Vegetable Oil Replacements for Petroleum Oil Adjuvants in Herbicide Sprays 1 R. G. ROBINSON AND W. W. NELSON z
The objectives o f this research were to observe plant response to vegetable oil sprays and to learn if vegetable oils - - s u n f l o w e r , soybean, linseed, or e a m e l i n a - can replace petroleum oil as an herbicide adjuvant. Vegetable oils were sprayed on grain sorghum /Sorghum bieolor (L.) Moench.] and sunflower (Helianthus annuus L.) at 4 7 L/ha and were neither harmful nor beneficial to the crops. When used as an adjuvant postemergenee with 1.68 kg/ha o f atrazine [2-ehloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], 2.3 L/ha o f vegetable oil were as effective in weed control as either 2.3 or 9.4 L/ha o f petroleum oil. All atrazine treatments gave c o m p l e t e control o f dicotyledonous weeds. B u t vegetable oil adjuvants with atrazine at 1.68 kg/ha gave significantly more grass weed control than atrazine alone at 2.24 kg/ha in two o f five trials and were equally good in the other trials. The cost o f the adjuvant is less than that o f the atrazine replaced, and the initial herbicide residue in the soil is reduced by 25%.
Fossil fuels -- petroleum, coal, and crops are a renewable resource from natural gas -- are becoming a less abun- annual crop production. Vegetable oils dant and more expensive source of ener- differ chemically from the hydrocarbon gy. Although solar energy is used by petroleum oils b u t have many similar crops, agriculture in the United States physical characteristics. Sunflower, soydepends on fossil fuels for crop produc- bean, linseed, and camelina vegetable oils tion. In addition to engine fuels and lubri- are esters of fatty acids and glycerol b u t cants, millions of gallons of petroleum oil differ greatly in fatty acid composition, are used in pesticide sprays. iodine number, and present usage. Phytotoxic petroleum oil is used in The objectives of this research were to formulations designed to kill vegetation, determine if vegetable oil sprays are harmwhereas phytobland or "superior" petro- ful or beneficial to grass and dicotyleleum oil is used in insecticide, fungicide, donous crops and if they are satisfactory and selective herbicide concentrates and adjuvants to replace petroleum oil in the as carriers or adjuvants in sprays. atrazine [ 2-chloro-4-(ethylamino)-6The petroleum shortage indicates a (isopropylamino)-s-triazine] plus oil postneed for inexpensive materials to replace emergence herbicide spray used on grain petroleum. In contrast with petroleum oil sorghum [Sorghum bicolor (L.) Moench.] obtained from declining fossil reserves, and corn (Zea mays L.). Because the o i l - h e r b i c i d e mixture is vegetable oils extracted from oilseed p e t r o l e u m sprayed as an oil-in-water emulsion, commercially formulated phytobland spray J C o n t r i b u t i o n from the Department of Agronomy and Plant Genetics, University of oils contain from 1 to 20% emulsifier. R e c o m m e n d e d amounts of these formulaMinnesota, St. Paul. Paper No. 7953 of the Scientific Journal Series, Minnesota Agricul- tions range from 2.3 to 18.8 L/ha. tural Experiment Station. Nalewaja (2) found that atrazine with Submitted for publication March 6, 1973. either petroleum oil at 9.4 L/ha or vege2Professor, Department of Agronomy and P l a n t Genetics; Superintendent, Southwest table oil at 2.3 L/ha gave more weed Experiment Station, Lamberton, Minnesota. control in corn than atrazine alone. But petroleum oil at 2.3 L/ha with atrazine
146
ECONOMIC BOTANY 29: 146-151. April-June, 1975.
size was four cultivated rows 0.76 m apart and 10 m long. Yields were determined from a 5-m length of the two center rows. Petroleum oil adjuvants included commercially formulated spray oils with 1% emulsifier at 9.4 L/ha and with 20% emulsifier at 2.3 L/ha in 1968-70. Petroleum spray oil with 5% emulsifier was used in MATERIALS AND METttODS 1971. Vegetable oil adjuvants were crude The effect of vegetable and petroleum raw linseed, soybean, sunflower, and oil sprays on sunflower (Helianthus camelina oils with 20% emulsifier in annuus L.) and grain sorghum was studied 1968-70 and 5% emulsifier in 1971 at 2.3 on Hubbard coarse sand at Elk River, L/ha. Treatments at Elk River included unMinn. in 1970 and on Waukegan siltloam soil at Rosemount, Minn. in 1971. In sprayed, atrazine at 1.12 and 2.24 kg/ha, 1970, sunflower was sprayed when 38 cm and sunflower oil adjuvant at 3.4 L/ha tall and again at heading, while sorghum plus atrazine at .84 and 1.68 kg/ha. Plot was sprayed when 20 cm tall and again in size was eight uncultivated rows 30 cm early boot stage. In 1971, sunflower was apart and 10 m long. Yields were detersprayed when 25 cm and sorghum when mined from a 2.5 m length of the two 15 cm tall. Application rate was 47 L/ha. center rows. Green foxtail [Setaria viridis (L.) Crude raw sunflower, soybean, linseed, and camelina 3 [obtained from Camelina Beauv.] and yellow foxtail [Setaria lutessativa (L.) Crantz] vegetable oils were cens (Weigel) Hubb.] were the major compared. A commercially-formulated weeds at Lamberton, but common lambsphytobland petroleum spray oil with 1% quarters (Chenopodium album L.), smartemulsifier was used at Elk River and a weed (Polygonum spp.), common ragphytobland petroleum spray oil without weed (Ambrosia artemisiifolia L.), redroot pigweed (Amaranthus retroflexus emulsifier at Rosemount. Varieties used were 'Minnesota 1' L.), and wild buckwheat (Polygonum conhybrid grain sorghum, 'Armavirec' sun- volvutus L.) were also present. The aboveflower at Elk River, and 'Mingren' sun- listed species plus carpetweed (Mollugo flower at Rosemount. Plot size was three verticillata L.) and clammyweed (Polanrows 0.76 m apart and 12 m long. Yields isia graveoIens Raf.) were present at Elk were determined from a 10-m length of River, but in contrast to Lamberton, the center row. dicotyledonous species particularly ragPetroleum and vegetable oil adjuvants weed predominated. to atrazine on grain sorghum were comWeed control on each plot was estipared in 1968 through 1971 on Nicollet mated at various times during the season silt loam at Lamberton, Minn. and in 1970 on a scale of 0 = complete weed cover to on Hubbard coarse sand at Elk River. 100 = weedfree. Sprays were applied in water at 159 L/ha In all trials, treatments were replicated at Lamberton and 325 L/ha at Elk River three times in a randomized complete when sorghum averaged 7 cm tall and block design. weeds were less than 4 cm. Data were analysed for variance and Treatments at Lamberton included un- treatments were compared in weed consprayed, atrazine at 2.24 kg/ha, and oil trol and sorghum head moisture and yield adjuvants plus atrazine at 1.68 kg/ha. Plot using Duncan's Multiple Range Test. Tabular average data for treatments not A c k n o w l e d g m e n t is made to W. H. Tallent, included in all years of trial were adjusted U S D A , Northern Utilization Research and (3).
did not give more weed control than atrazine alone. Strand (4) reported that vegetable oil and petroleum oil adjuvants were better than surfactant additives to atrazine in reducing weed yields in corn.
D e v e l o p m e n t Division, Peoria, Illinois for pilotplant e x t r a c t i o n of camelina oil.
R O B I N S O N A N D NELSON: V E G E I ' A B L s OIL FOR P E T R O L E U M
147
TABLE I YIELDS OF SUNFLOWERAND GRAIN SORGHUMSPRAYEDWITH PETROLEUMAND VEGETABLE OILS AT 47 L/ha IN 1970 AT ELK RIVER AND IN 1971 AT ROSEMOUNT
Treatment*
Elk River, kg/ha sunflower sorghum
Rosemount, kg/ha sunflower sorghum
None
448
963
2,532
5,233
Petroleum
293
708
2,498
4,931
Sunflower
337
963
2,381
5,555
Soybean
357
903
2,572
5,557
Linseed
407
927
2,588
5,822
2,690
5,378
468
671
Camelina LSD, 5%
123
365
* F for treatments not significant at the 5% level.
RESULTS AND DISCUSSION
Trials to detect toxic or beneficial effects of oil sprays on grain sorghum and sunflower were conducted under both favorable and very unfavorable growing conditions. Little or only short-time moisture stress occurred on the silt loam soil at Rosemount, but the crops suffered extreme moisture stress on the sand at Elk River. In addition to drought, sunflower head m o t h larvae (Homoeosoma electellure Hulst) reduced sunflower yields at Elk River. None of the treatments in Table I s i g n i f i c a n t l y affected yield, bushel weight, heading date, or sorghum head moisture. All sprays gave leaves an oily appearance for at least 5 days. Sorghum leaves appeared more oily than sunflower leaves. Petroleum oil spray gave considerable leaf margin killing of sunflower leaves at Elk River but only slight injury to sorghum. This injury may have been aggravated by the 1% emulsifier, because
148
in 1971 w i t h o u t emulsifier, injury was much less evident on sunflower and not evident on sorghum. These trials indicate that these vegetable oils can be rated phytobland because they did n o t harm either a grass (sorghum) or a dicotyledonous (sunflower) crop. Neither did these oils appear to have any beneficial effect on the crops. The recommended rate of atrazine on grain sorghum is 2.24 kg/ha (1). Petroleum or vegetable oils at 2.3 L/ha with atrazine at 1.68 kg/ha gave at least as much grass weed control as 2.24 kg/ha of atrazine alone in all trials and significantly more at Elk River and in 1971 at Lamberton (Tables II and III). All sprays gave 100% control of dicot weeds compared with an average 89% control from crop competition only. The cost of 2.3 L of oil is much less than that of the 0.56 kg of atrazine it replaced, and in addition atrazine residue in the soil is initially reduced by 25%. Atrazine is an herbicide which sometimes
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TABLE I I I EFFECT OF ATRAZINE WITH SUNFLOWEROIL ADJUVANT ON WEED CONTROL AND GRAIN SORGHUM HEAD MOISTURE AND YIELD IN 1970 AT ELK RIVER
Treatment and rate, kg/ha and L/ha
Weed control, % grass dicot
Head moisture, %
Grain y i e l d , kg/ha
None
23d+
36b
33
230b
Atrazine, 2.24 kg/ha
68b
lOOa
30
1560a
Atrazine, 1.68 kg/ha + sunflower, 3.4 L
80a
lOOa
33
1576a
Atrazine, 1.12 kg/ha
43c
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29
1225a
Atrazine, 0.84 kg/ha + sunflower, 3.4 L
50c
lOOa
29
1286a
II**
20**
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LSD, 5%
351"*
*Numbers in columns followed by the same letter do not differ significantly at the 5% level. **F significant at 1% level.
remains in the soil to injure susceptible crops the year after application. The petroleum oil formulation at 9.4 L/ha gave no better weed control than the petroleum or vegetable oil formulations at 2.3 L/ha. None of the treatments significantly affected sorghum head moisture using 1968 to 1971 average data. However the petroleum oil treatment resulted in significantly higher head moisture than the other treatments in 1971. The 1968 plots were weedfree and there were no differences among treatments in sorghum yield (Table II). However, the 4-year average data show all treatments exceeded no treatment in sorghum grain yield. The 1969 to 1971 yields are closely associated with weed control as evidenced by correlation coefficients of 0.97 and 0.98, respectively, between yield and grass weed control and between yield and dicot weed control. None o f the oil treatments differed significantly from the others in yield, and vegetable oils at 2.3 L/ha were as good as petroleum oil at 2.3 or 9.4 L/ha. Furthermore, vegetable oil treatments gave as high yields as a 33% higher rate of atrazine alone.
150
Although the reduction in atrazine rate with sunflower oil from 1.68 to 0.84 kg/ha in uncultivated sorghum at Elk River resulted in poorer weed control, it was much better than no treatment. If the crop is grown in wider rows and cultivated, the lower rate might be satisfactory on this sandy soil. This research indicates that vegetable oils of widely different chemical composition can be used in herbicide sprays and are as safe and effective as the petroleum oil c o m m o n l y used. Vegetable oil is more expensive than petroleum oil, b u t at 2.3 L/ha the difference in cost between vegetable and petroleum oil does n o t greatly increase production costs per hectare. Partly offsetting the slight cost disadvantage is the benefit to agriculture of a new market for oilseed crops. Of greater importance to society is the use of a product from annual crop production rather than a non-renewable resource like petroleum. LITERATURE CITED
1.
Miller, G. R., O. E. Strand, and A. G. Dexter. 1972. Cultural and chemical weed control in field crops-1973. Minnesota Agr. Ext. Fold. 212: 1-28.
ECONOMIC BOTANY
2.
3.
Nalewaja, J. D. 1968. Postemergence atrazinc t r e a t m e n t s for weed control in corn. Proc. North Central Weed Control Conf. 23: 12-13. Patterson, R. E. 1950. A m e t h o d of adjustm e n t for calculating comparable yields in v a r i e t y tests. Agron. J. 42: 509-11.
4.
Strand, O. E. 1970. A comparison of linseed oil and other adjuvants used with atrazine for early postemergence weed control in corn. U.S. Flax Institute 40: 23-24.
Book Reviews (continued from page 139)
The Biology of the Blue-Green Algae. Edited by
N. G. Carr and B. A. Whitton. 676 pp. illus. University of California Press, Berkeley and Los Angeles, 1973. $32.00 The Biology of the Blue-Green Algae is the ninth volume of the "Botanical Monographs" series. The lack of a broadly-based treatment of these procaryotic organisms was filled in 1973 with the publication of this text and of The Blue-Green Algae by G. E. Fogg et al. In fact, each co-author of the latter volume contributed a chapter to the Cart and Whitton text. Carr and Whitton have 25 chapters in their treatment; of these, only six consider ecology, and two chapters are on taxonomy. Surely, only the briefest discussion of the taxonomy of this enigmatic group can be presented in 14 pages. The opening statement of Desikachary's chapter on the "Status of Classical Taxonomy" (page 473) indicates that blue-green algae know "'no other taxonomy than the classical one" and that "the present-day problems or ailments are generated by the very practices adopted by phycologists." Like reviewer Stein (Phycologia 12: 250), I found the chapter difficult to read objectively. Noticeable differences between the two volumes are the more extensive treatments in the Cart and Whitton text of metabolic intermediates, lipids and lipid metabolism, biliproteins and bile pigments, and nucleic acids. The reference list is more extensive than that in Fogg et al. and by itself is a valuable contribution. Four appendices are found in the Carr and Whitton text. Appendix A includes a listing of the genera contained in the major culture collections of blue-green algae. The literature reference to the publication of each culture list is the most important contribution of this appendix. In Appendix B, there is a brief discussion of isolation and laboratory culture of cyanophyeean
algae. Information on nine of the more common growth media is included. The discussion of continuous culture and mass cultivation of Anacystis (Appendices C and D) could have been worked into the body of the text. This text and that of Fogg et al. are accurate and prepared well and will serve most of the needs of those interested in aspects of the biology of cyanophycean algae except their taxonomy. RICHARD A. PECORA University of Southwestern Louisiana Lafayette, Louisiana Agriculture and Environment. Vol. 1 +, 1974 +. Elsevier Scientific Publishing Company, Amsterdam, Netherlands. Vol. l: Dfl.87.00 + Dfl.8.00 "for postage and handling."
Agriculture and Environment, a quarterly journal in English, "deals with the infuences which agriculture exerts on the environment and the dependence of agriculture upon a sound management of the environment. Consideration is given to the quantitative and qualitative food requirements of a growing world population, and the effective production of food without overtaxing the environment. The journal aims to provide a medium for communication between experts from all over the w o r l d - whether in government, international organizations, scientific research institutes, universities, private enterprise, or any other sector of the community. It will facilitate the exchange of ideas on the problems of arable farming, animal husbandry, food production, forestry, etc. within the framework of conservation and healthy management of the biosphere. Articles in volume I(1) are: "The use of models in solving agricultural development problems," by N. A. de Ridder: "Odour and pathogen control from intensive animal and poultry Book Reviews &'ontinued on following pagel
ROBINSON A N D NELSON: V E G E T A B L E OIL FOR PETROL EU M
151