A preliminary evaluation of cotton herbicides for peasant farming in Northern Nigeria

Abstract

The effects of herbicide applications on the yield of seed cotton and on the amount of hand labour required for weed control were measured in experiments at sites in northern Nigeria. A foliage application of fluometuron depressed yields in one experiment. Both trifluralin incorporated pre-sowing and fluometuron applied at thinning gave measurable weed control until the end of the rains.     

Chemical Control of Weeds in Cotton in the Sudan Gezira

Abstract

Early work on chemical weed control in the fallow towards the end of the Second World War is reviewed briefly. Attempts to use contact residual herbicides as pre-emergence applications in the early 1950s are also described.

Pre-sowing applications of residual herbicides were found more phytotoxic to cotton than pre-emergence applications. The closer the time of pre-sowing application to cotton sowing, the more effective was suppression of weeds competing with cotton.

Mechanical cultivations and particularly disc ploughing and rotovation to a depth of more than 15 cm were found more effective in the control of Cynodon dactylon than pre-sowing herbicide applications.

Fluometuron, noruron and prometryne were found very effective as pre-emergence herbicides. Optimum rates of application were found to be only 25-50% of rates recommended for the USA and other countries. Resistant weeds included Cyperus rotundus, Cynodon dactylon, and Rhyncosia memnonia.

A large-scale trial with fluometuron, covering 125 feddans at Wad el Nairn showed that yields obtained were equal to those with normal weeding. Costs of herbicide treatments were also comparable to costs of hand-weeding in a year of exceptionally low hand-weeding costs.     

Problems of herbicide assessment in peanuts in Jamaica

Delays of 40 or 60 days in weeding peanuts (Arachis hypogaea L.) gave lower yields and fewer pods per plant but did not affect seed number per pod. Yield, pod number per plant, seeds per pod and mean weight per seed were all less in unweeded plots. In three herbicide trials crop yields were not closely correlated with crop vigour scores made several weeks before crop maturity, or with weediness scores. Correlations between yields and weed dry weights were better, but certain high-yielding herbicide treatments gave poor weed control and in some cases had low crop vigour scores. Most yield differences reflected differences in pod number per plant, with additional smaller compensating or additive effects on the other components. Certain herbicides apparently gave high mean seed weights without diminishing seed numbers per pod. Pre-emergence alachlor was the most promising herbicide, combined with preplant incorporated vernolate if nutgrass was serious. Napropamide and metobromuron merit further testing.     

The Ant Mosaic - Tropical Tree Crops and the Limiting of Pests and Diseases

Abstract

Field experiments were conducted to determine the effectiveness of herbicides in controlling Rottboellia cochinchinensis (Lour.) W. D. Clayton and Cyperus rotundus L. in upland rice (Oryza sativa L.) at different moisture regimes as imposed by a line source sprinkler system. Preemergence application of pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] was highly effective in controlling R. cochinchinensis irrespective of soil moisture after herbicide application. Bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide] and 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] applied at postemergence effectively controlled C. rotundus when moisture supply was well above pan evaporation. These herbicides also had no adverse effect on rice stand and resulted in higher yield over the control. Water application rates above upland pan evaporation for a season‐long period was essential to obtain a high response to weed control either by herbicides or hand weeding. The data suggest that proper weed control by herbicides or hand weeding will not result in high upland rice grain yields if moisture level from rains fall below the critical level.     

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.     

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.     

Evaluation of herbicides for maize production in three ecological zones of Nigeria

Abstract

Maize cultivation in Nigeria has increased rapidly in the last few years as fertilizers have become more readily available to farmers. Without the use of herbicides however, the area of land that can be brought under maize production will be limited. The following herbicides were evaluated in three ecological zones of Nigeria: atrazine and mixtures of atrazine and simazine, atrazine and metolachlor and atrazine and cyanazine. All herbicide treatments were applied at the rate of either 1.0 or 2.0 kg a.i./ha. The plots that received 1.0 kg a.i./ha also received one supplementary hand weeding. All treatments gave yields comparable to the weed free control, with the exception of the unweeded higher rate of the atrazine and cyanazine treatment which gave the lowest grain yield as a result of poor weed control.     

Assessment of Chemical and Manual Weed Control Approaches for Effective Weed Suppression and Maize Productivity Enhancement Under Maize-Wheat Cropping System

Effective weed management in maize-wheat (M-W) cropping systems are accountable for higher yield and plant biomass. The objective of this study was to evaluate the effectiveness of manual weeding and chemicals (pre- and post-emergence herbicide) for actual weed control to enhance maize yield and M?W system productivity. Herbicides were treated as pre-emergence (sole), post-emergence (sole) and its combined application (pre- and post-emergence) for weed eradication and suppression. Sole pre-emergence herbicide (acetyclour?+?atrazine) and sole post-emergence herbicides (nicosulfuron), and its mixed application were used in the experiments. The experiment was comprised on 6 treatments with one weedy check or control plot: W1?=?weedy check, W2?=?acetyclour?+?atrazine, W3?=?atrazine, W4?=?nicosulfuron, W5?=?nicosulfuron?+?atrazine, W6?=?acetyclour?+?atrazine?+?nicosulfuron and W7?=?manual weeding. Main weeds were Cyperus rotundus, Tribulus terrestris, Dactyloctenium aegyptium and Cynodon dactylon. Experiential findings revealed that manual weeding was found most effective in terms of controlling weed and suppression. Among the herbicides application, promising results in terms of weed destruction and suppression were shown by combined application of acetyclour?+?atrazine?+?nicosulfuron which effectively controlled weeds as compared to other treatments. It was concluded that manual weeding drastically reduced weeds frequency and biomass while among the herbicides application acetyclour?+?atrazine and nicosulfuron could be promising for weeds suppression and clamp downing as compared to all other treatments under M?W cropping system.

     

Problems in control of Rottboellia exaltata L.f. in maize in Bukidnon Province, Mindanao, Philippines

Various methods were tested to control the annual grass Rottboellia exaltata L.f. in maize (Zea mays L.) under small-farm conditions in Bukidnon Province, Mindanao, Philippines during 1977 and 1978. No single method was satisfactory. Despite adequate early season control, late-germinating Rottboellia tillered profusely. By harvest, plots had heavy infestations and were carpeted with seed. At harvest, untreated controls averaged 8·6 t Rottboellia dry matter ha^?1 and only half the maize yield of handweeded plots. The ‘karase’ spike-tooth harrow, or 0·2 kg paraquat ha^?1, effectively removed Rottboellia flushes before maize emergence, but these techniques delayed planting, which can intensify downy mildew disease (Sclerospora sp.). Even though handweeding increased maize yields and decreased Rottboellia dry weights, it is impractical on typical 3- to 5-ha maize farms. Mungbean (Vigna radiata (L.) Wilczek var. aureus), intercropped with maize, suppressed Rottboellia initially. Openings caused by mungbean harvest, however, allowed explosive late-season weed growth in maize. Three herbicide treatments were as effective as handweeding: pendimethalin plus atrazine, either banded over the maize row (followed by cultivation), or broadcast; and pendimethalin followed by 2, 4-D, both broadcast. In one experiment, low-cost practices, including weed flush removal, cultivation, or handweeding, provided high net returns, whereas expensive herbicide treatments produced low net returns. Fertilizer, applied without weed control, increased maize yield 62%. Without fertilizer, weed control increased yield 107%. Combining the two raised yield 167%.     

Effects of weeding and nitrogen treatmerts on maize yields in Nigeria

The effects of handweeding and of varying timing of applications of nitrogen were examined in three experiments on maize grown in Southern Nigeria. At two weedy sites which had been cropped for several years, weed competition lowered maize yields by 50% and two hand weedings at 3 and 7 weeks after planting were as satisfactory as more extended weedings. At the third site after an extended fallow period weed competition was not severe. Splitting of nitrogen application generally had no advantage over a single application of the same amount. There was no significant interaction between nitrogen and weeding treatments at any site.     

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.     

Pre-sowing herbicides in irrigated cotton (Gossypium barbadense L.) and ground nut (Arachis hypogaea L.) in the Sudan. I. Weed control and crop yields achieved with trifluralin and benfluralin.

Trifluralin in cotton and benfluralin in groudnut. incorporated pre-planting. gave satisfactory control of grass weeds and increased crop yields substantially. Oxadiazon as a pre-planting treatment did not give satisfactory additional control of dicotyledons resistant to the first two herbicides. A post-sowing mechanical ridging operation controlled some herbicide resistant weeds, but its effects depended on timing, weed species and growing conditions. Supportive hand weeding of resistant weeds (mainly dicotyledons) was most effective 4 weeks after crop emergence. Crop yields similar to clean weeded controls were achieved by combining trifluralin or benfluralin with moderate supportive hand weeding and re-ridging. Herbicide applications could be made several months before crop planting during the dry season, giving more effective use of spray equipment and operatives. Delays of up to 24 hours between spraying and incorporation by normal cultivation could be tolerated without loss of herbicidal activity.     

Promising herbicides for weed control in chickpea

Abstract

Chickpea suffers severe competition due to Chenopodium album L. infestation. Two to three hoeings are generally given to check C. album but increasing labour costs and scarcity of farm labour make the manual weeding difficult. Usage of herbicides appears to be a logical solution. Pre‐emergence applications of pendimethalin or ametryn alone at 1.5 kg ai ha^?1 or one handweeding at 35–40 days after seeding following either 1 kg ai ha^?1 of pendimethalin, ametryn or fluchloralin or metribuzin at 0.3 kg ai ha^?1 applied pre‐emergence gave effective control of C. album and seed yields similar to clean‐weeded chickpeas. There was an 84% reduction in seed yield of chickpea without weeding.     

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.     

The increasing importance of herbicides in worldwide crop production

Herbicide use is increasingly being adopted around the world. Many developing countries (India, China, Bangladesh) are facing shortages of workers to hand weed fields as millions of people move from rural to urban areas. In these countries, herbicides are far cheaper and more readily available than labor for hand weeding. History shows that in industrializing countries in the past, including the United States, Germany, Japan and South Korea, the same phenomenon has occurred—as workers have left agriculture, herbicides have been adopted. It is inevitable that herbicide use will increase in sub‐Saharan Africa, not only because millions of people are leaving rural areas, creating shortages of hand weeders, but also because of the need to increase crop yields. Hand weeding has never been a very efficient method of weed control—often performed too late and not frequently enough. Uncontrolled weeds have been a major cause of low crop yields in sub‐Saharan Africa for a long time. In many parts of the world, herbicides are being increasingly used to replace tillage in order to improve environmental conditions. In comparison with tillage, herbicide use reduces erosion, fuel use, greenhouse gas emissions and nutrient run‐off and conserves water. © 2013 Society of Chemical Industry     

Development of chemical weed control and integrated weed management in China

More than 200 species of weeds are infesting main crop fields in China, among which approximately 30 species are major weeds causing great crop yield losses. About 35.8 million hectares of crop fields are heavily infested by weeds and the annual reduction of crop yields is 12.3–16.5% (weighted average). Along with rural economic development, approximately 50% of the main crop fields undergo herbicide application. Chemical weed control has changed cultural practices to save weeding labor in rice, wheat, maize, soybeans and cotton. At the same time, continuous use of the same herbicides has caused weed shift problems and weed resistance to herbicides. Consequently, integrated weed management in main crops is being developed.     

Competition from weeds and their control in direct-seeded rice

In direct-seeded upland rice (Oryza sativa L.) yield reductions due to weed competition ranged from 42 to 65% in field experiments conducted in eastern Utter Pradash, India. The most critical period, when crop losses due to weed competition were most severe, ranged from 10 to 20 days after emergence. Yields generally continued to increase, however, as the length of the weed-free period increased. The weed flora consisted of various grasses, sedges and broadleaved species. The most effective herbicide treatment evaluated was a pre-emergence application of alachlor followed by a post-emergence application of propanil or one mechanical weeding.     

Improved chemical control of Conyza bonariensis in wheat limits problems in the following fallow

Conyza bonariensis is a major weed infesting zero‐tilled cropping systems in subtropical Australia, particularly in wheat and winter fallows. Uncontrolled C. bonariensis survives to become a problem weed in the following crops or fallows. As no herbicide has been registered for C. bonariensis in wheat, the effectiveness of 11 herbicides, currently registered for other broad‐leaved weeds in wheat, was evaluated in two pot and two field experiments. As previous research showed that the age of C. bonariensis, and to a lesser extent, the soil moisture at spraying affected herbicide efficacy, these factors also were investigated. The efficacy of the majority of herbicide treatments was reduced when large rosettes (5–15 cm diameter) were treated, compared with small rosettes (<5 cm diameter). However, for the majority of herbicide treatments, the soil moisture did not affect the herbicide efficacy in the pot experiments. In the field, a delay in herbicide treatment of 2 weeks reduced the herbicide efficacy consistently across herbicide treatments, which was related to weed age but not to soil moisture differences. Across all the experiments, four herbicides controlled C. bonariensis in wheat consistently (83–100%): 2,4‐D; aminopyralid + fluroxypyr; picloram + MCPA + metsulfuron; and picloram + high rates of 2,4‐D. Thus, this problem weed can be effectively and consistently controlled in wheat, particularly when small rosettes are treated, and therefore C. bonariensis will have a less adverse impact on the following fallow or crop.     

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.     

Conservation tillage systems for sorghum production under semi‐arid conditions in India

Abstract

Field research was conducted near Hyderabad, India, during 1981 and 1982 to investigate zero‐tillage and reduced‐tillage systems for production of sorghum (Sorghum bicolor (L.) Moench.) under semi‐arid tropical conditions. Part of the investigation compared post‐seeding hand weeding and herbicide treatments for weed control efficacy. The results showed that shallow pre‐seeding tillage was just as effective as deep cultivations in producing high sorghum fodder and grain yields provided weeds were controlled after crop emergence. Both tillage regimes were more effective than a no tillage regime which received only a mixture of glyphosate and 2,4‐D prior to seeding. Post‐seeding weed control practices were essential to maintain high fodder and grain yields of sorghum. Hand weeding and inter‐row blade harrowing were more effective than atrazine applied pre‐emergence or 2,4‐D applied post‐emergence.