Soil probe samples were taken in the upper 1 m of the soil profile 0.5 and 1 m from the base of five blueberry cultivars (Vaccinium spp.) grown in a modified-pH soil. The samples were divided into 12 sections by depth: mulch, 0-5, 5-10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80-90, and 90-100 cm. Weights of the organic fraction of blueberry roots were determined by subtracting ashed weights from dry weights for each sample section. Duplicate soil probe samples were taken and soil pH determined at the 12 depths and two distances. Root weights were highest in the upper 20 cm of the soil profile at the 0.5 m distance for all cultivars. Soil pH was 5 and below in the upper 20 cm of the soil. Yield of 11 cultivars was obtained for five years (1988-1992). Total yield averaged over 5 years showed `Blueray' as the highest yielding cultivar with 4.43 kg/plant per year. `Patriot', `Elliott', and `Colville' were lower than `Blueray' but similar to each other, with yields of 3.42, 3.11, and 3.03 kg/plant per year, respectively.
Gail R. Nonnecke
Gail R. Nonnecke
A learning community was developed for first-year students majoring in horticulture at Iowa State Univ. in 1998. Learning communities are a curriculum design that schedules courses for both students and faculty to encourage community and connections among students, between students and faculty, and among faculty. Learning communities can offer students more opportunities for interactions among each other, academic assistance through supplemental instruction and/or group study sessions, and planned horticulture-related activities, all of which are important for success and retention of first-year students. First-year students in the horticulture learning community enrolled in the same courses and sections of five courses. The first-year English composition course was linked to the second-year principles of horticulture course that requires writing-across-the-curriculum activities. Faculty mentoring was provided through local field trips to horticultural sites of keen interest to the students. Academic environment survey results showed students rated their expectations highly for developing a network of other students as a resource group and for learning cooperatively in groups. Iowa State Univ. supports learning communities by providing faculty development and facilitating course registration, peer mentoring, supplemental instruction for challenging core courses, and academic and student services, to strengthen undergraduate teaching programs within and outside of the classroom.
Gail R. Nonnecke and Henry G. Taber
The purpose of this project was to investigate the use of evapotranspiration (ET) as a guideline for trickle irrigation timing in field-grown day-neutral `Tristar' strawberry. Proper management of trickle irrigation would allow optimum yields and quality with minimum water inputs. A randomized complete block field design with four replications was used at the ISU Horticulture Station in central Iowa. Irrigation treatments were based on % of ET and number of applications per week. The four treatments included: 30, 60, and 90 % of ET applied once per week (1X) and 30% of ET applied 3 times per week (3X). Total yield data (kg of fruit per season) indicated the 30% of ET (3X) treated plants yielded 15% more fruit than the 30% of ET (1X) plants. Berry number was 14% greater from plants receiving the 30% of ET (3X) treatment than from those receiving the 30% of ET (1X) treatment. Average berry weights for the entire growing season were similar among all treatments.
Cheryll A. Reitmeier and Gail R. Nonnecke
Sensory and objective attributes of fresh fruit of five locally grown day-neutral strawberry (Fragaria × ananassa Duch.) cultivars (Tristar, Tribute, Mrak, Yolo, and Selva) were compared to those of California-grown strawberries available in the Iowa markets. `Tristar' and `Tribute' fruit were redder and more sour than fruit of other day-neutral cultivars, and `Tristar' fruit were the most juicy of the berries evaluated. `Tristar' and `Tribute' fruit had higher titratable acidity and lower Hunter L (lightness) values than those of other evaluated fruit. Sensory panelists rated the California-grown berries as the least red.
Dennis N. Portz and Gail R. Nonnecke
Yield of strawberry grown continuously on the same site often declines over time as a result of proliferation of weed seeds and pathogenic organisms in the soil. Plots were established and maintained in seven different cover crops and as continuous strawberry or continuous tillage for 10 years (1996 to 2005) in a site that was previously in strawberry production for 10 years (1986 to 1995). Cover crops included blackeyed Susan (Rudbeckia hirta L.), sorghum Sudangrass [Sorghum bicolor (L.) Moench], marigold (Tagetes erecta L.), big bluestem (Andropogon gerardii Vitman), perennial ryegrass (Lolium perenne L.), switchgrass (Panicum virgatum L.), and Indiangrass [Sorghastrum nutans (L.) Nash]. Treatments were ended in 2005 and plots were planted with ‘Honeoye’ strawberry in a matted row. Effectiveness of soil pretreatments in reducing weed populations and enhancing strawberry production was evaluated for four growing seasons by quantifying weed growth by type and biomass and strawberry plant density and yield. The results indicate that matted-row strawberry production plots that were either in continuous tillage or established in S. bicolor, P. virgatum, or A. gerardii before planting strawberry had lower weed biomass and greater strawberry plant establishment and yield than plots established in L. perenne or R. hirta or that had supported continuous strawberry production.
Gail R. Nonnecke, Lee-Ann M. Kastman and David R. Russell
A 200-level course at Iowa State Univ., Principles of Horticulture, has included a communication across the curriculum assignment for the past seven semesters involving ≈425 students. Each undergraduate student develops and writes an individual student newsletter on topics and for an audience of the student's choice. The semester-long project motivates students to practice a professional communication task, and teaches technical horticultural material and writing skills. The newsletters contain at least two separate articles for an intended audience, providing the students with an opportunity to learn technical information in subjects in which they are intensely interested, but may not be taught in a principles course. Drafts of the articles and newsletter project are peer-reviewed by the students to model the professional review process, provoke critical thinking, and provide students with more feedback than they would otherwise receive from the instructor alone. Additionally, peer-review facilitates writing intensive courses for the instructor who wishes to focus course activities on writing, but has limited time or resources for reviewing writing assignments. Student newsletter articles are selected to be included in quarterly department and extension newsletters, providing students with a real-world use of a communication across the curriculum assignment.
Craig A. Dilley, Gail R. Nonnecke and Nick E. Christians
Corn gluten meal (CGM), a by-product of corn wet-milling, has weed control properties and is a N source. The weed control properties of CGM have been identified in previous studies. The hydrolysate is a water soluble, concentrated extract of CGM that contains between 10% to 14% N. Our objective was to investigate corn gluten hydrolysate as a weed control product and N source in `Jewel' strawberry production. The field experiment was a randomized complete block with a factorial arrangement of treatments with four replications. Treatments included application of granular CGM, CGM hydrolysate, urea, urea and DCPA (Dacthal), and a control (no application). Granular CGM and urea were incorporated into the soil at a depth of 2.5 cm with N at 0, 29, 59, and 88 g/plot. Plot size was 1 × 3 m. Percent weed cover data on 12 Aug. showed plots receiving the 29 g N from CGM hydrolysate had 48% less weed cover than the control (0 g). Plant growth variables showed similar numbers of runners and runner plants among all nitrogen sources.
Khalid N. Al-Redhaiman, Gail R. Nonnecke and Richard J. Gladon
'Honeoye' (June-bearing) and 'Tristar' (day-neutral) strawberries were harvested, graded, and then stored for 7 days et 2C or 21C in air (control) or each of these 8 modified atmospheres: 1.5% O2, 3.5% O2, 15% CO2, 25% CO2, 1.5% O2 + 15% CO2, 1.5% O2 + 25% CO2, 3.5% O2 + 15% CO2, and 3.5% O2 + 25% CO2; all balance N2. When compared with storage at 21C, storage at 2C reduced weight loss and gray mold growth in all corresponding sets of storage atmosphere treatments. The combination of increased CO2 and decreased O2 controlled weight loss and gray mold growth more effectively than treatment with reduced O2 alone. Storage at 2C (versus 21C) reduced respiration of both cultivars. Respiration decreased as the O2 concentration decreased. 'Tristar' did not produce C2H4 at either temperature, whereas `Honeoye' produced more C2H4 at 21C than it did at 2C. Increased CO2 and/or decreased O2 concentrations in the storage atmosphere are not satisfactory substitutes for proper low-temperature storage of strawberries.
Ann Marie VanDerZanden, Cynthia Haynes, Gail R. Nonnecke and Robert Martin
Globalization affects many aspects of American society, including higher education. Many institutions of higher education realize the need to help students become global citizens and thus require an international perspectives course as part of their undergraduate curriculum. The goal of this research was to evaluate the Horticulture Travel Course (Hort 496), which includes an international travel component, to determine whether it meets the university and College of Agriculture's expected learning outcomes and competencies in international and multicultural awareness. A 23-question survey instrument consisting of open- and close-ended questions was mailed to 116 former Hort 496 participants. Forty-three percent of the questionnaires were returned and were usable. Survey questions were designed to gather information on student demographics, previous international travel experience, learning outcomes achieved through participation in the pretrip preparatory class and the study abroad experience, and how these experiences influenced career development. Responses indicate that both the pretrip preparatory class and study abroad experience helped participants achieve the course learning outcomes. Furthermore, student presentations and guest speakers, and interacting with locals and planned tours immersed students the most in the pretrip preparatory class and study abroad experience, respectively. A majority of participants observed recognizable differences in agricultural management or production practices between the United States and the country visited. Participants also noted that Hort 496 had a positive affect on their communication skills, interpersonal skills, and personal growth.
Craig A. Dilley, Gail R. Nonnecke and Nick E. Christians
The number of herbicides available for use in strawberry (Fragaria×ananassa Duch.) production is limited. Corn gluten hydrolysate (CGH) is a water-soluble extract of corn gluten meal (CGM), a by-product of corn wet-milling. Both CGH and CGM have been shown to inhibit root development of seedlings and can provide nitrogen (N). Four weed control and/or N- containing products were studied: CGH, CGM, urea (46N-0P-0K), and urea applied with DCPA at 8.4 kg·ha-1 a.i. Treatments were applied at N rates of 0, 9.8, 19.5, and 29.3 g·m-2. The 0 g·m-2 of N treatment served as the control. During the 1995 establishment season, all treatments were applied in June, July, and August. Treatments were applied in July and August during the 1996, 1997, and 1998 growing seasons. Dicot and monocot weed number and weed shoot dry weights were determined ≈30 days after both July and August treatments. Strawberry yield data were collected in June. Leaf N data were collected during the first week of July, before renovation. When CGH was applied in July, dicot weed number in August decreased in one of four years, but CGH never affected the number of monocot weeds. CGM application in July, reduced the number of dicot weeds found in plots in Aug. 1995 and 1998. Urea had no effect on dicot weed number from 1995 to 1997. However, in 1998, dicot weed number was reduced by as much as 79% as the rate of urea increased. In all study years, dicot weed number was reduced between 86% and 97%, for the high rate of DCPA + urea, compared with control plots. With few exceptions, rate of N had no effect on leaf N or yield. CGH exhibited limited potential as a natural weed control product; it reduced dicot weed number in one year, but did not affect the number of monocot weeds in any year. Strawberry yield in plots receiving CGH showed a linear increase in one year (1998), but did not show an increase in the other 2 years. Chemical name used: dimethyl tetrachloroterephthalate (DCPA)