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Abstract
Cabbage (Brassica oleracea L. Capitata Group ‘Market Prize’) was grown in the spring (February to April) 1981 and fall-winter (October to January) 1981–82 with 2 insecticidal spray schedules conducted weekly and on demand; 2 in-row spacings, 23 and 38 cm; and 2 fertilizer rates, low (152N–53P–139K and 8 Mg kg/ha), and high (257N–99P–261K and 15 Mg kg/ha). Fenvalerate [Cyano (3-phenoxyphenyl) methyl-4-chloro-alpha-(1-methylethyl) benzeneacetate] at 0.112 kg a.i./ha was applied either weekly or when a threshold of 0.5 lepidopterous larval feeding injuries/plant was equalled or exceeded. With the weekly insecticide treatment, 12 and 10 sprays were applied, respectively, in the spring and fall, vs. 1 and 2 applications, respectively, for the 2 seasons in the demand plots. Insect damage ratings were lower in the weekly sprayed than in the demand plots; however, marketable yields (kg/ha) and average head size were not affected by spray schedules. In both seasons, marketable yields were greater at the 28 cm spacing than at 38 cm, whereas average head sizes were greater at 38 cm than at 23 cm. The high fertilizer rate increased head size in both seasons, but increased marketable yields only in the spring.
Abstract
Response of tomatoes, Lycopersicon esculentum Mill., cv. Flora-Dade, to insecticides applied weekly or on demand and to 3 fertilizer levels, low (1 ×), medium (2 ×), and high (3 ×), was investigated in fall 1979 and spring 1980. Insecticide spray schedules had no effect on fruit size, marketable yield, and number of fruit per ha. The application of fertilizers above the 1 × level (148 kg/ha N, 30 P, 171 K, and 10 Mg) did not improve fruit size or increase tomato yields, but increased residual salt content of soil.
Flower color preference of western flower thrips [WFT (Frankliniella occidentalis) (Thysanoptera: Thripidae)] was assessed by observing insect location after introduction into chambers containing four different colored flowers of each of three plant species: transvaal daisy (Gerbera jamesonii), matsumoto aster (Callistephus chinensis), and chrysanthemum (Dendranthema ×grandiflorum). Preference was based on the number of WFT adults found on each flower 72 hours after infestation. Significantly higher numbers of WFT were found on yellow transvaal daisy and yellow chrysanthemum. When these accessions were compared in a subsequent experiment, WFT displayed a significant greater preference for the yellow transvaal daisy. Visible and near infrared reflectance spectra of the flowers used in the study were measured to determine the presence of distinct spectral features that would account for the relative attractiveness of the flowers. Likewise, the reflectance spectra of three commercially available sticky cards (blue, yellow, and yellow with a grid pattern) that are used to trap or sample for WFT were compared to those of the flowers to determine any shared spectral features that would support observed WFT flower color preference. The observed similarity between the yellow transvaal daisy and yellow sticky card reflectance spectra supports the hypothesis that flower color contributes to attractiveness of WFT. In particular, the wavelengths corresponding to green-yellow (500 to 600 nm) seem to be responsible for attracting WFT. These findings also indicate that yellow sticky cards may be more appropriate in sampling for WFT than blue sticky cards. Although further research is needed, under the conditions of this study, yellow transvaal daisy appears to be a potentially useful trap crop for WFT.
The effect of cover-crop management on growth and yield of `Bravo' cabbage (Brassica oleracea var. Capitata L.), `Market Pride' tomato (Lycopersicon esculentum Mill.), and `Mustang' snap bean (Phaseolus vulgaris L.) was determined. Each fall, `Wheeler' winter rye (Secale cereale L.) and `Oregon Crown' hairy vetch (Vicia villosa Roth) were interseeded. The following spring, the cover crops were killed by either applying glyphosate and mowing (CC-G) or mowing and disking (CC-D). Trifluralin was preplant incorporated into bare ground as a conventional tillage (CT) treatment. In 1992 and 1993, a chicken (Gallus gallus L.) based fertilizer was applied to half the subplots. The greatest snap bean and cabbage yields were in CT. The system with the greatest tomato yields varied. In 1991, the greatest tomato yields were in the CT treatment, while in 1992 yields were greatest in the CT and CC-D treatments, and in 1993 the greatest yields were in CT and CC-G. Cabbage yields were greater in the fertilized than the unfertilized treatments. In 1992, infestations of diamondback moth, imported cabbageworm, and cabbage looper were greater in CT than in the CC-G treatment. Three years of the CC-G treatment increased soil organic matter from 3.07% to 3.48% and increased soil pH from 6.30 to 6.51, while neither changed in the CT. Chemical names used: N-(phosphonomethyl) glycine (glyphosate); 2,6-dinitro-N,N-dipro`pyl-4-(trifluoromethyl) benzenamine (trifluralin).
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.
In recent years, several studies have demonstrated the potential of proteinase inhibitors (PIs) for controlling insect pests. Used as a component of an integrated pest management program, such an approach must, however, be considered with care, given the potential risks of interference on other control approaches. In particular, the effect of PIs on digestive proteinases of beneficial insects must be determined. As an example, this study analyzed the effect of oryzacystatins (OCs), two cysteine PIs isolated from rice, on digestive proteinases of Perillus bioculatus, a predator of the Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), a major pest. Electrophoretic analyses showed the existence of several cysteine proteinase forms in the digestive tract of P. bioculatus. For each developmental stage, OCs dramatically inhibited proteolytic activity, showing an affinity between these inhibitors and the digestive proteinases of the predator. Despite their potential for controlling CPB, the two rice cystatins thus represent possible growth-suppressing compounds for the beneficial insect P. bioculatus. Work is currently under way to assess the compatibility of the two control approaches.
The largest agricultural industry in New Jersey is the commercial landscape/nursery/turfgrass industry; it is also one of the highest users of pesticides. In the lawn care industry alone, >906,000 lb of pesticides (active ingredients) were used in 1990. A proven way to commercially reduce pesticide usage while maintaining landscape quality is through Landscape Integrated Pest Management (LIPM) tactics; however, adoption of LIPM nationally has been slow. In 1994–95, a survey of 525 landscape contractors, arborists, groundskeepers, and turfgrass professionals was conducted to determine attitudes towards adoption of LIPM tactics. Customer perceptions, products utilized, educational needs, and attitudes toward alternative control tactics were assessed. Results show the majority of landscapers do not wish to spray pesticides, and do utilize good horticultural methods. However, purchasing traditional pesticide products that are cost-effective and proven are favored relative to environmentally “safe” and new. Concerns constraining LIPM adoption include potential for customer dissatisfaction, recovering monitoring costs, increased knowledge requirement for LIPM tactics, and fear of inadequate control.
A rapid increase in municipal solid waste (MSW) production (2 kg/person per day), combined with a decreasing number of operating landfills, has increased waste disposal costs. Composting MSW can be an alternative method of waste disposal to traditional landfilling or incineration. Weed control methods using waste materials such as bark, straw, and sawdust were used in commercial crop production for many years before the advent of chemical weed control. Weed growth suppression by mulching can often be almost as effective as conventional herbicides. A 10 to 15 cm-deep mulch layer is needed to completely discourage weed growth in these systems, and best results are obtained with composted materials. In recent years, composts made from a large variety of waste materials have become available on a commercial scale. Preliminary investigations into the use of MSW compost as a weed control agent have shown that compost, especially in an immature state, applied to row crop middles reduced weed growth due to its high concentration of acetic, propionic, and butyric acids. Subsequently, compost can be incorporated into the soil for the following growing season to potentially improve soil physical and chemical properties. Integrated pest management programs that incorporate biological control should be adopted wherever possible because some weed species with persistent seeds can escape chemical control.
Research was conducted on the fungus-like organism Pythium to observe its sensitivity to the fungicide Subdue MAXX, active ingredient mefanoxam. Pythium is a plant pathogen that causes root and crown rot in plants that are exposed to extensive soil moisture and poor drainage. This study, conducted on Pythium isolated from Colorado greenhouse crops, began in Apr. 2004. Symptomatic tissues from bedding plants and perennials were placed on selective media (P10VP). Resulting isolations of Pythium were transferred to cornmeal agar amended with the recommended low and high label rates of mefanoxam. Mycelia growth was monitored for 72 hours. Pythium sp. showing 20% growth on amended mefanoxam agars, compared to the control growth, were considered resistant to mefanoxam. Results from this study showed that about 64% of the Pythium sp. isolated from greenhouse crops in Colorado are resistant to mefanoxam. Data compiled from greenhouse integrated pest management surveys in Colorado show a high dependence on the use of mefanoxam. Research and screening for mefanoxam-resistant Pythium sp. will continue to provide Colorado growers with effective control solutions for this pathogen.
Consumer concerns about pesticide residues and environmental degradation are having a significant impact on the California grape industry. Growers are using a variety of practices, from integrated pest management to certified organic production, to reduce the amount of pesticides and other synthetic inputs used in vineyards. This experiment was established to test selected sustainable cultural practices in a mature `Thompson Seedless' vineyard. Treatments included in the experiment were row middle management (cultivated vs. perennial legume cover crop) and nitrogen fertilization (compost vs. synthetic). Vine nutritional status, yield, fruit composition, pruning weight, and population levels of the variegated leafhopper were monitored each season (1992–1994). In addition, efforts were expanded during the 1994 season to include assessment of spider, herbivorous mite, and beneficial arthropod densities. Conventional cultural practices (cultivation and synthetic fertilizer) produced the highest yields during the 1992 and 1993 seasons. This result may have been due to the nutritional status of vines, which was generally better for the cultivation and synthetic fertilizer treatment, especially in 1992. In 1994, significant treatment effects on yield were not observed, indicating that legume cover crop plots had become fully established. Sustainable cultural practices had little impact on growth, fruit composition, or insect pest pressure. `Thompson Seedless' grapes were grown for three seasons without the use of insecticides or herbicides. Vine diseases were managed by cultural practices and application of sulfur.