Bielinski M. Santos

Efficacy of methyl bromide alternatives on purple nutsedge (Cyperus rotundus) control in tomato and pepper

Field trials were conducted to compare the effect of various soil fumigants along with in-bed pebulate and row-middle metribuzin applications on purple nutsedge control and on tomato and bell pepper growth and yield. Treatments consisted of combinations of soil fumigants, pebulate, and metribuzin. Fumigants levels were (1) untreated control, (2) methyl bromide (MBr) + chloropicrin (Pic) (67 + 33%, respectively), (3) Pic, (4) metham, (5) dazomet, and (6) 1,3-dichloropropene (1,3-D) + Pic (83 + 17%, respectively). Pebulate levels were either applied in-bed or not applied. Row middles were either sprayed with metribuzin or untreated. In both crops, purple nutsedge populations were independently influenced by fumigants and pebulate applications, with the highest number of purple nutsedge plants in the untreated control. The addition of pebulate reduced purple nutsedge populations in all treatments. In tomato trials, the yield was affected by fumigants, with the highest losses (53 and 50% reductions in fruit number and weight) observed in the nonfumigated control. In pepper trials, fruit number and weight were individually influenced by fumigants and metribuzin sprayings. Application of metribuzin to row middles increased yields 10% relative to nontreated plots. Nomenclature: Purple nutsedge, Cyperus rotundus L. #3 CYPRO; pepper, Capsicum annuum L.; tomato, Lycopersicon esculentum Mill. Additional index words: Chloropicrin, dazomet, 1,3-dichloropropene, interference, metham, metribuzin, pebulate, soil fumigants. Abbreviations: 1,3-D, 1,3-dichlopropene; MBr, methyl bromide; Pic, chloropicrin; WAT, weeks after transplanting.

Efficacy of 1,3-Dichloropropene Plus Chloropicrin in Combination with Herbicides on Purple Nutsedge (Cyperus rotundus) Control in Tomato1

A study was conducted to compare the effect of 1,3-dichloropropene (1,3-D) + chloropicrin (Pic) in a 83:17 ratio (C-17) used alone or in combination with herbicides on tomato. Treatments evaluated included 1,3-D (325 kg ai/ha) plus Pic (67 kg ai/ha) used either alone or with pebulate (4.5 kg ai/ha), napropamide (4.5 kg ai/ha), metolachlor (1.1 and 2.3 kg ai/ha), lactofen (2.3 kg ai/ha), or flazasulfuron (0.4 kg ai/ha). Pebulate was consistently more effective in controlling purple nutsedge than the other herbicides tested. Purple nutsedge was more effectively controlled with C-17 in combination with pebulate than with the fumigant alone. Shallow incorporation of pebulate failed to improve weed control and tomato fruit yield. Nomenclature: Chloropicrin; 1,3-dichloropropene; flazasulfuron; lactofen; metolachlor; napropamide; pebulate; purple nutsedge, Cyperus rotundus L. #3 CYPRO; tomato, Lycopersicon esculentum Mill. ‘Solar Set’. Additional index words: Flazasulfuron, lactofen, methyl bromide, metolachlor, napropamide, pebulate, soil fumigant. Abbreviations: C-17, 1,3-D + Pic (87:13); 1,3-D, 1,3-dichloropropene; MBr, methyl bromide; Pic, chloropicrin; WAT, weeks after treatment.

Effect of High Tunnels on the Growth, Yields, and Soluble Solids of Strawberry Cultivars in Florida

Two studies were conducted to compare the effects of high tunnel and open-field production on the growth, fruit earliness, yield, and soluble solid content of Florida strawberry cultivars. Three strawberry cultivars and two production systems were tested inside high tunnels and in open fields. The cultivars were ‘Strawberry Festival’, ‘Winter Dawn’, and ‘Florida Elyana’. Production systems and cultivars significantly affected strawberry early and total yields, but the interaction between both factors was not significant. Early yields increased by up to 54% inside high tunnels in comparison with those from open fields. Strawberry total marketable yields maximized inside high tunnels in comparison with open fields, with up to 63% fruit weight increments. Fruit yields after freezing events and soluble solid contents were also increased inside high tunnels. Using high tunnels in Florida for strawberry production might benefit growers by improving earliness and providing a competitive edge in the market, reducing sprinkler irrigation use for freeze protection, hence lowering fruit damage and fuel or electricity costs, and the incidence of foliar and fruit diseases.

Mechanisms of interference of smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) on lettuce as influenced by phosphorus fertility

Abstract Greenhouse studies were conducted to assess the intensity of smooth pigweed and common purslane aboveground interference (AI) and belowground interference (BI) with lettuce and to determine primary mechanisms of interference of each species as affected by P fertility rates. Lettuce was transplanted in mixtures with either smooth pigweed or common purslane according to four partitioning regimes: no interference, full interference, BI, and AI. Soil used was low in P for optimum lettuce yields, therefore P was added at rates of 0, 0.4, and 0.8 grams of P per liter of soil. Shoot and root biomass and plant height were measured for each species, as well as P tissue content. The data obtained indicated that smooth pigweed interfered with lettuce primarily through light interception by its taller canopy. A secondary mechanism of interference was the absorption of P from the soil through luxury consumption, increasing the P tissue content without enhancing smooth pigweed biomass accumulation. In contrast, common purslane competed aggressively with lettuce for P. Because the weed grew taller than lettuce, light interception was a secondary interference factor. Nomenclature: Common purslane, Portulaca oleracea L. POROL; smooth pigweed, Amaranthus hybridus L. AMACH; lettuce, Lactuca sativa L.

Effect of Tomato Packinghouse Wastewater Properties on Phosphorus and Cation Leaching in a Spodosol

Land application of wastewater is a common practice. However, coarse-textured soils and shallow groundwater in Florida present favorable conditions for leaching of wastewater-applied constituents. Our objective in this study was to determine phosphorus (P) and associated cations (Ca, Mg, K, Na) leaching in a Spodosol irrigated with tomato packinghouse wastewater. We packed 12 polyvinyl chloride soil columns (30 cm internal diameter × 50 cm length) with two soil horizons (Ap and A/E) and conducted 30 sequential leaching events by irrigating with wastewater at low (0.84 cm d), medium (1.68 cm d), and high (2.51 cm d) rates. The control treatment received deionized water at 1.68 cm d Leachate pH was lower (6.4-6.5) and electrical conductivity (EC) was higher in the wastewater-treated columns (0.85-1.78 dS m) than in the control treatment (pH 6.9; EC, 0.12 dS m) due to the low pH (6.2) and high EC (2.16 dS m) of applied wastewater. Mean leachate P concentrations were greatest in the control treatment (0.70 mg L), followed by the high (0.60 mg L) and low and medium wastewater-treated columns (0.28-0.33 mg L). Leachate concentrations of Na, Ca, Mg, and K were significantly ( < 0.05) greater in wastewater-treated columns than in the control. Concentrations of P, Na, and K in leachate remained lower than the concentrations in the applied wastewater, indicating their retention in the soil profile. In contrast, leachate Ca and Mg concentrations were greater than in applied wastewater during several leaching events, suggesting that additional Ca and Mg were leached from the soil. Our results suggest that tomato packinghouse wastewater can be beneficially land-applied at 1.68 cm d in Floridas Spodosols without significant P and cation leaching.

Influence of Nitrogen Fertilization on the Competitive Interactions of Cilantro (Coriandrum sativum) and Purple Nutsedge (Cyperus rotundas)

ABSTRACT The influence of nitrogen fertilization on the relative competitiveness of cilantro and purple nutsedge was determined using a single-density replacement series at 116 plants/m2. At the tested substitutive cilantro:purple nutsedge population proportions (100:0, 75:25, 50:50, 25:75 and 0:100) and four nitrogen application rates (0, 36, 72 and 108 kg/ha), the relative crowding coefficient indicated both species were equally aggressive at the 50:50 proportion after 40 days with 0 or 36 kg N/ha. As nitrogen was increased to 72 and 108 kg/ha, however, the competitiveness of purple nutsedge was enhanced (about 15 times more competitive than cilantro).

Influence of Nitrogen Fertilization Rates on the Performance of Strawberry Cultivars

Two sets of studies were conducted to examine the response of “Strawberry Festival” and “Winter Dawn” strawberries (Fragaria x ananassa Duch.) to different nitrogen (N) rates. The first set of studies consisted of two trials conducted during the 2005–06 and 2006–07 growing seasons. N rates were 0.5, 0.7, and 0.9 kg/ha per day (75, 105, and 135 kg/ha per season). The second set of studies was conducted during the 2006–07 and 2007–08 growing seasons. Nitrogen rates were 0.9, 1.4, and 2.0 kg/ha per day (75, 210, and 300 kg/ha per season) using the same cultivars. During the first set of studies, canopies of “Strawberry Festival” were 30% and 10% wider than “Winter Dawn” at 6 and 12 weeks, whereas N rates linearly increased canopy diameters of both cultivars. There was a significant cultivar by N rate interaction for total marketable fruit weight. Increasing N rates from 0.5 to 0.9 kg/ha per day linearly improved total marketable fruit weights of “Strawberry Festival,” but not those of “Winter Dawn.” For the second set of studies, N rates only influenced strawberry plant canopy diameters, but not early and total marketable fruit weight and number. There were no differences between the total marketable fruit weights of both cultivars. The data showed that the response of different strawberry cultivars depends on the range of N rates used for fertilization.

Weed Management with Oxyfluorfen and Napropamide in Mulched Strawberry

Two trials were conducted to evaluate the effects of herbicide and mulch on weed management and strawberry yield. Napropamide at rates of 4.50, 6.75, or 9.00 kg ai/ha; oxyfluorfen at 0.57 kg ai/ha; and napropamide plus oxyfluorfen at 4.50 plus 0.57 kg/ha were applied pretransplant on pressed beds covered with either low-density polyethylene mulch or virtually impermeable film. There was no herbicide by mulch interaction. Mulch types had no influence on weed counts and fruit yield, whereas herbicides affected both variables. The napropamide plus oxyfluorfen treatment resulted in the highest fruit number and weight, increasing yield by 20% with respect to the nontreated control. This herbicide combination provided the best weed suppression. Nomenclature: Napropamide; oxyfluorfen; strawberry, Fragaria × ananassa Duch. Additional index words: Acetamides, crabgrass, diphenylethers, interference, mulch, primrose, ragweed. Abbreviations: GCREC, Gulf Coast Research and Education Center; WAP, weeks after planting.

Strawberry Production in Mild Climates of the World: A Review of Current Cultivar Use

The supply of strawberry (Fragaria x ananassa) cultivars in the world can be restricted by several factors, such as environmental adaptation (mainly latitude), type of bearing (short-day and day-neutral cultivars), and industry strategies, among others. This review selected the area between the 42°north and south parallels as a production area of mild climates with somewhat similar conditions. A compilation was done about the current situation of the strawberry industry focusing on cultivar utilization in the U.S. (California and Florida), Mexico, Chile, Argentina, Brazil, Uruguay, Portugal, Spain, France, Italy, Morocco, Egypt, Turkey, China, Japan, and Australia. These countries represent over 85% of the world production. The day-neutral cultivar supply currently is very limited in comparison with short-day utilization. There is significant evidence of a successful utilization of cultivars, such as ‘Albion’, ‘Florida Festival’, ‘Florida Fortuna’, ‘Splendor’, and ‘Sabrosa’. Japanese cultivars have predominance in China and Japan.

Purple Nutsedge (Cyperus rotundus) Control with Fumigant and Pebulate Combinations in Tomato1

Field trials were conducted to determine the effect of fumigant-pebulate combinations on purple nutsedge density in fresh market tomato. Treatments consisted of methyl bromide plus chloropicrin (MBr plus Pic) [67:33] at rates of 270 and 130 kg/ha, respectively; Pic plus pebulate at 400 and 4.5 kg/ha, respectively; metham (MNa) plus pebulate at 485 and 4.5 kg/ha, respectively; dazomet plus pebulate at 950 and 4.5 kg/ha, respectively; and 1,3-dicholopropene plus Pic (C-17) [87:13] plus pebulate at 392 and 4.5 kg/ha, respectively. At 12 wk after treatment, MBr plus Pic controlled purple nutsedge more effectively (10 plants/m2) than the fumigant-pebulate combinations (50 to 70 plants/m2). Compared to MBr plus Pic, Pic plus pebulate had a 14% lower marketable yield. No differences in marketable yield were noted with dazomet plus pebulate or C-17 plus pebulate compared to MBr plus Pic. However, MNa plus pebulate produced a 15% higher yield than MBr plus Pic. Additionally, MNa plus pebulate had 15% higher marketable fruit weight than MBr plus Pic. Nomenclature: Purple nutsedge, Cyperus rotundus L. #3 CYPRO; tomato, Lycopersicon esculentum Mill. ‘Sunny’. Additional index words: Methyl bromide, chloropicrin, metham, dazomet, 1,3-dichloropropene. Abbreviations: MBr, methyl bromide; MNa, metham; 1,3-D, 1,3-dichloropropene; Pic, chloropicrin; C-17, 1,3-D plus Pic (87:13); MITC, methylisothiocyanate; WAT, weeks after treatment.