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Sanjun Gu and Kirk W. Pomper

The Japanese beetle ( Popillia japonica Newman) is an introduced scarab beetle that was first discovered in New Jersey in 1916 ( Fleming, 1976 ). It is the most widespread and destructive insect pest in the eastern United States, with a direct

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Arthur Villordon, Julio Solis, Don LaBonte and Christopher Clark

agroclimatic variables measured within 20 DAT and U.S. #1 sweetpotato yield from experimental plots under uniform management conditions. We assumed the absence of influence from weeds, disease, insect pests, and chemical injury. The long-term goal is to develop

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Robert Pendergrass, Roland K. Roberts, Dennis E. Deyton and Carl E. Sams

Using soybean oil to control insect pests, delay bloom, and thin fruit in peach [Prunus persica (L.) Batsch] production could reduce yield losses and fruit thinning costs compared to the current practice of using petroleum oil spray to control insect pests alone. The higher annua cost of soybean oil spray compared to petroleum oil spray was more than offset by higher average annual revenue from increased peach yields and lower thinning costs. At one location, soybean oil to delay bloom and thin fruit unambiguously reduced production risk. At another location, both mean and variance of returns were higher, but a lower coefficient of variation suggested lower relative risk for the soybean oil spray alternative. Risk resulting from the unanticipated influence of weather and mismanagement on the effectiveness of soybean oil spray were not considered in this analysis. More research is needed to hone in on the optimum soybean oil spray rates under alternative environmental and management conditions.

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D.M. Glenn, G. Puterka, T. van der Zwet and R. Byers

Fruit production requires extensive use of pesticides to control pest damage and maintain high product quality. Hydrophobic particles alter the leaf surface due to the hydrophobic and reflective nature of the particles and impart characteristics that make the plant surface incompatible, and/or unrecognizable to the pest. Hydrophobic particles were applied to apple and pear in field and greenhouse studies. Specific diseases, insect pests, plant growth, and yield were monitored and evaluated on treated plants in comparison to untreated and chemically treated controls. Powdery mildew in apple and Fabrea leaf spot in pear were controlled by the hydrophobic particles. Aphids, mites, and psylla were controlled in apple and pear. Hydrophobic clays have the potential of cross-protection for several disease and insect pests while imparting beneficial horticultural effects that would increase long-term productivity and sustainability of fruit production systems.

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Wenhua Lu, J.V. Edelson, Jim A. Duthie and B. Warren Roberts

Factors of crop management such as irrigation, cultivation, cultivar selection, and control of insect pests and plant diseases play important roles in watermelon production. To gain a better understanding of how intensity of crop management affects yield, we conducted a comparative study contrasting high and low intensity management in 1997, 1999, and 2000. High-intensity management (HM) included the use of trickle irrigation, black plastic mulch, insecticides, and fungicides, not used under low-intensity management (LM). We examined the effects of management intensity on watermelon productivity, the variation in such effects among watermelon cultivars, and the mediating effect of survival of watermelon plants, abundance of insect pests, and incidence of anthracnose (% leaves with anthracnose lesions). The results indicated that HM produced 100% greater marketable fruit yield per area and marketable fraction of total fruit than LM in 2 out of 3 years. The effect of management intensity on plant survival was related to this effect on yield in 1 out of 2 years, and contributed to the latter by increasing weight and number of marketable fruit per plant under HM. We detected no significant effect of abundance of insect pests and incidence of anthracnose on yield. There was variation in the effect of management intensity on yield among watermelon cultivars in 1 out of 3 years. The triploid `Gem Dandy' showed great differences in yield between HM and LM in 2 years, producing on average 28.9 Mg·ha-1 of marketable fruit yield under HM compared to 14.0 Mg·ha-1 under LM. `Gem Dandy' also produced 100% higher yield of marketable fruit per area, per plant, and marketable fraction of total fruit than the open-pollinated diploid `Allsweet' or the diploid hybrid `Sangria.' Each year during the 3-year study, all three cultivars had a similar density of insect pests, incidence of anthracnose, and plant survival after transplant and at harvest. This study provided information on the collective impact of multiple aspects of watermelon management on yield.

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John A. Juvik

Heliothis zea (Boddle) is one of agriculture's worst insect pests. Reduction in crop productivity and costs for insecticidal control of this cosmopolitan pest cost U.S. agriculture many millions of dollars annually. The sesquiterpenes (+)-E-å-santalen-12-oic and (+)-E- endo- β–bergamoten-12-oic acids isolated from hexane leaf extracts of the wild tomato species, Lycopersicon hirsutum, have been shown to attract and stimulate oviposition by female H. zea. Extracts from other host plants (tobacco, corn, and cotton) also possess attractant/oviposition stimulant activity to female H. zea. Studies are underway to assess the potential use of these and other phytochemicals for the control or monitoring of population levels of H. zea in tomato, corn and cotton fields.

The isolation and structural identification of insect pest oviposition stimulants in horticultural crop species can provide valuable information to plant breeders involved in developing cultivars with improved insect host plant resistance. This information could be used to develop cultivars lacking the chemical cues used by insects for host plant location and recognition. Risks of public exposure to toxic insecticides through consumption of agricultural produce and polluted ground water emphasize the critical need for the development of crop genotypes with improved best plant resistance as a supplementary method of insect pest management in agricultural ecosystems.

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Timothy K. Broschat and Thomas J. Weissling

The greenhouse orthezia (Orthezia insignis) is a serious and widespread pest of cultivated lantanas (Lantana sp.) in warmer regions of the world. Forty species and cultivars of lantanas were screened for their relative susceptibility to this insect pest. Results showed that two Florida native lantanas, pineland lantana (L. depressa) and buttonsage (L. involucrata), were highly susceptible to infestation, with trailing lantana (L. montevidensis) and its cultivars and hybrids being somewhat less susceptible. Shrub lantana (L. camara) and its cultivars and hybrids were the least susceptible to greenhouse orthezia infestation, but some of these varieties are rather unattractive as landscape ornamentals and can become serious weeds.

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Durward Smith, Jay B. Fitzgerald and George E. Meyer

Insect infestation of plant material is a serious problem to the greenhouse industry. Nonpesticidal destruction of insects on plant material before they are placed in the greenhouse would supply producers and growers with pest-free plant materials and decrease pesticide usage and exposure of workers and the environment to chemical insecticides. The efficacy of vacuum treating chrysanthemum (Chrysanthemum morifolium) and poinsettia (Euphorbia pulcherrima) plants for the reduction of insect pests (aphids and greenhouse whiteflies) was investigated. The effects of surfactants on insect elimination was determined. Properly controlled vacuum treatment in conjunction with surfactants was found to disrupt the physical integrity of the insects in all stages of their life cycle.

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J. Kabashima, T.D. Paine and R. Redak

Pesticide use in the landscape has been reduced through the implementation of integrated pest management (IPM) (Holmes and Davidson, 1984, Olkowski et al., 1978; Smith and Raupp, 1986). IPM emphasizes prevention, identifying pests and their symptoms, regular surveying for pests, determining action thresholds and guidelines, and using sound management methods. Monitoring techniques such as pheromone traps, degree-day models, and ELISA kits, in addition to traditional methods, have enabled pest managers to determine accurately when to apply IPM techniques. Examples of serious California landscape insect pests successfully controlled through IPM include the ash whitefly [Siphoninus phillyreae (Halliday)], the Nantucket pine tip moth [Rhyacionia frustrana (Comstock)], and the eucalyptus longhorned borer (Phoracantha semipunctata F.).

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U.K. Schuch, J.A. Bethke and R.A. Redak

Water stress and N fertilization can have a profound effect on populations of phytophagous insects. While species and cultivar selection can identify plants that are resistant to common insect pests, cultural practices may further decrease the susceptibility to insect attacks. Six poinsettia and six chrysanthemum cultivars were grown under well-watered or water-deficient conditions, and three fertilizer regimes with low, medium, or high concentrations of N. Vegetative plant growth and longevity and fecundity of various insect pests on these plants were determined. Host plant suitability to insects was estimated by the quantity of foliar soluble protein. Low irrigation reduced leaf area and leaf and stem dry weights 36% to 41% in poinsettias and 26% to 28% in chrysanthemum. Leaf area and leaf dry weight increased linearly in response to increasing fertilizer concentrations in poinsettia and chrysanthemum. Cultivar-specific differences were found for all variables of vegetative growth in poinsettiasand chrysanthemum. Cultivar also strongly affected insect preference, development, and fecundity. Low irrigation significantly reduced insect survivorship of the silverleaf whitefly on poinsettias. On chrysanthemum, leafminers, thrips, and melon aphids were unaffected by irrigation or fertilizer treatments. Chrysanthemum cultivar choice strongly affected the number of insects or development time.