A field planting of 18 selections and 10 named cultivars of pawpaw (Asimina triloba) was established in November 1996 near Clemson, S.C., as part of the Pawpaw Regional Variety Trial coordinated by Kentucky State University. Trees were planted at 2.0 × 5.5 m spacing with drip irrigation and straw mulch in a randomized complete block design consisting of 8 single-tree replications. Data collected through 2005 included tree survival, total tree yield, and yield and average weight of fruit weighing >150 g. Since the start of the trial, 3 selections, 1-7-1, 11-5 and 8-58 have been named and released as `Shenandoah', `Susquehanna' and `Rappahannock', respectively. The highest yielding cultivars were `Shenandoah', `Rappahannock', and `PA-Golden'. The cultivars with the largest percentage of large fruit were `Shenandoah' and `Susquehanna'. `Middletown', `Mitchell', `Rappahannock', `Taytwo', `Wells' and `Wilson' produced the largest percentage of small fruit (<150 g). After 9 years, 66% of the original trees (i.e., scions) were alive. `Rappahannock', `PA-Golden', `Sunflower' and `Wilson' had either one or zero trees die, whereas `Middleton' and `Wells' had only 2 trees alive. Among the selections, 2-54, 9-58, 11-13, 1-68, 3-11, and 8–20 had either 88% or 100% survival. The highest yielding selections were 10-35, 1-7-2, 1-68, and 2-10, and 1-7-2, 2-10, 4-2, and 5-5 produced the highest percent of large fruit. Fruit quality characters such as aroma, flavor, aftertaste and texture were not quantified or evaluated.
Gregory L. Reighard, David R. Ouellette, and Kathy H. Brock
Kathy H. Brock, Heather A. Hatt, and Dennis R. Decoteu
Winter cover crops (wheat or rye and crimson clover) in combination with three levels of nitrogen fertilizer (0, 60, 120 kg/ha) were evaluated as to their influence on bean and tomato production (fruit yield, disease and insect injury on fruit) over a three year period (1991-1993). A split plot design was used with the cover crop as the main treatment and nitrogen rate as the split treatment. Results indicate that total marketable and cull yields for bean increased significantly in 1992 but decreased again in 1993. Tomato yields were significantly greater in 1991 than in 1992 and 1993 for both early and total marketable yields while early cull yield increased each year and total cull yield was highest in 1993. Cover crop had an effect on non-marketable tomato fruit. There was a higher incidence of cracked and insect damaged tomato fruit in association with clover or fallow treatment. Marketable yields responded in a quadratic manner while the number of cull fruit increased linearly for both bean and tomato as nitrogen rate increased. The incidence of diseased bean pods increased linearly as nitrogen rate increased. Catfaced tomato fruit responded in a quadratic manner and cracked tomato fruit increased linearly as nitrogen increased. Results from the three year evaluation do not indicate an influence of cover crop on marketable yields of bean and tomato.
Sandra L. Barbour, Kathy H. Brock, B.A. Fortnum, and Dennis R. Decoreau
Pest control-related problems jeopardize the advancement of our nation's vegetable industry. Because of the adverse effects of many fumigants. the grower is increasingly pressured to utilize sustainable. environmentally sound agricultural practices yet still maintain a marketable, blemish-free product.
The effects of wavelength selective mulches and three different fumigants on overall plant development and nematode control were studied in field grown, staked tomatoes. Plots were fumigated with methyl bromide. Telone II, or Telone C17. Within rows, mulch color was established by application of either white or red exterior enamel paint to the black plastic surface of polyethylene mulch. Reflective light from each mulch color was measured using a LiCor 1800 Spectroradiometer. Temperature below the mulch surface was monitored with a datalogger.
Prior to the first marketable harvest, plants grown on white mulch produced greater fruit weight and total dry weight than plants grown on black or red mulch. Total marketable yields, however. were not significantly different between the three mulches. Early and marketable yields from fumigated plots did not differ from control treatments. The lack of response due to fumigation may have been due to low initial nematode populations in the field.
Christopher L. Ray, Sandra B. Wilson, Kathy H. Brock, Bruce A. Fortnum, and Dennis R. Decoteau
Pest management is of primary importance to the vegetable industry in our nation. In recent years producers have undergone much scrutiny concerning their pest control strategies, which often include the use of chemical pesticides. Due to the detrimental effects of many fumigants, growers are being forced to incorporate more environmentally sound agricultural practices while still producing a healthy, marketable commodity. The effects of three different fumigants and reflective mulches on plant growth and development were studied in field-grown, staked tomatoes. Methyl bromide, Telone II, or Telone C-17 were used in fumigation of plots. The establishment of mulch color was done via applications of exterior enamel paint, white or red in color, to the surface of black polyethylene mulch. With the exception of total marketable yields, no interactions existed between mulch color and fumigant. Red mulch and Telone II treatments resulted in the highest total marketable yield. Telone II application increased early marketable yield. White mulch color increased preharvest yield and black mulch color decreased early marketable yield. Low initial populations of nematodes may be the cause for lack of response due to fumigation.