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.     

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.     

Response of Potatoes to Soil-Applied Insecticides, Fungicides, and Herbicides

Non-target impacts of pesticides are well documented in crops such as soybeans and corn. However, little effort has been made to evaluate these impacts in potatoes. Field trials were conducted at the Parma and Aberdeen Research and Extension Centers during 2005 and 2006 to evaluate the potential for systemic insecticides, fungicides, and herbicides to affect disease development, crop injury, and tuber yield. The first set of trials evaluated six insecticide treatments (aldicarb, oxamyl, phorate, imidacloprid, thiamethoxam, and non-treated) in a factorial combination with in-furrow application of the fungicide azoxystrobin. Azoxystrobin significantly decreased Rhizoctonia stem canker, while aldicarb and phorate tended to increase it compared to the non-treated control. There was a significant insecticide by fungicide interaction due to a bigger reduction in disease index by the fungicide when certain insecticides were used. Despite the association of these insecticides with increased disease incidence, there was no significant impact on yield. In the second set of trials, sulfentrazone herbicide was applied just prior to plant emergence to potatoes treated with the same six insecticides to evaluate the potential for the in-furrow treatments to increase plant injury. Sulfentrazone caused stunting and visible plant injury, but the level of plant injury was influenced by insecticide treatment in only one out of four trials.     

The joint action of nitrogen and nematicides onPratylenchus penetrans and potato yield

The joint action of nitrogen fertilizer and nematicides onPratylenchus penetrons and yield was investigated using three potato varieties (Superior, Onaway and Russet Burbank), three rates of nitrogen (84, 168 and 336 kg/ha), five edaphic pesticides (disulfoton, aldicarb, 1,3-D + MIC, carbofuran and thiofanox), and an insecticide spray to minimize the role of foliar feeding insects In 1977, disulfoton, aldicarb, and disulfoton plus 1,3-D + MIC significantly increased the yield of Superior at all nitrogen rates. The yield increases ranged from 37–56% for Superior, 15–35% for Onaway and 13–27% for Russet Burbank. Nitrogen had no detectable influence on yield. Population densities ofP. penetrans were significantly reduced by disulfoton plus 1,3-D + MIC and by aldicarb. Superior was most susceptible toP. penetrans, Onaway intermediate, and Russet Burbank moderately tolerant. Neither the potato variety or nitrogen significantly influenced the population densities ofP. penetrans In 1978 aldicarb, 1,3-D + MIC and thiofanox significantly increased yields of Superior at all nitrogen rates. Nitrogen also significantly increased yields, but only where aldicarb and 1,3-D + MIC were applied. Total yield was increased 12–14% and 17–23% by 1,3-D + MIC and aldicarb at 168 and 336 kg N/ha, respectively. Aldicarb, 1,3-D + MIC, and thiofanox appeared to increase tuber set, while nitrogen increased tuber size. Although all of the nematicides provided some control ofP. penetrans, aldicarb had the highest degree of efficacy and gave excellent season-long control     

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.     

The effect of systemic pesticides on total glycoalkaloid content of potato tubers at harvest

Two studies were conducted to determine the effect of systemic pesticides on the potato tuber total glycoalkaloid (TGA) content at harvest. In a field study, a pretuberization application of three systemic insecticides (disulfoton, aldicarb, carbofuran) and three systemic fungicides (thiabendazole, benomyl, thiophanate methyl) on three potato cultivars (Cobbler, Katahdin and B5141-6) showed carbofuran to be the only treatment significantly different (P= .05) from the control. The tuber TGA content of the carbofuran treatment was lower than that of the control. In a greenhouse study, carbofuran applied during tuberization to three potato varieties (Norland, Kennebec, Abnaki) produced a highly significant increase (P= .01) in the tuber TGA content. A significant varietal difference (P=.01) in response to the carbofuran treatment was also evidenced.     

Economic analysis of cotton-insect control in the Sudan Gezira

Changes in net returns from modifications in insecticide use are evaluated by estimation of three component models: a yield function, a cotton-quality relationship and an alternative pesticide use equation. Data from 41–99 production regions and 3 crop years are used to evaluate a shift from conventional insecticides to ground-applied aldicarb for late-season insect control. Analysis of multiple effects of insecticides reveals that net returns from aldicarb use in the short term are about 220%. This change in pesticide use has improved yields and increased cotton quality.     

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.     

Assessment of pesticide use in the U.S. potato industry

Pesticide use in US fall crop potato production was surveyed for the years 1990 to 1994. The purpose of the study was to provide information about the relative importance of each pesticide and potential alternatives. The objectives were to: (1) inventory pesticides used on potatoes, (2) rank the target pests and (3) estimate the economic value of the major pesticides. Extension specialists working on potatoes in twelve states provided the main source of survey data. The most commonly used pesticides in four categories were: fungicide —chlorothalonil, insecticide —methamidophos, herbicide —metribuzin, and “other” -diquat. The most frequent target pests were: early blight (Alternaria solani), late blight (Phytophthora infestans), aphids (primarily Myzuspersicae), Colorado potato beetle (Leptinotarsa decemlineata), lambsquarter (Chenopodium album), and pigweed (Amaranthus spp.). The pesticides that provided the most annual value to potato growers were methamidophos ($281 million), diquat ($86 million), metribuzin ($81 million), CIPC ($56 million) and esfenvalerate ($52 million).     

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.     

河北省一季作区马铃薯病虫害发生及综合防控

河北省一季作区马铃薯主要病虫害有晚疫病、早疫病、黑痣病和二十八星瓢虫,此外,病毒引起的品种退化比较普遍,造成不同程度的损失。本文根据河北省一季作区马铃薯病虫害发生特点总结出一套综合防控技术体系,包括将马铃薯与玉米、大白菜等非茄科作物轮作3年减轻黑痣病危害;采用脱毒薯克服病毒引起的品种退化问题;种薯和(或)土壤消毒控制黑痣病和晚疫病;待马铃薯生长至封垄后,遇到适宜晚疫病发生的天气,喷施1～3次保护性杀菌剂预防晚疫病和早疫病;一旦监测到晚疫病中心病株后即拔除并装入塑料袋带出田外,并交替喷施有治疗效果、能兼治早疫病且作用机制不同的内吸性杀菌剂及混剂;田间出现马铃薯二十八星瓢虫成虫,在杀菌剂中混入高效氯氰菊酯或高效氯氟氰菊酯等高效杀虫剂防虫;马铃薯成熟前1～2周将地上部分割掉并运出田外后收获块茎。     

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.     

Effect of repeated applications of insecticides to potatoes on numbers of Myzus persicae (Sulzer) (Hemiptera: Aphididae) and on the frequencies of insecticide-resistant variants

Numbers of Myzus persicae on potatoes (Solanum tuberosum) receiving three insecticide regimes were recorded in 1985 and 1986. Frequencies of insecticide-resistant variants were determined using an immunoassay for esterase-4 (E4), the enzyme responsible. M. persicae was more abundant at the end of the season on plots sprayed alternately throughout the experiment with a mixture of pyrethroid with oil and pirimicarb, than on those treated with pirimicarb alone. Frequency distributions of E4 activity showed that very resistant variants intermediate between R₂ and R₃ levels accounted for >50% of the populations. Further samples of aphids, collected on separate farms from defoliated patches in late-growing potato crops where repeated spraying had failed to control aphids, showed that these highly resistant variants had again been selected. Possible reasons for the observed increase in numbers of M. persicae following pyrethroid/oil treatment and consequences for virus control are discussed.     

Continuation of cropping sequence studies on coarse textured soils in southeastern Idaho

A potato cropping rotation study was initiated on coarse textured soils in 1969 to compare annual cropping to potatoes with potato-grain rotations. At the completion of the 1975 season, those treatments annually cropped to potatoes had been planted to potatoes for seven consecutive years. After this period of time, total yields were reduced by 14% or 55 cwt/acre (6 T/ha) when compared to yields from potato-grain rotation treatments. Soil fumigation with 30 gpa (285 1/ha) of soil fumigant (Shell D-D) resulted in no beneficial effects on tuber yield or quality.     

Insecticide control of the potato tuberworm in late-crop potato foliage

The systemic insecticides, Dasanit^®, carbofuran (Furadan^®), phorate (Thimet^®), aldicarb (Temik^®) and disulfoton (Di-Syston^®) were applied in the planting furrow at 2–3 lb actual/acre for potato tuberworm (Phthorimaea operculella (Zeller)) control in Irish potato foliage. None of these compounds gave entirely satisfactory results. Dasanit was the best with slightly over 80% decrease in the number of mines and was followed closely by carbofuran; all treatments needed to be supplemented by foliage sprays for satisfactory tuberworm protection. Azinphosmethyl (Guthion^®) gave consistently outstanding results as a foliage spray at 0.5 lb/acre with over 99% tuberworm reduction. Other foliar-applied insecticides giving at least 98% tuberworm control included: Monitor^®, monocrotophos (Azodrin^®), phosphamidon, Orthene^®, Torak^®, methomyl (Lannate^®) and Dursban^® (all at 0.5 lb/acre) and Phosvel^® (1 lb/acre).     

Effects of soil-borneRhizoctonia solani Kühn on yield and quality of ten potato cultivars

Summary The effects of soil-borneRhizoctonia solani on yield and quality of potato were studied by an extensive individual plant sampling procedure. From 1983 to 1986, stem canker and stolon pruning were examined in 10 768 plants growing on a sandy soil. Tuber yield and quality and haulm yield per plant were also recorded. The degree of attack byR. solani depended on the cropping frequency of potato. Severe and very severe stem and stolon attacks decreased fresh yield, dry matter yield and dry matter content of tubers and increased the number of deformed and small tubers, whereas the effect on haulm yield and stem number was small. Potato cultivars differed in susceptibility toR. solani, but yield response did not differ significantly between cultivars at the same levels of stem and stolon infection.     

The vertical distribution of green peach aphids and its effect on a model quantifying the relationship between green peach aphids and a predator

The vertical distribution of green peach aphids (GPA) on potato plants was studied to estimate its impact on a model simulating the effects of a predator on GPA populations. This model is based on laboratory studies of a ladybird beetle feeding on GPA that was placed exclusively on the bottom leaf of a three leaf stem section. The model predicts the impact ofColeomegilla maculata (DeGeer) adults and third instar larvae on GPA populations over a range of temperatures and GPA densities. The vertical distribution of GPA in a potato field and the effects of different levels of aldicarb on this distribution were determined by counting all GPA on the upper, middle, and lower thirds of a stem in situ. A one leaf sub-sample was taken from each stem section as a comparison. The vertical distribution of GPA changed with aldicarb dose. Most GPA were found on the lower third of stems from plots treated with the lowest aldicarb doses. However, most GPA occurred on the upper third of the stems from plots treated with the highest aldicarb doses. This distribution changed midway through the season until most GPA occurred on the bottom third of the stems. C. maculata adults and third instar larvae preferentially search the upper and lower thirds of potato plants. This suggests thatC. maculata would be an effective early season predator, and that our model should over-predict the effect ofC. maculata on GPA populations late in the season.     

Direct application of reduced rates of aldicarb to potato seedpieces

Aldicarb was applied directly to potato seedpieces at 0.3, 0.6, 1.1, 2.2 and 3.4 kg AI/ha at planting and at 2.24 kg Al/ha over the plants at crop emergence. All seedpiece treatments resulted in superior early season protection from Colorado potato beetle,Leptinotarsa decemlineata (Say). Lower seedpiece rates lost effectiveness by early July, while higher rates protected foliage into early August. In a second study, plots treated with 1.1 kg AI/ha to the seedpiece produced crop yields as high as those treated with additional aldicarb at crop emergence. It is suggested that low rates of aldicarb applied directly to the seedpiece at planting could offer effective early season insect control while reducing the risk of groundwater contamination.     

Effects of soil disinfection and potato harvesting methods on stem infection byRhizoctonia solani Kühn in the following year

Summary A two year field experiment was conducted twice to assess effects of chemical soil disinfection at planting and methods of harvesting potatoes on stem infection withRhizoctonia solani in the subsequent year. In the first year of the experiments seven methods. including one with soil disinfection at planting, were applied in August. In the following year,R. solani stem and stolon infection (disease severity) on potato plants were assessed in June. Soil treatment at planting with pencycuron resulted in lowest disease severity in the following year. Compared with chemical haulm killing and haulm pulling. immature-crop-harvesting also resulted in a lower disease severity, but only when black scurf was scarce on tubers at harvest in the preceding year.     

Integrated pest management of potato tuber moth in field and storage

Summary The potato tuber moth (PTM),Phthorimaea operculella (Zeller), is one of the most damaging pests of potatoes in field and storage. Tuber moth is active throughout the year in North Africa but is most active from late April to early August. Many cultural practices that are used by farmers to improve the yield and quality of potato can also limit the development of the potato tuber moth and minimise damage to tubers. As the farmers gain more experience with both agronomic practices and chemical insecticides, they are likely to rely more heavily on cultural practices and less on insecticides to manage PTM. Measures which could keep PTM damages in rustic and diffuse light stores to a minimum are discussed. Ideally, there is need to integrate pest management in potato fields and stores. PTM control in stores was found to be more effective if infestation in fields was kept to a minimum. Low infestation at harvest and rapid handling of the potatoes going into store established good initial storage conditions and decreased the likelihood of post-harvest losses. Biological insecticides in particular were more effective in preventing losses by insects in stores in cases where the initial level of infestation was relatively low.