ESTER FORMULATION AND SURFACTANT AFFECT RESPONSE OF RADIATA PINE AND GORSE SEEDLINGS TO 2,4,5-T

Size: px

Start display at page:

Download "ESTER FORMULATION AND SURFACTANT AFFECT RESPONSE OF RADIATA PINE AND GORSE SEEDLINGS TO 2,4,5-T"

Aron Lloyd
5 years ago
Views:

1 44 Vl. 9 ESTER FORMULATION AND SURFACTANT AFFECT RESPONSE OF RADIATA PINE AND GORSE SEEDLINGS TO 2,4,5-T DAVID PREEST Frest Research Institute, New Zealand Frest Service, Rtrua (Received fr publicatin 7 Nvember 978) ABSTRACT In a replicated 2 (ester) x 4 (rate) x 2 (surfactant) factrial experiment the is-ctyl ester f 2,4,5-T was fund t be mre effective in cntrlling seedling grse (Ulex eurpaeus L.) and less damaging t radiata pine (Pinus radiata D.Dn) seedlings than the butyl ester. The additin f 0.5% v/v surfactant significantly enhanced the activity f the is-ctyl ester against the grse, but nt that f the butyl ester, and resulted in marginally less tree grwth suppressin by 2,4,5-T. Further investigatin f the effects f ester frmulatin and surfactant n 2,4,5-T activity in relatin t grse cntrl and tree selectivity appears warranted. INTRODUCTION 2,4,5-Tr ichlrphenxyacetic acid (2,4,5-T) has lng been the majr herbicide fr grse cntrl in New Zealand frestry and agriculture. In the past a fairly wide range f ester frmulatins have been marketed (including butyl, ctyl, is-ctyl, butxyethanl, ethyl hexyl, is-prpyl) but there has never been a clear understanding f their relative merits as far as grse cntrl and selectivity twards trees (principally radiata pine) are cncerned. On the basis f extensive field bservatins it seems t have been accepted that there are n differences f practical significance between the esters. Even vlatility (shrt chain esters v. lng chain esters) is nt thught t be a significant factr in New Zealand with generally mild summer temperatures. Nn-vlatile frmulatins are ften specified in frestry applicatins, but nly as an envirnmental precautin. Mre recently the number f esters available cmmercially has diminished s that tday nly the butyl and is-ctyl esters are marketed, and it seems pssible that nly the butyl ester may be cmmercially available in the future. It is well knwn that there are marked differences in the absrptin f 2,4-D and 2,4,5-T depending n frmulatin and mlecular cnfiguratin (Nrris and Freed, 964, 966). Mre specifically the "heavy" (less vlatile) esters f 2,4-D are mre effective against certain perennial weeds than the "light" (vlatile) alkyl esters (Crafts, 96). Despite the fact that in peratinal use differences between the effects f varius esters f 2,4,5-T n grse have nt been detected, there are gd grunds fr suspecting that differences wrth expliting may exist. The different alchl mieties vary greatly in size and structure, and cnfer n the frmulated esters marked differences in vlatility, N.Z. J. Fr. Sci. 9(): (979).

2 N. Preest Seedling Respnse t 2,4,5-T 45 in lngevity as liquids in the air and n leaf surfaces, and in their ability t disslve in the leaf waxes the latter prbably being f particular significance fr grse (Rlstn, 974; Zabkiewicz and Gaskin, 978). If significant ester-dependent variatin in herbicidal effectiveness and/r selectivity f 2,4,5-T were fund this culd be a factr in determining which esters shuld be manufactured and marketed fr grse cntrl in New Zealand. Surfactant enhancement f herbicide activity is a well-knwn phenmenn (Jansen et al., 96; Jansen, 964; Bland and Brian, 975) but it may be less prnunced in the case f emulsifiable ester frmulatins which already cntain surface active agents in the frm f emulsifiers (Crns and Dai, 967). Adding surfactant is smetimes recmmended t imprve wetting and cverage f dry r dusty fliage by aqueus emulsifiable ester sprays f 2,4,5-T, but therwise n recmmendatin is usually given. Althugh Rlstn (974) fund that surfactants culd duble the amunt f 2,4-D dimethylamine salt and piclram ptassium salt absrbed by grse fliage, n infrmatin was available n the effect f additinal surfactant n the activity f 2,4,5-T emulsifiable esters n grse and radiata pine. Infrmatin n this pint was a further bjective f the wrk reprted here. METHODS Only tw esters were prcurable, the butyl and the is-ctyl (supplied by Ivn Watkins-Dw Ltd, New Plymuth: butyl ester, 60 g a.e./litre, batch n. 06/76; isctyl ester, 60 g a.e./litre, batch n. 07/76). These were each applied at fur rates, 0.5,.0, 2.0 and.0 kg a.e./ha, bth with and withut 0.5% v/v surfactant ("Multifilm X-77"), t small 2m X 2m nursery plts each cntaining nine /0 radiata pine and 6 /0 grse transplants within the central m X Im area. The treatments were applied as aqueus sprays in tw passes f 50 litres/ha each, using an verhead, C0 2 - pwered bm sprayer. The experiment was a thrice replicated, 2 (ester) X 4 (rate) X 2 (surfactant) factrial f fully randmised design. The plts were planted in August 976 and sprayed n December 6 976, when bth grse and trees were well established and new grwth well underway. The grse plants were 5-0 cm tall with 5-5 cm f sft, new grwth. The first pst-applicatin rain, 50 mm, fell three days after treatment. Tree heights were measured at the time f treatment and percent fliage brwn-ff was estimated eight weeks later. The experiment was terminated after ten mnths when height and the number f terminal leaders were recrded fr each tree, and tree and grse survival and sht fresh weights were determined. Three-factr analyses f variance (ANOVA) f the fliage brwn-ff, survival, height increment, fresh weight and terminal leader data were made. RESULTS AND DISCUSSION The ANOVA results, in terms f the prbability levels assciated with the main effects and interactins f the factrs, are summarised in Tables and 2. Arcsin and lgarithmic transfrmatins f the grse survival and fresh weight data (respectively) were perfrmed befre ANOVA in rder t stabilise the variance. Althugh this tended t increase the F-values btained, the cnclusins drawn were essentially the same as thse using the untransfrmed data. Sme f the effects and interactins are pltted in Figs. -4. The main effects f the factrs n grse seedling survival are shwn in Table.

3 46 New Zealand Jurnal f Frestry Science Vl. 9 TABLE Prbabilities (p) assciated with the variance ratis (F-values) frm the three-way analyses f variance f the radiata pine individual tree data Surce f variatin Ester Rate Surfactant Ester x Rate Ester x surfactant Rate x surfactant Errr d.f. 40 Fliage brwn-ff NS NS Variable Number f leaders 0.70 NS 0.26 NS NS NS NS NS = nt significant at the 0.05 prbability level d.f. = degrees f freedm Height increment NS NS NS Sht fresh weight 0.59 NS 0.2 NS NS TABLE 2 Prbabilities (p) assciated with the variance ratis (F-values) frm the three-way analyses f variance f the transfrmed grse plt mean data Surce f variatin Ester Rate Surfactant Ester x rate Ester x surfactant Rate x surfactant Ester x rate x surfactant Errr d.f. 2 Variable Survival % Sht fresh weight (arcsin-tr ansf rmed) (Lg e -tr ansf rmed) NS 0.67 NS 0.87 NS NS 0.95 NS NS = nt significant at the 0.05 prbability level d.f. = degrees f freedm NS NS NS NS TABLE Main effects f ester, 2,4,5-T rate and surfactant n seedling grse survival and ttal sht fresh weight Factr Ester Rate Surfactant Level is-ctyl butyl Survival <%) Ttal sht fresh weight (g)

4 N. Preest Seedling Respnse t 2,4,5-T 47 Tree Respnses Tree mrtality was negligible. The few deaths which did ccur were nt attributable t the treatments. Althugh the main effects f ester, rate and surfactant n fliage brwn-ff were significant r highly significant statistically (Table ); nne had a significant effect n the number f terminal leaders prduced; rate and surfactant significantly affected height increment, but nly rate had a significant effect n sht fresh weight. Except, perhaps, fr the effect f rate n sht fresh weight nne f the statistically significant effects wuld be f great practical significance (Figs. -). FIG.. 40 FIG I FIG.. ~ E OS IEE SHOOT FR ES Fi O E 00 n QJ V> > j -. a ea c urfactant «/» 2^ un \ -* O) CD \ JC *" «s JC \ O) CN j= re \ en * a CO FIG. Main effects f ester frmulatin, surfactant and fliage brwn-ff eight weeks after treatment. FIG. 2 Main effects f ester frmulatin, surfactant and height increment. FIG. Main effects f ester frmulatin, surfactant and sht fresh weight. rate rate rate f 2,4,5-T f 2,4,5-T f 2,4,5-T n n n radiata pine radiata pine radiata pine

5 New Zealand Jurnal f Frestry Science Vl. 9 Several interactins were statistically significant, but culd nt n the whle be meaningfully interpreted. There were significant ester X rate interactive effects n fliage brwn-ff, height increment and fresh weight (Figs. 4-6). The first appeared t be due t the passing f sme frm f threshld between the 2 and kg/ha rates in tree respnse t the butyl ester (Fig. 4). This interactin culd nt be interpreted fr height increment r fresh weight (Figs. 5, 6). The surfactant X rate effects n sht fresh weight (Fig. 7) suggested that the surfactant increased the damaging effect f the lwest rate f 2,4,5-T but prtected the trees t sme extent at the ther three rates. On the whle the trees were affected slightly less by the is-ctyl ester than the butyl ester, and, surprisingly, respnded mre favurably t the presence f surfactant than its absence. Althugh the presence f surfactant significantly increased fliage brwn-ff (Table ; Fig. ) it appeared t amelirate the grwth depressive effects f the herbicides (Figs. 2, ), especially f the is-ctyl ester (Fig. 8). In view f the lack f cmpetitin g OC CO CS < ,4,5-T RATE (Kg a.e./ha.) FIG. 4 Effect f ester frmulatin n radiata pine fliage brwn-ff respnse t 2,4,5-T eight weeks after treatment.

6 N. Preest Seedling Respnse t 2,4,5-T FIG. 5. Butyl ester Is-ctyl ester 500 r FIG Butyl ester Is-ctyl ester "E 0 OC z 20 CS z CS 00 CO h- 200 CO FIG r " \ 8. i N surfactant % v/v surfactant. 40 h E u h- 0 h 20 * Is-ctyl, n surf. Kls-ctyl, plus surf. Butyl n surf. Butyl plus surf. 00 0h ,4,5 -T RATE (kg a.e./ha.) FIG. 5 Effect f ester frmulatin n radiata pine average height increment respnse t 2,4,5-T. FIG. 6 Effect f ester frmulatin n radiata pine sht average fresh weight respnse t 2,4,5-T. FIG. 7 Effect f surfactant n radiata pine sht average fresh weight respnse t 2,4,5-T. FIG. 8 Effect f surfactant n radiata pine sht average height increment respnse t the is-ctyl and butyl esters f 2,4,5-T.

7 50 New Zealand Jurnal f Frestry Science Vl. 9 FIG. 9. Butyl ester Is-ctyl ester 4000 FIG. 2. Butyl ester Is-ctyl ester ^_ ,4,5 - T RATE (Kg a.e. / ha.) 2,4,5 - T RATE (Kg a.e. / ha.) 4000 N surfactant i 0.5% v/v surfactant FIG.. m N surfactant A 0.5% v v surfactant ,4,5-T RATE (Kg a.e. / ha.) 2 2,4,5 -T RATE (Kg a.e. / ha.) * * Is-ctyl, n surf, -ttls-ctyl, plus surf. Butyl n surf. Butyl plus surf. * * Is-ctyl, n surf. Is-ctyl, plus surf. Butyl n surf. Butyl plus surf. 2,4,5-T 2 RATE (Kg a.e. / ha.) 2 2,4,5 - T RATE (kg a.e. / ha.)

8 N. Preest Seedling Respnse t 2,4,5-T 5 ffered the trees by the grse plants n the plts, and the fact that tree grwth was verall weakly, but psitively, crrelated with grse survival and fresh weight, it seems unlikely that the amelirating effect f added surfactant was due merely t a "releasing" effect resulting frm better grse cntrl (see later and Figs., 4). This apparent prtective effect f the surfactant was cntrary t expectatins and cannt at this stage be explained. Grse Respnses Bth ester and rate had highly significant effects n grse seedling survival and fresh weight (Tables 2, ). Fewer seedlings survived at all rates with the is-ctyl ester than with the butyl (Fig. 9); the higher the rate the greater the difference between the esters, althugh the interactin was nt statistically significant. At the kg/hr rate nly 2% f the is-ctyl ester-treated seedlings survived cmpared with 20% f the butyl ester-treated seedlings. Similarly, there was a cnsistently larger reductin in ttal seedling fresh weight frm the is-ctyl ester than frm the butyl ester (Fig. 2). In this case the ester X rate interactin was highly significant, but this is almst certainly due t the large difference in respnse t the tw esters at the 0.5 kg/ha rate. Althugh the tabulated and graphed results indicated definite negative surfactant effects n grse seedling survival and fresh weight (Table ; Figs. 0, ) the initial analyses shwed them t> be f a lw r dubtful rder f significance, statistically (Table 2). Frm Fig. 4 it was evident (as in the tree data) that the effect f surfactant was different fr the tw esters. Supplementary separate analyses f the is-ctyl ester and butyl ester subsets f the data shwed that surfactant had a large, highly significant negative effect (p < 0.00) n grse seedling fresh weight respnse t the is-ctyl ester, but nly a small, nn-significant (p = 0.758), negative effect n the respnse t the butyl ester. Surfactant enhancement f the is-ctyl ester resulted in reductins f 50% r mre in fresh weight cmpared with the is-ctyl ester alne. Althugh the supplementary ANOVAs did nt indicate that the survival respnse t surfactant was statistically very significant (p = 0.284), Fig. strngly sugests that a wrthwhile enhancement f seedling mrtality may be btained when a surfactant is used with the is-ctyl ester but nt with the butyl ester. CONCSIONS The is-ctyl ester f 2,4,5-T caused greater seedling grse mrtality and grwth suppressin than the butyl ester thrughut the kg a.e./ha range investigated. The additin f surfactant at 0.5 % v/v increased grse grwth suppressin and mrtality FIG. 9 Effect f ester frmulatin n grse seedling survival respnse t 2,4,5-T. FIG. 0 Effect f surfactant n grse seedling survival respnse t 2,4,5-T. FIG. Effect f surfactant n grse seedling survival respnse t the is-ctyl and butyl esters f 2,4,5-T. FIG. 2 Effect f ester frmulatin n ttal grse seedling sht fresh weight respnse t 2,4,5-T. FIG. Effect f surfactant n ttal grse seedling sht fresh weight respnse t 2,4,5-T. FIG. 4 Effect f surfactant n ttal grse seedling sht fresh weight respnse t the is-ctyl and butyl esters f 2,4,5-T.

9 52 New Zealand Jurnal f Frestry Science Vl. 9 by the is-ctyl ester but nt by the butyl ester. Use f the is-ctyl ester did nt significantly affect tree height r fresh weight cmpared with the butyl ester. Surfactant significantly imprved tree height respnse but nt fresh weight. In general is-ctyl ester and surfactant treatments resulted in larger mre rbust trees than the butyl ester and surfactant-less treatments. Surfactant enhancement f the is-ctyl ester was limited t the rates belw.0 kg/ha. It wuld appear that in the is-ctyl ester-plus-surfactant cmbinatins we have treatments which are significantly mre active against seedling grse than the butyl ester-plus-surfactant treatments, while at the same time being marginally less damaging tward the yung radiata pine tree crp. These results suggest that further wrk n the influence f ester frmulatin n 2,4,5-T activity against grse and selectivity twards radiata pine culd well yield wrthwhile dividends in selective and nn-selective grse cntrl in farming and frestry. ACKNOWLEDGMENTS Messrs N. A. Davenhill and H. Sandersn laid ut, established and maintained the trial plts, and assisted in their treatment and assessment. Mr R. M. H. C. Sctt carried ut the cmputer prcessing f the data. Ivn Watkins-Dw Ltd, New Plymuth, supplied the tw esters f 2,4,5-T used. REFERENCES BLAND, P. D. and BRIAN, R. C. 975: Surfactants and the uptake and mvement f paraquat in plants. Pesticide Sci. 6(5): CORNS, W. G. and DAI, T. 967: Effects f added surfactant n the txicity f piclram, 2,4-D and 2,4,5-T t Ppulus tremulides Michx. and P. balsamifera L. saplings. Can. J. Plant Sci. 47(6): 7-2. CRAFTS, A. S. 96: "The Chemistry and Mde f Actin f Herbicides." Interscience Publishers, Inc. N.Y. 269 pp. JANSEN, L. L. 984: Surfactant enhancement f herbicide entry. Weeds 2(4): JANSEN, L. L., GENTNER, W. A. and SHAW, W. C. 96: Effects f surfactants n the herbicidal activity f several herbicides in aqueus spray systems. Weeds 9(): NORRIS, L. A. and FREED, V. H. 984: Effects f frmulatin and mlecular cnfiguratin n absrptin and translcatin f sme phenxy herbicides in bigleaf maple seedlings. Western Weed Cnf. Res. Prg. Rep.: :The absrptin and translcatin characteristics f several phenxyalkyl acid herbicides n bigleaf maple. Weeds Res. 6(): 20-. RICHARDSON, R. G. 977: A review f fliar absrptin and translcatin f 2,4-D and 2,4,5-T. Weeds Res. 7(4): ROLSTON, M. P. 974: Sme aspects f absrptin, translcatin and metablism f tw fliar applied auxin herbicides in grse (Ulex eurpaeus L.). M. Agr. Sci. Thesis, Massey University, Palmerstn Nrth. ZABKIEWICZ, J. A. and GASKIN, R. E. 978: Seasnal variatin in grse (Ulex eurpaeus L.) surface wax and trichmes. New Phytl. 8: in press.

Scientia Horticulturae, 3 (1975) Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

Scientia Horticulturae, 3 (1975) Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands Scientia Hrticulturae, 3 (1975) 89--94 Elsevier Scientific Publishing Cmpany, Amsterdam -- Printed in The Netherlands EFFECT F NITRGEN FERTILIZATIN N YIELD AND FRUIT IL CNTENT F AVCAD TREES A.B. ABU AZIZ,