Effects of systemic insecticides on potato growth and their interaction with metribuzin

Effects of the soil systemic insecticides aldicarb, phorate, and disulfoton on potato growth were measured from 1984–1986 on the cultivars Russet Burbank and Centennial. In all seasons, aldicarb was observed to cause a significant promotion of flowering and in one season also caused increased haulm growth. Phorate caused a reduction in these growth parameters in one season. Temporary effects on early season yields were observed from the aldicarb treatment in one year but final yields were never significantly affected by insecticide use alone. During 1985–1986 additional treatments were investigated involving insecticide combinations with the herbicide metribuzin to determine possible insecticide-herbicide interactions. Phorate-metribuzin combinations caused synergistic metribuzin injury symptoms, decreased haulm growth and yield in 1986. Metribuzin also decreased yields of aldicarb treated potatoes in 1986 and disulfoton treated potatoes in 1985. Disulfoton-metribuzin combinations decreased flowering in 1985. These data suggest that soil systemic insecticides can have direct effects on potato growth, independent of effects on pest suppression, and that they may interact with other crop protection chemicals.     

Effects of new field resistant cultivars and in-furrow applications of phorate insecticide on tomato spotted wilt of peanut

Field experiments were conducted at Tifton, Georgia from 2008 to 2014 to determine the effects of new peanut (Arachis hypogaea) cultivars and in-furrow applications of phorate insecticide on severity of tomato spotted wilt (TSW) caused by Tomato spotted wilt virus. Several cultivars, including Florida-07, Georgia-06G, Georgia-07W, Georgia Greener, and Tifguard, had final incidence of TSW that were less than that of Georgia Green. In-furrow applications of phorate insecticide reduced incidence of TSW in Georgia Green in three experiments in which that cultivar was included. In-furrow application of phorate insecticide reduced incidence of TSW in most cases where incidence in nontreated plots was 10% or higher. Cultivars Georganic, and Georgia-10T, had final incidence of TSW that was lower than that of Georgia-06G, or Florida-07 within nontreated plots across 2011–2012. Georgia-10T and Georgia-12Y had final incidence that was lower than that of Georgia-06G, Georgia-07W, Georgia-09B and Georgia Greener across insecticide treatments in 2013. In-furrow application of phorate increased yields across cultivars in 2008–2009, and increased yield of Georgia-09B in 2010. In most other cases, phorate had no significant effect on yield. With higher levels of field resistance in most of these cultivars, especially those such as Georgia-12Y, benefits from use of phorate insecticide for TSW suppression were small, and typically did not result in yield increase. Based on these results, several of these cultivars should allow greater flexibility for insecticide choice for thrips management without increasing the risk of losses to TSW.     

Systemic insecticides,soil fumigation,and nitrogen fertilization for verticillium wilt control

Fumigation of Verticillium infested soils with Telone®+chloropicrin in 1966 increased yields of Russet Burbank potatoes 178 and 147 cwt/a (200 and 165 q/ha) over yields in unfumigated plots near Othello and Prosser, Washington, respectively. Systemic insecticides disulfoton and aldicarb banded at planting, sidedressed after planting, or applied in combination treatments did not increase yield at either location. Plots fumigated with Telone®+chloropicrin and fertilized with ammonium nitrate (150 and 350 lb N/a?168 and 392 kg N/ha) in 1967 significantly increased yields over that of the unfumigated, fertilized plots. Application of disulfoton and aldicarb to plots fertilized with ammonium nitrate (150 and 350 lb N/a?168 and 392 kg N/ha) did not increase yields over that of fertilized plots receiving no systemic insecticide.     

Effect of soil applied systemic insecticides on yield of Norland potato

The effects of systemic phosphate insecticide applications in the fertilizer band at planting were studied on Norland variety potatoes grown on irrigated Plainfield sand for 3 years while the effects of systemic carbamate insecticides were studied for 2 years. Systemic carbamate and phosphate insecticides were studied on Norland variety potatoes grown on non-irrigated Parr silt loam for 2 years. A trend toward increased tuber yield over the untreated control when systemic carbamate insecticides were applied and decreased yield when systemic phosphate insecticides were applied on the irrigated Plainfield sand was evident. All systemic insecticide treatments yielded significantly more tubers than did the untreated conrol on the non-irrigated Parr silt loam.     

Improvements to newly sown ryegrass by use of combined fungicide and insecticide treatment

Fungicide seed treatment using benomyl+captan, combined with postemergence sprays of the insecticides chlorpyrifos and omethoate increased herbage yield 10 weeks after sowing in five of eight sowings of Italian and perennial ryegrass. At one sowing, five other fungicide seed treatments—carbendazim+captan, thiabendazole+captan, thiabendazole+thiram, thiabendazole+metalaxyl, and drazoxolon—combined with the insecticide sprays, also increased yield. The insecticides were shown to give good control of shoot-fly larvae, but the yield response to insecticides alone was not as great as that from the combined treatment. As fungicide seed treatment alone increased seedling emergence at one sowing only, possibly the fungicides improved seedling vigour by reducing sub-lethal attacks from soil-borne diseases. The combination of a fungicide and insecticide seed treatment was used at five sowings with no effect.     

Increased severity of Rhizoctonia root rot in sugar beet treated with systemic insecticides

The systemic insecticides aldicarb 15G (15% granules) at 2·6 kg active ingredient (a.i.)/ha and phorate 1OG (10% granules) at 1·7 kg a.i./ha, applied as side dressings about 1 month after planting in 1979 and 1980, significantly increased the severity of root rot, caused by Rhizoctonia solani Kühn, in sugar beet (Beta vulgaris L.). Carbofuran 10G (10% granules) at 2·2 kg a.i./ha also increased root rot, but not significantly. Numbers of harvestable roots were reduced by all treatments but significantly by phorate only. Both aldicarb and phorate were slightly fungistatic to R. solani when the pathogen was grown on potato-dextrose agar incorporating 0·5, 5·0, and 25 μg a.i./ml. Trichoderma sp., a potential antagonist of Rhizoctonia, was slightly inhibited by aldicarb and phorate initially, but soon overcame the effect. Thus, the increase in disease severity in the field may be attributable to some metabolic or physiological effect of the chemicals either on the host or on the infection process of the pathogen. Indiscriminate use of these insecticides should therefore be avoided in areas where root rot is prevalent but where insects are not a problem.     

The impact of a fungicide and an insecticide on soybean growth, yield, and profitability

A growing number of soybean producers have begun to incorporate below threshold fungicide and insecticide treatments into their management programs in attempts to increase yield. The objective of this study was to determine the influence of a fungicide and insecticide on soybean yield and growth when disease and insect pressure is minimal. Soybean was planted at three locations across Indiana, USA, in 2009 and 2010 and treated with various combinations of glyphosate, pyraclostrobin, and lambda-cyhalothrin. Yield was increased by 100 kg ha⁻¹ and 150 kg ha⁻¹ by a R4 application of pyraclostrobin alone and by lambda-cyhalothrin alone, respectively. Seed mass was increased 3% by pyraclostrobin, while seed number m⁻² was increased 5% by lambda-cyhalothrin. No other yield component was influenced by the fungicide or insecticide. Economic analysis using Simulation and Econometrics to Analyze Risk (SIMETAR) demonstrated a single, post application of glyphosate to be the most efficient treatment option across a range of risk attitudes. This study indicates that yield increases are possible using below threshold applications of fungicides and insecticides. However, growers may not benefit from such applications if input costs are higher than the economic returns of the increased yield.     

种植抗虫品种和减量使用杀虫剂的白背飞虱可持续治理技术的田间试验

采用田间虫情和天敌数量调查、水稻产量与千粒重测定和水稻生产实际收益比较的方法,在浙江富阳和重庆秀山两地进行了种植抗虫品种和减量使用杀虫剂的白背飞虱可持续治理技术的田间试验.设使用杀虫剂2次和农户管理(使用杀虫剂4～5次)两个处理,无杀虫剂作为对照.试验结果表明,抗虫品种嘉花1号在各种杀虫剂处理中,白背飞虱成、若虫数量最低(0.9～3.3只/株),是感虫品种中香1号无杀虫剂处理的0.12%.无杀虫剂处理的蜘蛛数量分别是农户管理和杀虫剂2次处理的2.8～5.5倍和1.6～4.1倍.在同样的杀虫剂处理条件下,抗虫和耐虫品种的稻谷损失量和损失率较感虫品种明显地低.水稻生产的实际收益比较显示,无杀虫剂处理,种植嘉花1号可以增收1.13%～15.91%.因此,稻农种植抗虫或耐虫品种,减量使用杀虫剂至2次或不使用杀虫剂,充分利用蜘蛛等天敌的控制作用,完全能够有效地抑制白背飞虱种群的发生和发展,获得与常规杀虫剂用量(4～5次)相仿或更高的收益.     

Interactions of fungicide-insecticide combinations against Rhizoctonia solani in vitro and in soil

The inhibition of mycelial growth of Rhizoctonia solani in vitro was strongest with pencycuron, followed by tolclofos-methyl, carboxin and thiabendazole. Against cowpea seedling rot in soil infested with R. solani, tolclofos-methyl was most effective, followed by pencycuron, thiabendazole and carboxin. Of nine insecticides tested, only parathion-methyl and quinalphos suppressed mycelial growth of R. solani in vitro, although their activity was much lower than that of the four tested fungicides. The inhibition of mycelial growth by fungicide-insecticide mixtures was antagonistic in only two out of 36 combinations; it was additive in most cases or synergistic, e.g. for most mixtures of pencycuron and insecticides. Quinalphos, applied to the soil, was the only insecticide which reduced cowpea seedling rot in soil infested with R. solani. Soil application of parathion-methyl, phorate, aldicarb or carbofuran and seed treatment with phosphamidon, monocrotophos, endosulfan or dimethoate had little or no effect on seedling rot. Carboxin gave better disease control when applied to the seed already coated with phosphamidon, monocrotophos, endosulfan or dimethoate and when carboxin-treated seeds were sown in soil treated with quinalphos, parathion-methyl, aldicarb or carbofuran. Efficacy of thiabendazole seed treatment was slightly higher in the presence of insecticides, particularly dimethoate. Pencycuron and tolclofos-methyl as seed treatment gave nearly 100% disease control both in the presence and absence of insecticides. The synergistic interactions detected between fungicides and insecticides represent interesting opportunities for the control of R. solani.     

Agronomic and economic assessment of intensive pest management of dry bean (Phaseolus vulgaris)

Two common production constraints of dry bean (Phaseolus vulgaris) in Ontario are annual weeds and anthracnose (caused by Colletotrichum lindemuthianum). Dry bean is not considered a competitive crop and weed interference can result in substantial yield losses, while anthracnose is considered one of the most devastating diseases in dry bean production. A study conducted in Ontario Canada, examined the effect of two herbicide programs on weed management, thiamethoxam insecticide treatment on plant enhancement and three fungicide programs on anthracnose development in a navy bean cv. ‘OAC Rex’. The premium herbicide program (s-metolachlor + imazethapyr) reduced percent weed ground cover relative to the economic herbicide program (trifluralin) in five of six locations. Thiamethoxam increased emergence and vigour at only one location, which contradicts reported benefits of thiamethoxam on plant health. The herbicide or thiamethoxam treatments did not affect anthracnose disease severity, visible seed quality, net yield or economic return. The fungicide seed treatment was often superior to the untreated control, for a number of the parameters measured. The application date of the foliar fungicide, relative to the onset of disease, varied between site-years. This dramatically influenced the fungicide’s effectiveness. Foliar fungicides increased seed quality and net economic return compared to the control when applied prior to disease development. The combination of fungicide seed treatment followed by a foliar fungicide provided the largest reduction in anthracnose severity.     

The effect of nematicides onPratylenchus penetrans and potato yields

Aldicarb applied as Temik 10% or 15% granular at 1.68, 2.24 or 3.36 kg/ha active ingredient (a.i.) in the row at planting reduced the size of populations ofPratylenchus penetrons in experimental plots and commercial fields. Both aldicarb and the soil fumigant, Telone-II, were associated with yield increases of about 40% in Superior and Sebago potatoes in experimental plots in 1978, but there were no significant increases in yield in 1979 and 1980. A comparison was made between areas treated with aldicarb 10% granular at 2.24 kg/ha a.i. or disulfoton 15% granular at 3.36 kg/ha a.i. in 24 commercial fields. Average yields from the combined results of Kennebec, Superior, Sebago, and Russet Burbank cultivars were about 13% higher in the aldicarb treatments. Yields in six fields where aldicarb was applied at 3.36 kg/ha a.i. were not different from yields in adjacent fields treated with the lower rate of aldicarb. Superior potatoes inoculated withP. penetrons, or uninoculated, were grown in pots in the greenhouse in fine sandy loam at moisture levels of 35–55% or 70–100% field capacity. The lower soil moisture level and the nematode treatment reduced tuber weights. The nematode-soil moisture interaction was significant in one of the two experiments.     

Evaluation of some systemic granular insecticides againstMyzus persicae Sulzer on potatoes

Summary Field evaluation of seven granular insecticides againstMyzus persicae revealed that phorate, aldicarb and disulfoton (both Di-Syston and Solvirex) are effective in reducing and keeping down the population ofM. persicae when applied either at sowing or at first earthing up.     

The effects of pesticides and crop rotation on the soil-inhabiting fauna of sugar-beet fields. Part I: The crop and macroinvertebrates

The effects of two insecticide treatments (seed-furrow aldicarb, and gamma-HCH sprayed overall), herbicide and crop rotation on pest attack to sugar-beet seedlings, and pest and predator populations, were studied in a 3-year field trial. On continuous-beet plots without insecticide, seedling establishment declined sharply from the first to the third year of the trial due to a build-up in the numbers of pygmy beetles, Atomaria linearis Steph., a sugar-beet pest. Crop rotation, and both insecticides, decreased damage by the pest and thereby increased establishment considerably, in the second and third years of the trial whereas herbicide had no effect. The effects of the insecticides on numbers of creatures caught in pitfall traps varied with species and with insecticide. For example, more Bembidion lampros Herbst., a carabid beetle, were trapped on plots treated with gamma-HCH than on untreated plots, whereas the effect was less marked on aldicarb-treated plots and was not observed in other carabid species with either insecticide.     

Effects of nematicides on the chemical composition of the fruits of egg-plant (Solanum melongena L.)

Five nematicides — aldicarb, carbofuran, phorate, fensulfothion and DBCP — were studied in a field experiment to investigate their effect on the chemical composition of the fruits of egg-plant. There were no significant differences in the dry matter content of fruits from different treatments. A significant decrease in the crude protein content was observed with nematicide treatments. Phenolic compounds increased on application of phorate while all other treatments, except carbofuran, decreased these compounds. A significant increase over control in solasodine content of fruits was observed with all treatments.     

Susceptibility of Idaho populations of Colorado potato beetle to four classes of insecticides

A laboratory study was conducted in 1984 to establish base-line data on insecticide tolerance and to detect incipient resistance to representative insecticides within the four major classes of insecticides that are used to control Colorado potato beetles in Idaho. Insecticides tested were aldicarb (a carbamate), endosulfan and DDT (chlorinated hydrocarbons), azinphosmethyl and disulfoton (organophosphates) and fenvalerate (a pyrethroid). Compared with results obtained elsewhere, Idaho populations of Colorado potato beetle proved relatively susceptible to the insecticides tested. However, significant differences were detected among sample populations indicating the potential for insecticide resistance exists.     

Effect of watered-in demethylation-inhibitor fungicide and paclobutrazol applications on foliar disease severity and turfgrass quality of creeping bentgrass putting greens

Preventive, watered-in applications of DMI fungicides provide control of several soilborne turfgrass diseases on golf putting greens. The objectives of this two-year field study were to determine the impact of these applications on foliar diseases, and evaluate the impact of application timing of paclobutrazol, a plant growth regulator, on disease severity and turfgrass quality. Triadimefon (1.58 kg a.i. ha⁻¹), tebuconazole (0.82 kg a.i. ha⁻¹), metconazole (0.43 kg a.i. ha⁻¹), and triticonazole (0.64 kg a.i. ha⁻¹), were applied twice in late April and May and immediately watered in to the soil profile with 5 mm of post application irrigation. Paclobutrazol (0.28 kg a.i. ha⁻¹) was applied alone, in a tank-mix with the fungicide application, 7 days or 14 days after the fungicide application. Overall dollar spot severity, assessed as area under the disease progress curve (AUDPC), was significantly lower in fungicide treated plots than non-treated plots in both trial years. The date of threshold symptom observation (≥5 infection centers per plot), however, was not different between fungicide treated and non-treated plots in 2011. Triadimefon treated plots had lower AUDPC values than other fungicide treatments. Brown patch severity was not significantly different among treatments. Paclobutrazol applied alone did not reduce dollar spot or brown patch severity, however, paclobutrazol + fungicide treatments resulted in lower dollar spot severity than plots treated with fungicide alone. Short-lived phytotoxicity (bronze discoloration) was observed in plots treated with triadimefon or paclobutrazol + fungicide. Spring preventive fungicide applications targeted at soilborne disease control also provided residual control of dollar spot in this study.     

Field study of the relative susceptibility of eleven potato (Solanum tuberosum L.) varieties and the efficacy of two fungicides against Rhizoctonia solani attack

Rhizoctonia black scurf is an economically important disease of potatoes in Tunisia and around the world. It reduces the quality and yield of potatoes and has become an important impediment for export of potatoes, especially to Europe. The information on comparative susceptibility of potato cultivars will help the growers make informed decisions regarding the management of this disease. The eleven potato cultivars used in this study showed a range of susceptibility reactions to Rhizoctonia solani but none of these was completely resistant to the disease. The Spunta variety showed the least percentage of infection of progeny tubers by R. solani sclerotia at harvest, while the varieties Nicola, Santana, Labadia, Liseta and Tango showed a high percentage of infection of progeny tubers. Seed treatment using fungicides, presently registered in Tunisia, are not effective in controlling the disease to growers’ satisfaction. Field experiments conducted to evaluate the efficacy of two newly introduced fungicides pencycuron (Monceren^®) and azoxystrobin (Amistar^®) showed that they were effective for the control of the disease. Seed potatoes treatment and in-furrow application of azoxystrobin consistently provided superior protection in two years of experimentation.     

Influence of Growth Regulators on Plant Growth, Yield, and Skin Color of Specialty Potatoes

2,4-D has been used since the 1950’s to enhance color in red-skinned potatoes, but there is little research on the potential use of other plant growth regulators to improve tuber skin color in the wide range of specialty potatoes now available on the market. Field trials conducted at Parma, ID in 2009 and 2010 evaluated the effect of foliar applications of 2,4-D, NAA, and LPE on plant height, foliar injury, tuber yield, size distribution, and skin color of six specialty potato cultivars. Skin color was rated visually and via HunterLab colorimeter at harvest, and again after storage (132 days in 2009 and 93 days in 2010) at 4 °C and 95 % R.H. 2,4-D caused slight foliar injury and reduced tuber size in all cultivars. It also increased visual skin color rating in the red-skinned cultivars ‘Red LaSoda’ and ‘TerraRosa’ at harvest and after storage, and influenced incidence of pink coloration around the eyes of ‘Yukon Gem’ tubers, but did not affect color of blue/purple-skinned cultivars. NAA and LPE did not consistently influence plant growth, yield, tuber size or visual skin color in any cultivar. Colorimetric evaluations mostly agreed with the visual ratings, and indicated that storage significantly altered skin color in all cultivars, regardless of growth regulator treatment.     

Nematicides induced changes in the chemical constituents of potato tubers

Changes in the chemical constituents of potato tubers grown under different concentrations of 3 synthetic organic nematicides (carbofuran, aldicarb and phorate) and a natural plant product (sawdust) were investigated. There were no significant differences in the specific gravity, dry matter and starch content of tubers from different treatments. A significant increase in the content of non-reducing and total sugars was observed in all the treatments. Nematicidal treatments had significant effects on reducing sugars, true protein, free amino acids, orthodihydroxy phenols, beta-carotene and ascorbic acid. Application of nematicides reduced the content of total phenolic compounds which is a desirable change from a processing viewpoint. Potatoes grown under different nematicidal treatments can be processed into chips and French fries as they contain permissible levels of reducing sugars required for these forms of processing.     

The Influence of Plant Growth Regulators and Inflorescence Removal on Plant Growth,Yield, and Skin Color of Red LaSoda Tubers

Foliar applications of the synthetic auxin compound 2,4-dichlorophenoxyacetic acid (2,4-D) have been used to enhance skin color of red potato cultivars for many years. Relatively, little is known about the mode of action of this compound, but it has been proposed that 2,4-D stimulates ethylene production and enhances the activity of enzymes involved in anthocyanin biosynthesis. The objective of this study was to compare several other plant growth regulators to 2,4-D for their effect on plant growth, tuber yield, and skin color of the light red-skinned cultivar “Red Lasoda.” Trials were conducted in 2010 and 2011 to evaluate the effects of foliar applications of the ethylene-stimulating growth regulator ethephon, the ethylene-inhibitor 1-methylcyclopropene (1-MCP), and 2,4-D. Manual inflorescence removal was also included as a treatment to determine the influence of anthocyanin sink competition between tubers and flowers on tuber skin color. Ethephon application caused floral abscission in treated plants and reduced plant height compared to other treatments and the non-treated control. While 2,4-D caused foliar injury and ethephon slightly increased the yield of <56 g tubers, neither growth regulator affected total and marketable yield. Both ethephon and 2,4-D increased tuber skin color at harvest compared to the non-treated control. In contrast, 1-MCP and inflorescence removal had no effect on yield, tuber size, and skin color. The results indicate that ethephon and 2,4-D foliar applications have similar effects on skin color and appearance, supporting the hypothesis that 2,4-D works by stimulating ethylene production within the plant.