<p>The efficacy of intensive rotational targeted grazing (IRTG) for suppression of the invasive shrub, multiflora rose (Rosa multiflora) was investigated in upstate New York. Sheep stocked at high density were rotated through a circuit of enclosures at a frequency of 3-d per enclosure, from May-September, 2011 and 2012. The photosynthetic surface areas (PSA) and vitality of R. multiflora plants were evaluated before (May 2011) and after treatment by grazing (Sept 2011). Changes over time were compared with similar measurements of ungrazed plants. Species richness (S) was estimated in each enclosure before (May) and after (September) treatment. PSA in grazed enclosures declined by 56.8% over the 2011 season and by 62.5% during the 2012 season. One year after ITRG treatment, healthy R. multiflora plants in grazed enclosures had declined by 91% and unhealthy and dead plants had increased by more than 200%. The distributions of healthy, unhealthy and dead plants, in grazed and ungrazed enclosures, though not different before treatment (chi square goodness of fit test; p>0.05?? were different one year later (p<0.001). Mean S in grazed enclosures increased by 27% over the season and by the end of the study, S was 12% higher than ungrazed enclosures. Evidence of stress in R. multiflora (clumping, dwarfing and reddening of leaves) at the end of the 2011 season led me to investigate the possible presence of rose rosette disease (RRD) during 2012. Potential stress was confirmed in plants experiencing leaf reddening. Chlorophyll a concentrations were significantly lower in red than green leaves (Student?s t = 5.20, df=28, p<0.001). Not unexpectedly, Normalized Difference Vegetative Index (NDVI) lso differed in red and green leaves (Student?s t = 2.76, df=32, p<0.01). Green leaves had higher dry weights than red leaves (Student?s t=14.13, df=151, p<0.001). Wool from the sheep, and R. multiflora leaf and petiole samples were collected to determine if the eriophyid mite, Phyllocoptes fructiphilus, a vector for RRD was present. No significant evidence of P. fructiphilus in leaf and petiole (Mean=0.00 N=414 SD=.71) or wool samples (Mean=0.00 N=11 SD=0) was found. This was unexpected, although it would only take one mite to be the vector if that particular mite was carrying the rose rosette virus. Further studies would be required to test whether rose rosette was confirmed in this population. Visual evidence of RRD symptoms were more prevalent in grazed enclosures than ungrazed locations, and a greater decline in grazed enclosures was clear.
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10075087 |
| Date | 01 April 2016 |
| Creators | LaBarge, Erin R. |
| Publisher | State University of New York at Albany |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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