Effects of mechanical and chemical methods on weed control,weed seed rain and crop yield in maize,sunflower and soyabean

Eight field experiments with maize (Zea mays L.), sunflower (Helianthus annuus L.) and soyabean (Glycine max (L.) Merr.) were carried out in central Italy in order to evaluate the effects of mechanical and chemical methods (spring-tine harrowing, hoeing, hoeing-ridging, split-hoeing, finger-weeding, herbicides in the row + inter-row hoeing, herbicides broadcast) on weed control, weed seed rain and crop yield. The choice of chemical and mechanical treatments in maize and soyabean compared to sunflower, required to be managed more carefully in order to maximize the weed control reducing yield losses. A global rating of weed control methods, based on their weed control efficacy, was obtained as useful means to assist farmers and technicians to choose the more appropriate weed control method. The combination of herbicides intra-row and hoeing inter-row gave best efficacy (on average 99% of weed control), with a 50% reduction in the chemical load in the environment. Hoeing-ridging gave good results, both inter- and intra-row (on average 93% of weed control); this method was also effective in reducing competitive ability and seed production of uncontrolled weeds. Split-hoeing or finger-weeding showed some limitations giving satisfactory results only when combined. Harrowing gave lowest weed control, although when combined to other mechanical methods, can help achieve a better efficacy.     

乙羧氟乳油防除春大豆田苗杂草示范总结

近几年大豆田杂草对大豆的生长造成极大威胁,在大豆生长期间,杂草与大豆争水、争肥,严重影响大豆产量,经试验证明江苏连云港立本农药化工有限公司生产的10%乙羧氟草醚乳油、江苏长青农化股份有限公司生产的20%乙羧氟·精喹禾乳油对春大豆田一年生阔叶杂草防除效果较好,对大豆田各种杂草的防除达90%以上。     

Effect of herbicide application on weed flora under conservation agriculture in Zimbabwe

Increased challenges of weed control in the smallholder farming sector of southern Africa have often resulted in small yields. The objective of this study was to evaluate the effects of different weed control strategies on weed flora and composition under conservation agriculture (CA) systems in Zimbabwe. This study was conducted at three on-station trial sites namely Domboshawa Training Centre (DTC), University of Zimbabwe farm (UZ farm) and Henderson Research Station (HRS) in a maize–soybean rotation for four seasons from 2009–2010 to 2012–2013 seasons. Hand weeding was done whenever weeds were 10 cm tall or 10 cm in circumference for weeds with a stoloniferous growth habit. Weed identification was done up to the weed species level, and the Shannon–Weiner diversity and evenness index was used to determine the response of weed flora to herbicides. Results showed that there were more weeds in the early years which decreased gradually until the final season. Weed species diversity was not affected by herbicide application and the results indicated that weed species diversity was small in CA systems. Annual weed species constituted a greater proportion of species, and species richness decreased with the duration of the study. Richardia scabra L. and Galinsoga parviflora Cav. were the most common dominant weed species at all sites and in all seasons. Moreover, herbicide application had no effect on the evenness of weeds in the plots but site characteristics had a significant effect on the distribution of weed species (weed species evenness). The results presented in this study suggest that herbicide application facilitates a depletion of weed seed bank/number of weeds over time. Thus, herbicide application in CA has potential to reduce weed density, species richness and species diversity in the long term which may lead to more labour savings and larger yields.     

Control of apple diseases and pests with low spray volumes and reduced chemical rates

Fungicides applied in volumes of either 100, 200 or 800 l/ha controlled apple scab in large-scale field experiments from 1982 to 1985. Either Sonax C, a formulated mixture of etaconazole and captan applied at 1 kg/ha (one-third the recommended rate), or fenarimol at 112 ml/ha (one-quarter the recommended rate), controlled scab when applied in 100 or 200 l/ha respectively. Scab was controlled with either eight protectant or at least five eradicant applications of Sonax C at either 3 or 1 kg/ha in 200 1 of water per hectare. In all years, weather conditions favoured the development of scab. In unsprayed trees the incidence of scabbed fruit ranged from 60% in cv. Granny Smith to 26% in cv. Jonathan. In sprayed trees fruit infection rarely exceeded 1%. The control of powdery mildew was unsatisfactory with Sonax C applied at 1 kg in 100 l/ha. Better control was achieved by either increasing the spray volume or the rate of fungicide per hectare. Two-spotted and European mites were controlled with propargite at the recommended rate of 5·5 kg/ha at either 200 or 800 l/ha. Codling moth was controlled with 160 ml/ha of azinphos-methyl (one-quarter the recommended rate) applied in 800 l/ha.     

转基因抗除草剂油菜对春油菜田间昆虫群落的影响

本文对转基因抗除草剂油菜品种、受体及当地常规品种田间昆虫多样性进行了调查。结果表明,不同品种间昆虫、害虫和天敌的物种数及个体数量之间存在极显著或显著差异;进一步分析表明,这种差异主要表现为转基因抗除草剂品种与受体品种之间的差异,而与当地的常规品种之间无显著差异。群落特征值群落丰富度、多样性指数在油菜的苗期及抽薹期,均以受体品种为最高;而在油菜的花期及结荚期,除花期的群落丰富度外,则以转基因抗除草剂的品种为最高。     

25％氟磺胺草醚水剂（新型）防除春大豆田杂草示范

通过示范,了解25%氟磺胺草醚水剂对春大豆田一年生阔叶杂草的防除效果,为大面积推广提供准确依据.试验结果表明,25%氟磺胺草醚水剂(新型)100 mL/667m2综合株防效为95.4%,鲜重防效94.5%,除草效果最好,建议大面积推广使用.     

Physical,chemical and biological appraisal of alternative spray techniques in cereals

In a multidisciplinary study, spinning disc, rotary cage, electrostatic aqueous and electrodynamic methods of atomization were compared with conventional systems based on various types of flat-fan hydraulic-pressure nozzles commonly used in farm practice. The 80-degree type hydraulic nozzles at 200 l/ha rate produced the largest proportion of droples greater than 350 μm whereas the 110-degree type at the same rate produced the largest quantity of droplets below 50 μm. The effects of electrostatic charging on droplet spectra of aqueous sprays was slight at 200 l/ha rate but at 70 l/ha the proportion by volume of both the largest and smallest droplets was significantly reduced. The rotary cage atomizers produced a droplet spectrum of intermediate width whereas the spinning disc and electrodynamic systems yielded the narrowest spectra. In terms of tracer deposition, the hydraulic nozzles (especially the 110-degree type) used at about 200 l/ha produced the most even partitioning of spray within the crop and yielded the lowest coefficients of variation (CV) of mean deposits both on cereal plant parts and on weeds. The rotary cage, spinning disc and ‘Electrodyn’ either yielded high CV values or lacked penetration into the crop structure. In barley at an early growth stage (GS 31), there was little effect on tracer deposition by electrostatic charging of aqueous sprays, whereas at GS 57 charging at the 70 l/ha rate increased deposition in the upper plant parts. The hydraulic nozzle systems (especially the 110-degree type) were generally the most effective for weed and disease control and produced the highest grain yields from fungicide applications. All methods of spraying, however, produced a significant yield gain from fungicide applications.     

Economic returns from fungicide application to control husk spot of macadamia in Australia is influenced by spray efficiency,rates and costs of application

Fungicides are commonly applied as prophylactic sprays, with the expectation of increased yield and kernel quality, to control husk spot of macadamia in Australia. However, economic benefits from fungicide applications to control husk spot have rarely been quantified. We investigated the effectiveness, efficiency and economic returns of fungicide spray applications for husk spot control using three different spray application volumes and two dose rates of tank mixtures of carbendazim and cupric hydroxide under commercial macadamia orchard conditions. Husk spot incidence and severity were significantly (P < 0.001) different among the treatments and between the two years. In both years, the rate of fruit abscission was highest in the untreated control followed by low spray application volumes, but reduced with increasing spray volume. The quality and value of nut-in-shell increased when nut abscission was delayed. Poor quality and low nut-in-shell value of $2.85 kg⁻¹ in 2010 and $2.12 kg⁻¹ in 2011 were obtained in the untreated control trees that abscised early in the harvest period compared with the average nut-in-shell value of $2.95 kg⁻¹ in 2010 and $2.46 kg⁻¹ in 2011 in the fungicide treated trees. Gross margins for each fungicide treatment schedule compared to the untreated control averaged over both years showed positive contributions of 20%, 10% and 6% for the high, moderate and low dilute rate volume applications, respectively. Our data further indicates that dilute rate applications at higher volume may be more beneficial and cost-effective than concentrate rate applications in husk spot control programs. Overall, harvest yield increased by 11%–33% when husk spot was controlled using fungicide sprays compared to no fungicide spray applications. The benefit-cost ratios revealed highly significant benefits for the implementation of husk spot management programs.     

Dosage rates and application methods with PCNB for control of potato scab and rhizoctonia

American Journal of Potato Research - Pentachloronitrobenzene (PCNB) controlled potato scab in fine sandy loam of the Yakima Valley when applied at the rate of 50 pounds per acre broadcast before...     

Broadleaved weed control in wide-row soybean (Glycine max) using conventional and glyphosate herbicide programmes

A field study was conducted in 2001 and 2002 at Blackville, SC, to evaluate broadleaved weed control and economics of conventional and glyphosate-containing herbicide programmes in glyphosate-resistant soybean planted in 97-cm-wide rows. Treatments included chlorimuron plus sulfentrazone or chlorimuron plus metribuzin applied pre-emergence followed by post-emergence applications of lactofen or glyphosate 4 wk after soybean emergence (WAE). Other treatments were glyphosate applied 4 WAE, sequential applications of low dose glyphosate applied 2 and 4 WAE, and a non-treated control. Pre-emergence herbicides followed by glyphosate, controlled Ipomoea lacunosa L. 8 WAE. I. hederacea var. integriuscula Gray control with pre-emergence herbicides followed by glyphosate was 100% with similar control from chlorimuron plus sulfentrazone followed by lactofen, whereas control following the single glyphosate application was 84%. Amaranthus palmeri S. Wats. control 9 WAE was 100% following single or sequential glyphosate applications, while control ranged from 76% to 96% with pre-emergence herbicides followed by lactofen. However, early season weed interference when a single application of glyphosate was delayed until 4 WAE reduced soybean yields an average of 389 kg/ha compared to pre-emergence herbicides followed by glyphosate. Based on mean contrasts, pre-emergence herbicides followed by glyphosate had greater gross profit margins than a single glyphosate application alone, but were similar to sequential glyphosate applications. Gross profit margins from pre-emergence herbicides followed by lactofen were not different from glyphosate alone.     

Effect of herbicide and cover crop on weed control in no-tillage jack-o-lantern pumpkin (Cucurbita pepo L.) production

Field experiments were conducted to evaluate cover crop (none, winter wheat, or winter rye) and pre-emergence (PRE) applications of clomazone plus ethalfluralin alone or with halosulfuron [PRE or post-emergence (POST)] for smooth crabgrass [Digitaria ischaemum (Schreb. ex Schweig) Schreb. ex Muhl.] and redroot pigweed (Amaranthus retroflexus L.) control in no-tillage ‘Aspen’ jack-o-lantern pumpkin (Cucurbita pepo L.). At pumpkin harvest, cover crops had reduced smooth crabgrass density, but not redroot pigweed. Although PRE or POST applications of halosulfuron alone were more effective at reducing redroot pigweed density than clomazone plus ethalfluralin PRE, the combination of halosulfuron plus clomazone and ethalfluralin PRE reduced redroot pigweed density to the greatest extent. Pumpkin yields were not affected by cover crop, although average pumpkin sizes were greater with the inclusion of cover crop residues. Pumpkin fruit sizes and yields were the greatest with clomazone and ethalfluralin PRE in combination with halosulfuron applied PRE or POST. Overall, cover crop had relatively little influence on pumpkin yields compared with herbicide treatments. The addition of halosulfuron to clomazone and ethalfluralin provided greater broadleaf weed control resulting in greater jack-o-lantern pumpkin yields.     

转基因抗除草剂油菜对春油菜区主要害虫发生数量的影响

对转基因抗除草剂油菜品种、受体及当地常规品种在春油菜区主要害虫种群的数量进行了调查。结果表明,不同品种间几种主要害虫的发生数量之间存在极显著或显著差异,进一步分析表明,这种差异主要表现为转基因抗除草剂品种与受体品种之间的差异,而与当地的常规品种之间无显著差异。     

Fumigants,rates, and application methods affecting Verticillium wilt incidence and potato yields

A three year comparison was made among fumigants, rates and placement for control ofVerticillium albo-atrum (microsclerotial type). Fumigants were placed in the soil by (i) row method [one shank with duck-foot tool attached to give two bands of fumigant 9 inches (22.8 cm) deep and 9 inches apart (4.5 inches = 11.4 cm from center of a 36-inch row = 91.44 cm)], (ii) deep shank method [one shank in center of a 36-inch row, 18–20 inches (45.7–50.8 cm) deep], (iii) and by the standard broadcast method (four shanks spaced 9 inches deep and 9 inches apart per 36-inch row). The row and deep shank methods were no more effective than the broadcast method when the fumigant rate was equal (calculated on an acre basis and not on the actual portion of the row treated by the method of application). Fewer wilted plants and increased yields (120–160 hundredweight per acre = 134–179 quintals per hectare) were found in plots treated with (i) DD + Picfume (4:1), (ii) Telone + Picfume (4:1), (iii) Telone C, (iv) Terr-o-cide 30, (v) Terr-o-cide 30D and (vi) Vorlex at 25 gal per acre (233.8 liters per hectare) for all years tested. Yield was increased in plots treated at 12.5 gal per acre (116.9 liters per hectare) in 1968 and 1970, but not in 1969. Rates below 12.5 gal per acre were not effective in increasing yield and there was no advantage to applying fumigants above 25 gal per acre. All the six fumigants were equally effective in their control.     

两种喷雾方法对茶棍蓟马防治效果的研究

比较了静电喷雾和常规喷雾技术对茶园茶棍蓟马防治的效果。结果表明,以2000倍吡蚜酮水溶液喷雾,静电喷雾的单位面积药剂用量比常规喷雾减少32．7％,用药7天后的防治效果提高18．8％;而且吡蚜酮在茶叶的残留量为0．010mg/kg,约为常规喷雾的1／8。     

Effect of tillage systems and herbicide treatments on weed abundance and diversity in a glyphosate resistant crop rotation

The effect of exclusive application of glyphosate and glyphosate in combination with residual herbicides on weed species density and composition in summer crops was studied over 2 years. Field experiments consisted of three rotations including soybean and maize glyphosate-resistant cultivars in two tillage systems. Regardless of the tillage system, both glyphosate application alone and in combination with residual herbicides had a pronounced impact on the reduction in density and richness of summer herbaceous annual weeds, but the effect was greater with glyphosate in combination with residual herbicides.     

Grass weed control in sunflower in the spring and kharif (summer) seasons under barani (rainfed) conditions in Pakistan

In field trials conducted at the National Agricultural Research Centre (NARC) near Islamabad and in farm fields, control of grass weeds including Cynodon dactylon (bermudagrass), Sorghum halepense (johnsongrass), Echinochloa colonum (junglerice) and Dactyloctenium aegyptium (crowfootgrass) increased yields of sunflower by 25–100%. The trials were conducted in the spring (February–May) and kharif (July–October) seasons in 1985 and 1986. Hand weeding generally resulted in the greatest yield response but this method was highly labour intensive and considered to be impractical by local farmers. The average time required to maintain 1 ha weed free in the spring and kharif seasons was 41 and 90 eight-hour man-days, respectively. In three of four trials conducted in the spring season, fluazifop-butyl at 0·25 and 0·5 kg/ha did not provide satisfactory control of grass weeds and did not result in significant increases in sunflower seed yields. The performance of fluazifop-butyl in these trials was adversely affected by hot dry conditions causing severe moisture stress after treatment. In contrast, in the fourth spring trial at NARC in 1986 and in all kharif season trials, fluazifop-butyl at 0·25 kg/ha effectively controlled both annual and perennial grasses and resulted in seed yields comparable to those obtained by hand weeding. Value/cost ratios indicate that, in the spring season under drought stress conditions, application of the herbicide would not be profitable; however, in the kharif season, herbicide treatment to control actively growing grass weeds would provide a cost-effective alternative to hand weeding.     

Postemergence directed application of bentazon + metribuzin for broadleaf weed control in Russet Burbank potatoes

Field studies were conducted to evaluate potato (cv. Russet Burbank) injury and weed control with mid- or late-postemergence directed applications of bentazon at 0.56, 0.84, or 1.12 kg ha^?1 + metribuzin at 0.28 kg ha^?1 + petroleum oil concentrate (POC) at 2.3 L ha^?1. Potato injury was 5% or less when bentazon + metribuzin + POC was applied as a postemergence directed spray. Hairy nightshade, redroot pigweed, and common lambsquarters control were excellent with all rates of the bentazon + metribuzin + POC mixture tested at either application time. In weed-free trials, neither U.S. No. 1 nor total tuber yield was reduced compared to the untreated control by any rate of the bentazon + metribuzin + POC mixture applied as a directed spray. Thus, postemergence directed applications of bentazon + metribuzin + POC show excellent potential for broadleaf weed control in Russet Burbank potatoes.     

Differential feeding by grasshoppers and levels of foliar diseases in various cultivars of spring cereals

Sixty-four cultivars and strains of cereals were evaluated under field conditions for differential feeding by grasshoppers, (Orthoptera:: Acrididae) and for their resistance to foliar disease. Grasshoppers actively fed on all triticale and durum wheat lines, on 11 of 12 bread wheat lines, and on 11 of 24 barley lines. Both the incidence and severity of foliar disease were high in all cereals. There was no correlation between grasshopper damage and resistance to foliar disease (r+ −0·059) in the barley but a positive trend appeared in wheat lines (bread r= +0·487; durum r= +0·295). The data suggest that present trends in breeding disease-resistant cereal cultivars will not introduce increased susceptibility to grasshopper damage.     

Effects of 1,3-dichloropropene on nematode,weed seed viability and soil-borne pathogen

1,3-dichloropropene (1,3-D, C₃H₄Cl₂) is one of the potential candidates as soil disinfectant since the restriction of methyl bromide (MeBr) in soil fumigation due to its ecological risk. Its nematode, soil-borne pathogen and weed control efficacies were evaluated in a laboratory dose-response study and in two commercial tomato fields. Laboratory studies found that the seeds of Digitaria chinensis Hornem. were the most sensitive to soil fumigation with 1,3-D, followed by Eleusina indica (Linn.) Gaertn., Echinochloa crusgalli (L.) Beauv. and Amaranthus retroflexus L. with the LC₉₀ values between 14.23 and 73.59 mg kg⁻¹ soil. Among the pathogens, Phytophthora capsici Leonian was the most sensitive and Fusarium oxysporum f. sp. fragariae was the least sensitive to 1,3-D fumigation with the LC₅₀ values were 0.24 and 1.55 g m⁻². Rhizoctonia solani Kühn., Phytophthora nicotianae var. nicotianae and Botrytis cinerea Persoon exhibited intermediate susceptibility. Field trials revealed that 1,3-D applied to the field at 180, 120 and 80 L ha⁻¹ could suppress Meloidogyne incognita root galling while maintaining high tomato marketable yields, better than Dazomet at the concentration of 400 kg ha⁻¹. Our results indicated that 1,3-D was an excellent nematicide and could provide good to moderate weed and pathogen control. Based on our results, 1,3-D, in combination with other alternatives to MeBr is recommended to reach an integrated pest management.     

Effects of nitrogen fertilizer and weed control on nutritive quality of carrots (Daucus carota L.)

The nutritive quality of carrots, obtained from different herbicide-treated plots and under different levels of nitrogen application ranging from zero to 80kg nitrogen/ha, was compared. There were significant differences in carotene content, T.S.S. (total soluble solids) and organolptic characteristics under the influence of different treatments. The maximum carotene content, T.S.S. and organoleptic characteristics were observed with the application of 80 kg. nitrogen/ha and fluchloralin herbicide at 0.90 and 1.20 kg/ha.