Search Results
You are looking at 1 - 7 of 7 items for
- Author or Editor: John S. Caldwell x
Twenty students from six disciplines in a farming systems course and in a human nutrition course were organized into four interdisciplinary teams during a joint laboratory. Through lectures, videotapes, and actual interviews of farm families, students were trained to work as a team collecting and processing information from informal interviews. Most students (63%) found the joint laboratory “very useful,” but 41% considered the overall work load excessive. Students rated achievement of team-related objectives significantly higher than course-related objectives. The actual interviewing of farm families was rated the most useful training technique. Student contributions to the team were more discipline-based than integrative, with 63% of the students contributing knowledge and skills from their own discipline. Students' gains from the team were more integrative, with 94% gaining from the team process, knowledge from other disciplines, and integration of disciplines, but only 31% gaining new knowledge or skills in their own disciplines.
Abstract
The Gambian climate is well-suited for the production of horticultural crops. There are two distinct seasons: a short wet season, from June until September, when temperatures and humidity are quite high; and a long dry seas the rest of the year. From November until March, the dry season is cool and especially suitable for the production of a wide variety of vegetables.
Cucumber (Cucumis sativus L.) and squash (Cucurbita pepo L.) were grown in a replicated trial on three types of plastic mulch: solid black plastic mulch, solid aluminum-coated plastic mulch with a silver reflective appearance, and black plastic mulch with two aluminum-coated strips attached. Striped cucumber beetle (Acalymma vittata Fabricius) and spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) (Coleoptera: Chrysomelidae) counts on yellow sticky cards were obtained over eight weekly samplings. For cucumber, on the peak beetle population date, there were six times as many striped cucumber beetles in solid black plastic mulch as in aluminum-coated plastic mulch, and nearly three times as many as in black plastic mulch with aluminum strips. For squash, both striped and spotted cucumber beetle counts were significantly higher on solid black plastic mulch on three peak sampling dates than on aluminum-coated plastic mulch and black plastic mulch with aluminum strips, with counts 4.9 to 5.5 times higher in solid black plastic mulch than in aluminum-coated plastic mulch, and 2.2 to 2.6 times higher than in black plastic mulch with aluminum strips. Using a threshold of 15 beetles/sticky card, no insecticidal applications were needed on solid aluminum-coated mulch, while an average of 1.8 insecticidal applications were needed on solid black plastic mulch, and 0.8 insecticidal applications on black plastic mulch with aluminum strips. The cost of solid black plastic mulch and its insecticidal applications, $186/acre ($459/ha), was $102/acre ($252/ha) less than the cost of aluminum-coated plastic mulch without insecticidal application, $288/acre ($711/ha). However, squash fruit from plants grown on aluminum-coated plastic mulch could be direct marketed as pesticide-free, at a price 25% higher than fruit on which pesticide had been applied. For an average yield in Virginia of 600 boxes/acre (1,482 boxes/ha) [20 lb/box (9 kg/box)] of squash, this translates to a $1,200/acre ($2,964/ha) increase in revenue. Yield on aluminum-coated plastic mulch was delayed by one week, but there were no significant differences in cumulative yield over 14 harvests.
Abstract
The Gambia is a small country on the West African coast, located along the Gambia River and surrounded on three sides by Senegal. The climate is a bimodal rainfall (800-1400 mm precipitation yearly) type with distinct dry (October-May) and wet (June-September) seasons. Mean monthly air temperatures range from a minimum of 14.5°C to a maximum of 41° (15).
To assess the value of uncultivated vegetation for control of cucumber beetles, populations of striped (Acalymma vittatum Fabr.), spotted (Diabrotica undecimpunctata howardi Barber), and western cucumber beetles (Acalymma trivittatum Mann.) (Coleoptera: Chrysomelidae) and natural enemy Diptera flies (as an indicator of Celatoria spp. parasitoids), Pennsylvania leatherwings (Chauliognathus pennsylvanicus DeGeer) (Coleoptera: Cantharidae), lady beetles (Coleoptera: Coccinellidae), Hymenoptera wasps, and spiders were monitored with sticky traps on 50-m transects running through a field of Cucumis sativa L. `Arkansas Littleleaf' into bordering uncultivated vegetation. Plant species composition was determined in square plots around each sticky trap by estimating total plant cover and height distribution of plants from 0 to 1.0 m. In both years, numbers of cucumber beetles increased and numbers of Diptera decreased towards the crop. These trends increased monthly to peaks in Aug. 1995 (0.3 to 6.0 striped cucumber beetles; 40.0 to 15.3 Diptera) and July in 1996 (0.1 to 7.1 striped cucumber beetles; 46.7 to 15.5 Diptera). Abundance of individual plant species contributed more to maximum R 2 regression of insect populations than did measures of plant diversity in sampling squares. Diptera were negatively correlated with sweet-vernal grass (r = –0.65 at 0 m) and wild rose (r = –0.62 at 0.5 m) in 1995, and goldenrod (r = –0.31, –0.59, and –0.53 at 0.5, 0.75, and 1.0 m, respectively) in 1996, but positively correlated with wild violets (Viola spp.) (r = +0.38 at 0 m) in 1996. Cucumber beetles were negatively correlated with wild violets (r = –0.30 at 0 m) and white clover (Trifolium repens) (r = –0.37 at 0 m) in 1996. These results suggest that increasing or decreasing specific plants in uncultivated vegetation might be useful for influencing pest and beneficial insect populations in cucurbit production.
Cucumber beetles Acalymma vittatum (Fab.) and Diabrotica undecimpunctata howardi (Barber) (Coleoptera: Chrysomelidae) are major pests of cucurbits, and biological methods are needed for their control. A floral border of buckwheat Fagopyrum esculentum (Moench) was planted perpendicular to Cucumis sativa L. `Arkansas Littleleaf' and Cucurbita pepo L. `Seneca' rows to assess effects on populations of cucumber beetles and the presence of natural enemies. Numbers of Diptera were used as an indicator of potential border attractiveness to natural enemies Celatoria diabroticae (Shimer) and Celatoria setosa (Coquillett) (Diptera: Tachinidae). Sticky traps and modified Malaise traps at increments from the border were used to monitor insect numbers. There was a quadratic decline from 19.5 Diptera in the border to 2.8 Diptera at 20 m from the border in June 1995 and linear declines from 14.8 and 14.2 Diptera in the border to 9.8 and 6.8 Diptera at 36 m in June and Aug. 1996, respectively. Numbers of striped cucumber beetles were variable, with a non-significant (P = 0.08) linear increase from 13.0 insects in the border to 17.5 insects at 36 m in June 1995, but quadratic decreases to 27 m in June, July, and Sept. 1996. Similar declines as distance from the border increased were found in numbers of tachinid flies (Diptera: Tachinidae) and Hymenoptera wasps and Pennsylvania leatherwings, Chauliognathus pennsylvanicus (Deg.) (Coleoptera: Cantharidae) and lady beetles (Coleoptera: Coccinellidae) in 1996. No meaningful effects on cucumber (1995) or squash (1995 and 1996) yield were found. Although the natural populations of Celatoria spp. were not high enough to achieve control, these results suggest that flowering borders may be useful as habitats for releasing natural enemies of cucumber beetles. Numbers of Pennsylvania leatherwings, Chauliognathus pennsylvanicus (Deg.) (Coleoptera: Cantharidae) showed a significant linear decline from 2.1 insects in the border to 0.2 insects at 36 m in June 1996, but no significant relationship was found in 1995 or in Aug. 1996.
Abstract
In the article “Use of Farming Systems Research Extension (FSR/E) Methods to Identify Horticultural Research Priorities in The Gambia, West Africa”, by G.O. Gaye, Isatou Jack, and John S. Caldwell (HortScience 23(l):21–25, February 1988), the authors wish to make the following acknowledgment: “The work reported herein was done under the Gambia Agricultural Research and Development Project of the Ministry of Agriculture, Government of The Gambia; the United States Agency for International Development; and the Univ. of Wisconsin. We express our appreciation to these institutions for their support.”