infested plants wilt and die during the late summer or early fall of their first yearof growth. Above-ground symp- toms are similar to those caused by cotton root rot. The roots of infested plants show numerous grooves and burrows and a small white worm may be found, Figure 17. This insect has not been found on annual sweetclovers such as Hu- bam. Because of its early maturity, Hubam prob- ably escapes damage. No control measures are known (12). Tarnish plant bug, a member of the lygus group, often is a serious pest on sweetclover used for seed. This insect sucks the plant sap and of- ten concentrates on the buds and flower parts, causing them to wilt and die. It also will feed on the young pods, causing the seed to shrivel and turn brown. The use of 25 pounds of 10 per- cent DDT dust or sufficient emulsion spray to give 11/2 pounds of DDT per acre gives effective control. A single application as the plants begin to bud often gives adequate protection. Forage treated with DDT should not be used as a feed for dairy animals, animals being finished for slaughter, or for poultry. Several other insects that may damage sweet- clover are webworms, cutworms, stink bugs, green clover worms and grasshoppers. 15 10. wmi~hfi'nm'5l!%\§'*i i i I LITERATURE CITED Binford, E. E. Progress report, Substation No. 1, Beeville, Texas, 1910-1914 Tex. Agr. Exp. Sta. Bull. 214, 1917. Brooks, L. E. Hubam clover as a cash and soil-im- proving crop for the Wichita Valley. Tex. Agr. Exp. Sta. P. R. 1069, April 1947. Connell, J. H. and Clayton, James. Field experiments at McKinney substation and Wichita Falls substation with wheat, corn, cotton, grasses and manures; field experiments at College Station with corn, cotton, graslses, pea and manures. Tex. Agr. Exp. Sta. Bull. 34, 895. Cory, V. L. Progress report Texas substation No. 6, Denton, Texas. Tex. Agr. Exp. Sta. Bull. 199, 1916. Forage Crops. Tex. Agr. Exp. Sta. Bull. 59, 1901. Hill H. 0., et.al. Hubam clover in rotations causes higher yields and less root rot. Tex. Agr. Exp. Sta. P. R. 868, December 1943. Jackson, J. W. Progress report. Substation No. 9, Pecos, Texas, 1910-14. Tex. Agr. Exp. Sta. Bull. 221, 1917. Johnston, J. R. Research sets patterns for the cen- tral Blacklands. Tex. Agr. Exp. Sta. Misc. Pub. 65, 1951. Karper, R. E. Progress report, Substation No. 8, Lub- bock, Texas. Tex. Agr. Exp. Sta. Bull. 219, 1917. Laude, B. S. Progress report, Substation No. 4, Beau- mont, Texas. Tex. Agr. Exp. Sta. Bull. 200, 1916. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Lyle, E. W., et. al. Control of cotton root j sweetclover in rotation. Tex. Agr. Exp. Sta. 699, July 1948. Norris, M. J. New insect pest attacks biennial s clover in North-Central Texas. What’s new int and soils. Vol. 4, No. 4, January 1952. Norris M. J., et.al. Effect of legume manag and nitrogen on corn yields at Denton. Tex. Exp. Sta. P. R. 1439. February 1952. . Pittuck, B. C. Grasses and forage plants. Tex.» Exp. Sta. Bull. 46, 1898. Rea, H. E., et.al. Effect of legumes, nitroig" row systems on the yield of corn on Miller cla Tex. Agr. Exp. Sta. P. R. 1440, February 1952., Tippit, O. S. and Jones, J . H. Soil conservation‘ agement system for best production in the Blaci of Texas. Tex. Agr. Exp. Sta. M. P. 90, March Trew, E. M. Yield and adaptation of certain ' species in the Lower Rio Grande Valley. Tex. Exp. Sta. P. R. 1269, September 1950. 5 Weaver, Nevin, et.al. Pollination of Hubam i by honey bees. Tex. Agr. Exp. Sta. P. R. 1559, , 1953. a Winters, N. E. Experiments at Substation l Angleton, Texas, 1909-16. Tex. Agr. Exp. '3 229, 1918. - Dow Chemical 00., Down to earth, v01. 1, No. 1, mer 1954.