Number Of Pesticide Applications Research Articles

Avocado (Persea americana Mill.) production in Huatusco, Veracruz, Mexico

Objective: To characterize the avocado production system in Huatusco, Veracruz. Design/Methodology/Approach: Interviews based on the snowball method were applied to avocado producers in Huatusco, Veracruz. Meanwhile, fruit and water samples were used to perform a multiresidue analysis of pesticides. Results: The monoculture plantations are rainfed. They have a density of 100-150 trees ha-1. The Hass variety predominates in Andosols, with 5-100% slopes. Most of the producers (92%) carry out conventional management, applying pesticides and chemical fertilizers. Herbicides and brushcutters are used to control weeds. No pesticides were detected in the water samples, while Imidacloprid, Thiabendazole, and alpha-Cypermethrin were identified in a fruit sample, with 0.0038 ± 0.0014 mg/kg, 0.0022 ± 0.0009 mg/kg and 0.0703 ± 0.000 mg /kg concentrations, respectively. These concentrations fall within the limits allowed in Mexico. Study Limitations/Implications: A detailed and frequent sampling of avocado fruits should be carried out to determine pesticide residues. It is also necessary to analyze samples of running water near the orchards to prevent pollution. Findings/Conclusions: The empirical knowledge of the producers about the type of soil is more precise than the scientific classification: they identify five classes of soils beyond Andosols. Additionally, there is a marked inequality in land tenure, since large-scale producers (25% of all producers) own 86% of the established area. Although, in a preliminary sampling, pesticide concentrations did not exceed the limits of residues allowed in the avocado pulp, the number of pesticide applications should be reduced.

Development of a Disease and Pest Management Program to Reduce the Use of Pesticides in Sweet-Cherry Orchards

A protocol for managing the main diseases and pests of sweet cherry in Spain (New IPM) has been implemented in order to reduce the use of pesticides. This New IPM includes nonchemical strategies, such as biological products against diseases and mass trapping of pests, and adjusts the timing and number of pesticide applications according to damage thresholds and a predictive model of diseases based on climatic factors. The New IPM was compared—in commercial orchards from the main cherry-producing areas in Spain (Aragon and Extremadura)—to the integrated management usually carried out in these areas (Standard IPM). Furthermore, a multiresidue method for the determination of the residues in cherries was developed. The number of applications, active ingredients used, and residue levels in fruit were reduced very significantly with this New IPM without affecting the effectiveness in the control of the main cherry diseases (brown rot, shot-hole, and leaf-spot) and pests (European cherry fly, spotted wing drosophila, and black cherry aphid). Neither significant differences in the abundance and diversity of microorganisms in flowers and fruit nor soil and canopy dwelling arthropods were observed between the two protocols, although some positive effects of this New IPM were seen on some groups of natural enemies.

Cumulative effects of incorrect use of pesticides can lead to catastrophic outbreaks of pests

Modeling external perturbations such as chemical control within each generation of discrete populations is challenging. Based on a method proposed in the literature, we have extended a discrete single species model with multiple instantaneous pesticide applications within each generation, and then discuss the existence and stability of the unique positive equilibrium. Further, the effects of the timing of pesticide applications and the instantaneous killing rate on the equilibrium were investigated in more detail and we obtained some interesting results, including a paradox and the cumulative effects of the incorrect use of pesticides on pest outbreaks. In order to show the occurrences of the paradox and of hormesis, several special models have been extended and studied. Further, the biological implications of the main results regarding successful pest control are discussed. All of the results obtained confirm that the cumulative effects of incorrect use of pesticides may result in more severe pest outbreaks and thus, in order to avoid a paradox in pest control, control strategies need to be designed with care, including decisions on the timing and number of pesticide applications in relation to the effectiveness of the pesticide being used.

Agricultural factors affecting Fusarium communities in wheat kernels

Fusarium head blight (FHB) is a devastating disease of cereals caused by Fusarium fungi. The disease is of great economic importance especially owing to reduced grain quality due to contamination by a range of mycotoxins produced by Fusarium. Disease control and prediction is difficult because of the many Fusarium species associated with FHB. Different species may respond differently to control methods and can have both competitive and synergistic interactions. Therefore, it is important to understand how agricultural practices affect Fusarium at the community level.Lower levels of Fusarium mycotoxin contamination of organically produced cereals compared with conventionally produced have been reported, but the causes of these differences are not well understood. The aim of our study was to investigate the effect of agricultural factors on Fusarium abundance and community composition in different cropping systems. Winter wheat kernels were collected from 18 organically and conventionally cultivated fields in Sweden, paired based on their geographical distance and the wheat cultivar grown. We characterised the Fusarium community in harvested wheat kernels using 454 sequencing of translation elongation factor 1-α amplicons. In addition, we quantified Fusarium spp. using real-time PCR to reveal differences in biomass between fields.We identified 12 Fusarium operational taxonomic units (OTUs) with a median of 4.5 OTUs per field. Fusarium graminearum was the most abundant species, while F. avenaceum had the highest occurrence. The abundance of Fusarium spp. ranged two orders of magnitude between fields. Two pairs of Fusarium species co-occurred between fields: F. poae with F. tricinctum and F. culmorum with F. sporotrichoides. We could not detect any difference in Fusarium communities between the organic and conventional systems. However, agricultural intensity, measured as the number of pesticide applications and the amount of nitrogen fertiliser applied, had an impact on Fusarium communities, specifically increasing the abundance of F. tricinctum. There were geographical differences in the Fusarium community composition where F. graminearum was more abundant in the western part of Sweden. The application of amplicon sequencing provided a comprehensive view of the Fusarium community in cereals. This gives us better opportunities to understand the ecology of Fusarium spp., which is important in order to limit FHB and mycotoxin contamination in cereals.

Current status of pesticide use among rice farmers in Cambodia

Knowledge about the current status of pesticide use in Cambodia is critical to attempts to establish an effective pest control system. Semi-structured interviews were conducted to clarify pesticide use by farmers, the number and timing of pesticide applications, and the active ingredients of the pesticides used during rainy season cropping in three study areas in the Takeo (TK), Prey Veng (PV), and Svay Rieng (SR) provinces. The number of pesticide applications and the major active ingredients of those pesticides varied across these areas according to the pesticide package labels stored by farmers. Insecticides and growth activators were often used in TK and PV but were rarely used in SR, except for some herbicides. The farmers tended to apply more insecticides and fungicides, especially when they observed certain pests in their fields. When the three study areas were compared, pesticide application also seemed to depend on demographic profile, the varieties of the crops cultivated, and the reason for cultivation. These results will be useful for determining the optimal approach to pest management in Cambodia.

Management of Legume Podborer, <i>Helicoverpa armigera</i> with Host Plant Resistance

Helicoverpa armigera is the most important insect pest on wide variety of food, fibre, oilseed, fodder and horticultural crops commonly called as legume pod borer. Enormous amount of loss has been reported in deferent crops worldwide. Apart from being highly polyphagus, H. armigera is widely adapted to feeding on various plant parts. However, damage to the reproductive parts particularly to flowers and developing seeds results in direct loss. Hence, the level of Helicoverpa infestation during the flowering and fruiting phase is widely used as the basis for assessment of loss, and to quantify the genotypic resistance to this insect. Varieties of chickpea showing varying degrees of resistance to H. armigera have been developed at ICRISAT in India and some of these varieties have been used successfully by the farmers. Screening of more than 14800 germplasm accessions under natural infestations at ICRISAT has resulted in the identification of 21 donor showing antixenosis, antibiosis and tolerance mechanism of resistance, and these sources can be used in breeding programs. A high per cent of crude fibre and non reducing sugars and low per cent of starch have been found to be related with low incidence. Recent reports on significant variation in Helicoverpa gut proteinase inhibitors among chickpea genotypes escape insect attack or suffer less damage as compared to other genotypes because of phonological asynchrony. Deployment of Helicoverpa-resistant cultivars should be aimed at conservation of the natural enemies and minimizing the number of pesticide applications. Host plant resistance is compatible with other methods of insect control, exercises a constant and cumulative effect on insect populations over time and space, as no adverse effects on the environment, reduces the need to use pesticides, and involves no extra cost to the farmers.

Comparison of Integrated Pest Management approaches and conventional (non-IPM) practices in late-winter-season cauliflower in Northern India

On-farm research was conducted in Northern India during the late-winter seasons of 2008–2009 and 2009–2010 to develop and validate an Integrated Pest Management (IPM) approach for cauliflower (Brassica oleracea var. Botrytis L. subvar. Cauliflora DC). Cauliflower has traditionally received considerable use of pesticides to manage insect pests, such as the mustard aphid, Lipaphis erysimi (Kaltenbach), and diseases such as damping-off and Alternaria leaf spot. This study compared the conventional farmers' practice, which is pesticide-based and is a non-IPM approach, with an IPM approach, which used cultural, chemical and biological methods to manage the insect and two diseases of cauliflower. Yields for both seasons were consistently greater in the IPM treatment, averaging 24 t/ha (10% greater yields) in the IPM treatment than in the non-IPM treatment. Economic analysis showed higher net economic returns (1410 USD/ha) and benefit: cost ratio (3.6:1) than from the non-IPM treatment (1152 USD/ha net return; 2.9:1 benefit: cost ratio). Compared to the non-IPM treatment, growers using IPM reduced the amount (a.i./ha) of pesticide by 63.8% and the number of pesticide applications by more than 50%. In addition, the IPM treatment replaced hazardous pesticides with safer bio-pesticides and reduced-risk pesticides. This study demonstrated that IPM can be cost-effective for managing pests and diseases of cauliflower in late winter.

Pesticide use and risk perceptions among farmers in the cotton belt of Punjab, Pakistan

The need to evaluate pesticide use in rural populations, particularly in developing countries, is urgent. Pesticide use and related risk perceptions were studied among 318 randomly selected farmers from two areas of the cotton belt of Punjab, Pakistan. A total amount of 4875 kg of pesticide active ingredients was reported to be applied by the farmers per annum and most of these active ingredients were classified as moderately hazardous (55%) or highly hazardous (23%) according to WHO classification. The number of pesticide applications per growing season ranged from 6 to 16, with an average of 10 or 11 applications, depending on district. Better-educated farmers were found to spray less. Most farmers (52%) considered the risk from pesticide use to be low, whereas a solid fraction (12%) considered there was no risk at all. To model farmers' behavior on pesticide overuse, a binary probit regression model was used expressing behavior as a function of age, education, level of risk perception, health effects, pesticide toxicity class, and Integrated Pest Management (IPM) training. Irrespective of age, there was a clear tendency towards pesticide overuse, but the probability decreased with IPM training, a high level of education, and use of highly toxic pesticides. Awareness of the high toxicity of a pesticide product tended to discourage overuse. On the contrary, neither the experience of health effects nor the levels of risk perception affected overuse. Farmers were not well informed about correct application practices and safe handling of pesticides. Overall, findings affirm an urgent need for training programs on pesticide use in the study area with the aim of conveying more specific information on health hazards from pesticides that will avert hazardous behaviors of farmers derived from misleading beliefs about pesticide use.

Species Composition and Occurrence of Thrips on Tomato and Pepper as Influenced by Farmers’ Management Practices in Uganda

Abstract A biological monitoring survey was carried out in central Uganda for two consecutive seasons to provide information on species composition and occurrence of thrips on tomato and pepper as influenced by farmers’ management practices. A total of 50 farms for each crop participated in the study. Data was collected on cropping system, crop variety, type of pesticide used, pesticide spray regime, and on thrips populations. Results indicated that a total of six thrips species: Frankliniella occidentalis, Thrips tabaci, F. schultzei, Scirtothrips dorsalis, Ceratothrips ericae and Megalurothrips sjostedti infest tomato in the region. Pepper had the same thrips profile with the exception of F. schultzei. There was a distinct seasonal effect on thrips occurrence in the case of tomato. Higher thrips populations (61%) were recorded in the first season of the study as compared to the second. The majority of the thrips were recorded in the flowering stage of crop development for both crops, and 100% in the case of pepper. Generally, for both crops, plants in intercropped arrangements had higher thrips counts than the monocropped ones. Different tomato/pepper varieties sustained variable thrips populations. All the farmers applied pesticides to manage the complex of pests on the crops, albeit to variable extents. In this region, thrips populations were reduced when an increase in the number of pesticide applications in a given week was used.

Limiting factors for yields of field tomatoes grown by smallholders in tropical regions

Tomatoes are widely cultivated in developing countries and are a major source of income for small-scale farmers. Yields of field-grown tomatoes vary considerably under tropical conditions but the main factors that limit yields remain to be identified. To this end, we conducted an on-farm survey in 22 fields in 2003 and in 28 fields in 2005 in a range of socio-economic settings typical of smallholder farms on the island of Mayotte (Indian Ocean). Data on crop management, fulfilment of water requirements, weed density, nitrogen absorption by the crop and nutrient availability in the soil, as well as the sanitary status of the crop were recorded at two-week intervals throughout the crop cycle. The data were analysed by principal component analysis, and multiple linear regression. Yields varied between years and sites from 0.7 to 45.3 t ha−1 in 2003 and from 8.1 to 89.1 t ha−1 in 2005. In 2003, the number of fruits per m2, fruit weight, the health status of the crop, and the cation exchange capacity of the soil explained 84.7% of yield variability among fields. In 2005, the number of fruits per m2 and the health status of the crop explained 84% of yield variability. In 2003, 61.8% of the variability of the number of fruits per m2 was explained by health status and the number of plants per m2, whereas in 2005, 65.6% of the variability was explained by health status, the number of pesticide applications, and planting density. The results of this study indicate that tomato yield could be increased by improving the health status of the crop by improving the efficiency of crop protection practices and by increasing planting density.

Acceptance of artificial nesting sites by pollinating mason bees in commercial fruit plantations (Hymenoptera, Megachilidae: mixed Osmia cornuta and O. rufa population)

During a four yeas long experiment a simple bee shelterswas found to be a propermethod to increase the size ofmixed natural populations of the early season Osmia cornuta and O. rufa under practical farm conditions. Instead of the number of pesticide applications the earliness of the flowering of the fruit species in the orchards was found to be themost important factor in the rate of acceptance of reed as nestingmediumby Osmias in the bee shelter. This relationship was negative and highly significant (r = –0.829, p<0.001). This means that much higher acceptance of artificial nestingmedia in bee shelters and consequentlymuch higher population increase of the two early seasonmason bee species can be expected in orchards with early than with late flowering fruit species. Mixed orchards or early flowering orchards surrounded by other orchards falling in bloom later consecutively may also be much favourable to mason bees because they can find continuous food (pollen) supply there for a much longer time during their period of activity than in orchards planted with a single fruit species and being apart from orchards of other fruit species.

EVALUATION OF ECONOMIC AND ENVIRONMENTAL IMPACTS OF INTEGRATED PINEAPPLE PRODUCTION IN THE STATE OF TOCANTINS-BRAZIL

Integrated pineapple production in Brazil was initiated in the States of Tocantins, Paraiba and Bahia. In Tocantins where the new crop management system advanced faster, integrated production has reached commercial level: 150 hectares in 2007, cultivated by 15 pineapple growers in 11 municipalities. Evaluation of economic and environmental impacts was performed according to the “AmbitecAgro System”, composed by a pool of indicators and components related to technology efficiency, environmental preservation and recovery. Eight growers were surveyed, all of them at the same integrated production level, as well as three experts that work on the project. In the conventional production system pesticides are applied in a preventive way, usually there are nine insecticide and six fungicide applications during the crop cycle. In the integrated production system, the decision to spray pesticide is based on the monitoring of pests and diseases. In addition to promoting the use of less toxic pesticides, the practice of integrated pineapple production has reduced the amount and the number of pesticide applications, resulting in lower production costs in comparison with the conventional system. Reductions in pesticide use were as follows: herbicides, 47%, insecticides, 37% and fungicides, 20%. The use of herbicide decreased from four pre-emergence applications to two post-emergence applications during the crop cycle. The positive effect of the integrated pineapple production on the environment was due to the improvement on soil quality and reduction of pesticides applications, resulting in an index equal to 2.34, on a scale ranging from –15 to +15.

Farm Work-Related Injury among Middle School Students in Rural China

Farm work-related injuries are considered an important issue facing rural area adolescents. However, little research has been done in developing countries, including China. This study evaluated agricultural work-related injuries among Chinese middle school adolescents, focusing on the potential association between farm work hours, sleep patterns, school-related stress, and farm work-related injuries. This cross-sectional study surveyed 1,551 middle school students in Hunan Province who reported working on farms. The surveys assessed their involvement in farm work, sleep patterns, school activities, and farm work-related injuries during a three-month recall period. The cumulative incidence of farm work-related injury was 15.6% among the 1187 students who reported working on a farm. Average days per month farming, number of pesticide applications per month, sleep disturbances, and school-related stress were significantly associated with farm work-related injuries (p < 0.05). Multivariable logistic regression analysis revealed that after adjusting for possible confounding effects of age, gender, and farm work days per month, sleep disturbance (less than 7 hours of sleep: OR = 2.36, 95% CI = 1.07-5.22; awakening at night and having trouble falling back to sleep: OR = 2.70, 95% CI = 1.36-5.37; having nightmares: OR = 2.24, 95% CI = 1.18-4.24) and school-related stress (difficult homework: OR = 2.45, 95% CI = 1.21-4.99; extra homework assigned often by parents: OR = 3.62, 95% CI = 1.88-6.97; and scolded/chastised by parents for poor school performance: OR = 2.53, 95% CI = 1.75-3.65) were statistically significant risk factors for farm work-related injuries (p < 0.05).

Assessing the intensity of temperate European agriculture at the landscape scale

The intensity of agricultural production was assessed in 25 landscape test sites across temperate Europe using a standardised farmer questionnaire. The intensity indicators, nitrogen input (to arable crops and to permanent grassland), density of livestock units and number of pesticide applications (herbicides, insecticides, fungicides and retardants), were recorded and integrated into an overall intensity index. All three components were needed to appropriately characterise the intensity of agricultural management. Four hypotheses were tested. (i) A low diversity of crops is related to higher intensity. The contrary was observed, namely because diverse crop rotations contained a higher share of crops which are more demanding in terms of nitrogen and of plant protection. (ii) Intensity decreases when there is more permanent grassland. This was confirmed by our study. (iii) Large farms are managed more intensively. There was no relation between farm size and intensity. (iv) Large fields are managed more intensively. There was a tendency towards higher nitrogen input and livestock density in landscapes with larger fields but only a few of the results were statistically significant. The aggregated overall intensity index was of limited usefulness mainly because of limitations in interpretability.

Seasonal population trends of Liriomyza huidobrensis (Blanchard, 1926) (Diptera: Agromyzidae) on cucumber ( Cucumis sativus L.) in Western Turkey

Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) is an important pest in cucumber greenhouses in Izmir, Western Turkey. This study was carried out during the spring and autumn seasons of 1999 and 2000 in two adjacent cucumber greenhouses, each 1,000 m2 in size. Population densities of adult L. huidobrensis in insecticide-treated and non-treated greenhouses were compared by using yellow sticky traps. Ten traps were placed in the non-treated greenhouse and ten traps in the insecticide-treated greenhouse. Yellow sticky traps were changed weekly and the number of flies counted in order to compare the two greenhouses. In addition to monitoring the leaf miner population, in each greenhouse 100 plants were checked and the ratio of infested plants, the ratio of infested leaves per plant and the number of mines per leaf were recorded weekly. The population density of the leaf miner was almost the same in both insecticide-treated and non-treated greenhouses. Thus, it was concluded that using yellow sticky traps will be healthier and more cost effective than using pesticides. Furthermore using pesticides is risky for the environment and the use of yellow sticky traps can easily reduce the number of pesticide applications. If yellow sticky traps are used in the greenhouse in a completely isolated environment and the appropriate insecticide is used when it is necessary, this will provide successful and integrated management against L. huidobrensis.

Management of Diamondback Moth (Lepidoptera: Plutellidae) in Cabbage Using Collard as a Trap Crop

Collard greens (Brassica oleracea var. acephala L.) were planted in the peripheries of cabbage (Brassica oleracea var. capitata L.) fields in the spring growing seasons of 1997 and 1998 to evaluate their effectiveness as a trap crop to manage the diamondback moth (DBM) [Plutella xylostella (L.)]. The numbers of DBM never exceeded the action threshold for application of insecticides in any of thefields that were completely surrounded by collards, but did exceed the action threshold in three of the fields without collards on four sampling dates in 1998. In both years, the numbers of DBM larvae in the collards exceeded the action threshold of 0.3 total larvae/plant in eight of nine fields. Larval counts in cabbage surrounded with collards were not significantly higher than in the conventionally planted cabbage, even though the number of pesticide applications was reduced in the former. The few pesticide applications in fields surrounded by collards probably targeted the cabbage looper [Trichoplusia ni (Hübner)], which was not impeded by the collards from infesting the interior cabbage. There was no significant reduction in marketability, and damage to cabbage was similar to that in fields where collards were planted and in fields where only conventional pesticides were used. The reduced number of pesticide sprays, as well as the high concentration of host larvae in the collards, may help maintain populations of natural enemies of DBM in the agroecosystem. Planting collards in field peripheries is a potentially effective tactic to manage DBM in cabbage.

Management of Diamondback Moth (Lepidoptera: Plutellidae) in Cabbage Using Collard as a Trap Crop

Collard greens (Brassica oleracea var. acephala L.) were planted in the peripheries of cabbage (Brassica oleracea var. capitata L.) fields in the spring growing seasons of 1997 and 1998 to evaluate their effectiveness as a trap crop to manage the diamondback moth (DBM) [Plutella xylostella (L.)]. The numbers of DBM never exceeded the action threshold for application of insecticides in any of the fields that were completely surrounded by collards, but did exceed the action threshold in three of the fields without collards on four sampling dates in 1998. In both years, the numbers of DBM larvae in the collards exceeded the action threshold of 0.3 total larvae/plant in eight of nine fields. Larval counts in cabbage surrounded with collards were not significantly higher than in the conventionally planted cabbage, even though the number of pesticide applications was reduced in the former. The few pesticide applications in fields surrounded by collards probably targeted the cabbage looper [Trichoplusia ni (Hübner)], which was not impeded by the collards from infesting the interior cabbage. There was no significant reduction in marketability, and damage to cabbage was similar to that in fields where collards were planted and in fields where only conventional pesticides were used. The reduced number of pesticide sprays, as well as the high concentration of host larvae in the collards, may help maintain populations of natural enemies of DBM in the agroecosystem. Planting collards in field peripheries is a potentially effective tactic to manage DBM in cabbage.

Trends in pesticide use and efficacy during 26 years of changing agriculture in southern England

We report on trends in agricultural pesticide use from1970 to 1995 inclusive in arable crops on the SouthDowns, West Sussex, U.K. Information is given on theproportion of cropped area treated with pesticides,the percentage spray area, the number of pesticideapplications per field, and the number of compoundsapplied per field for herbicides, foliar fungicidesand insecticides. Compared to national publishedfigures, our data are broadly representative of thenational picture; they provide a complete and detailedtime series whereas national figures are available foronly 7 out of the 26 yr. In general, the areatreated (fungicides, insecticides) and the intensityof use (all three types of pesticide) increased overthe 26 yr. The spectrum of activity of theherbicides applied to arable crops increased from anaverage of 22 weed taxa susceptible in 1970 to 38 weedtaxa susceptible in 1995. The odds on herbicide andfungicide use in break crops were, respectively, 93%and 99% lower than average; odds on insecticide usein spring cereals were 98% lower than average. Comparing winter wheat on the most traditional farm(grass/cereal rotation) with the most modern one(monoculture winter wheat), the proportion of fieldstreated with herbicides was similar, but the odds onbeing treated with fungicides were 129% higher on themodern farm. Insecticides were used in only 2% ofthe fields on the traditional farm, while on themodern farm over the same time period, 79% of thefields were treated. This fits previously observeddifferences in wildlife abundance on the two farms.

Effect of Second-Stage Ipm Practices on Parasitism of Apple Blotch Leafminer (Lepidoptera: Gracillariidae) Larvae in Massachusetts Apple Orchards

In 1989 and 1990, parasitism of the apple blotch leafminer, Phyllonorycter crataegella (Clemens), was assessed in 17 and 16 apple orchards, respectively, in Massachusetts to determine the effect of integrated pest management (IPM) practices that reduced pesticide use between early June and late August. In test blocks on each farm, broadcast pesticide applications for control of the apple maggot, Rhagoletis pomonella (Walsh), were replaced by use of either red spherical sticky traps on perimeter apple trees to intercept immigrating apple maggot flies or by applications of pesticides to perimeter apple trees. In either case, no insecticides or miticides were applied to the interior of test blocks after early June. Use of these methods was designed as second-stage IPM, and apple blotch leafminer parasitism under such management was compared with an adjacent block in each orchard using conventional pesticide tactics. Average parasitism of tissue-feeding apple blotch leafminer larvae across all orchards was slightly greater in the second and third host generations in blocks in which second-stage IPM practices were used than in conventionally managed blocks on the same farms. Most enhancement of apple blotch leafminer parasitism occurred in orchards in which traps were used to control apple maggot flies. Orchards in which perimeter-pesticide applications were made showed little or no difference in parasitism levels from those of full spray blocks. None of six orchard or insect variables examined (block size, ratio of interior trees to edge trees, nature of surrounding vegetation, number of pesticide applications per leafminer generation, density of tissue-feeding stage apple blotch leafminer mines, or percentage parasitism in the previous apple blotch leafminer generation) explained a significant proportion of the variation in parasitism seen among orchards and blocks in correlation analyses. Suppression of first generation apple blotch leafminer densities in 1990 was followed by lower average parasitism across orchards compared with 1989.

Integration of Pesticide Application Schedules for Disease and Insect Control in Apple Orchards of the Northeastern United States

(…) To provide a framework to achieve this goal, we begin with the following objectives: reduce to a minimum the number of pesticide applications per season by optimizing the timing of applications to control the complex of economically important pests present at certain key times during the growing season; maintain or exceed current levels of insect and disease control; insofar as practical, use forecasting and monitoring systems to increase lead time for control decisions and actions. (…)