James E. Brown

Integration of soil solarization with chemical, biological and cultural control for the management of soilborne diseases of vegetables

The long-term effectiveness of soil solarization integrated with (integration of pest management [IPM]) a biological control agent (Trichoderma virens), chemical fungicide (pentachloronitrobenzene [PCNB]), organic amendment (chicken litter) or physical method (black agriplastic mulch) to reduce southern blight (Sclerotium rolfsii) and southern root-knot diseases (Meloidogyne incognita) were evaluated on vegetable production. Results showed that the long-term effectiveness of IPM plus soil solarization reduced soilborne diseases of vegetables more than two years following the termination of solarization. These disease management strategies in 1991 and 1992, following soil solarization in 1990, reduced the numbers of sclerotia in the soil, and the number of plants killed by southern blight and root-knot of tomatoes, compared to nonsolarized bare soil treatment. The integration of a reduced dosage level of PCNB or T. virens in field plots, reduced southern blight of tomatoes by 100% and 71%, respectively, in solarized soil, compared to nonsolarized bare soil two years following soil solarization. PCNB effectively controlled southern blight in nonsolarized bare soil both years. All solarized treatments, except PCNB plus solarized soil increased tomato yields compared to nonsolarized bare soil plots. In the second study (1992) following soil solarization in 1991, the effectiveness of solarized bare soil, and nonsolarized bare soil mulched with black agriplastic film, with or without Reemay spunbounded polyester row cover, were effective in reducing root-knot of tomatoes as indicated by the root-knot gall index. Following a one year fallow period in 1994 three years following soil solarization, the root-knot gall index for severity of tomato roots grown in solarized bare soil, nonsolarized bare soil, black agriplastic mulched bare nonsolarized soil and black agriplastic mulched solarized bare soil, were 1.0, 3.0, 3.0 and 2.0, respectively, on a 0–5 scale, where 0=0% and 5=100% root-knot galled. In the third study 1992 and 1993, different dosage levels of chicken litter were used to amend soil artificially infested with sclerotia of S. rolfsii at different depths following solarization, decreased the number of viable sclerotia by 85–100%. All solarized treatments and nonsolarized bare soil amended with 18.8 MT/ha of chicken litter, were effective in controlling southern root-knot damage, and postharvest storage root rots of sweetpotato storage roots (Fusarium root rot [Fusarium solani] and Java black rot [Diplodia tubericola]). Our study showed that all soil solarization treatments, and soils amended with chicken litter, stimulated a shift in the soil microbial population dynamics. Rhizobacteria of Bacillus spp. and fluorescent pseudomonads increased significantly in the rhizosphere, rhizoplane, and interior root tissues of tomatoes and sweetpoatoes, grown in solarized soil compared to nonsolarized soil. These microorganisms may have contributed to the increased growth response of vegetables and some were probably suppressive to soilborne diseases

Black Plastic Mulch and Drip Irrigation Affect Growth and Performance of Bell Pepper

ABSTRACT Bell peppers were grown in the field on bare soil and in black plastic mulch with and without drip irrigation. Black plastic mulch alone and black plastic mulch plus drip irrigation increased pepper yields by 18 MT and 16 MT per hectare (571% and 631%), respectively, over yields on bare soil. The study was conducted at Sand Mountain Substation, Crossville, DeKalb County, Alabama on a fine sandy loam soil.

Plastic Mulches and Row Covers on Growth and Production of Summer Squash

ABSTRACT Row covers and colored plastic mulch are used routinely throughout the United States to grow vegetables but are rarely used in conjunction to produce a crop. Summer squash (Cucurbita pepo L.), cv. Prelude II, was grown on an Orangeburg sandy loam soil in Shorter, AL. The summer squash was direct seeded in single rows. The experiment consisted of 12 treatments including: (1) black plastic mulch (BPM)+spunbonded row cover (RC), (2) BPM alone, (3) white plastic mulch (WPM)+RC, (4) WPM alone, (5) red plastic mulch (RPM)+RC, (6) RPM alone, (7) bare soil (BS)+RC, (8) BS alone, (9) silver plastic mulch (SPM)+RC, (10) SPM alone, (11) blue plastic mulch (BLUPM)+RC, and (12) BLUPM alone. Year and mulch color affected all variables, row cover affected plant height and stem diameter, and the mulch color × row cover interaction affected yield variables. Mulch color and year significantly affected air and soil temperatures and row cover significantly affected air temperature. Soil temperatures were more than 5°C lower than air temperatures in all treatments and air temperatures were 2–5°C higher with row covers than without. Increased soil and air temperatures did not always result in yield increases. Colored plastic mulch with or without row covers did not increase early fruit yield in squash. Lack of a mulch/row cover induced temperature effect on yield was attributed to the relatively high mean air temperatures that may have masked treatment temperature effects.

Effect of Three Row Covers and Black Plastic Mulch on the Growth and Yield of ‘Clemson Spineless’ Okra

ABSTRACT Okra (Abelmoschus esculentus ‘Clemson Spineless’) was grown on a sandy loam soil at the E.V. Smith Research Center, Shorter, Alabama. Okra was direct seeded in single rows spaced 2.1 m apart. Treatments were: (1) black plastic mulch (BPM), (2) BPM + clear, slitted plastic (CSP) row tunnel, (3) BPM + Kimberly Farms row cover (KFRC), (4) bare soil (BS), and (5) BPM + white, tinted, slitted plastic (WTSP) row tunnel. BPM and BPM + WTSP treatments induced the highest yields, an increase of 112% and 90%, respectively, over those produced on BS.

Nitrogen Requirements for Sweetpotato Following a Crimson Clover Cover Crop

Sweetpotato [Ipomoea batatas (L.) Lam.] is an economically important crop in the southeastern United States, and sustainable production practices that include reducing fertilizer costs and improving soil organic matter are needed. Field studies were conducted in the Spring of 2007 and 2008 to evaluate nitrogen fertilization requirements of sweetpotato. Treatments of 0, 50, and 101 kg·ha−1 nitrogen (from ammonium nitrate applied preplant broadcast) were applied following a crimson clover (Trifolium incarnatum L.) cover crop along with a conventional no cover crop treatment using 101 kg·ha−1 N (from ammonium nitrate). Sweetpotato yields for all rates of N fertilizer following the cover crop were similar (for ‘Beauregard’ in 2007) or greater (for ‘Xushu 18’ in 2008) than yields from plants grown using the conventional treatment. Percentage of dry matter of storage roots was not affected by treatment. Nitrogen fertilization can be reduced or eliminated when sweetpotatoes are produced following a crimson clover winter cover crop.

Lime applications to aged pine media increase early-season sweet potato transplant production in heated beds

Abstract Aged pine sawdust and bark are likely to be the most widely used media for sweet potato transplant production in heated beds in north Alabama. Transplant production in these media, however, may be limited by acid conditions. This experiment was conducted to determine the effects of the application of lime (0.0, 2.2, and 4.4 kg/m3) on early‐season production of ‘Georgia Jet’ sweet potato transplants. Differences in transplant yield and quality due to media were not obtained at the first harvest, but heavier total early‐season transplants were obtained with aged pine bark than with aged pine sawdust. At the first harvest, the highest transplant number (936 transplants/m2) and weight (1.685 kg/m2), and the greatest mean transplant length (23.4 cm) were obtained with 2.2 kg/m3 of lime, but the total early‐season transplant numbers increased linearly from 1025 to 1154 transplants/m2 with the addition of lime. Total early‐season transplant quality parameters, however, did not respond to the addition of...

Effects of media on early‐season sweet potato transplant production in heated beds

Abstract ‘Georgia Jet’ sweet potato transplants were produced in heated beds to determine the effects of aged pine sawdust and builders’ sand (traditional media) and fresh and aged pine bark, and fresh pine sawdust (alternative media), on early‐season transplant production and media characteristics. At the first harvest, higher transplant numbers were obtained with the fresh pine sawdust or pine bark (mean 1,053 transplants/m2) than with the other media (mean 619 transplants/m2). Transplant fresh weights at the first harvest responded in a similar manner. The total early‐season number of transplants obtained with fresh pine bark (1,455 transplants/m2) was also greater than the total number of transplants obtained with the traditional media and aged pine bark (mean 951 transplants/m2), but not greater than the total number of transplants obtained with fresh pine sawdust. Mean lengths and weights of transplants obtained with the alternative media were at least as great as the values obtained with transplant...

Evidence of rhizobacteria changes associated with the increased growth response of vegetables grown in agrimulch systems.

ABSTRACT Results from three vegetable experiments using agriplastic mulch systems showed a positive relationship between the increase of rhizobacteria dynamics and the increased growth response (IGR) of vegetables grown on black plastic (BM) and clear plastic (CM) mulches with or without row covers during early spring and summer. In the first experiment, no significant differences were observed for IGR of ‘Flora-dade’ tomatoes grown on bare soil following soil solarization (SBS) and nonsolarized bare soil (BS) plus BM. However, tomatoes grown on SBS, BM and BM mulched SBS plus Reemay spunbonded polyester row cover treatment showed a greater IGR compared to the non-row cover treatments. In the second experiment, plots containing ‘Crimson Sweet’ watermelons grown on CM had higher soil temperature and IGR than those grown with BM with and without VisPore row cover. When TU-82-155 swectpotato cultivar was double cropped on CM and BM plots following the removal of mulching films, sweetpotatoes showed improved yield compared to those grown in BS. In the third experiment, watermelon transplants grown on CM and BM mulches with or without VisPore row cover that were applied 21 days prior to planting had higher IGR and bacteria population in root rhizosphere than transplants grown on agrimulch systems applied just one day prior to transplanting. In all studies, there were significant increases of rhizo-bacteria in the rhizoplane, rhizosphere and root interior tissue of tomatoes and watermelons grown in solarized soil and all agrimulch systems compared to BS.

Tomato fruit yield response to nitrogen source and percentage of drip- or band-applied nitrogen associated with leaf potassium concentration

Abstract Field experiments were conducted during the spring and fall of 1994 to evaluate two nitrogen (N) sources [ammonium nitrate (AN) and polymer‐coated urea (PCU)] and five levels of drip‐ or band‐applied N on the yield of drip irrigated ‘Solar Set’ tomatoes (Lycopersicon esculentum Mill). Early‐season yields obtained with PCU were similar to or greater than yields obtained with AN. Highest yields of large fruit early in the season were produced with 100% preplant‐applied AN or 100% band‐applied PCU. Total‐season yields were greater with AN than PCU and were not affected by placement of N. Increasing the percentage of drip‐ or band‐applied N resulted in leaf N concentrations that were inconsistent with trends in marketable fruit production; however, trends in leaf K concentration early in the season were similar to those of early‐season large fruit yields.

Leaf mineral nutrient concentrations or media pH affect Georgia Jet sweetpotato transplant number, length, and weight 1

Abstract The results of four experiments were combined to determine the relationships between leaf mineral nutrients or media pH and sweetpotato transplant production. The relative number of transplants and the relative mean transplant lengths or weights were determined by comparing the values obtained with unamended aged pine sawdust, a traditional medium. These values were regressed against leaf mineral concentrations and media pH. There was no relationship between relative transplant production and leaf nitrogen (N), potassium (K), or manganese (Mn) concentrations. Compared to sufficiency ranges for nearly mature sweetpotatoes, concentrations of N and K were low and Mn was sufficient. An upper value of 1210 mg/L leaf iron (Fe) was obtained for relative mean transplant weight, but concentrations of this mineral were not associated with relative transplant numbers or relative mean transplant lengths. Leaf calcium (Ca) and magnesium (Mg) concentrations were related to all three transplant characteristics ...