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Marjorie E. Ross* and Emily E. Hoover

Cultivar may cause variation in arbuscular mycorrhizal fungi (AMF) colonization levels leading to differences in shoot growth and runner formation, and in pathogen control in strawberries. However, a clear consensus has not been reached regarding the degree to which cultivar affects the formation of the symbiosis or its functioning. The study was conducted on four commercial strawberry farms in Minnesota and Wisconsin to compare, within a farm, mycorrhizal colonization and plant response among three strawberry cultivars: `Winona', `Anapolis' and `Jewel'. At each farm, two 6 × 6 meter plots of each cultivar were randomly selected. On each of three sampling dates, 4 whole plants and soil samples were collected from these plots in the 2003 field season. Roots were separated from shoots and leaves, and fresh and dry weights were taken. Leaves and soil were dried, weighed, and submitted for nutrient analysis. Soil nutrient analyses include phosphorus (Bray P), potassium, pH, buffer pH and organic matter. Leaf tissue analyses include P, K, Ca, Mg, Na, AL Fe, MN Zn, Cu, B, Pb, Ni, Cr, and Cd. Roots were collected, frozen, and prepared for scoring using methods adapted from Koske and Gemma (1989). Presence of mycorrhizal colonization is being scored using the methods of McGongle et al. (1990). Levels of mycorrhizal colonization among different strawberry cultivars will be compared. We will also use biomass measurements, to determine mycorrhizal effects on plant growth among different cultivars. Soil and leaf analysis data will be used to determine effects of AMF on plant nutrition and compare effects among cultivars.

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Doug S. Foulk and Emily E. Hoover

Horticulture students in an entry-level course (plant propagation) and an upper-level course (small fruit crop production) were assigned brief lecture-based writing tasks at the end of each class period. For the first 5 minutes of each subsequent class period, students divided into small groups to discuss their responses to the previous day s task and to generate questions related to the task topic. The class then reconvened as a whole for a question-and-answer session before the lecture was resumed. Students collected their task responses in a workbook that they turned in for experimental evaluation at the end of the quarter. When compared to previous and concurrent sections of the same courses, students engaging in the writing tasks more frequently posed questions in class, posed questions of increased complexity, and demonstrated improved ability to perform well on complex exam questions requiring integration and synthesis of information.

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Doug S. Foulk and Emily E. Hoover

Horticulture students in an entry-level course (Plant Propagation) and an upper-level course (Small Fruit Crop Production) were assigned brief writing tasks at the end of each class period based upon that day's lecture. Student writing was intended to be expressive in nature, i.e., for the author's use only. For the first five minutes of each class period, students divided into small groups to discuss possible responses to the previous day's task and to generate questions related to the task topic. The class then reconvened as a whole for a question-and-answer session before lecture was resumed. Students collected their writings in a workbook which they turned in for experimental evaluation only at the end of the quarter. When compared to previous and concurrent sections of the same courses, students engaging in the writing tasks asked more numerous and thoughtful questions in class and demonstrated increased ability to perform well on complex exam questions requiring integration and synthesis of information.

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Doug S. Foulk and Emily E. Hoover

This decision case concerns the need to make management decisions in a commercial apple orchard planted largely with `Haralson,' a russet-susceptible cultivar. The growers described in this situation had to decide whether applying GA4+7 for russet suppression was appropriate for their operation, given the financial, cultural and pesticide issues that required addressing. The case is intended for use in fruit production or other intermediate to advanced undergraduate horticulture courses and assumes a knowledge of basic perennial-crop production practices. Students assume the role of a decisionmaker in the complicated issue of orchard management.

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Doug S. Foulk and Emily E. Hoover

`Haralson,' the most widely-grown cultivar in Minnesota, is highly susceptible to russetting and cracking in many orchards. Because wax platelet arrangement has been proposed as a cause for russettting in `Golden Delicious' apples, we examined the wax platelet arrangement of `Haralson' apples. When compared to the wax platelet arrangement found on the russet-susceptible `Golden Delicious,' and on `McIntosh,' a cultivar which does not russet in our region, `Haralson' platelets were large and upright in orientation, more numerous than found on `Golden Delicious,' but unlike the smaller, more granular platelets found on `McIntosh.' In a concurrent study, we made four GA,,, (Provide) applications, at petal fall and at p.f. +10, 20, and 30 days. At harvest, the treated and untreated blocks of trees were examined for incidence of russet, 25-ct. wt., and total yield per tree. Treated trees produced a greater number of fruit of slightly larger size and with reduced incidence of russet than untreated trees in the study.

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Christopher D. Gran, Rea Jean Lonneman and Emily E. Hoover

Leaf removal has been reported to be beneficial to fruit quality of several grape cultivars. However, climatic conditions, time of leaf removal and genotype have a strong influence on the effect of leaf removal on fruit quality traits, such as soluble solids and titratable acidity. The effect of leaf removal on fruit quality of two vinifera grape cultivar grown in Minnesota was examined in this study. The first six basal leaves were removed from four canes on each vine of `Riesling' and `Chardonnay'. Leaf removal was carried out at two different times after the onset of verasion--early August (8/2) and late August (8/23). Fruit was harvested in late September and yield and fruit quality data were recorded. The results of the 1989 study will be discussed here. Leaf removal did not significantly affect yields obtained from either cultivar, regardless of leaf removal date. Early leaf removal on `Chardonnay' vines resulted in significantly higher soluble solids and significantly lower titratable acidity than that observed for fruit of control or late removal treated vines. Similar results were observed for `Riesling', however the differences were not significant. Data from 1989 and 1990 will he presented and discussed in the talk.

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Neil O. Anderson, Peter D. Ascher and Emily E. Hoover

Decreases in fertility are most common among interspecific, wide crosses of Phaseolus; intraspecific hybrids are less likely to exhibit sterility. Intraspecific CBC hybrid pedigrees were created to test for comparative fertility losses. Eight P. vulgaris cultivars from different centers of origin, polymorphic for seed proteins (15, 20, 50 kDa), were used to create 16 CBC populations: dry (`Cuarenteño', `Great Northern Harris', `Sulfur', `Swedish Brown') and snap beans (`Purple Pod Pole', `Romano Bush', `Royal Burgundy Bush', `White Half Runner'). Despite repeated attempts, two crosses failed to produce primary hybrids. Primary hybrids had decreased percent stainable pollen from the parents. Female sterility was more severe, necessitating the screening of the F1–F3 before producing the next CBC. Yield was significantly lower than midparent values for all F3 CBC pedigrees. In several cases, phaseolin was no longer the major seed protein. Other hybrid breakdown symptoms were similar to those found with wide crosses, indicative of incongruity between centers of origin.

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Helene Murray, Donald L. Wyse and Emily E. Hoover

Minnesota has a long history of strong citizen involvement in environmental, community development, economic development, and human rights issues. Therefore, it is not surprising there are many individuals, organizations, communities, and educational institutions in Minnesota actively involved in the sustainable agriculture debate. The challenge we face is how to help these strong forces work in collaboration to solve rural problem s.

In 1990 representatives of five community-based organizations and the U of M agreed to form the Minnesota Institute for Sustainable Agriculture (MISA) to be housed at the University and governed by a board of community and University representatives. The purpose of MISA is to bring farmers and other sustainable agriculture community interests together with University administrators, educators, researchers, and students in a cooperative effort to undertake innovative, agenda-setting programs that might not otherwise be pursued in the state.

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Neil O. Anderson, Peter D. Ascher and Emily E. Hoover

Two-species CBC hybrids between Phaseolus vulgaris and P. acutifolius exhibit transgressive segregation for seed color and patterning, root peroxidases, and seed proteins. CBC pedigrees between P. vulgaris and P. coccineus (differing for species-specific traits) were created to test whether variation would be similar or greater than with P. acutifolius. P. vulgaris `Soldier' (Vermont) × 2- and 4-way intraspecific P. coccineus accessions were used as parents. CBC1 through CBC3 were evaluated for segregation of species-specific genes. Hybrid breakdown was evident in all CBC generations, particularly nonflowering dwarf cripples. Transgressive segregants were found as early as CBC2. One individual was found that had crossovers for species traits: a determinate, red-flowered plant with P. coccineus flowers and P. vulgaris introrse stigmas. By CBC3, all of the variation reported for three-species CBC hybrids (P. coccineus × [P. vulgaris × P. acutifolius]) was evident.

Open access

Heidi C. Anderson, Mary A. Rogers and Emily E. Hoover

Consumer demand for local and organic strawberries (Fragaria ×ananassa) is increasing. Growers who can meet this demand have a competitive edge in the direct-to-consumer market. Innovations in strawberry production for northern climates offer new opportunities for growers to meet the demand for local organic strawberries. Typically adopted for season extension, the use of poly-covered tunnels for crop protection provides other benefits including protection from adverse weather. Low tunnels are easy to install, low cost, temporary protective structures that are well-adapted for annual day-neutral strawberry production, and they are more space efficient than high tunnels for these low-stature crops. A range of specialty tunnel plastics that modify and diffuse light are available, but there is little information on how these influence strawberry plant growth and performance in the field. Our objectives were to determine the effects of experimental ultraviolet blocking and transmitting plastics on light and microclimate in low tunnel environments and assess differences in fruit yield and quality in the day-neutral strawberry cultivar Albion in an organic production system. This research was conducted on U.S. Department of Agriculture-certified organic land over 2 years, in 2016 and 2017. We found that ultraviolet intensity and daily light integral (DLI) were lower in covered plots than in the open field. Maximum daily temperatures were slightly higher in covered plots. Both ultraviolet-blocking and ultraviolet-transmitting plastics improved marketable fruit yield compared with the open-field control. Strawberries grown in the open-field treatment were lower in chroma than covered plots in 2017, and there was no difference in total soluble solids between treatments in either year. Low tunnel systems allow for increased environmental control and improved fruit quality and are well-adapted for day-neutral organic strawberry production systems.