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Karim Al-Juboory, Robert M. Skirvin and David J. Williams

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Karim H. Al-Juboory, David J. Williams and M.H. Nayfeh

This study was initiated to investigate the effect of pulsed XeCL excimer laser radiation (308 nm) at 25 and 50 pulses per second at radiation levels of 0, 100 mJ, 200 mJ, and 300 mJ on microorganism contamination of in vitro cultures of Heder a canariensis. Explants were cultured on Murashige and Skoog (MS) medium supplemented with 8 mg/BA and 0.2 mg/NAA. The medium was adjusted to pH 5.7. The cultures were maintained for 16-hours photoperiods at 25.5°C. One day following transfer the explants were treated with pulsed excimer laser radiation. The percentage of contamination was reduced by laser radiation treatments. The effect of 5 0 pulses of radiation was found to increase the petiole length, leaf blade width, and leaf number of explants.

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Mary B. Musgrove, J. David Williams, Bridget K. Behe and Kenneth M. Tilt

Before analyzing the responses of Alabama garden center employees about the training they had received, we determined how satisfied 100 Alabama Master Gardeners were with the employee-s who helped them in the store from which they most often purchased plants for their homes, landscapes, or gardens. We mailed the primary survey to 472 employees of 130 retail garden center businesses in Alabama to determine the percentage of employees who received job training and the amount, frequency, and methods of training they received while working for their current employers (37% responded). Employees were categorized as managers (28%) or subordinate employees (72%) and full-time (72%) or part-time (28%). Forty-four percent of the employees had received some training at the time they were hired. Training continued for 68% of the respondents. Only 39% of the employees had a written description of their job responsibilities discussed with them. Most (85%) believed the training they received had prepared them to do their jobs well, but 82% said more training would increase their confidence in their work performance. Most employees were trained by one-on-one instruction (60%) and small-group sessions (5 or fewer persons) (65%). Few employees received training from videotapes (5%) or educational seminars (26%), and most that did were managers and full-time employees.

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Kiffnie M. Holt, George Opit, James R. Nechols, David C. Margolies and Kimberly A. Williams

Biological and chemical control strategies for the twospotted spider mite (TSM; Tetranychus urticae) were evaluated in a greenhouse experiment replicated over time in mixed production of ivy geranium (Pelgargonium peltatum ‘Amethyst 96’) and two impatiens cultivars (Impatiens wallerana ‘Impulse Orange’ and ‘Cajun Carmine’). Chemical control using the miticide bifenazate was compared with two release strategies for biological control using the predatory mite, Phytoseiulus persimilis. Specific treatments included 1) a single application of bifenazate at 0.3 g·L−1 formulation (22.6% a.i.); 2) a single release of predatory mites at a 1:4 predator to pest ratio based on sampled pest density; 3) a weekly release of predatory mites at numbers based on the area covered by the crop; and 4) an untreated control. TSM populations were monitored for 4 weeks. After another 4 weeks, when plants were ready for market, plant quality ratings were recorded. The number of TSM per leaf dropped for all treatments on all genotypes but increased in the untreated plants. On ivy geranium, the fact that there were significantly more TSM on untreated plants was not reflected in average plant quality, but it did reduce the proportion of containers rated as salable at full price compared with both chemical and biological control. On impatiens, both treatment and cultivar had significant effects on the mean plant quality rating and on the proportion of containers rated as salable at full price. The use of a sampling plan to determine the appropriate number of predators to release was as effective as the currently recommended management treatments for TSM in bedding plants.

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Mark A. Ritenour, Ellen G. Sutter, David M. Williams and Mikal E. Saltveit

This study was undertaken to determine if endogenous IAA content and axillary bud development correlate with phenylalanine ammonia-lyase (PAL) induction and russet spotting (RS) susceptibility among RS susceptible and resistant cultivars of Iceberg lettuce (Lactuca sativa L.). Final levels of ethylene-induced PAL activity and RS development were highly correlated among cultivars, field conditions, and harvest dates. Harvested Iceberg lettuce midribs contained relatively low amounts of free IAA (maximum of 5.2 ng·g-1 fresh weight). There was poor correlation between free IAA content in lettuce leaf midribs and final RS development among all cultivars, growing conditions, and harvest dates. Axillary bud development, as measured by the number of visible buds per head, bud weight, or bud length, were not significantly correlated with final RS development or midrib IAA content. Cultivars with higher initial free IAA content lost much of their IAA after 8 days storage at 5C in air ± ethylene.