Weed Control In Maize Research Articles

Evaluation of herbicide mixtures for weed control in maize (Zea mays L.) under middle gujarat conditions

A field experiment was carried out to evaluate the herbicide mixtures for weed control in maize (Zea mays L.) under middle Gujarat conditions at College Agronomy Farm, Gujarat Agricultural University, Anand during Kharif seasons of 2001-2002 and 2002-2003. The experiment was laid out in a randomized block design with four replications. The treatments comprised of viz., atrazine, alachlor and metolachlor each @ 1.0 kg a.i./ha, metribuzin @ 0.30 kg a.i./ha, pendimethalin @ 0.5 kg a.i./ha and their feasible mixtures were applied at half of the rate, weed free (2 hand weeding at 20 & 40 days after sowing) and weedy check. It was observed that maximum weed control efficiency (> 98 %) was achieved with pre-emergence application of atrazine @ 0.5 kg a.i./ha in combination with pendimethalin @ 0.25 kg a.i./ha and atrazine + alachlor each applied @ 0.5 kg a.i./ha and twice hand weeding carried out at 20 and 40 DAS. Similar trend was observed in grain yield.

New results in the hybrid-specific weed control of maize (Zea mays L.)

The effects of herbicides containing different active agents and applied at different times (early, normal and late post-emergence) were studied on a chernozem soil in the Hajdúság region of E. Hungary in stands of different hybrid maize genotypes. The results proved that the extent of weed cover was equally influenced by the forecrop and the year. In a drier year with wheat as the forecrop, moderate weed infestation was recorded, while with maize as the forecrop and more favourable water supplies, infestation was more severe. The hybrid did not have a significant effect on the extent of weed cover. Little (2-6%) or no visible phytotoxicity was observed in the maize hybrids as a consequence of post-emergence herbicide treatments. The yield-enhancing effects of the various herbicides changed in proportion to the weed cover (in comparison to the untreated weedy control). In the case of low weed cover (in 2002 the weedy control was 7.6-8.4%) there were yield increases of 0-500 kg ha-1, which increased to 700-2700 kg ha-1 in the case of moderate weed cover (in 2003 the weedy control was 27.4-35.1%) and to 3200-4200 kg ha-1 when weed infestation was severe (in 2004 the weedy control was 52.3-57.4%). The study proved that maize hybrids with different genotypes demonstrated general and specific types of herbicide sensitivity (active agent, timing of application).

Evaluation of a new formulation of atrazine and metolachlor mixture for weed control in maize in Nigeria

Field studies were conducted in 2002 and 2003 at Ibadan, Nigeria, to evaluate the effects on weed control in maize of a new formulation of a mixture of atrazine and metolachlor. The treatments were the new formulation of the mixture at doses from 1.0 to 4.0 kg a.i. ha –1 and the old formulation of the mixture at the recommended dose of 2.5 kg a.i. ha –1. The new formulation of the mixture gave complete control of Panicum maximum, Commelina benghalensis, sedges ( Mariscus alternifolius, Kyllinga squamulata, and Cyperus spp.), and Tridax procumbens, and good control (>94%) of Passiflora foetida at 4 weeks after treatment (WAT) in 2002. At 8 WAT, the new mixture gave good control (>73%) of P. maximum and C. benghalensis in 2002, and of P. foetida, sedges, and T. procumbens in both years. The hoeweeded control and all herbicide treatments at 4 WAT had lower weed dry matter than the untreated control in both years, and at crop harvest in 2002. In both years, the lowest weed dry matter was obtained from the hoeweeded control at crop harvest. In 2003, the old formulation of the mixture at the recommended dose had similar weed dry matter with the new formulation at all doses. The treatments did not significantly affect maize grain yield in 2002. However, in 2003, the new formulation of the mixture at a dose of 4.0 kg a.i. ha –1 and the hoeweeded control had 33% higher maize grain yield than the untreated control. The new formulation of a mixture of atrazine and metolachlor is effective for weed control in maize at lower doses than the recommended dose of the old formulation.

Screenhouse evaluation of atrazine for soil residual activity on growth, development and nutritional quality of okra ( Abelmoschus esculentus Moench) in southwestern Nigeria

Atrazine is still by far the most widely used herbicide for selective weed control in maize in southwestern Nigeria following which vegetable crops may be sown to ‘catch’ remaining moisture under rainfed multiple cropping. This study examined under screenhouse conditions the effects of soil residual activity of atrazine at the recommended dose of 3.0 kg a.i. ha −1 on the growth, development and nutritional quality of okra at intervals of 0, 3, 6, 9 and 12 weeks after treatment (WAT). Results indicated that atrazine significantly ( P < 0.05 ) reduced plant height, total crop leaf area, and pod fresh weight in all the herbicide treatments relative to the control, but leaf number remained unaffected. Plant height, among other yield and nutritional quality indices, was found to be linearly and positively correlated with time interval between atrazine applications ( P ⩽ 0.001 ; r = + 0.98 ). The results of proximate analysis and determination of Vitamin C content of matured okra pods showed significant reductions in the levels of protein, fat, ash, crude fibre, carbohydrate, Vitamin C, calcium, iron, and moisture content in all the treatments involving atrazine application compared with control. It was concluded that okra should not be sown after maize in which atrazine has been used in order to avoid crop injury and reduced yield of pods with low nutritional value.

Efficacies of Reduced Herbicide Rates for Weed Control in Maize (Zea mays L.) During Critical Period

The sensitivities of Amaranthus retroflexus L., Chenopodium album L., Xanthium strumarium L. and Portulaca oleraceae L. at different growth stages were compared against two common herbicides used in maize (nicosulfuron and 2.4-D-amine). The sensitivities of weeds at 2-4 leaves growth stages were higher than at 5-8 leaves; they could be controlled by 90% with about 30-40% lower rates. Based on the results of pot experiments the performances of reduced rates were evaluated under naturally weed-infested conditions in the field experiments conducted in 2002 and 2003. Results from the experiment conducted in 2002 suggested that none of the herbicide alone provided acceptable weed control under practical growing conditions, even at the recommended rates, but the mixture of reduced rates was highly efficient against weeds. Therefore the efficacy of this herbicide mixture alone; in combination with ammonium-sulphate additive or with hand hoeing was evaluated in two field experiments under practical maize growing conditions in 2003. Results showed that low rate herbicide mixture provided acceptable weed control during critical period, provided highest grain yield and it`s efficacy against difficult to control weeds was improved by ammonium-sulphate addition.

Sorption–desorption of ‘aged’ isoxaflutole and diketonitrile degradate in soil

SummaryIsoxaflutole is a relatively new herbicide used for weed control in maize. The objective of this research was to increase the understanding of the behaviour and environmental fate of isoxaflutole and its diketonitrile (DKN) degradate in soil, including determination of the strength of sorption to soil and whether sorption is affected by ageing. In sandy loam (SL) and silty clay (SiCl) soils, 14C‐isoxaflutole was found to dissipate rapidly after application to soil; recovery ranged from ∼42% to 68% at week 0, and recovery had decreased to &lt;10% at week 12. Decreases in 14C isoxaflutole residues over time in SL and SiCl soils are consistent with hydrolysis of isoxaflutole and formation of bound DKN residues in the soil. DKN recovery from freshly treated SiCl and SL soils was 41% to 52%. After a 12‐week incubation in SL soil at pH 7.1 and 8.0, recoveries were similar, ∼40%. However, at week 12 in SL soil pH 5.7, DKN recovery decreased to ∼28%. DKN recovery in SiCl soil at week 12 was &lt;10%. Increases in sorption of DKN in SL at pH 5.7 and SiCl soil over time indicate that the DKN degradate is tightly bound to the soil and sorption is affected by soil pH and soil type. Sorption of 14C‐DKN in the SiCl soil more than doubled with ageing compared with the lower Kd sorption coefficient values of the SL soils. In the SiCl soil at time 0, the Kd was 0.6; at 1 week, Kd increased to 2; and at the end of the 12‐week incubation period, Kd was 4.5. This strong binding of DKN to the soil may be due to chelate formation in the interlayer of the clay.

Effect of weeds on insect pests of maize and their natural enemies in Southern Mexico

A pilot study performed on the Pacific coastal plain of Chiapas, Mexico, focused on the prevalence of maize crop infestation by insect pests, parasitism of pests and the abundance of insect predators in maize plots with weeds compared with plots under a regime of rigorous manual weed control. Sampling was conducted on four occasions at 20, 32, 44 and 56 days post-planting. Infestation of maize by fall armyworm larvae, Spodoptera frugiperda (Lepidoptera: Noctuidae), was more than twice as great in plots with strict weed control compared with weedy plots at 20 days post-planting, but declined thereafter in both treatments. The prevalence of aphid infestation and the abundance of nitidulid beetles were consistently greater in weed-controlled plots. In contrast, the density of beneficial predatory Coleoptera increased significantly in plots with weeds, and it is suggested that this probably explains the lower incidence of pests. S. frugiperda egg masses placed in experimental plots suffered a significantly higher incidence rate of parasitism by Chelonus insularis (Hymenoptera: Braconidae) in clean plots (42.0%) compared with those placed in weedy plots (3.75%); it is suspected that weeds may hinder the location of egg masses by parasitoids. Overall, the presence or absence of weeds had a marked influence on the arthropod community present in maize fields. The weeds did not affect maize plant height, the levels of plant damage or the yield of grain from plants under each type of weed regime, implying that competitive effects of weeds may be offset by greater numbers of beneficial insects in weedy plots. Our pilot study indicates that strict weed control in maize may be unnecessary.

Site-Specific Weed Control in Maize, Sugar Beet, Winter Wheat, and Winter Barley

A four-year study of site-specific weed control is presented in this paper. Weed seedling distribution was sampled and mapped prior to and after post-emergence herbicide application in four fields planted with maize, sugar beets, winter wheat and winter barley, rotating on one site. Herbicides and other weed control strategies were applied site-specifically according to the spatial variation of weed populations. Different decision algorithms were used for chemical weed control methods in each crop. A weed treatment map was created to direct location and dosage of herbicide application. The sprayer was coupled with a differential Global Positioning System (DGPS). The solenoid valves of the sprayer were opened automatically when the tractor entered a weed patch characterized in the weed treatment map. For site specific herbicide application, a patch sprayer was developed that allowed variable rate application and the selective control of each section of the spray boom.

Effects of atrazine residue on the growth and development of celosia ( Celosia argentea) under screenhouse conditions in Nigeria

Atrazine is by far the most widely used herbicide for selective weed control in maize in southwestern Nigeria, following which vegetable crops may be sown to ‘catch’ remaining moisture under rainfed multiple cropping. This study investigated the effect of soil residual activity of atrazine at the recommended rate of 3.0 kg a.i. ha −1 on the growth and development of Celosia argentea under screenhouse conditions at intervals of 0, 3, 6, 9 and 12 weeks after treatment (WAT). Experimental findings indicated that atrazine significantly ( P<0.05) reduced total crop leaf area, fresh weight and dry weight of Celosia in all the herbicide treatments compared with the control. Similarly, it caused significant reductions in plant height during the first 6 weeks of plant growth relative to the control. Plant height was found to be linearly and positively correlated with time interval between atrazine application ( r=0.96). It was concluded that the maximum interval of 12 WAT examined in this study was insufficient for safe and effective cultivation of Celosia. Consequently, it should not be sown after maize crop in which atrazine has been used for weed control in order to avoid crop injury and yield reduction.

Inhibition of Pigment Biosynthesis in Cucumber Cotyledons by Isoxaflutole

Isoxaflutole [5-cyclopropyl-4-(2-methylsulphonyl-4-trifluromethylbenzoyl)isoxazole] is a new preemergence herbicide for broad-spectrum weed control in maize. The effect of isoxaflutole on chlorophyll (Chl) and carotenoid (Car) biosynthesis was investigated in cucumber (Cucumis sativus L.) cotyledons. Etiolated tissue was incubated with 5 mM isoxaflutole for 24 h and irradiated (60 μmol m-2 s-1). The irradiation for 3 h did not reduce Chl a, Chl b, and Car contents, but after a 28-h irradiation the contents of Chl a and Car decreased by 35 and 15 %, respectively, and the content of Chl b increased by 24 %. Increasing the concentration of isoxaflutole beyond 5 mM resulted in reduction of Chl a (71 %), Chl b (20 %), and Car (31 %) contents. Similarly, increase in irradiance from 60 to 180 μmol m-2 s-1 resulted in larger reduction of Chl and Car contents. Exogenously supplied 5-aminolevulinic acid did not reverse the isoxaflutole-inhibited Chl synthesis, whereas an exogenously supplied homogentisic acid lactone reversed the inhibition of pigment synthesis due to isoxaflutole.

Determination of the critical period of weed control in corn using a thermal basis

Field studies were conducted over 3 years in southeast Buenos Aires, Argentina, to determine the critical period of weed control in maize (Zea mays L.). The treatments consisted of two different periods of weed interference, a critical weed-free period, and a critical time of weed removal. The Gompertz and logistic equations were fitted to relative yields representing the critical weed-free and the critical time of weed removal, respectively. Accumulated thermal units were used to describe each period of weed-free or weed removal. The critical weed-free period and the critical time of weed removal ranged from 222 to 416 and 128 to 261 accumulated thermal units respectively, to prevent yield losses of 2.5%. Weed biomass proved to be inverse to the crop yield for all the years studied. When weeds competed with the crop from emergence, a large increase in weed biomass was achieved 10 days after crop emergence. However, few weed seedlings emerged and prospered after the 5-6 leaf maize stage (10-20 days after emergence).

Inhibition of Plant Acetolactate Synthase by Nicosulfuron, Rimsulfuron, and Their Mixture DPX-79406

Nicosulfuron and rimsulfuron are two selective postemergence sulfonylurea herbicides commercialized, respectively, in Europe and USA for weed control in maize. They are under development in Canada as a 1:1 premix (DPX-79406). The objective of the present study was to investigate the effects of these herbicides and their interactions on acetolactate synthase (ALS) activity of selected annual weed species. Each nicosulfuron and rimsulfuron treatment used over a concentration range of 0.01 to 10 μM produced a distinct pattern of ALS inhibition for common ragweed, proso millet, redroot pigweed, smooth crabgrass, and wild oats. Based on ALS specific activity, I50values for each herbicide differed slightly among the five weed species. However, rimsulfuron was much more inhibitory to ALS than was nicosulfuron. Common ragweed ALS activity increased linearly from 30 to 120 min, even in the continual presence of both herbicides in the assay buffer. This suggests the reversibility of their interaction with ALS. Delaying nicosulfuron (1 μM) or rimsulfuron (0.1 μM) additions to the assay buffer, after initiating the reaction with the enzyme, resulted in a quadratic increase of common ragweed ALS activity. In the continual presence of 0.1 μM of rimsulfuron, addition of 0.1 or 1 μM nicosulfuron did not affect ALS activity any further. However, in the continual presence of 0.1 μM of nicosulfuron, delaying rimsulfuron addition caused an increase in ALS activity. This increase was lower in the presence of 1 μM of nicosulfuron. Inhibition of common ragweed ALS by nicosulfuron and rimsulfuron was not independent of each other, suggesting some competition between the two herbicides for a common binding site on ALS.

Grass weed control in maize with tridiphane herbicide

Grass weed control in maize with tridiphane herbicide

Control of problem weeds of maize on the Transvaal Highveld (South Africa). II. Datura stramonium L.

SummaryAs was described in a previous publication, the influence of a number og herbicides and herbicide mixtures which are being used for the post‐emergence control of weeds in maize on the Transvaal Highveld, have been tested for their efficiency in the control of problem weeds. Both the percentage mortality and percentage dry mass difference between the test plants and the controls 10 days after application of the respective herbicides were used as bioassay methods. Datura stramonium L. was very susceptible to most of the herbicidal treatments up to the nine‐leaf stage. The reason why it is considered a problem weed should perhaps be sought in the erratic germination of its seeds over a number of years, thus evading common practices of weed control.

Control of problem weeds of maize on the Transvaal Highveld (South Africa). I. Tagetes minuta L.

Summary:A number of herbicides and herbicide mixtures which are being used for the post‐emergence control of weeds in maize on the Transvaal Highveld, have been tested for their efficiency in the control of problem weeds. The evaluation was done under standardized conditions. The influence of the herbicides on the plants was evaluated by using the following bioassay methods: percentage mortality and the percentage dry mass difference between the test plants and the control 10 days after treatment.Recommendations are made as to which herbicides could be used most effectively on problem weeds post‐emergence in maize fields. The developmental stage (age) at which each herbicide is most effective, has been determined.

Weed control in maize on high organic matter soils

Weed control in maize on high organic matter soils

Persistence of some herbicides used for weed control in maize

Persistence of some herbicides used for weed control in maize

Chemical Weed Control in Maize - Wheat Rotation in Semi Arid Tropics

Results of a five year field trial in a permanent layout showed that no more then 100 per cent replenishment of nitrogen removed by weeds was necessary to reduce weed competition. Increasing rates of simazino significantly increased maize yield but since it tended to decrease wheat yields, half a kilogram of simazine as pre-emergence rear- ment was the best treatment vis-a-vis treedom from harmful residual effect of higher rates on wheat. Pre+post-emergence application providing 0.5 kg 2,4-D/ha along with replenishment of 100 per cent N removed by weeds was the most beneficial treatment. Increase in maize yield and reduction in weed dry matter production with the use of simazine at half a kg/ha rate were 4.2 and 13.2 g/ha. respectively without harmful effect on wheat.

Post-emergence weed control in maize with paraquat

An effective method of eliminating grasses and broad-leaved weeds in maize at the late post-emergence stage has been developed in Europe, which involves using the contact non-selective herbicide paraquat in a directed spray covering the weeds but only the lower part of the maize stems. Drift is minimized by using special low-pressure flood nozzles. The method is cheap, quick and economical in labour, and yields are increased by the removal of weed competition.

THE USE OF A LOW DOSE OF ATRAZINE ALONE AND IN MIXTURES WITH OTHER HERBICIDES IN THE MAIZE CROP

Summary. Linuron, 2,4‐D‐aniine, propachlor, pyriclor and cypromid, singly and mixture with atrazine, were compared with atrazine and fluromidine alone for effectiveness of weed control in maize on Oxford clay soil. Pre‐emergence applications were made under wet conditions and atrazine, even at 0·28 kg/ha a.i. gave an excellent control of three main weeds, Stellaria media, Veronica spp. and Polygonum aviculare, and at 0·56 kg/ha also killed Aethusa cynapium. Fluromidine was comparable with atrazine, but linuron,2,4‐D‐amine, propachlor and pyriclor were less effective. Post‐emergence treatments were less satisfactory. High doses of atrazine were needed for good weed control. Acynapium was resistant to pyriclor and cypromid and P. aviculare to fluromidine. 2,4‐Daminewas ineffective, but atrazine/2,4‐D‐amine mixtures were more effective than the individual components for the control of P. aviculare. Pyriclor, at 0·56 kg/ha pre‐emergenceand cypromid at 2·24 kg/ha post‐emergence directly reduced the yield of the crop.Utilisation de I'atrazine à faible dose, seule et en mélange avec d'autres herbicides, dans les culturesde maïs