UVM Theses and Dissertations
Format:
Print
Author:
Bradshaw, Terence L.
Dept./Program:
Plant and Soil Science
Year:
2011
Degree:
MS
Abstract:
Organic agriculture represents a significant and growing market in the United States, but organic apple production in Vermont has not been widely adopted. Production difficulties limiting adoption of organic production practices of apples include increased production costs; lower marketable yield; limitations in insect, disease, and weed control measures; and decreased options for effective fruit thinning. In 2006, the USDAfunded Organic Apple Research and Demonstration (OrganicA) Project established research plantings at the University of Vermont Horticulture Research Center in South Burlington, VT. Tree growth in one newly planted high density orchard was poor during the initial three years of establishment. Organic farmers commonly use natural biostimulants in their fertility program to supplement mineral nutrition.
These materials are a poorly-defined group of products that are not plant fertilizers, but which when used in small quantities may improve plant growth or function. Two biostimulant materials extracted from the kelp Ascophyllum nodosum, Stimplex and Seacrop16, were assessed against a non-treated control over two seasons in 2009 and 2010 in a certified organic apple orchard in South Burlington, VT planted in 2006. The objectives of this study were to assess effects from application of kelp extract biostimulants on tree growth, crop yield, fruit quality, and arthropod and disease incidence in the study orchard. Kelp extracts were applied at labeled rates seven times during each growing season to each of five replicates of the five applecultivars Ginger Gold, Honeycrisp, liberty, Macoun, and Zestar!
Treatments were applied in a completely randomized design and were applied to the same trees in both study years. Data were analyzed with a two-way ANOVA with separate cultivar and kelp extract treatments, and Tukey's HSD was used to test mean separations between treatments. The majority of the data showed no effect from kelp extracts on tree growth, crop yield, fruit quality, or arthropod and disease pest incidence. Kelp extract treatment reduced incidence of sunburn and frost rings on fruit in 2010. Effects from application of kelp extracts on yield were not statistically significant, but observed differences may be of practical interest to commercial growers. Both kelp extract treatments reduced incidence of apple maggot damage on fruit, but overall pressure was low in both study years. Impacts on disease incidence included a reduction in powdery mildew on Ginger Gold in one year versus the non-treated control, and an increase in fruit rots on kelp extract-treated Honeycrisp in one year.
These materials are a poorly-defined group of products that are not plant fertilizers, but which when used in small quantities may improve plant growth or function. Two biostimulant materials extracted from the kelp Ascophyllum nodosum, Stimplex and Seacrop16, were assessed against a non-treated control over two seasons in 2009 and 2010 in a certified organic apple orchard in South Burlington, VT planted in 2006. The objectives of this study were to assess effects from application of kelp extract biostimulants on tree growth, crop yield, fruit quality, and arthropod and disease incidence in the study orchard. Kelp extracts were applied at labeled rates seven times during each growing season to each of five replicates of the five applecultivars Ginger Gold, Honeycrisp, liberty, Macoun, and Zestar!
Treatments were applied in a completely randomized design and were applied to the same trees in both study years. Data were analyzed with a two-way ANOVA with separate cultivar and kelp extract treatments, and Tukey's HSD was used to test mean separations between treatments. The majority of the data showed no effect from kelp extracts on tree growth, crop yield, fruit quality, or arthropod and disease pest incidence. Kelp extract treatment reduced incidence of sunburn and frost rings on fruit in 2010. Effects from application of kelp extracts on yield were not statistically significant, but observed differences may be of practical interest to commercial growers. Both kelp extract treatments reduced incidence of apple maggot damage on fruit, but overall pressure was low in both study years. Impacts on disease incidence included a reduction in powdery mildew on Ginger Gold in one year versus the non-treated control, and an increase in fruit rots on kelp extract-treated Honeycrisp in one year.