Solarization for the control of Pueraria montana (kudzu)

The effects of translucent polyethylene sheeting as a thermal covering to eradicate Pueraria montana (kudzu) were investigated at Clemson, South Carolina on a clay loam. In 2005, the highest reduction of live root crowns was observed where P. montana was covered for the entire growing season (May–October) with a reduction of 42% of live root crowns compared with the control plots. Where P. montana was covered for alternate weeks throughout the growing season live root crowns were reduced by 35%. Covering P. montana for one week and then uncovering for four weeks repeatedly through the season killed 24% of root crowns. In 2006, the second year of treatment to the same plots, the three solarization treatments had similar efficacy of about 97%. The use of polyethylene sheeting appears not to be cost‐effective for general control of large P. montana infestations, but may be useful for small patches.     

Pine growth response to different site-preparation methods with or without post-plant herbaceous weed control on North Florida's Lower Coastal Plain

A study was initiated in 1994 to evaluate the effects of bedding timing and frequency and pre-plant herbicide application, with and without post-plant herbaceous weed control, on growth of three slash pine (Pinus elliottii Engelm.) plantations and one loblolly pine (Pinus taeda L.) plantation on flatwoods sites. Site preparation treatments included early bedding alone, late bedding alone, double bedding, early bedding plus banded pre-plant herbicide, and early bedding plus broadcast pre-plant herbicide. Each site preparation treatment was tested with and without a first-year post-plant herbicide application for herbaceous weed control (HC). Results ranging from age 5 to 11 are reported, depending on installation. Pine growth following late bedding alone was similar or greater than that with early bedding alone. Double bedding did not consistently increase pine growth as compared with single bedding alone. Early bedding plus either broadcast or banded pre-plant herbicide application generally exhibited greater pine growth than did bedding alone treatments or bedding plus post-plant herbaceous weed control treatments. Broadcast pre-plant herbicide application resulted in similar or greater growth than banded pre-plant herbicide application. Post-plant herbaceous weed control improved loblolly pine growth across all site preparation regimes on the one test location. For slash pine plantations evaluated, post-plant herbaceous weed control resulted in significant growth increases on some but not all sites. The differences in growth response to bedding and pre- and post-plant herbicide applications are discussed in relation to treatment efficacy in controlling woody shrub and herbaceous competing vegetation. Effective bedding and chemical site preparation reduces the need for post-plant herbicide applications for slash pine on certain sites. Good site preparation, including the application of herbicides for competition control, is essential for fast growing slash and loblolly pine plantations in the flatwoods.     

Effect of cultural practices and fungicides on Phytophthora fruit rot of watermelon in the Carolinas

Phytophthora fruit rot of watermelon, caused by Phytophthora capsici, is an important and emerging disease in Southeastern U.S.A. The effects of two cultural practices (raised bare ground and raised plastic mulched beds) used for growing watermelon and different fungicide treatments on development of Phytophthora fruit rot were evaluated. The experiments were conducted over three years (2005-2008) at research stations in North Carolina and South Carolina, U.S.A. Fungicides were applied at weekly intervals on the diploid cv. Mickey Lee for an average of five applications. Fruit rot incidence was recorded at the end of each experiment. Fruit rot incidence in the non-treated plots was 66% across two states and six trials. Overall, the levels of fruit rot on the raised bare ground and raised plastic mulched beds were not significantly different. Based on percent disease reduction relative to the non-treated check plots, the fungicide Captan was the most effective across years and locations (range = 23-70%, mean = 57%), followed by mandipropamid (25-65%, mean = 50%), fluopicolide (24-65%, mean = 43%) and cyazofamid (0-48%, mean = 31%). Mefenoxam, the current standard treatment reduced fruit rot by 8-28% (mean = 18%). The addition of copper hydroxide to the spray mix did not significantly enhance effectiveness of Captan or mandipropamid. The variability in fungicide efficacy observed in these experiments across locations and years demonstrates the importance of environmental conditions in disease development and management. Even when the most effective fungicides are used, heavy losses may occur when conditions are highly favorable for disease development. Ultimately, effective control of Phytophthora fruit rot of watermelon will require an integrated management strategy that includes well-drained fields, water management and crop rotation in addition to fungicides.     

Response of two sweet potato cultivars to weed interference

Field experiments were conducted at the U.S. Vegetable Laboratory, Charleston, SC, U.S.A in 2000, 2001, and 2004 to assess the effect of different durations of weed interference on two sweet potato cultivars with different shoot growth habits. The cultivars were Beauregard, which has a spreading growth habit that is typical of U.S. sweet potato cultivars and Carolina Bunch, with an erect growth habit. Weed interference treatments included control plots that were maintained weed free throughout the growing season and plots that were maintained weed free for 0, 10, 20, and 30 days after transplanting. In general, Carolina Bunch was more tolerant of weed interference than was Beauregard. In two of three years Carolina Bunch storage root yields were higher than Beauregard yields in plots that received no weeding; whereas, yields of the two cultivars in weed free plots were not different. Weed interference affected shoot growth to a greater extent than it affected storage root production. At the end of the growing season, Carolina Bunch shoot biomass was greater than Beauregard shoot biomass in plots receiving no weeding and in plots that were maintained weed free for 10 days in all three years. Shoot biomasses of the two cultivars were not different in weed-free plots. Weed shoot biomasses were greater in Beauregard plots than in Carolina Bunch plots in several instances. These results demonstrate that sweet potato cultivars with a vigorous, erect shoot growth habit (with shorter stems, greater branching, and a denser and taller canopy early in the growing season) may be less susceptible to weed interference than cultivars with spreading shoot growth. This study also confirmed previous observations that sweet potato productivity is not greatly affected by moderate weed interference; thus, it may not require intense weed management to produce high yields.     

Opportunities for Small-Scale Forestry in Carbon Markets

This paper presents an explanatory framework of how greenhouse gas emissions offsets produced from natural and planted forests (‘carbon forestry’) feature in voluntary and regulated carbon markets. An introduction to the convoluted policy malaise surrounding the use of forests in regulated carbon markets is also presented. Whilst there are many opportunities and potential benefits of using forests to produce offsets, relatively few carbon forestry projects currently exist, particularly in regulated carbon markets. This seems due to financial, institutional and administrative obstacles, with prohibitive transaction costs often cited as the most prominent constraint to expanded carbon forestry development. The papers in this special issue present a wide coverage of carbon forestry development policy issues. The special issue provides a unique insight into the state of carbon forestry globally and highlights the pressing need for policy and market reform to facilitate more sustainable carbon forestry development.