Efficiency of Different Herbicides for Weed Control in Peas

Abstract

A field experiment was conducted for two years during 1977–78 and 1978–79 to evaluate the efficiency of methabenzthiazuron, terbutryn and metoxuron in controlling weeds in peas (Pisum sativum) at the Punjab Agricultural University, Ludhiana, India. Pre-emergence application of methabenzthiazuron at 1.05 and 1.40 kg a.i./ha gave efficient weed control and gave comparable yields to two hand hoeings. Post-emergence application of methabenzthiazuron proved inferior. Terbutryn pre-emergence showed promise but as a post-emergence application it was ineffective. Metoxuron both pre- and post-emergence showed phytotoxic effects on the crop.     

Correspondence

Abstract

Twenty-seven different herbicides were tested at the AUB Agricultural Research and Education Center in the Beqa'a, Lebanon, to determine their effects on weeds in wheat, barley, maize, onion and sugar beet. Each herbicide was tested at three different rates as pre-emergence and post-emergence applications. Unweeded and hand-weeded check plots were included. Data on yield, quality and other agronomic characteristics of the crops tested were recorded.

Concentrations of 1,000 and 10,000 ppm of 2, 4–D caused a significant decrease in the height and grain yield of wheat and barley when sprayed at the 3-leaf stage. At the 5-leaf stage, injury to wheat and barley occurred only when sprayed at 10,000 ppm, whereas an increase in the grain yield was obtained at 1,000 ppm of 2, 4–D acid equivalent (1 kg a.i./ha).

Pre-emergence treatments of atrazine and simazine at 2.5 kg a.i./ha caused a significant increase in the forage and grain yields of maize as compared to unweeded check plots. Wheat, oats, vetch and sugar beet were injured when planted after triazine-treated maize, whereas onions and soyabeans were tolerant. Other promising herbicides tested on maize were C 3095 (N–3–trifluoromethylphenyl–N'–methyl–N'–methoxyurea) and BV– 201 (1–(3′, 4′–dichlorophenyl)–3–methylpyrrolidin–2–one) applied as a pre-emergence spray at 1 and 2 kg/ha respectively.

Pre-planting treatment of EPTC and pre-emergence treatment of pebulate at 2 kg/ha gave a slight increase in the yield of roots of sugar beet. BV–201 and BV–207 (1–(3–chloro–4–methylphenyl)–3–methylpyrrolidin–2–one) were phytotoxic to beet.

In onions, nitrofen, BV–201 and BV–207 at 1–2 kg/ha were promising as pre-emergence and post-emergence sprays. DNOC and dinoseb at 1.5 kg/ha and ioxynil at 0.5 kg/ha sprayed post-emergence increased the yield of onions significantly over the check. No significant effects of these herbicides were observed on the bulb index, moisture content and total soluble solids of onions.     

Possible Methods for Controlling Ischaemum afrum (J. F. Gamel) Dandy,in Fallow

Abstract

Different mechanical cultivations and herbicide treatments were compared for controlling Ischaemum afrum in a heavily infested fallow area. Of the mechanical cultivations, disc ploughing to a depth of more than 15 cm, following removal of tufts and watering, was found very effective (83% reduction). Incorporated pre-emergence triluralin (1.90 kg a.i./ha) alone or in tank mixtures with oxadiazon (0.95 + 0.95 kg a.i./ha) was also found promising (79 and 76% reduction respectively). Three applications of dalapon (8.09 kg a.i./ha), as post-emergence, at two weekly intervals or two applications followed by another application at 4.05 kg a.i./ha gave almost complete eradication of Ischaemum afrum seedlings for about 12 weeks (99% reduction).     

Insect Pests of Cotton – Western Herbaceum Region of India

Abstract

Pre-plant and pre-emergence herbicides were tested for effective weed control in a seed crop of okra during 1974–75 and 1975–76. All treatments significantly decreased the weed population and increased the seed yield as compared to the unweeded control. Fluchloralin (0.90 and 1.20 kg a.i./ha pre-plant), alachlor (2.50 kg a.i./ha pre-em) and EPTC plus alachlor (3.75 kg a.i./ha pre-plant and 1.25 kg a.i./ha pre-em) proved to be the most effective and economical treatments. No residual effects were observed with any herbicide on the succeeding crops of radish, carrot, turnips, peas and spinach.     

Chemical control of perennial nutsedge (Cyperus rotundus L.) in tropical upland rice

Five herbicides were tested in the dry and in the wet season for their effectiveness in conlrolling perennial nutsedge (Cyperus rotundus L.) in direct-seeded upland rice in the tropics. K-223 [N-(α,α-dimethylbenzyl)-N'-P-tolyl urea] gave the best results. When broadcast sprayed at 8.0 kg a.i./ha in the dry season and 10 kg a.i./ha in the wet season and immediately mixed into the soit just before drilling, K-223 gave excellent perennial nutsedge control with no visible crop damage and increased the grain yield. Bentazone at 2.0 kg a.i./ha applied 7 days after crop emergence was highly selective and gave fair control of nutsedge without being toxic to the crop. MBR 8251 [1.1,1-trifluoro-4′-(phenylsulfonyl) methane-sulfono-o-toluidide] at 2.0 kg a.i./ha, mecoprop (MCPP) at 1.5 kg a.c./ha and fenoprop (silvex) at 1.0 kg a.e./ha applied 7, 14 and 7 days, respectively after crop emergence provided a fair degree of nutsedge control. Fenoprop and MBR 8251 caused slight and mecoprop moderate initial toxicity, but the injury sustained did not significantly affect crop yield.     

Weed Control in Berseem using Stale Seed-bed,EPTC, and MCPB

Abstract

A field experiment was conducted in 1973 and 1974 at Udaipur, India to evaluate the selective weed control efficacy of stale seed-bed prepared with paraquat (1 kg/ha) or by cultivation, pre-planting incorporation of EPTC (1.5 kg/ha), and post-emergent application of MCPB (0.5 kg/ha). Two crop protectants, NA and activated carbon, were also field tested as seed treatments against injury by EPTC. It was found that stale seed-bed prepared by desiccation of weed seedlings with paraquat a day before planting berseem (Trifolium alexandrinum L.) and pre-planting incorporation of EPTC were both effective in significantly reducing weed growth and boosting yields of berseem. Berseem seeds coated with activated carbon before planting provided appreciable protection to the crop against EPTC, but NA stunted berseem growth. A combination of stale seed-bed and EPTC caused maximum reduction in weed growth. Post-emergent MCPB, though efficient in controlling weeds, was highly phytotoxic to the crop. Chenopodium spp. and Phalaris minor were lower in net energy content than berseem.     

A World-Wide Organization to Promote the Development of Biological Control

Abstract

Three experiments were conducted to evaluate the efficacy of metribuzin in tea fields. These were a field trial in plots infested with a wide range of weeds, a pot experiment using Paspalum conjugatum and a microplot experiment with 100 Ageratum conyzoides plants/plot. Metribuzin at 0.70, 1.05, 1.40 and 2.10 kg a.i./ha was applied in 450 l water/ha. All rates were satisfactory after 1 week but residual activity increased with application rate; metribuzin at 2.10 kg a.i./ha was significantly superior after 6 weeks. Control after 8 weeks was reduced due to the presence of resistant species. Against Paspalum conjugatum metribuzin at 1.40 kg/ha gave good control for 8 weeks but 2.10 kg/ha was necessary for 12 weeks control. All rates compared favourably with dalapon (4.48 kg a.i./ha). Against Ageratum conyzoides metribuzin at all rates gave good control for up to 12 weeks and significantly better than 2, 4-D at 1.12 kg a.i./ha. Most other grass and broadleaved weeds were satisfactorily controlled at 1.40 kg a.i./ha. Metribuzin with its marked post-emergent effect and prolonged soil residual activity from 6-12 weeks after application, depending on weed species, may become an important tool in pre-monsoon weed control programmes in tea fields. It did not induce any phytotoxic symptoms on mature tea.     

Chemical control of Eleusine indica and other weeds in Setaria anceps

In field experments on the Altherton Tableland. Queensland. Auslralia, methabenzthiazuron used at 1 2 kg ha pre-emergence was the most effective herbicide for selectively controlling Eleusine indica (L.) Gaertn in seed crops of Setaria anceps Stapf. Bromoxynil. bromoxynil plus MCPA, simazine and terbutryne were either ineffective or phytotoxic to S anceps. A more reliable technique was the use of diuron applied at 2.8 kg ha pre-emergence when the crop row was physically protected with metal shields at spraying or when activated carbon applied as a slurry in water at 168 kg per sprayed ha was sprayed in a 3 cm wide band over the crop row at sowing Three successive applications of paraquat over a 39 day period prior to sowing the crop were necessary for effective control of E. indica using the ‘stale seed bed’ technique     

Plant Diseases

Abstract

Field experiments conducted at Punjab Agricultural University, Ludhiana during 1972–73 and 1973–74 showed that post-emergence application of oxadiazon at 1 kg a.i./ha in transplanted onion gave remarkable weed control and maximum crop yield. Other treatments which performed well include pre-planting alachlor at 2.5 kg a.i./ha plus post-emergence propanil at 1.8 kg a.i./ha and also pre-planting nitrofen at 1.25 kg a.i./ha plus post-emergence nitrofen at 1.25 kg a.i./ha. Herbicides did not significantly influence the bulb quality, soil microflora or the emergence and yield of following crops of okra, bitter gourd and radish.     

Seed dressing insecticides for bean fly [Ophiomyia phaseoli (Tryon) (Diptera: Agromyzidae)] control in Ethiopia

Abstract

Six seed dressing insecticides were tested for efficacy against Ophiomyia phaseoli (BF) in 1987 and 1988 at two locations in south‐central Ethiopia. Endosulfan and aldrin, at 5 g a.i./kg of seeds, were the least phytotoxic and the most effective. The rest gave variable results; BF control with some insecticides (e.g. furathiocarb) was comparable, but they showed varying degrees of phytotoxicity. The maximum seed yield loss was 36.5%. The results suggest that aldrin be replaced with endosulfan, which is less persistent.     

Chemical weed control in rainfed upland rice in Nigeria

Abstract

Two field experiments on chemical weed control in Faro 41 upland rice (Oryza sativa L.) variety were conducted at a rainforest site near the National Cereals Research Institute, Amakama Substation in 1989 and 1990. The herbicides tested were a coformulated mixture of pretilachlor and dimethametryne at 1.5, 2.0 and 2.5 kg a.i./ha, a co‐formulated mixture of piperophos and propanil applied at 3.16 and 3.95 kg a.i./ha, and Oxadiazon at 1.0 kg a.i./ha. Two hand weedings and a ‘no weeding’ treatment were included. The herbicides were applied 5 days after planting. All were safely selective to the crop. Most provided adequate weed control through 8–12 weeks after planting. Weeds controlled included Cynodon dactylon, Commelina benghalensis, Dlgitaria horizontalis, Eleusine indica, Panicum maximum and Pennisetum purpureum as grass weeds. The broadleaf weeds were Emilia sonchifolia, Ageratum conyzoides, Portulaca oleraceae, Richardia brasiliensis and Ipomoea Involuncrata. The sedges Mariscus alternifolius and Cyperus esculentus were encountered in the plots. Pretilachlordimethametryne at 2.5 kg a.i./ha had the best weeding score. Twoyear average grain yields of 1.7–2.6 t/ha were obtained from the herbicide treatments. With only 0.4 t/ha from the unweeded treatment, yield losses of more than 80% were recorded.     

The Institute of Phytopathological Research

Abstract

Further work with the herbicide C 19490 (S-(2-methyl-1-piperidyl-carbonylmethyl)-O,O-di-N-propyl dithiophosphate) in the mixture C 288 with the triazine C 18898 in the ratio 4:1, and with 2,4-D isopropyl ester (2,4-D IPE) in the ratios 2:1 and 3:2 have been completed. New toxicological data show that the risk of toxicity hazards to the user or to other mammals by contamination is low. Residue work shows that C 19490 leaves very low or undetectable residues in rice grain and soil, though C 18898 was detected in both, but never at more than 0.28 ppm in soil or more than 0.04 ppm in grain. There was no interaction between either C 19490 or C 288 and commonly used insecticides. Uptake of the products by plants was shown to be preferentially through emerging shoots, and less through roots.

Field trials resulted in recommendations for around 2 kg C 288 total a.i./ha in Japan, optimum timing depending on the prevailing temperature. Successful control was achieved in Taiwan with C 288 at 1 kg a.i./ha in both the cool and warm season crops, applied 7–12 days after transplanting. In equatorial Asia, mixtures worked well: C 288 at 0.75–1.25 kg a.i./ha, C 19490 at 0.75–1.0 + 2,4-D IPE at 0.5 kg a.i./ha and the 3:2 mixture at 0.75 + 0.5 kg a.i./ha (granular), applied four DAT on dense weed stands, but up to ten DAT on stands comprising predominantly moderate infestations of Echinochloa crusgalli, Monochoria vaginalis and annual Cyperus spp. These recommendations resulted in yields which were never significantly different from those of hand-weeded areas. On light, permeable soils, e.g. in Pakistan, C 288 at 1.0–1.25 kg a.i./ha, 8–10 DAT was less harmful to the crop than lower rates applied earlier, and was better than the 2,4-D IPE mixture for weed control. In Egypt, C 19490 + 2,4-D IPE at only 0.375 + 0.25 kg a.i./ha was successful, because of the susceptible weed flora.     

Factors effecting the performance of metoxuron and chlortoluron in controlling blackgrass in winter wheat

Blackgrass (Alopecurus myosuroides Huds.) was controlled by 2 kg/ha of metoxuron in glasshouse trials while winter wheat, cultivar Cappelle Desprez, tolerated 4 kg/ha. Blackgrass was controlled by 1.2 kg/ha of chlortoluron. Winter wheat previously damaged by freezing was injured by 2.5 kg/ha of chlortoluron applied at an early stage. Seedlings not exposed to freezing were not damaged by 2.5 kg/ha applied at the 4- and 5-leaf stage. Breakdown of chlortoluron and metoxuron in the soil was attributed, in part, to microbial action. More than one-third of the chlortoluron applied at 2 kg/ha disappeared in 6 weeks when applied in early spring while one half disappeared in 3 weeks when applied 2 months later. The bioassay, used to determine the amount of chlortoluron or metoxuron in the soil, was found to be adequate for metoxuron in only one of three soils. The bioassay results, for both herbicides, were affected by the addition of calcium carbonate to the soil, by sterilization of the soil, and by leaching. In comparisons of results in two sandy loams and a clay loam, the observed differences could not be altogether accounted for by differences in pH nor by changes in adsorption of metoxuron. When perennial ryegrass was grown in sandy loam, and treated with metoxuron before or after emergence, different watering regimes did not give any difference in weight of top growth.     

Weed control in wheat with pyroxasulfone and its combinations with other herbicides

Field and pot investigations were conducted to determine the effectiveness of pyroxasulfone alone and its combinations with other herbicides against diverse weed flora of wheat (Triticum aestivum L.) including multiple herbicide-resistant (MHR) littleseed canarygrass (Phalaris minor Retz.). Applications of pyroxasulfone 100–127.5 g/ha as pre-emergence (PE) or early post-emergence (EPOE) @ 63.75 g/ha at 21–23 days after sowing (1 day before irrigation) were highly effective for control of grass weeds namely P. minor and wild oat (Avena ludoviciana Dur.). It was poor for control of broad-leaved weeds (Medicago denticulata Willd. and Rumex dentatus L.). However, pyroxasulfone in tank-mix combination with metsulfuron 4 g/ha, triasulfuron 20 g/ha, and pyroxsulam 18 g/ha effectively controlled (96.5%–99.8%) the diverse weed flora and improved the wheat grain yield (69.5%–285.9%) over untreated weedy control. Also, the pre-mix of pyroxasulfone + pendimethalin applied as PE was superior to either of these applied alone for weed control and grain yield. Pyroxasulfone 100–127.5 g/ha had yield gain of 119.6%–125.4% and 10.1%–26% over untreated control and pendimethalin 800–1250 g/ha, respectively. In pot studies, straw burnt ash drastically reduced the pyroxasulfone efficacy against P. minor and A. ludoviciana. Pyroxasulfone was also effective in pot studies for control of MHR P. minor having resistance against acetyl-coA carboxylase (ACCase), acetolactate synthase (ALS), and photosynthesis at the photosystem-II site-A (PS-II) inhibitor herbicides (clodinafop, sulfosulfuron, and isoproturon, respectively). The studies indicate that pyroxasulfone as PE or EPOE can be an alternative grass weed control herbicide in wheat in particular for the control of MHR P. minor.     

Sodium 2,2,3,3-tetrafluoropropionate,a New Herbicide for Jute Field Weeds

Abstract

Sodium 2,2,3,3-tetrafluoropropionate (TFP) was tested as pre-planting and post-emergence applications on jute heavily infested with grasses and sedges. The herbicide was applied by two methods, at several rates and at different times before sowing. As a post-emergence application it was sprayed over a three week old crop. The best results were obtained when the herbicide was incorporated into the soil ten days before sowing at 3–4 kg a.i./ha. This practice controlled all grasses and sedges except nutsedge, which was only reduced by 30–40%, although higher rates gave better control. No phytotoxic effects on jute were observed with this rate and method of application.     

Studies on the Efficacy of Various Insecticides Against Mustard Aphid [Lipaphis erysimi (Kalt)]

Abstract

An experiment was designed to test the efficacy of various insecticides for the control of mustard aphid (Lipaphis erysimi (Kalt)) on mustard (Brassica juncea), variety RL 18 at the Research Farm of the Haryana Agricultural University, Hissar (India). Out of the 13 insecticides tried, each at two levels, it was found that methyldemeton 250 ml and menazon 250 g a.i. gave the maximum control of mustard aphid. Maximum yield of 1111 kg/ha was obtained with methyldemeton 250 ml (a.i./ha) against 360 kg/ha of the control.     

The Coconut Rhinoceros Beetle Oryctes rhinoceros (L)[Coleoptera: Scarabaeidae: Dynastinae]

Abstract

Field experiments were conducted during two dry seasons in northern Nigeria to identify suitable pre‐transplant herbicides for weed control in irrigated tomatoes. At Samaru in the northern Guinea savanna, diphenamid at 1.5 kg a.i./ha followed by supplementary hoe‐weeding, metribuzin at 0.5 kg a.i./ha, diphenamid at 3.0 kg a.i./ha, metolachlor plus metobromuron at 1.0 + 1.0 kg a.i./ha and two or three hoe‐weedings, resulted in higher tomato yields than the untreated controls, and most of these treatments reduced weed infestations significantly in both years. At Bakura, in the Sudan savanna zone, metribuzin at 0.25 and 0.5 kg a.i./ha, diphenamid at 3.0 g a.i./ha and chloramben at 1.5 kg a.i./ha plus supplementary weeding consistently resulted in yields that were similar to two hoe‐weedings and higher than the untreated controls. Three kg a.i./ha of chloramben depressed yields in all the trials. At both sites hoe‐weeding once six weeks after transplanting gave unacceptably low crop yields, but similar high yields were obtained with two or three hoe‐weedings. Supplementary hoe‐weedings were unnecessary with the application of metribuzin at 0.5 kg and metolachlor plus metobromuron at 1.0 + 1.0 kg a.i./ha. Uncontrolled weed growth resulted in a 53–67% reduction in tomato fruit yield.     

Herbicide Performance in Rainfed Cabbage

Abstract

The effectiveness of butralin (2.0 and 4.0 kg a.i./ha pre-plant, 2.0 and 4.0 kg a.i./ha pre-em), chlorthal-dimethyl (10.0 and 12.0 kg a.i./ha pre-em), trifluralin (0.6 and 1.1 kg a.i./ha pre-plant) chloramben (2.0 kg a.i./ha pre-em) and nitrofen (2.0 kg a.i./ha pre-em) in controlling weeds in transplanted ‘Kono Cross’ cabbage and the influence of these treatments on the yield and quality of marketable heads and on the economics of weed control were evaluated in three replicated field experiments on River Estate loam soil in Trinidad during the wet seasons of 1976 and 1977. While herbicides did not affect the size of the cabbage plant population or the date to maturity of the crops, they reduced the cost of weed control by over 30% and increased the net returns relative to the clean-weeded control by over 9%. Butralin at 4.0 kg a.i./ha pre-plant and pre-em and the trifluralin treatments were superior to nitrofen which gave good weed control up to five weeks and higher yields than the clean-weeded control. Chlorthal-dimethyl gave encouraging results but caused slight, temporary stunting. The application of one of these treatments followed by one hand weeding at about four weeks should give full-season weed control and an acceptable yield of marketable heads with increased financial returns. Chloramben was the least effective herbicide tested and its use may not be justified under similar conditions to those of this study.     

Recent Developments in the Use of Herbicides in Rubber and Oil Palm

Abstract

Recent developments in the use of herbicides during the establishment of leguminous cover crops and the mature phases of rubber and oil palm plantings are discussed. Results of 12 semi-commercial and commercial scale trials showed that chemical weeding using paraquat and diuron post-emergence or oxyfluorfen pre-emergence with supplementary manual or chemical control was considerably cheaper than exclusive manual weeding during the six months following the sowing of legumes. Reductions in weeding costs ranged from 6 to 66%. In the mature phase a wide range of herbicide treatments involving extensively used herbicides such as paraquat, MSMA, 2, 4-D amine and sodium chlorate for the suppression of weed growth along rubber tree rows and in oil palm circles and harvesters' paths were compared. Results indicate that there are several suitable alternatives to sodium arsenite, a formerly widely used herbicide which is now banned for general weed control. In both crops, the most cost effective treatments for controlling mixed vegetation were Ustinex Special (MCPA + diuron + amitrole, 2:3:6) at 1.48 kg a.i.ha + Gramoxone (paraquat) at 0.22 kg a.i./ha and Paracol (paraquat + diuron, 1:1) at 0.56 kg a.i./ha + DMA Amine (2, 4-D) at 0.50 kg a.e./ha.     

Evaluation of herbicides against Phalaris minor in wheat in north-western Indian plains

Phalaris minor, the most serious weed in wheat in north‐western India, has developed extensive isoproturon resistance due to continuous isoproturon use. For its control, alternative herbicides (flufenacet, metribuzin and sulfosulfuron) at different application rates and timing were evaluated in wheat. In addition, herbicide carryover risk onto rotational crops (sorghum; maize and green gram, Vigina radiata) was also assessed. Isoproturon at 1 and 2 kg a.i. ha^?1 provided only 10.5% and 51.8%P. minor control respectively. Of the other herbicides, early post‐emergent [15–21 days after sowing (DAS)] flufenacet at 180–480 g a.i. ha^?1 provided acceptable control of P. minor, but failed to control broad‐leaved weeds and was phytotoxic to the wheat crop. Metribuzin at 210 g a.i. ha^?1 was effective in controlling both Phalaris and dicotyledonous weeds. Mixtures of both flufenacet and metribuzin at reduced rates were better than flufenacet for weed control and grain yield. The efficacy of flufenacet and metribuzin was drastically reduced with later growth stages of P. minor (four to five leaf). Whereas sulfosulfuron at 25–30 g a.i. ha^?1, applied either early post‐emergence (19 DAS) or post‐emergence (30–42 DAS), was quite effective. Overall, sulfosulfuron was the most effective treatment with regard to weed control and crop yield. However, maize and sorghum grown in rotation after harvest of sulfosulfuron‐treated wheat plots showed 65–73% crop biomass inhibition. The residual effect of sulfosulfuron was also noticed on Trianthema portulacastrum (Horse purslane), causing 73.5% dry matter reduction. By contrast, no carryover damage with flufenacet was observed on maize, sorghum and green gram. Glasshouse pot experiments and field trials investigating crop sensitivity to pre‐plant applications of sulfosulfuron found the decreasing order: sorghum > maize > green gram. The risk of carryover onto rotational crops should be considered when choosing alternative herbicides for P. minor control in wheat.