Persistence of Dinitroaniline Herbicides and Potential for Injury to Sugarbeets-l<

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1 Persistence of Dinitroniline Herbicides nd Potentil for Injury to Sugrbeets-l< J. E. Wrner, S. R. Winter nd A. F. Wiese Received for Publiction September 29, 1986 INTRODUCTION Preplnt pplictions of dinitroniline (DNA) herbicides hve been used for weed control in soybens (Clycinr mx (L.) Merr.) nd cotton (Cossypium hir s utum L.). Also, lyby pplictions re used in sorghum (Sorghum 6ic ol {' ( L.) Moe n c h) nd cor n ( Z e m y 5 L.). The y re b r d spectrum herbicides which control most grsses nd mny brodlef weeds (7). Mny reports show tht DNA's dissipte to nonphytotoxic level in one growing seson (2, 6, 9), while others give evidence of persistence for much longer periods (3, 1). Some fctors involved in DNA persistence re photodecomposition, voltiliztion, dsorption to cly nd orgnlc mtter, leching, runoff, tillge, biodegrdtlon, soil temperture, nd soil moisture ( 6, 1, 11, 14, 15, 17). Periodic flooding nd even windy conditions following ppliction pper to ffect persistence (1, 13). Differences in moleculr structure of DNA's lso ffect persistence nd phytotoxicity (5, 8). In recent yers, growers hve reported injury to sugrbeets (Brt v ul gri s L.) when DNA's were used for weed control in soyben, cotton, sorghum, or corn tht preceded sugrbeets in rottions. DNA's hve been know~ to cuse injury to crops including sugrbeets (1, 4, 5, 6, 1, 12, 16). Abernthy nd Keeling (1) showed tht DNA residues remining fter cotton crop could be high enough to injure whet ( Triti cum u pstivum L. em Thell.) or sorghum, nd to control pigweed (Am r ~nthus seson. spp.) during the second *Contribution from the Texs Agri. Exp. Stn., Texs A & M Univ. System. Th e uthors re Reserch Associte, Associt e Professor, nd Professor, respectively, Texs Agri. Exp. Stn., P. O. Drwer 1, Bushlnd, TX 7912.

2 S8 JOURNAL OF THE A.S.S.B.T. The purpose of these studies ws to determine if triflurlin, fluchlorlin, proflurlin, nd pendimethlin used preplnt incorported (PPI) before or t lyby in previous crop will injure sugrbeets nd how residues of these herbicides interct with PPI sugrbeet herbicides to cuse injury. MATERIALS AND METHODS There were two types of experiments. In one, known mounts of herbicides were pplied just prior to plnting sugrbeets; in the second, DNA's were pplied PPI or t lyby to 'Clrk 63' soybens the yer prior to plnting sugrbeets. Both studies were done on Pullmn cly lom (Torrertic Pleustolls; fine, mixed, thermic) consisting of 23, 46, nd 31 % of snd, silt, nd cly, respectively, with ph of 7.4 nd 1.S% orgnic mtter. The sugrbeet vrieties were 'HH23', 'D2', nd 'Tx9', respectively, in experiments conducted in 198, 1981, nd In the first study, triflurlin [2,6-dinitro-N,N-dipropyl - 4-(trifluoromethyl)benzenmine], pendimethlin [N (1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenmine], nd proflurlin [N-(cyclopropylmethyl)-2,6-dinitro-~-propyl-4 (trifluoromethyl)benzenmine] were spryed in 216 L / h of wter crrier t.7,.14, nd.28 kg/h ech; fluchlorlin [~-(2-chloroethyl)-2, 6-dinitro-~-propyl-4-(trifluoromethyl)benzenmine] ws pplied t.14 kg/h only. It ws surmised tht these rtes would be similr to the mounts of herbicide tht would persist in the soil from 6 to 12 months, In ddition, DNA herbicides were ov~rlid with either 3.3 kg/h ethofumeste [(~)-2-ethoxy-2,3-dihydro-3,3-dimethyl-S-benzofurnyl methnesulfonte] or 4.S kg / h cyclote [S-ethyl cyclohexylethylcrbmothiote], PPI sugrbeet herbicides, in split plot design, to determine possible interctions of DNA's with regulr sugrbeet herbicides" The DNA herbicides nd check were min plots nd were spryed on three.7s-m rows tht were 7.Sm long. Then the two sugrbeet herbicides or nothing were ech o v erlid in one of the three rows s sub-plots. After spry ppliction, the herbicides were ll incor

3 VOL. 24, NO. 1, APRIL 1987 S9 ported with rolling cultivtor which mixed them into th~ top 4 to 6 cm of soil. Tretments were replicted three times. Sugrbeets were plnted in dry soil nd furrow lrrigted the sme or following dy for emergence. These plots were rted for sugrbeet injury bout 4 to 6 weeks fter plnting" The percent injury score reflected generl condltion of the crop considering both stnd nd vigor reduction Seprte estimtes of stnd nd vigor were not mde, In the second study, which ws strted in 1981 nd repeted in 1982, triflurlin t.8 kg/h, proflurlin nd fluchlorlin t 1.1 kg / h, nd pendimethlin t 1.1 nd 1.7 kg / h were spryed brodcst on beds spced 75 cm prt nd then incorported with rolling cultivtor bout 2 weeks before plnting soybens in lte My. In mid-july, the sme herbicides were spryed brodcst t lyby on soybens nd incorported into the beds with rolling cultivtor to simulte use in corn nd sorghum. These studies were estblished on level borders nd the soybens received preplnt irrigtion, rinfll, nd four dditionl irrigtions during the summer. There ws totl of 5 cm of irrigtion wter pplied ech ye r. The soyben studies were rndomized blocks with four replictions. The seson following soybens, sugrbeets ~ere plnted on beds mintined from the soybens nd jrrigted twice for emergence before visully e s timting i.njury. Ech yer, soil smples from the surfce 7.5 em were tken t 3 different dtes before plnti.ng sugr beets. Smples were tken t five loction s in ech plot with spde nd combined. The soil smples were quntittively nlyzed for DNA's with n Antek 3 gs chromtogrph using 3% silicone OV-IOI on chromosorb W-HP 8/1 mesh pcking mteril. Differences in ll studies were determined with nlysis of vrince nd Duncn Multiple Rnge Tests using 5% level of sig nificnce. RESULTS AND DISCUSSION In the 198 toxicity study, pendimethlin t.28 kg / h cu s ed the most injury, 26%, to sugrbeet (Tble 1).

4 6 JOURNAL OF THE A.S.S.B.T. Tble 1. Sugrbeet injury in 198 from low rtes of DNA nd sugrbeet herbicides. DNA Herbicide Triflurlin Pendimethlin Proflurlin Fluehlorlin Check Averge Appliction rte (kg/ h) DNA Plus DNA Ethofumeste Cyelote lone 3.3 kg/h 4.5 kg/h Averge ( % Injury) d d b 7 3 d bc d cd bed d o o o o d 7 B 2 A 17 A Averges followed by the sme letter of the sme cse re not different t P.5 ccording to the Duncn's Multiple Rnge Test. When the DNA herbicides were overlid nd mixed with ethofumeste nd cyclote, verge injury to sugrbeets incresed significntly. Highest injury, 6%, occurred when pendimethlin t.28 kg/h ws mixed with either ethofumeste or cyclote. Injury ws still high, bout 4 %, when pendimethlin t.14 kg / h ws mixed with either sugrbeet herbicide. Triflurlin t.28 kg/h mixed with ethofumeste cused 53 % injury. Proflurlin nd fluchlor lin either lone or mixed with the sugrbeet herbicides were less toxic. On the verge, none of the.7 kg/h tretments cused significnt injury to the sugrbeets. In 1981, there ws very little injury when sugrbeets were plnted directly into soil treted with DNA herbicide lone or combintions of DNA herbicides with either ethofumeste or cyclote (Tble 2). There ws slightly more injury to sugrbeets from triflurlin nd pendimethlin thn proflurlin nd fluchlorlin. Results in

5 VOL. 24, NO.1, APRIL Tble 2. Sugrbeet i njury in 1981 from low rtes of DNA nd sugrbeet herbicides. DNA Plus DNA Appliction DNA Ethofumeste Cyclote Herbicide rte lone 3.3 kg / h 4.5 kg/ h Averge (kg/h) (% Injury) Triflurlin bc b b Pendimethlin bc Prof l u r lin bc.14 c.28 c Fluchlorlin bc Check o o o o c Averge 3 A 5 A 5 A Averges followed by the sme letter of the sme c se re not different t P.5 ccording to the Duncn ' s Multiple Rnge Test were similr to 1981, with triflurlin nd pendimethlin cusing the most injury. However, differences were not significnt (Tble 3). The generl level of injury in 1982 my hve been reduced when the sugrbeets hd to be replnted 1 month fter herbicide ppliction becuse hrd rin crusted the soil. It is not known if vriety differences plyed prt in the differences from yer to yer. In the second type of study, two field experiments were strted in 1981 nd In ech cse, DNA's were pplied to soybens PPI or t lyby. Soil smples were tken to ssy DNA residues three times prior to plnting sugrbeets the next yer in erly April. In 1981, DNA residues in the soil rnged from.15 to.41 ppm in August for PPI pplictions (Tble 4). For lyby pplictions in July, the rnge ws from.22 to.78 ppm. By October, the residue resulting from ll PPI pplictions hd dropped to.13 ppm or less. For lyby tretments, resi

6 62 JOURNAL OF THE A.S.S.B.T. Tble 3. Sugrbeet injury in 1982 following ppliction nd incorportion of DNA nd sugrbeet herbicides. DNA Herbicide Appliction rte DNA lone DNA E] lls Ethofumeste Cyclote 3.3 kg/h 4.5 kg/h Averge Triflurlin (kg/h) ( % Injury) Pendimethlin Fluchlorlin Proflurlin Check o o o o Averge 6 A 2 A 15 A Averges followed by the sme letter of the sme cse re not different t P.5 ccording to the Duncn's Multiple Rnge Test. dues in August nd October were higher thn the PPI pplictions. By Februry, residues in the soil hd dropped to.8 ppm or less with the exception of where 1.7 kg/h of pendimethlin hd been pplied t lyby. A totl of 9.7 ern of rinfll in the second week of August, 1981, occurred shortly fter lte summer irrigtion nd flooded the level borders for 3 dys. The nerobic conditions probbly cused rpid brekdown of the DNA herbicides (13). Sugrbeets plnted in Mrch of 1982 were not significntly injured by herbicide residues in the soil (Tble 4). In the 1982 experiment, flooding did not occur nd herbicide residues in the soil did not decrese s much from August to Mrch s in 1981 (T ble 5). The exceptions were for the PPI pplictions of triflurlin, fluchlorlin nd the 1.1 kg/h rte of pendimethlin. Herbicide residues with lyby pplictions with triflurlin nd proflurlin did not decrese much from August to

7 VOL. 24, NO. 1, APRIL of.8 PPI l,yby.4 h.1 gh 13 2 cd.2 h.1 h PPI Lyby O h.15.3 c-f b.3.32 be.5 41 h-k.3 bed bc Mrch. About 5% decrese occurred with fluchlorlin nd pendimethlin. The following spring, sugrbeet injury ws s high with 1.7 /h pendimeth pplied lyby (Tble 5). With the exception of pendimethlin t 1. fh, of the PPI tretment cused significnt injury. Triflurlin t.8 kg/h ws the only

8 64 JOURNAL OF THE A.S.S.B.T. tretment tht did not cuse injury to the sugrbeets. Toxicity studies showed tht triflurlin nd pendimethlin t.28 kg j h hve the potentil for seriously injuring sugrbeets. When the soil hs this level or more of the two herbicides, sugrbeets should not be plnted. Assuming tht the top 7.5 cm of h of soil weighs bout 1 million kg, 1. kgjh rte of herbicide incorported into the top 7.5 cm equls 1. ppm. In 1983, residues in the soil following lyby ppliction to soybens in 1982, rnged from.14 to.5 ppm. This cused similr or more toxicity to the subsequent sugrbeet crop thn occurred in the toxicity studies where the top rte of ppliction ws.28 kg j h. These studies indicte tht PPI pplictions of triflurlin nd pendimethlin t norml rtes of 1 kg j h or less to previous crop re not likely to inj u re sugrbeets the following yer. Lyby pplictions pplied to corn or sorghum re likely to cuse injury. Also, ethofumeste nd cyclote pplied preplnt on sugrbeets increse the potentil for injury from DNA herbicides used the previous yer. SUMMARY The injury to sugrbeets cused by trif l urlin, pendimethlin, fluchlorlin, nd poroflurlin pplied immeditely before plnting sugrbeet s or when ppl i ed preplnt incorported (PPI) or incorported t lyby for soybens grown prior to sugrbeets w s determined on cly lom soil. In 3 yers of toxicity studies, the herb~cides were pplied nd i ncorported t. 7,.14, nd.2 8 kgjh immeditely before plnting sugrbeets. Then, either n o herbic i de, ethofumeste t 3.3 kg/h, or cyclote t 4.5 kgjh were mixed with the DNA herbicides. In nother 2 yer study, the DNA herbicides were pplied t from. 8 to 1.7 kg j h, either PPI o r lyby in soybens. The toxicity studies showed tht pendimethlin nd triflurlin were more toxic to sugrbeet s thn proflurlin or fluchlorlin. When ethofumeste nd cyclote were dded to the DNA' s, toxicity incresed. Studies showed tht PPI

9 VOL. 24, NO.1, APRIL pplictions of triflurlin or pendimethlin to rottionl crop 12 months before plnting sugrbeets myor my not injure the sugrbeets. The chnce for injury decresed when soil ws flooded by combintion of irrigtion nd rin. Lyby tretments of triflurlin or pendimethlin to rottionl crops bout 8 months prior to plnting sugrbeets re likely to cuse injury. LITERATURE CITED 1. Abe rn thy, J. R., nd J. W. Ke elin g E f f i c c y nd rottionl crop response to levels nd dtes of dinitroniline herbicide pplictions. Weed Sci. 27: Berner, R. C Efficcy nd persistence of five dinitroniline herbicides. M.S. Thesis Texs Tech University. 3 pp. 3. Burnside, O. C Triflurlin dissiption in soil following repeted nnul pplictions. Weed Sci. 22: , 4. Hrvey, R. Go Field comprison of twelve dinitroniline herbicides" Weed Sci. 21: Hrvey, R. Go Reltive phytotoxicities of dinitroniline herbicides. Weed Sci. 21: Helling, C. S Dinitroniline herbicides in, so i 1 s. J. Environ. Qu 1. 5 : Beste, C. E., N. E. Humburg, H. M. Kempen, G. R. Mille, R. O. Rdke, J. D. Rigglemn, nd J. F. Stritzke. Herbicide Hndbook of The Weed Science Society of Americ th Ed. Weed Sctence Society of Americ, 39 West Clrk St. Chmpign, ILL. 8. Jordn, T. N., R. S. Bker, nd W. C. Brrentine Comprtive toxicity of severl dinitroniline herbicides. Weed Sci. 26: Kerney, P. C., J. R. Plimmer, W. B. Wheeler, nd A. Kontson Persistence nd metbolism of dinitroniline herbicides in soils. Pesticide Biochem. nd Physiol. 6 : Miller, J. H., P. E. Keeley, C. H. Crter, nd R. J. Thullen Soil persistnce of triflurlin, benefin, nd nitrlin. Weed Sci. 23:

10 66 JOURNAL OF THE A.5.S.B.T. 11. Nelson, J. E., W. F. Meggitt, nd D. Penner Frctiontion of residues of pendimethlin, triflurlin, nd oryzlin during degrdtion. Weed Sci. 31: Oliver, L. R., nd R. E. Frns Inhibition of cotton nd soyben roots from incorported triflurlin nd persistence in soil. Weed Sci. 16: Svge, K. E Persistence of severl dinitroniline herbicides s ffected by soil moisture. Weed Sci. 26: Svge, K. E., nd T. N. Jordn Persistence of three dinitroniline herbicides on the soil surfce. Weed Sci. 28: Smith, D. T., nd A. F. Wiese Delyed incorportion of triflurlin nd nitrlin. Weed Sci. 21: Schweizer, E. E Aberrtions in sugrbeet roots s induced by triflurlin. Weed Sci. 18: Wiese, A. F., E. W. Chenult, And E. B. Hudspeth, Jr Incorportion of preplnt herbicides for cotton. Weed Sci. 17: