J. R. Akridge

Auburn University, Auburn, Alabama, United States

Are you J. R. Akridge?

Claim your profile

Publications (8)0 Total impact

  • Journal of Environmental Horticulture. 01/2011;
  • A. K. Hagan, J. R. Akridge, K. L. Bowen
    Plant Health Progress 01/2009;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned. Abstract Reaction of selected shrub and ground cover roses to black spot, Cercospora leaf spot, and powdery mildew, as well as the impact of fungicide inputs on the control of the above diseases, was assessed from 1999 through 2003 in a simulated landscape planting in Brewton, AL. Chlorothalonil at 1.25 g ai/liter was applied at 2-and 4-week intervals from mid-March until October to randomly selected plants in each replicate. An unsprayed control was also included in each replicate. Although black spot was the predominate disease observed, a number of rose selections suffered from objectionable Cercospora leaf spot-induced leaf spotting and premature defoliation. Few mixed outbreaks of black spot and Cercospora leaf spot on a single selection were seen. In all years, significant differences in the reaction of rose selections to black spot and Cercospora leaf spot were noted. Of the roses damaged by black spot, the least leaf spot and defoliation were noted on the unsprayed Ice Meidiland®, Mystic Meidiland®, Red Cascade™, 'Hansa', 'Pink Grootendorst', 'Pink Pet', and to a lesser extent Carefree Wonder™ and Pearl Sevillana™. In a residential planting, monthly applications of chlorothalonil or other recommended fungicide would be needed to protect the above rose selections from a destructive black spot outbreak. The Fairy™, and 'Therese Bugnet', considerable Cercospora leaf spot development occurred on all of the above rose selections. Of these roses, Polar Ice™, Fuchsia Meidiland®, and Fire Meidiland® exhibited the highest resistance to Cercospora leaf spot and may not require any fungicide inputs to maintain plant health and vigor. Magic Carpet™ and Knock Out™ roses, which were susceptible and resistant to black spot, respectively, as well as Flower Carpet®, and White Flower Carpet® appeared to be poorly adapted to the hot and sometimes dry summer weather patterns of South Alabama. In nearly all years, chlorothalonil gave better control of both diseases when applied on a 2-week than on a 4-week schedule. Significant chlorothalonil-induced leaf burn was seen on First Light™, Flower Carpet®, 'Hansa', Happy Trails™, Magic Carpet™, Mystic Meidiland™, 'Nozomi', and Raven™. Consistent powdery mildew development was found only on 'Therese Bugnet' and to a lesser extent on Red Cascade™ and 'Petite Pink Scotch'. Canopy spread of the roses that were heavily damaged by black spot and Cercospora leaf spot often was often reduced in size when compared with that of adjacent chlorothalonil-treated plants of the same selection. In contrast, little if any increase in growth was obtained with fungicide inputs for the more disease resistant rose selections.
    J. Environ. Hort. 07/2005; 23:77-85.
  • Source
    A K Hagan, J R Akridge, M E Rivas-Davila
    [Show abstract] [Hide abstract]
    ABSTRACT: To direct, fund, promote and communicate horticultural research, which increases the quality and value of ornamental plants, improves the productivity and profitability of the nursery and landscape industry, and protects and enhances the environment. The use of any trade name in this article does not imply an endorsement of the equipment, product or process named, nor any criticism of any similar products that are not mentioned. Abstract Drenches and directed sprays of two rates of azoxystrobin (Heritage 50W) were evaluated at 2-and 4-week intervals for the preventative control of Phytophthora shoot blight (Phytophthora parasitica) in a simulated landscape planting of annual vinca (Catharanthus roseus). 'Tropicana Rose' and 'Pacifica Punch' annual vinca were planted in May 1998 and April 1999, respectively, adjacent to beds known to be heavily infested with the causal fungus P. parasitica. Regardless of application rate and fungicide placement, the survival rate of plants was often higher when treated with azoxystrobin on a 2-week rather than on a 4-week schedule. Fungicide placement appeared to have little impact on the efficacy of azoxystrobin for the control of Phytophthora shoot blight. In 1998, survival rates of 85 and 90% for 'Tropicana Rose' were obtained with directed sprays of 0.35 (9.6 oz/100 gal) and 0.7 gm a.i./liter (19.2 oz/100 gal), respectively, of azoxystrobin applied on a 2-wk schedule as compared with a 10% survival rate for the unsprayed control. Overall, directed sprays of 0.7 gm a.i./liter (19.2 oz/100 gal) of azoxystrobin applied at 2-week intervals gave the best protection from Phytophthora shoot blight. Among the azoxystrobin drench treatments, 10.7 gm a.i./100 m 2 (0.7 oz/1000 ft 2) applied at 2-week intervals had the highest survival rate in both years.
    J. Environ. Hort. 01/2001; 19:163-165.
  • Source
    A. K. Hagan, J. R. Akridge
  • Source
  • Source
  • Source