Agriculture & Natural Resources
Non Technical Summary
Invasive species are becoming a problem throughout the state of Delaware and the rest of the United States. An invasive species, whether it is a plant or animal, is a species that has been introduced to an area to which it is not native and subsequently disrupts the natural balance in that habitat. While there are both plant and animal invasive species in Delaware, many of the hardest to control are weeds. For example, invasive Canada thistle and Johnson grass are two noxious weeds in Delaware according to the USDA's list of noxious weeds. While these are not the only invasive weed species in Delaware they are prime examples and methods of effective control need to be evaluated. Animal grazing is a very effective tool for managing weed and brush growth. Goats, sheep, cattle, and horses have all been previously used to control brush and weeds. In addition, goats have been successfully used for the control of abandoned farmland pastures invaded by herbaceous weeds, vines, multiflora rose bushes and hardwood saplings for years. When goats are used to manage defoliation this has been shown to result in a substantial increase in vegetative cover by favorable grass and legume species while reducing or eliminating unwanted shrub species (Luginbuhl et al., 1995). Concurrently, goats are becoming increasingly important contributors to the income of many producers in Delaware as indicated by a 43% increase in goat numbers from 2002 to 2007 (Delaware Census of Agriculture, 2007). Therefore, due to increasing goat numbers in the state of DE combined with environmental concerns of herbicide use and the inefficacy of other control methods, the proposed study aims to evaluate the effectiveness of goats as a biological control agent for the control of invasive weeds in DE. This project is in collaboration with the Delaware Department of Transportation and hopes to promote a sustainable and environmentally friendly means of invasive weed control to the citizens of Delaware.
Animal Health Component
Research Effort Categories
Goals / Objectives
It is the objective of the proposed project to evaluate whether or not goats can be an effective method of invasive weed control in Delaware and how many seasonal grazing periods are required for successful control. Expected outputs include a research project at Delaware Department of Transportation's Wrangle Hill site, incorporation of new techniques (forage biomass, nutritive analysis, and botanical) into undergraduate and graduate research projects at DSU, presentations/seminars on the use of goats in invasive weed control to producers, researchers and other professionals, and publication of two scientific articles. This experiment will be conducted within 3 years (February, 2010 - January, 2013) to evaluate whether or not goats can be an effective and sustainable method of invasive weed control in Delaware. Data will be collected and analyzed by the end of the experiments for each year. This timeline was developed such that enough data will be available in order to submit abstracts and present at the 2010, 2011 and 2012 Southern Section American Society of Animal Science Meetings as well as American Society of Animal Science Meetings each year. Potential products from conducting this project include the development of new skills and techniques by students, staff, and faculty at DSU as well as the promotion of a sustainable and environmentally friendly means of invasive weed control in DE. In addition, one graduate student will be trained in these techniques and will use the data as part of their thesis work at DSU. Undergraduate students will also be provided opportunities to work and volunteer on this project, therefore increasing the teaching capacity at DSU and help in training well-qualified students for Food and Agricultural Science professions.
A grazing experiment will be conducted during the 2010, 2011, and 2012 growing seasons at Delaware Department of Transportation's Wrangle Hill site in New Castle County to investigate the potential effects of goat grazing on pastures infested with browse and weedy species. The experimental design will be a randomized complete block design with pastures being the experimental unit. The two treatments will include a no grazing control and a goat alone grazing. Three replicates will be used for grazed treatment and two for the control. Replicate paddocks for grazing will be 1.2 ha each and control replicates will be 0.4 ha each. Forty goats will be allocated to each grazing treatment and will be rotationally stocked among replicates by grazing one replicate for approximately two weeks and then allowing 4 weeks rest. Water and trace minerals will be provided free choice at all times. Animals will be weighed at each rotation time during the growing season (spring, summer, and fall). Grazing will be initiated during May and end during September of each year. Pastures will be evaluated for forage biomass, nutritive values, species diversity and effect of grazing on browse species during spring, summer, and fall of each grazing season. Forage biomass will be determined according to Webb (2008). Prior to harvesting the forages within each quadrant, the area will be visually evaluated by trained evaluators for botanical composition using the double DAFOR scale as described by Brodie (1985) and Abaye et al. (1997). The scale (D=dominant, A=abundant, F=frequent, O=occasional, and R=rare) will be used to evaluate the relative abundance of species. Visual estimates of percentage ground cover and percentage of grass, legume, and weed species will also be made. Autumn olive and muliflora rose measurements will include shrub height, branch length, and shrub survival. Shrubs will be randomly identified and tagged with a letter in each paddock in the grazing treatments and control plot. Shrubs will be measured at spring, summer, and fall during each growing season. Any broken or dead branch due to goat browsing will also be recorded. Shrub survival will be also be measured in May and September by counting the number of shrubs or clumps surviving in each treatment. All data will be analyzed using SAS and data will be presented annually at national Animal Science and Invasive Weed control meetings as well as to goat producers at workshops/seminars. Acceptance of the information by this community, assessed by interest generated after presentations, and by goat producers, assessed by surveys administered to producers at workshops/seminars, will be used as an evaluation criterion. Impact will also be evaluated by information obtained from collaborating personnel at Delaware Department of Transportation to evaluate the impact and accomplishments of the proposed study.