TIN 902 APRIL ‘I958 A & m LEW 21;. r riVTA.‘ a‘! QLLEGE 5"“ S‘ SPEIT-SPRAYINB JDHNSUNGRASS (tollege Station, Texas TEXAS AGRICULTURAL EXPERIMENT STATIUN - - - TEXAS AGRICULTURAL EXTENSIUN SERVICE Summary Cy‘: "It Grazing. mowing. tillage. cultivation, rotary weeding. hand hoeing and various combinations 3 A oi these practices can be used ior mass control oi Iohnsongrass in fields. Pre-emergence chemical ; treatments. lateral applications oi chemicals and flaming are used ior this purpose in some areas but are not suited to many Texas conditions. Mass methods are eiiective ior reducing Iohnson- grass stands but ordinarily do not get rid oi this grass. However. the old grass in most Teams row crops can be eradicated in one season by consistent use oi cultural methods supplemented by § spot-spraying. Herbicidal oils and water solutions oi sodium dalapon. sodium TCA and maleic hydrazide are some oi the sprays used ior spot-treating Iohnsongrass. Oils are commonly applied to the ‘ crown. Water solutions are applied as wetting sprays to either the ioliage or the soil or both. ~ These and other sprays suitable ior spot-treating Iohnsongrass must be applied selectively ii the‘ crop plants in the treated spots are to be saved. A hali-and-hali mixture oi naphtha and diesel iuel oil is the oil spray most generally used. ; Various other oil mixtures may be used ior. economy. ior increased contact toxicity. or ior a 7' combination oi contact toxicity and residual eilectiveness. Oil sprays kill on contact and are ' most eiiective when applied to the crown oi Iohnsongrass sprouts 6 inches or less in height. Sodium dalapon is used at the concentration oi 20 pounds in 100 gallons oi water. It is a l’ translocated herbicide but also has a residual eiiect. Sodium dalapon kills the tops oi the grass and many underground buds. Previously. it was used primarily ior nonselective treatment oi large spots oi Iohnsongrass in sparsely iniested cotton iields and ior treatment oi noncrop sites. A new sprayer developed at College Station now permits selective use oi this herbicide in cotton f» and sorghum. Sodium TCA at a concentration oi 50 pounds in 100 gallons oi water is used ior controlling Iohnsongrass spots in noncrop sites and in iields during noncrop periods. A mixture oi 40 v A pounds oi sodium "TCA and 20 pounds oi sodium dalapon can be used ior spot-treating sparsely iniested cotton iields. It is a knock-out spray under some conditions. Maleic hydrazide (lVlH-30) is a translocated growth inhibitor with no residual. It is used as a ‘l wetting spray to the ioliage at a concentration oi 21/2 gallons in 100 gallons oi water ior preplant- p ing treatment oi established Iohnsongrass spots beiore any spring crop when no residual can be tolerated. Subsequent killing oi the aiiected tops eradicates the grass. A man on ioot using a hand sprayer does the best and saiest iob oi spot-spraying Iohnson- grass in crops. The Texas Agricultural Experiment Station has developed three excellent hand f sprayers ior this purpose: the Texas Gravity Sprayer, the Texas Ietgun and the Texas Slidegun. The iirst two sprayers are ior close work when Iohnsongrass iniestations are interspersed between crop plants. The Slidegun is ior rapid spraying in iields when it is more economical to kill “i. the crop plants in the treated spot than to save them. Texas Blade. a combination weeder and shield. also has been developed ior shielding a crop plant while making a close application oi spray with a Ietgun. Cover Picture The 1955 cotton crop in two iields is shown in this picture. Both had a similar infestation i oi Iohnsongrass sprouts early in 1954. Spot-spraying eradicated the grass in cotton in the upper iield in 1954. The grass in the lower iield was hoed both years. p BASS (SORGHUM HALEPENSE) is an aggressive l’ ial which infests over 5,000,000 acres of Texas. Farmers long have used grazing, 5- age, cultivation, rotary weeding and hoeing ~:: control of this grass. Some of them have , usually have not accepted, pre-emergence "j treatments, lateral application of chemicals rd for this purpose. These methods are ._f0r reducing Johnsongrass stands when they A persistently. y-spraying was introduced by the Texas Agri- _ riment Station in 1954-. This practice was I ' popular as a supplement to cultural practices ntrol of Johnsongrass, particularly for scat- ations in cotton. Spot-spraying was used on “res of infested cotton land in 133 Texas in 1956. Subsequent progress by the Texas t; increased the efficiency of the spot-spraying '3 d extended its use. ilopment of Johnsongrass F of stand, intensity of light, temperature, length of day and soil conditions such as _ , fertility and moisture influence the growth ‘ngrass. Although frost kills the tops, this ' ds rapidly from seed and rootstocks. New I ass plants arising from rootstocks are called distinguish them from seedlings. LOHNSONGRASS SEEDLINGS fngrass seedlings emerge throughout the I: son and are the primary source of new infes- 1. ‘e seed germinate under a wide range of L and seedlings emerge from a depth of 2 more in the soil. Seed remain viable in the ng periods, but under Texas conditions, most rminate within 3 years after they are pro- gs first have a single erect stem. However, in soon start growing from the crown and a “ormed in a sliort‘ time. Killing the top of a ass seedling without destroying the crown ulates the production of secondary stems. “of the buds from the crown make underground Ar- startrootstock formation early. As a root- Spot-spraying Johnsongrass H. E. REA, Associate Professor Department of Agronomy stock grows, it forms nodes or joints at intervals of 3 inches or less. These nodes may bear a bud which can emerge at any time. Each new stem forms its own crown and is capable of independent development. Root- stock development usually is well advanced by the time a seedling reaches the boot stage. The seedling may be 6 weeks old and up to 3O inches tall by that time. Flowering and seed production follow rapidly. JOHNSONGRASS SPROUTS Johnsongrass propagates itself vegetatively by means of rootstocks. Any detached or intact rootstock that remains in moist soil survives and can produce one or more sprouts either during the current season or the next. Ordinarily rootstocks do not survive to the third year. Johnsongrass sprouts emerge sooner in the spring and grow more vigorously than seedlings. Otherwise, their development is similar to that of a secondary stem of a seedling. CONTENTS Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Development of Iohnsongrass . . . . . . . . . . . 3 Iohnsongrass Seedlings . . . . . . . . . . . . . . . 3 Iohnsongrass Sprouts . . . . . . . . . . . . . . . . 3 Effect of Farming Practices.- . . . . . . . . . . . . . 4 Chemicals for Spot-spraying . . . . . . . . . . . . 5 Herbicidal Oils . . . . . . . . . . . . . . . . . . . . . . 5 Water-soluble Herbicides . . . . . . . . . . . . . . 7 Sodium Dalapon . . . . . . . . . . . . . . . . . . . 7 TCA Alone and in a Mixture _ . . . . . . . 8 Maleic Hydrazide . . . . . . . . . . . . . . . . . . . 9 Spot-Sprayers . . . . . . . . . . . . . . . . . . . . . . . . .. 9 Cost of Spot-spraying . . . . . . . . . . . . . . . . . . 9 Sparse Infestations . . . . . . . . . . . . . . . . . . . .10 Moderate Infestations.» . . . . . . . . . . . . . . . .11 Heavy Infestations . . . . . . . . . . . . . . . . . . . .12 Reinfestations . . . . . .. . . . . . . . . . . . . . . . . . .12 Recommendations . . . . . . . . . . . . . . . . . . . . . .12 Spot-treating Iohnsongrass . . . . . . . . . . . .12 Spot-sprayers . . . . . . . . . . . . . . . . . . . . . . . .12 Sprays for Spot-application . . . . . . . . . . .13 Effect of Farming Practices Close and continuous grazing of Johnsongrass re- duces seed production, depletes seed stocks in the soil, causes shallow rootstock formation and reduces stand. Frequent mowing has some of the same effects as grazing but is less effective in depleting stands of the grass. Tillage depletes Johnsongrass stands to the extent that seedlings and sprouts are uprooted regularly and rootstocks are desiccated. Johnsongrass has a remark- able capacity to recuperate. Sharp tools set at the TABLE l. CONTACT SPRAYS FOR SPOT-TREATING ESTAB- LISHED IOHNSONGRASS IN CROPS Approximate . . cost of SPMYS Adillffiitlitlggfillfns mime per gallon. dollars For contact killing of Iohnsongrass sprouts Naphtha‘ None. Toxicity greater than needed for crown-oiling 6-inch sprouts under most conditions. 0.23 Diesel fuel None. Toxicity low. Reliable oil‘ or for crown-oiling 6-inch sprouts kerosene‘ only during hot weather. Use di e s e l and kerosene inter- changeably in mixed sprays. 0.13 1/2 naphtha None. Reliable for crown-oiling 1/2 diesel 6-inch sprouts under most con- ditions. 0.18 C-56in C-56 (hexachlorocyclopenta- kerosene diene)” increases penetration of plant tissue. 1 qt. C-56. Toxicity equal to 1/2 naphtha and 1/2 diesel for crown-oiling 6-inch sprouts. 0.17 2 qt. C-56. Reliable for basal oiling of lower 8 inches of stems in boot stage. 0.21 4 qt. C-56. Useful for oiling 8-inch stubs of Iohnsongrass in flowering stage. 0.29 Dinitro in 1 qt. oil soluble dinitro?’ (Dow kerosene General or others). Toxicity equal to 1/2 naphtha and 1/2 die- sel for crown-oiling 6 -inch sprouts. 0.16 Pentachloro- 4 gal. pentachlorophenol (44 phenol in 'percent).“ Toxicity equal to 1/2 kerosene naphtha and 1/2 diesel for crown-oiling 6-inch sprouts. _ 0.19 C-56 + 1 gal. C-56, 1 pt. dinitro. Toxi- dinitro in city superior to equivalent con- kerosene centration of C-56 in kerosene. 0.31 C-56 + pen- 1 gal. C-56, 4 gal. pentacholoro- tachloro- phenol (44 percent). Toxicity phenol in and penetration equivalent to kerosene C-56 + dinitro in kerosene. 0.37 ‘Bulk oil dealers. “Hooker Electrochemical Co., Niagara Falls, N.Y. “Dow Chemical Co., Houston, Texas; or Southwest Sprayer 6. Chemical Company, Waco, Texas. ‘Local lumber yards. 4 Figure 1. Large spots with dense stands occur/i season or two unless lohnsongrass infestations r cated promptly. proper depth and operated to overlap are tf uproot all the Johnsongrass. Repeated sum l? to kill this grass before it is 1O inches tall redui and sometimes eradicates it. Ordinary seedbed‘ tions for most crops retard the spread of I0 g but do not reduce stands greatly. Good drainage is essential for timely use practices in row crops. Uniform row spacingf the bed at planting and good crop stands help Johnsongrass. Pre-emergence chemical treatments someti trol shallow emerging Johnsongrass seedlings bu reliable under many Texas conditions. l Rotary weeding under suitable soil-crustin tions is an inexpensive method of materially f the stand of Johnsongrass seedlings shortly a emerge in cotton, corn and sorghum. Lateral oiling kills Johnsongrass seedlings i’ 2 inches tall and can be used safely in cotton , inches tall (prior to bark formation) if surface y. along the row are suitable for operating oiling e This practice is not compatible with plantip in a furrow or with bed planting and cultivati tices used in Texas. Some farmers in the State u, oiling on an emergency basis when early rains beds. Beds can be leveled by early rotary hoeing. thereafter smooth them satisfactorily for the use t, equipment. f Timely sweep cultivation cuts or upiroots g grass in the middles and covers small seedling row. Covering the seedlings before crown form uprooting them prior to rootstock formations. them. Cutting older seedlings and sprouts only g; owth. Dull and improperly set sweeps, careless- _. guiding a cultivator and the occurrence of wide ‘I reduce the efficiency of cultivation. fie efficiency of hand hoeing for the control of qngrass depends 0n how it is done. All seedlings be cut below the crown before rootstocks are 1 Sprouts should be cut off before they make p. Old clumps of the grass should be dug up. aming and lateral application of suitable water- herbicides kill Johnsongrass seedlings less than 1 d can be used safely in cotton after bark is formed l: larger than a pencil). However, these practices ye a level bed and are not compatible with the [cultivation practice of dirting cotton. hading, particularly in cotton, is effective for con- }; late germinating Johnsongrass seedlings. p, e use of supplementary irrigation. greatly compli- “the control of Johnsongrass in row crops. Irrigation ces that cause crops to lodge are objectionable. Early harvest and prompt preparation of the soil t-control Johnsongrass. §Methods used for growing cotton in Texas retard dread of Johnsongrass and sometimes eradicate it. used for growing corn favor the spread of Johnson- and most other weeds. Stands of this grass in- ‘ in sorghum but less rapidly in forage sorghum g in grain sorghum. Johnsongrass stands usually se in cool season cereal crops, but their early fist permits subsequent use of intense summer tillage. j a and other closely mowed or grazed crops grown or more consecutive years deplete Johnsongrass stocks in the soil. i hemicals for Spot-spraying Aéspot-spraying is an effective and convenient method filling Johnsongrass sprouts and seedlings that other- fare neglected in row crops. Herbicidal oils and r solutions of sodium dalapon, sodium TCA and ic hydrazide are some of the sprays used for this se. Tables 1 and 2 give some spray mixtures that be used under various conditions. These and other {available for spot-treating Johnsongrass must be ed selectively. Crop plants in the treated spots are ely stunted or killed if they are sprayed. Herbicidal oils are cqrrrrnonly applied to the crowns hnsongrass sproutsli‘? Water solutions are applied tting sprays to either the foliage or the soil or both. addition of 2 to 4 pounds of Fab or other wetting f per 100 gallons of water usually improves the iveness of coarse foliage sprays. HERBICIDAL OILS Most petroleum products that flow are called oils. Gasoline, naphtha, kerosene and diesel fuel oil flow freely and are widely available. Gasoline ignites too easily for safe use in spraying weeds and is too expensive. Naphtha, TABLE 2. SYSTEMIC AND RESIDUAL SPRAYS FOR SPOT- TREATING ESTABLISHED IOHNSONGRASS IN CROPS Approximate Additions to 100 gallons c?“ of Sprays and effectiveness mixture per gallon. dollars For contact and systemic killing of Iohnsongrass by crown or basal application in cotton or sorghum HCA in 3 gal. HCA (90 percent hexa- kerosene chloroacetone)? Contact toxicity equals 1/2 naphtha and 1/2 diesel. Residual effectiveness during rainy months similar to equiva- lent concentration of TCA in water. 0.35 For systemic killing of Iohnsongrass by foliage application Dalapon l0 lb. sodium dalapon.” 4 lb. Fab“ in water or equivalent wetting agent. For cheap selective spraying of ter- minal foliage of 3-leaf sprouts under humid conditions. 0.13 20 lb. sodium dalapon. 4 lb. Fab or equivalent wetting agent. Most reliable treatment for vig- orously growing foliage of Iohn- songrass of varying ages. 0.23 For systemic killing of Iohnsongrass by temporary soil sterili- zation TCA in 50 lb. sodium TCA.‘ For fall water application prior to cotton for 80 percent or more reduction in stand of established Iohnson- grass without subsequent effects on cotton. 0.20 HCA in See‘ above. kerosene For potential knockout of sparse infestations by nonselective spot applications TCA- 40 lb. sodium TCA, 20 lb. sodium dalapon dalapon, 4 lb. Fab or equivalent mixture wetting agent. For foliage and inwater soil application in cotton and sorghum. Kills crop in treated spots. 0.43 HCA in See above. kerosene For spring preplanting spot-spraying before any row crop Maleic 21/2 gal. maleic hydrazide (MH- hydrazide 30).“ Stops growth of grass in- in water eluding underground buds. De- struction of affected tops eradi- cates or nearly eradicates the grass. 0.44 ‘General Chemical Div., Allied Chemical d. Dye Corp., Hous- ton, Texas. ‘Dow Chemical Co., Houston, Texas; or Southwest Sprayer 6'. Chemical Company, Waco. Texas. “Local grocery store. ‘Dow, DuPont or Orchard Brand Dealers, or Southwest Spray- er 6. Chemical Company. Waco. Texas. “Naugatuck Chemical Co., Bethany, Connecticut. Figure 2. This is an aerial view of a row-crop field with a sparse infestation of large lohnsongrass spots. Use clumps of lohnsongrass. Use selective spot-spray‘! nonselective spot-application of a systemic 0r residual supplement cultural practices for their eradication ' herbicide t0 eradicate them rapidly. row crop. kerosene and diesel fuel oil are used alone and in mix- Naphtha is the name for a group of oils i! tures in various Weed sprays. They are contact herbicides used for cleaning clothes and thinning paint. and have no systemic or residual effects. naphthas are more toxic than necessary for use in Figure 3. This is about a 25 percent infestation. of fohrz- Figure 5. This is about a 50 percent infestation of songrass. Such infestations can be spot-sprayed saf ly in songrass. Spot-spraying‘ eradicated such an infes cotton and corn with a Texas fetgun. in irrigated cotton at College Station. " ‘ 6 nder Johnsongrass sprouts and can be diluted ifliper and less toxic oils such as kerosene and ll oil. A mixture of one-half naphtha and one- fuel oil (Or kerosene) is a reliable spray for ing 6-inch Johnsongrasssprouts under a wide weather conditions. iosene and diesel fuel oil are the cheapest oils - to Texas farmers and can be used interchange- imost weed-spraying mixtures. Ordinarily, their too low for crown-oiling Johnsongrass sprouts uring hot weather. However, various chemicals dded to these oils to increase their effectiveness. fkerosene sprays containing either C-56 (hexa- clopentadiene), oil-soluble dinitro, pentachloro- jfor HCA (hexachloroacetone) are listed in Tables l 6 is a wax solvent and increases the penetration t tissue by oil sprays. Additional information i:C-56 is given in Texas Agricultural Experiment Progress Report 1995. Oil-soluble dinitro and ‘lorophenol are strong contact herbicides. They the efficiency of oil sprays for killing plants. ‘is a systemic herbicide with residual effectiveness. grown-oiling a 6-inch Johnsongrass sprout with a or a similar oil spray induces wilting within 3 in strong sunlight and causes lodging and brown- lithin 24 hours. The oil soaks through the stem ills the crown. Also, some of the oil seeps to the ocks and may kill themto a depth of several inches. sprouts soon emerge from rootstocks remaining Repetition of the crown-oiling practice to kill at about 10-day intervals eradicates established ongrass after four to six treatments. rown-oiling tender sprouts when they are about es tall is always more efficient than treating older and is safer in crops. Treating older grass should nfined to emergencies. As the grass approaches Qot stage of growth the lower portions of the stems e glazed and resistant to ordinary oils. About ime it is advisable to add C-56 to an oil spray. ntrations of C-56 to use for treating Johnsongrass A ying stages of growth are given in Table 1. can be added to an oil spray to obtain prompt killing of .1 ohnsongrass sprouts followed by pos- i’ eradication after one to three treatments. Rain kin 2 weeks after treatment usually is required for ‘mum residual effectiveness of HCA. Under favor- conditions a single treatment may eradicate the grass frequently three treatfnents are required. Ordinarily A a spray should be used only for nonselective treat- of sparse infestations of large spots in crops or for tive application in infested cotton and sparsely ted sorghum. y 1w s» - a . , 4 A a a _ . Figure 6. This field was abandoned to a severe infestation of lohnsongrass for 1O years prior to growing this crop of dryland cotton in 1955. Spot-spraying before and after the cotton was planted‘ eradicated the fohnsongrass while 11/; bales of cotton an acre were being produced. Subsequent control of Johnsongrass seedlings has kept this field clean. - l‘ WATER-SQLUBLE HERBICIDES Sodium Dalapon Sodium dalapon, a water-soluble salt, is primarily a grass killer but stunts or kills most crop plants. Treat- ing the foliage of Johnsongrass sprouts with a spray containing 2O pounds of sodium dalapon in 100 gallons of water usually kills the sprouts and most of the underground buds. Two to four treatments of new sprouts usually are required to eradicate the grass. This concentration of the spray has been reliable for the treat- ment of vigorously growing Johnsongrass at College Station for several years. Also, a spray containing 1O pounds of this herbicide in 100 gallons of water has been Figure 7. Effectiveness of spot-oiling for control of Johnsongrass is shown by the treated area at right as opposed to the check plot, which received normal hoeing, at left. i“ Figure 8. A Texas Slidegun is being used here for non- selective spraying" of a spot of lohnsongrass. Figure 9. Two nonselective applications of sodium dala- pon nearly eradicated this spot of Johnsongrass. The first application killed the cotton in the spot. An addi- tional treatment was needed to eradicate the grass. Figure l O. Use selective spot-spraying to save all the crop plants. Treat the foliage of three to five-leaf John- songrass sprouts when water sprays are used. Treat the crowns of 6-inch sprouts when oil is used. 8 effective when the terminal foliage of three to: Johnsongrass sprouts was treated. Treatment 0f the tender foliage of John with a dalapon spray is followed by translocatio: chemical to underground buds. Buds nearest th and those least active are affected most. Those; from the crown and those growing rapidly may ' Partially affected sprouts are stunted and d‘; Prompt re-treatment kills them. Cutting them o lates resprouting. Warm, moist conditions favor rapid growth c. songrass sprouts and prompt translocation a effectiveness of dalapon. These conditions prev‘ frequently during April and May in Texas. T a tion of dalapon in Johnsongrass may occur in hours, but maximum translocation usually requires‘; days. Low temperatures, dry weather and slow of Johnsongrass delay and may prevent adequati location. Dalapon sprays are most effective early season and should be used only in infested col sparsely infested sorghum or in noncrop sites. . usually become progressively less effective at V, Station as the summer advances. Dalapon seldo trols nearly mature grass. f Dalapon may have a temporary sterilizing e the soil and heavy spring applications before could reduce crop stands. ‘Corn and sorghum a“ susceptible to the soil effects of dalapon. Planting, should be delayed 3O days when rain occurs shortl‘ a preplanting application of dalapon. However, Q Johnsongrass sprouts the day before planting co College Station reduced infestations 6O percent of»; on several occasions Without subsequent effect l cotton. Also a heavy infestation of Johnsongrass in cotton at College Station was eradicated in l‘ selective application of dalapon with only tem imr-v-‘Cbn: stunting of an occasional cotton plant. h-l hi0 TCA Alone and in a Zllixture ; A solution of 5O pounds of sodium TCA, a d’; in 1OO gallons of water applied as a wetting spy Johnsongrass sprouts and the soil in the fall is and economical for controlling this grass inthe‘ portion of the State.» The primary action of through the soil and the presence of the grass is ; terial except to outline the spots to be spraye; treated area should not be disturbed until aft _ occurs to wash the TCA into the soil. This commonly has reduced the stand of established I’ grass 8O percent or more at College Station g affecting cotton planted the next spring. Crops than cotton should not follow the fall use of TC 5 A mixture of 4O pounds of TCA and 2O p0 dalapon in 1OO gallons of water often is preferred iITCA alone 0r dalapon alone. It has been a f: and versatile knockout spray for treating John- at College Station for several years. Spring i. mer use of the spray in crops must be limited i: with infestations sparse enough to permit eco- iacrifice of crop stands in the treated spots. Hydrazide fraying Johnsongrass sprouts with, a mixture of lons of maleic hydrazide (liquid formulation) in 100 gallons of water stops the growth of the i, d most of the underground buds for about 1O By that time, the leaves have developed varigated jjrple and white splotehes. Killing the tops of the romptly thereafter either by cultural or chemical eradicates or nearly eradicates the grass. The influencing the effectiveness of maleic hydrazide i» ilar to those discussed for dalapon, but there pf aftereffects from the spring use of maleic hydra- lfore planting any crop. i e maleic hydrazide method of controlling Johnson- : sprouts has been used successfully at College in several fields during each of the past three Usually the old grass was eradicated prior to iergence of late-planted crops such as sesame and Ordinarily, stands were reduced 6O ‘percent or prior to the emergence of cotton.’ t l Spot-sprayers g man on foot using a hand sprayer does thelbest Iafest job of spot-spraying Johnsongrass in row i Since most commercial hand sprayers are too 'ng to carry and operate all day, the Texas Agri- dial Experiment Station has developed three excellent eight, easy-to-operate hand sprayers for spot-treat- ‘is grass. They are the Texas Gravity Sprayer, the ation weeder and plant shield, has been developed f- with the Jetgun. e Gravity Sprayer and the Jetgun are for close where the crop is to be saved. Johnsongrass sprouts fver too close to crop plants for safe treatment with when a Texas Blade is used as a plant shield. idegun is for. rapid spraying in fields where it is economical to kill the crop in the treated spots than e it. Also, the Slidegun is handy for treating non- is sites when the use of a power sprayer is incon- t. TAES Progressiiilteport 1987 gives further in- l: ion about these sprayers. arious tractor and other power sprayers are effi- jfor continuous spraying both in and out of crops. of them can, be adapted for spot-spraying. ‘ i g Jetgun and the Texas Slidegun. Texas Blade, a Figure 11. The lohnsongrass sprouts in this cotton have been crown-oiled. The excess oil on the ground was wasted. Cost of Spot-spraying Spot-spraying is for cleanup purposes when estab- lished Johnsongrass in a field is to be eradicated. The cost of spot-spraying varies with the degree of infestation, the method used, the growth of the grass and seasonal weather conditions. Costs cited in this report are for controlling Johnsongrass on highly fertile soils of the Brazos River Valley near College Station, Texas. Figure 12. The Texas Gravity Sprayer is satisfactory for crown-oiling 6-inch ‘Johnsongrass sprouts when infesta- tions are moderate, This sprayer was new in 1954 and soon became popular. 9 4-4. 4. mania- Figure 13. C rown-oiling hills tender Johnsongrass sprouts to the ground within a few hours. Four to six crown- oilings of sprouts at about 10-day intervals exhaust John- songrass rootstochs. Two of the sprouts in this clump were untreated. Fields are classified on the basis of the row footage occupied by Johnsongrass. ~An infestation is designated as 100 percent when the entire row footage in a field has to be treated to kill the sprouts by nonselective spraying. A descriptive statement is used for experimental records to give information on the density and distribu- tion of the grass and the contamination of the soil by Johnsongrass seed. SPARSE INFESTATIONS Nonselective application of a spray with a knockout potential is preferred for treating infestations of less TABLE 3. SPOT-SPRAYING COSTS FOR ERADICATING IOHNSONGRASS SPROUT INFESTATIONS OF l0 PERCENT LESS IN ROW CROPS Figure 14. The Texas Blade and Texas letgun l new in 1957. A fetgun is the most efficient spray’ use for selective spot-application of any spray. The is used to protect crop plants from the spray when C sary and to cut scattered tall weeds. than 1 percent and for treating widely scattered spots infesting 1O percent or less of the row foota a field. Small clumps and sprouts interspersed be g crop plants should be sprayed selectively. A large- is one occupying a space of more than 2 feet in the» ' The 1O percent limit on nonselective application isi gested as the maximum loss of crop stand that a might tolerate to permit rapid spraying of large spl The sprays shown in Table 3 for nonselective =_ cation with a Slidegun are suitable for use in cottons sorghum and are most effective under humid condi Cost an l I l 0 ll . . . , nogslgzyons Treat grass m Apply to Apply times Apply with inccrirsssian don Nonselective treatment l Clump infestation under 1 percent and large spots up to 10 percent 40 lb. TCA 20 lb. dalapon Cotton, sorghum Foliage, 1-3 Slidegun 6-16 soil or 3 gal. HCA 97 gal. kerosene Cotton. sorghum Foliage, 1-3 Slidegun . 6-10 soil Selective treatment Clump infestation of 1 to 10 percent 50 gal. naphtha 50 gal. diesel Row crops Crown 4-6 Gravity 6 a Sprayer 5O gal. naphtha 5D gal. diesel Row crops Crown 4-6 - Ietgun 6 1/4 gal. C-56 1 993/4 gal. kerosene Row crops Crown 4-6 Ietgun 6 20 lb. dalapon in water Cotton. sorghum Foliage 3-4 Ietgun 3 l0 lb. dalapon - in water Cotton. sorghum Foliage 3-5 Ietgun l 3 3 gal. HCA a 97 gal. kerosene Cotton, sorghum Crown 3-4 Ietgun 6 10 i. eradicate the grass following a single treatment y-two or three are needed. 3 also gives information on the cost of several selectively treating Iohnsongrass sprout infes- f 1 to 10 percent. Cost ‘estimates given in this more reliable than those subsequently given for festations. n-oiling 6-inch Iohnsongrass sprouts is safe in Vycrop and is reliable anywhere in the State. A diesel mixture applied with a Gravity Sprayer inost commonly. This is mainly because these gill-Widely available and manyTexas farmers already avity Sprayers. A quart of C-56 in 100 gallons is as reliable as a naphtha-diesel mixture .3 little eheePer- A150» a Jetgun ea" be used Figure 15. A small or a large target can be sprayed with. i iciently than a Gravity Sprayer. a single shot from a Jetgun. will???’ " ee gallons of HCA in 100 gallons of kerosene use in cotton is safe but it should be used cautiously in used to advantage for crown-oiling under humid Sorghurm ans when early eradication of the grass following Ieatments is desired. HCA is a residual herbicide i} be used cautiously in severely infested cotton erately infested sorghum. Its use in other crops be avoide-d until further research is done. MQDERATE lNFESTATIQNS Information on the cost for spot-treating Johnson- grass infestations of 15 to 25 percent in a few fields at College Station in 1956 is given in Table 4. Costs cited ‘ilctgun is most efficient for the selective appli- do not include those for normal cultural practices or if water soluble herbicides such as sodium dalapon. the use of pre-emergence and lay-by sprays. Cotton was ‘containing this herbicide are most reliable under hoed only when it was thinned. A Gravity Sprayer i conditions and usually eradicate Iohnsongrass equipped with a special nozzle was used for selective fan oil sprays de-void of HCA. However, they are application of dalapon in cotton and sorghum. Preplant- to apply selectively and the ZO-pound con- ing spot-treatment of Iohnsongrass sprouts in the corn 'on generally recommended is a little expensive. field was with a tractor. A pro-emergence and a lay-by i-pound concentration is cheap but might not eradi- treatment for the control of seedling weeds and grasses ‘hnsongrass sprouts as fast as the higher concen- were used in corn and the corn was hoed once. A Dalapon has a residual effect in the soil and Gravity Sprayer was used for making all crown-oilings. be used only in the crops specified. Its selective An occasional cotton and corn plant were killed in spot- ; 4. TREATMENTS AND COST PER ACRE FOR CONTROLLING IOHNSONGRASS INFESTATIONS OF 15 TO 25 PERCENT AT COLLEGE STATION IN 1956 . Percent Cost Crop Treatments control an acre, dollars Cotton 3 weekly applications of 10 lb. sodium dalapon in 100 gal. water plus a wetting agent to terminals of 3-leai Iohnsongrass sprouts followed . by 4 crown-oilings with 1/2 naphtha and 1/2 diesel as needed for control of late seedlings. 100 10.63 Cotton 4 weekly crown-oilings oi 3-leal Iohnsongrass sprouts with 1/2 naphtha t and 1/2 diesel followed by 3 crown-oilings as needed for control of late - y seedlings. 100 10.58 i; Forage 3, application of 2O lb. sodium dalapon in 100 gal. water plus wetting f sorghum . agent and one with 1O lb. dalapon in 100 gal. plus wetting agent to terminals oi S-leai Iohnsongrass sprouts followed by 2 crown-oilings with 1/2 naphtha and 1/2 diesel as needed for control of late seedlings. 98 11.78 Corn Preplanting spot-treatment of Iohnsongrass sprouts with 11/4 gal. maleic hydrazide (MH-30) followed by 5 crown-oilings oi 6-inch Iohnsongrass in corn. - 100 17.75 11 Figure 16. The right hand normally is used to operate the pump of a letgun and to aim the spray at the desired target. The Texas Blade is used in the left hand. treating Johnsongrass in these crops. Also, minor reduc- tions in the stand of sorghum were caused by the initial . spot-application of dalapon in this crop. HEAVY INFESTATIQNS Spot-spraying becomes increasingly expensive as Johnsongrass sprout infestations approach 5O percent. Ordinarily the use of cheap methods such as intensive tillage during noncrop periods should precede the use of spot-spraying for controlling such infestations. How- ever, economic considerations often require the continua- tion of cotton production in highly fertile irrigated fields despite Johnsongrass infestations. In such a case spot- spraying should be started promptly. Some costs for eradicating a 50 percent infestation of Johnsongrass sprouts in irrigated cotton at College Station in 1957 and for controlling leftover seedlings until August 2-1 are given in Table 5. F igure 17. A Texas Blade is used here to protect the stem of a cotton plant while a Johnsongrass sprout is being oiled with a letgun. 12 All sprays were applied with a Texas Jetgun cotton plants were protected with a Texas Blade» necessary. Oil sprays were applied to the crowns t! grass and dalapon. was applied to the terminal Q The stand of the grasswas thick and the sprouts: 6 to 7 inches tall when spraying was started. The 0' was rotary hoed once and a-normal cultivating sch was used. All hand hoeinguthiht contributed to the ct, of the grass was included in costs. Spraying the grass prior to’ and shortly afte first cultivation was tedious but subsequent treafin, new sprouts was as fast as hoeing. An occasionfdl y, plant was killed by crown-oiling and a few were by the dalapon spray. About the same volume pe was required for each spray and one could be a about as fast as theother. The cost per acre for tr the grass was lowest when the cheapest spray was HCA and dalapon sprays were more expensive unfortified oil but eradicated the sprouts faster. l REINFESTATIONS The risk of reinfestation must be considered ' spot-spraying program. Contamination of the soi rent seed production, and the introduction of ne I are major factors affecting reinfestation by Johnsof seedlings. Ordinarily, their standsare sparse i crops preceded by 3 or more years of close mow: grazing and by cotton that has been hoed close several seasons. However, stands increase rapidly crops neglected during any part of the growing andraffective control measures should be initiated. firs__t.,_lsign of possible reinfestation. ‘ Recommendations SPOT-TREATING JOHNSONGRASS Use spot-spraying to supplement tillage, culti hoeing and other mass practices for eradicating-i-"l infestations of established Johnsongrass, particul row crops. Treat any acreage for controlling infes t up to 1O percent. Treat limited to moderate ai more heavily infested. ’ "iSsPOTisPsRAYERs g Use a Texas Gravity Sprayer for crown-oilin 5 percent infestations of 6-inch Johnsongrass (from rootstocks) in cotton, corn, sorghum an other row crops. Expect a few crop plants to be ' Use a Texas Jetgun for crown-oiling up to 50 infestations of 6-inch_]ohnsongrass sprouts in cot i to 25 percent infestations corn and up to l0 i infestations in sorghum. Use a Texas Blade to, crop plants while making close applications to at ‘rass sprouts with a Jetgun. Expect to save all n and corn but expect a few sorghum plants to Also, use a Jetgun for basal application of s for control of Johnsongrass sprouts more than it»; tall. a Jetgun for making swirl (terminal leaves) “ons of water sprays for the control of up to 5O infestations of three-leaf Johnsongrass sprouts in “and up to 1O percent infestations in sorghum. exas Blade to shield crop plants when necessary. p, a Slidegun for rapid nonselective application lys with a knockout potential for controlling up “rcent infestations of large spots of Johnsongrass l1 when it is more economical to kill the cotton the treated spots than to save them. Also, use gun for treating spotted infestations in fields i noncrop periods and on noncrop sites. I 5. TREATMENTS AND COST PER ACRE FOR ERADI- 1‘ CATING 50 PERCENT INFESTATION OF ESTAB- LISHED IOHNSONGRASS IN IRRIGATED COTTON AT COLLEGE STATION. 19-57 _. aying Spray _ d after mixture used 20 pounds 1 , 1/2 dalapon + 3 gallons D°nar5 ‘ - . naphtha 4 pounds . HCA Per acre H°°“‘g 1/2 Fab in 10o 97 gallons i" diesel gallons kerosene water 17.75 1 20.50 3 2‘ 21.00 l 3” 3 22.50 1 3’ 3 22.50 24.80 3 4 25.50 $1.50 per acre for hoeing Iohnsongrass seedlings on -(_areas on August 23. Considerable reinfestation by ”ongrass seedling occurred thereafter. te season control of Iohnsongrass sprouts and seedling. il-SPRAYS FDR SPOT-APPLICATION Use a mixture of one-half naphtha and one-half fuel oil or a mixture of one-quart of C-56 (hexa- Qgyclopentadiene) in 100 gallons of kerosene or g=i$ils with similar contact toxicity for crown-oiling Johnsongrass sprouts. Expect to use 4 to 6 appli- is at intervals of about 1O days for eradication of ts and seasonal cogtrpl of scattered Johnsongrass r . f? ' IlgS. iUse 2 to 4 quarts of C-56 in 100 gallons of kerosene iasal spraying of Johnsongrass sprouts more than fhes tall. Spray the lower 8 inches of the sprouts aching hoot stage. Use the higher concentration Figure 18. Selective spot-spraying with a Jetgun was used to eradicate a severe infestation of Johnsongrass sprouts in this irrigated cotton field in 1957. Half of the row footage in the field was as severely infested as is shown here. of C-56, hack off the stems and treat 8-inch stubs of grass in the bloom stage. Use 3 gallons of HCA (90 percent hexachloroace- tone) in 100 gallons of kerosene or other suitable oils for combined contact and residual effectiveness in con- trolling Johnsongrass sprouts in cotton and on noncrop sites. Use HCA fortified oil only during months when rain of 1 inch or more can be expected within 2 weeks after application. Expect cotton stands to be killed in thickly infested spots unless a Texas Blade is used to shield crop plants while using a Texas Jetgun to make close application. Use a concentration of 2O pounds of sodium dalapon and 4- pounds of Fab (wetting agent) in 100 gallons of Figure 19. This shows the same field as Figure 18. Right, after one spot-spraying and cultivation; left, after cultivation only. l3 water for all sprays where this herbicide is used alone. Spray three-leaf Johnsongrass sprouts interspersed in cotton. Use three to four applications at 7 to 1O day intervals for eradication of sprouts. Thereafter, use two or three crown-oilings for controlling scattered late germinating Johnsongrass seedlings. Use similar meth- ods for controlling sparse stands of three-leaf Johnson- grass sprouts in sorghum. Use 4O pounds of sodium TCA, 20 pounds of sodium dalapon and 4- pounds of Fab in 100 gallons of water for nonselective spraying of large spots of Iohnsongrass in cotton and sorghum with infestations of less than 1O per- cent. Treat vigorously growing grass, preferably before it is 1O inches tall. Expect the first treatment to kill crop 14 __ plants in treated spots. Expect eradication of I‘ grass sprouts after one to two treatments. Use. methods on noncrop sites. Use 3 gallons of HCA gallons of kerosene for similar purposes durin months. l Use 21/2 gallons of maleic hydrazide (MH-30): gallons of water for springrpréplanting treatment . songrass sprouts before any crop. Expect the r grass to show red to purplish coloration in f days after treatment. Then destroy the affected cultivation, planting or by the application of :1‘ spray. Expect stand reductions in sprouts or era“ depending on the degree of emergence of sprout time of the initial treatment. ‘ i [Blank Page in Original Bulletin] -snx9_1_ 1101111115 9591103 '1o1:>911(1 ‘$111291 -q '11 'uo11n15 1u9u1119dx3 1nm11ri9115y snxe; 'su191qo1d 11999111 o1 suo11n1os p111; o1 A11u95111p 2199s 110111913 ~ 1u91n119dx3 1nm11n9115y snx9_1_ 9111 1o s11un p191; 91.11 pun i 110111315 111mm 91.11 1o $1921.10!“ -9m11n9115n fiuyues 1o p. uo 5u1pu9d9p $9111snp111 Aumn 91.11 pun ‘seqnun: pun 5111119110 s1o1n19do 1110111109 11911141 s1u91qo1d 1o spazpunq 1 1° SMOI-I 9H1 Pun SHHHHAA 9H1 ‘SNHHAA 9m ‘SAHM r all! ‘SLVHM 9H1 5399s HOHYHSHH ‘IVHIILTIIOIHDY "$1211u99 p112 ‘d99>1dn p112 9011211911112111 912 $11121301d 12u0111pp2 OM l . $9$29$1p 1112M $911110u099 121n11n011%2 1211111 $199$u1 1 $91u1011099 9u1011 12mg SPQQM pu2 11$n1g ' p01d 121n11no11fi1a fiu119>112w $1u21d 1211191112u1O ‘ $$9u1$nq 119u21 pu2 1111211 $11019 p99$ 110 13u1199u1%119 119u21 pu2 11112 J $1n11 pu2 $11n1_1 A; 911123 pu2 11$1:1 $11n11 1291d011qn$ 191110 pu2 $111113 11921211 pu2 $9$29$1p 121111uV $11019 91112193911 ’ $A9>11111 pu2 $u9>19111Q $11019 191111 191110 pu2 1101103 9u1MS $d019 u1219 $1203 pu2 1199115 s9111nfi91 p112 $9$$219 911129 A112(1 1912M 10 9$n p112 110112AJ9$110D 911129 199g 110$ 10 11191119A01d1111 p112 1101121119$u0:) I 91B QSQqI 1 ‘$21191 u1 91n11no11fi2 10 $9$211d 112 9pn19111 1191111111 ‘su121fio1d g3 111 1 ‘$199_[01d 119129$91 9111192 0017 1n0q2 %11119np1109 $1 MOLLVLS SVXHL 21111. 1129111011 121m u1 pu2 $91191121 pu2 $111121 110 p919np1109 912 $1119u1119dx9 11911211 fiu1)1 9111 pu2 $9111$np111 pu2 $111; 10 9391103 $21191 ‘9391103 01111991 $21191 ‘$21191 10 A11$19A1u11 ‘91n11no11fiv 10 1119111112d9q ‘S '11 S 11os11c1 $21191 ‘$21191 10 u01$$1111u10D 11$1¢1 pu2 9u12Q ‘991A19g 1$910fl > 9111 9pn19111 $919119%2 §§u11219d00Q 991911932 191110 A01 p911M0 $u01121$ ‘ 009 171 912 919111 ‘u0111pp2 u1 '$91101210q21 p1911 6 p112 $u01121$qn$ 13 19111 10 $2912 121n11n911%2 10_[2u1 9111 u1 1n0 p91290'1 '1121$ 9A11211$1u1111p2 _9 $991A19$ A10121n391 g ‘$1u9111112d9p 991AJ9$ Z ‘s1119u1112d9p 19112111 fs 91 912 ‘11011219 9391103 1B S-IQI-IBIIBPPQQ 1111M ‘NOLLVJS mvw 21111 NI @1953 9591103 W191] 912x91 9111 1o $11nd 91 1o 9uo s1 pun ‘snxal 1o 91mg 9111 1o u95n 1191n9s91 1n1n11n9115n 911qnd 9111 s1 ‘fang 1u9111119dx3 1n1n11n9115y snxa _1_ 91.1 _1_ pqoreesea €P§M-€I|.E].S (7179-1509! F‘ movmowog F6‘ 73J199§79fl V‘ 991G198 110151191 my 19112111291131; svxal 9111 f0 szsgjvgoads pun 9121959 Mzm09 16g swajznuawoq pun 11911111911121 ‘suawm svxa 01 91.11129 9w s1 11991 91z29s9 _ l P. I 11 NOIlVHHdO NOILVZINVDHO s919u95n 51111n19doo9 pun uo11n1g 11.191111191121151 1n1n11na115y snxal 9111 1o $11un 1191n9s91 p191; 1o 1101119901