Mountain Pride Research Articles

Rural Cooperatives Magazine, July/August 2011

Features- Taking the plunge; Pilot mountain pride forges links between growers and buyers; Hogs on the range; Market edge for the wedge; Finding a way; Banking on butanol; Split decision

Pollination of the red-hot poker Kniphofia laxiflora (Asphodelaceae) by sunbirds

Most of the species in the large African genus Kniphofia have floral traits that conform to the bird pollination syndrome, however there has been very little empirical work to confirm that birds are effective pollinators of Kniphofia species. From selective exclusion experiments, behavioural observations and pollen load analyses, we identified Amethyst Sunbirds ( Chalcomitra amethystina) and Malachite Sunbirds ( Nectarinia famosa) as the primary pollinators in two populations of Kniphofia laxiflora, with bees playing a smaller role. Bird visitors obtain moderate volumes (∼ 9 µl) of relatively concentrated (∼ 15%) hexose-rich nectar in the flowers. This species is shown to be genetically self-incompatible, and thus reliant on pollinator visits for seed set. Although mountain pride butterflies ( Aeropetes tulbaghia) have been identified as important pollinators of this species at two other populations, they did not occur at the two populations we studied.

Fresh-market Tomato Gas Exchange, Biomass, and Fruit Yield are Similar with Legume Cover Crops or Synthetic Nitrogen Fertilizer

Conventional production of tomatoes (Lycopersicon esculentum Mill.) requires substantial investments, intensive management and high inputs of nitrogen. High N rates invariably leave residual soil NO3-N with the potential of polluting ground water and posing health hazard to humans and animals. The objective of this study was to examine the value of cover crops as a substitute to synthetic N fertilizer in growing of tomatoes. The experimental treatments consisted of control (no N fertilizer or cover crop), Abruzzi rye (Secale cereale L), hairy vetch (Vicia villosa Roth), or crimson clover (Trifolium incarnatum L.) cover crop, and fertilization of N at 90 or 180 kg·ha-1. The treatments were replicated four times over 2 years in a randomized complete block experiment for growing `Mountain Pride' tomato on a Greenville fine sandy loam soil. The parameters used to evaluate the performance of tomato consisted of leaf area index (LAI), gas exchange (GE), above ground plant dry weight, number of fruits, dry weight of fruits, and marketable fruit yield. Tomato LAI was similar under legumes and N fertilizers. Hairy vetch and applied N at 90 kg·ha-1 influenced net photosynthesis (Pn) and transpiration (E) the most in both years at all stages of growth. Highest number of tomatoes were produced in hairy vetch and applied N at 90 kg·ha-1 plots. There was no significant difference in the above ground plant dry weight, fruit yield and dry weight of fruits between legumes and N fertilizers. The results suggested that the legume cover crops compared favorably to N fertilizers in promoting tomato growth and development and may have potential of substituting N fertilizers in fresh-market tomato production.

Economic Evaluation of Alternative Production Systems for Fresh-Market Tomatoes in the Mid-Atlantic Region

ABSTRACT Growing competition in tomato production and marketing, in conjunction with environmental concerns, requires innovative systems for fresh-market tomato production that are profitable and environmentally sound. This study evaluated the performance of fresh-market tomato production in systems representing different levels of off-farm inputs from 1997 to 1999 at the Beltsville Agricultural Research Center in Maryland. These experimental systems included different cultivars (‘Sunbeam’, ‘Mountain Pride’), soil mulch practices (bare soil, black polyethylene, compost, hairy vetch cover crop), and fungicide application schedules (no fungicide, weekly application, and application determined by TOMCAST model predictions). Gross margins were computed based on experimental yields, production costs from enterprise budgets for staked and tied tomato crops, and weekly prices at the Baltimore fruit and vegetable wholesale market. The Roy's safety-first criterion was used to compare the preferred tomato systems for a risk-averse tomato grower. Gross margins from the hairy vetch system were higher than those from the other mulch systems in 1997, but tended to be lower in the other years. The black polyethylene system had the least overall economic risk, and the hairy vetch system had the highest risk. Gross margins among fungicide treatments were highest in the TOMCAST and weekly-based systems compared to the no fungicide system across all years. Economic risk also was similar in the weekly and TOMCAST systems. These results indicate that the TOMCAST system may be implemented to reduce fungicide applications with no additional economic risk, but that the environmental benefits of the hairy vetch system may require more economic risk to growers.

Leonardite and Fertilizer Levels Influence Tomato Seedling Growth

New Mexico-mined raw leonardite was characterized by comparing it with the International Humic Substances Society's Standard Leonardite. In the first experiment, adding as little as 1/64 leonardite (v/v) to a sand medium increased tomato [Lycopersicon esculentum (L.) Mill. `Mountain Pride'] root and shoot growth compared with plants produced with fertilizer alone. Growth increased linearly with increasing leonardite levels, from 0% to 25%; however, 50% leonardite inhibited growth. In a second experiment, leonardite alone had no effect on plant height, shoot or root fresh and dry weight, or total leaf area, but stimulated growth when combined with a complete fertilizer. Adding 1/3 leonardite (v/v) (the highest level) and a complete fertilizer increased plant height 40%, total leaf area 160%, shoot fresh weight 134%, root fresh weight 82%, shoot dry weight 133%, and root dry weight 400%.

Responses of Potato (Solanum tuberosum), Tomato (Lycopersicon esculentum), and Several Weeds to ASC-67040 Herbicide1

The experimental sulfonylurea herbicide ASC-67040 was evaluated preemergence (PRE) and postemergence (POST) at 25 to 100 g ai/ha and PRE at 50 g/ha followed by ASC-67040 POST at 50 g/ha for broadleaf weed control in potato and tomato. In Virginia, ASC-67040 POST at 50 and 100 g/ha gave 70 to 98% control of common lambsquarters, common ragweed, and jimsonweed with slight (0 to 6%) ‘Superior’ potato and moderate (0 to 23%) ‘Agriset’ tomato injury. This crop injury was present primarily as chlorosis in terminal growth and disappeared by 3 wk after treatment (WAT). Potato tuber and tomato fruit yields were high in ASC-67040-treated plots. In North Carolina, ASC-67040 PRE and POST at 50 and 100 g/ha controlled 10 species of annual broadleaf weeds and grasses, and at 25 g/ha ASC-67040 gave greater than 90% control of most species. ASC-67040 injured ‘Fontenot’ potato more than Superior and caused 10 to 13% injury to ‘Mountain Spring’ tomato but did not injure ‘Mountain Pride’ tomato. Mountain Spring tomato recovered rapidly and produced high yields. In the greenhouse, yellow nutsedge control by ASC-67040 POST at 25 to 100 g/ha was 59 to 86% 3 WAT and yellow nutsedge height, dry weight, and regrowth dry weight were reduced by all rates. Lower rates of ASC-67040 might control weeds and cause less injury to potato and tomato.Nomenclature: ASC-67040 (proposed name fluazasulfuron), 1-(4,6-dimethoxypyrimidin-2-yl)-3-[3-trifluoromethyl-pyridin-2-yl)sulfonyl]urea; metolachlor; metribuzin; trifluralin; common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; jimsonweed, Datura stramonium L. # DATST; yellow nutsedge, Cyperus esulentus L. # CYPES; potato, Solanum tuberosum L. ‘Fontenot’, ‘Superior’; tomato, Lycopersicum esculentus L. ‘Agriset’, ‘Mountain Pride’, ‘Mountain Spring’.Additional index words: Metolachlor, metribuzin, trifluralin, Ambrosia artemisiifolia, Cyperus esculentus, Datura stramonium, AMBEL, CHEAL, CYPES, DATST.Abbreviations: ALS, acetolactate synthase (EC 4.1.3.18); DAP, days after planting; DATP, days after transplanting; DAT, days after treatment; fb, followed by; POST, postemergence; PPI, preplant incorporated; PRE, preemergence in potato and pretransplant surface applied in tomato; WAT, weeks after treatment.

Influence of Cover Crops and Inorganic Nitrogen Fertilization on Tomato and Snap Bean Production and Soil Nitrate Distribution

ABSTRACT Commercial vegetable production depends almost solely on inorganic fertilizers. In an era of environmental sensitivity, enrichment of soils with green manures and cover crops may reduce the dependence on these fertilizers while maintaining and enhancing crop yields. The objectives of this research were to determine (1) if supplemental nitrogen (N) at 60 or 120 kg · ha−1 following winter cover crops of wheat (Triticum aestivum L.) or crimson clover (Trifolium incarnatum L.) affect yield of tomato (Lycopersicon esculentum Mill.) and snap bean (Phaseolus vulgaris L.) grown in rotation; and (2) the distribution and retention of soil nitrates in the soil profile as affected by N fertilization and cover cropping. ‘Mountain Pride’ fresh market tomato and ‘Strike’ snap bean were grown in rotation for four years. Clover and wheat cover crops increased total marketable yield of ‘Mountain Pride’ tomato in one out of four years. Total marketable tomato yield increased as fertilizer N increased to 60 kg · ha−...

Involvement of Ethylene in Development of Chilling Injury in Fresh-cut Tomato Slices during Cold Storage

Experiments were conducted to determine if ethylene influences chilling injury, as measured by percentage of slices exhibiting water-soaked areas in fresh-cut tomato slices of `Mountain Pride' and `Sunbeam' tomato (Lycopersicon esculentum Mill.). Ethylene concentration in containers without ventilation significantly increased during storage at 5 °C, whereas little or no accumulation of ethylene occurred in containers with one or six perforations. Chilling injury was greatest for slices in containers with six perforations, compared to slices in containers with one perforation, and was over 13-fold greater than that of slices in control containers with no perforations. An experiment was also performed to investigate the effectiveness of including an ethylene absorbent pad in containers on subsequent ethylene accumulation and chilling injury. While ethylene in the no-pad controls increased continually during storage of both `Mountain Pride' and `Sunbeam' tomatoes at 5 °C under modified atmosphere conditions, no increase in accumulation of ethylene was observed in containers containing ethylene absorbent pads throughout storage. The ethylene absorbent pad treatment resulted in a significantly higher percentage of chilling injury compared with the no-pad control. In studies aimed at inhibiting ethylene production using AVG during storage of slices, the concentration of ethylene in control containers (no AVG) remained at elevated levels throughout storage, compared to containers with slices treated with AVG. Chilling injury in slices treated with AVG was 5-fold greater than that of controls. Further, we tested the effect of ethylene pretreatment of slices on subsequent slice shelf life and quality. In slices treated with ethylene (0, 0.1, 1, or 10 μL·L-1) immediately after slicing, ethylene production in nontreated controls was greater than that of all other ethylene pretreatments. However, pretreatment of slices 3 days after slicing resulted in a different pattern of ethylene production during storage. The rate of ethylene production by slices treated with 1 μL·L-1 ethylene 3 days after slicing was greater during storage than any of the other ethylene treatments. With slices pretreated with ethylene, both immediately and 3 days after slicing, the rate of ethylene production tended to show a negative correlation with chilling injury. Chemical name used: 1-aminoethoxyvinylglycine (AVG).

642 Three-year Effects of Nitrogen Sources on Plant Component and Yields of Tomato

This study was conducted over 3 years for the purpose of determining how tomato yield, fruit number, and vegetative dry matter are affected by winter cover crop and recommended fertilizer N rates. The following winter-spring fertility treatments were applied using randomized complete-block design with four replications: 1) 0 N winter–0 N spring, 2) 0 N winter–90 kg N/ha spring, 3) 0 N winter–180 kg N/ha spring, 4) 0 N winter+abruzi rye–0 N spring, 5) 0 N winter+hairy vetch–0 N spring, and 6) 0 N winter+crimson clover–0 N spring. In Spring of 1996, 1997, and 1999 `Mountain Pride' tomatoes were transplanted in all plots. Total yield was compiled over 6 weeks, while seasonal fruit number and plant dry matter were measured at final harvest. In 1999, highest plant dry matter (350.5 g/plant) was produced by vetch and highest fruit number (36/plant) by 180 kg N/ha. Total yield were highest (85.8 Mg/ha) at 90 kg N/ha in 1996 and lowest (35.3 Mg/ha) for control during 1997. Organic nitrogen from hairy vetch and crimson clover affected plant dry weight, tomato number and yield comparable to those receiving synthetic N. Results over three years for this study indicate that legume cover crops can be an effective N fertilizer in supporting plant dry matter, fruit number and fruit yield of tomato.

398 Three Years of Tomato Gas Exchange Response to Nitrogen Sources at Fruiting

The purpose of this 3-year study was to compare organic and inorganic N sources for promoting gas exchange (GE) in tomato at fruiting. Measurements of transpiration (E), photosynthesis (Pn) and internal leaf CO2 concentration (Ci) are reported. The following winter–spring fertility treatments were applied using randomized complete block design with four replications: 1) 0 N winter–0 N spring, 2) 0 N winter–90 kg N/ha spring, 3) 0 N winter–180 kg N/ha spring, 4) 0 N winter+abruzi rye–0 N spring, 5) 0 N winter+hairy vetch–0 N spring, and 6) 0 N winter+crimson clover–0 N spring. In spring of 1996, 1997, and 1999, `Mountain Pride' tomatoes were transplanted in all plots. Maximum E (14.3 μmol·m–2·s–1), Pn (22.8 μmol CO2/m2 per s), and Ci (352.2 μL·L–1) occurred in 1997, 1996, and 1999, respectively. In general, E was affected mostly by treatments 2, 3, 5, and 6 and Pn by treatments 2 and 5, while treatments 1 and 4 affected Ci the most. Results indicate that N from both legumes and synthetic fertilizer enhanced GE of tomato similarly.

470 Ethylene Inhibits the Development of Chilling Injury in Fresh-cut Tomato Slices during Storage at Low Temperature

Experiments were conducted to determine if ethylene influences chilling injury, as measured by percent of slices showing some water-soaked areas and associated fungal growth in fresh-cut tomato slices (Lycopersicon esculentum Mill.; cvs. Mountain Pride and Sunbeam). Ethylene concentration in containers without a perforation (perforations were made by piercing the lid of the container forming a 0.7-mm hole) significantly increased during storage at 5 °C, while little or no accumulation of ethylene occurred in containers with from one to six perforations. Chilling injury was greatest in slices in containers with six perforations, compared to slices in containers with one perforation an,d was over 12-fold greater than that of slices in control containers with no perforations. The percent ofage visible fungal growth of slices was roughly correlated with the degree of chilling injury. An experiment was also performed to investigate the effectiveness of including an ethylene absorbent pad in containers on subsequent ethylene accumulation and chilling injury. While ethylene in the no-pad control increased continually during storage at 5 °C under modified-atmosphere conditions, no increase in accumulation of ethylene was observed in containers containing ethylene absorbent pads throughout storage with `Sunbeam' and `Mountain Pride' tomatoes. The ethylene absorbent pad treatment resulted in a significantly higher percent of chilling injury and visible fungal growth compared with the no-pad control. In studies aimed at inhibiting ethylene production using 1-aminoethoxyvinylglycine (AVG) during storage of slices, the concentration of ethylene in control containers (no AVG) remained at elevated levels throughout storage compared to containers with slices treated with AVG. Chilling injury in controls was 5-fold greater than that in slices treated with AVG. All slices treated with AVG had visible fungal growth, while the percent of slices showing visible fungal growth in no-AVG controls was 54%. Furthermore, we tested the effect of ethylene pretreatment of slices on subsequent slice shelf-life and quality. In slices treated with ethylene (0, 0.1, 1, and 10 μL·L-1) immediately after slicing, ethylene production in untreated controls was greater than that of all other ethylene pretreatments. However, pretreatment of slices at 3 days after slicing resulted in a different pattern of subsequent ethylene production during storage. The rate of ethylene production by slices treated with 1 μL·L-1 ethylene at 3 days after slicing was greater during storage than any of the other ethylene treatments. With slices pretreated with ethylene both immediately and 3 days after slicing, the rate of ethylene production tended to show an negative correlation with chilling injury.

602 Influence of Tillage and N Source on Gas Exchange in Tomato

The purpose of this study was to evaluate the tillage method effects of N sources on gas exchange (GE) at the flowering, fruiting, and pre-senescence in tomato. Measurements of transpiration (E), stomatal conductance (gs), photosynthesis (Pn), and internal leaf CO2 concentration (Ci) were reported. The following fall/spring tillage and fertility treatments were applied: 1) fall-fallow/spring-moldboard, 2) fall-fallow/spring-moldboard + 90 kg·ha–1 N, 3) fall-moldboard + hairy vetch/spring-chisel, 4) fall-moldboard + hairy vetch/springchisel + 90 kg·ha–1 N, 5) fall-minimum till+hairy vetch/spring-chisel, and 6) fall-minimum till + hairy vetch/spring-chisel + 90 kg·ha–1 N. During the 2nd week of Apr. 1995, `Mountain Pride' tomato was transplanted in all plots. Maximum E (11.9 mmol·m–2·s–1), gs (1465.1 mmol·m–2·s–1), and Pn (22.23 μmolCO2/m2 per s) occurred at the fruiting and highest Ci (301.2 μL·L–1) at the flowering. Throughout the growing seaon, treatments 5 and 3 affected GE rates the most, while treatments 1 and 3 at flowering affected Ci the most. Results indicate that fall moldboard or minimum-till + hairy vetch/spring chisel had greatest influence on GE of tomato.

005 Investigations Into the Cause of Gold Flecking on the Surface of Ripe Tomato Fruit

In recent years there has been an increase in the incidence of “gold flecking,” which develops on the surface of ripe tomato fruit. Gold flecking looks like a light sprinkling of gold on the skin of the fruit. There are no lesions and the interior of the fruit is not affected. Usually, gold flecking is barely noticeable. In 1998, however, gold flecking was severe enough in some cases to cause economic losses. It has been suggested that gold flecking is due to use of the insecticide Asana or it may be a genetic disorder. The objective here was to determine if gold flecking is caused by Asana and/or is cultivar-dependent. Treatments consisted of three cultivars (Mountain Fresh, Celebrity, and Mountain Pride) and four insecticides (Asana XL, Karate 1 EC, Thiodan 50 WP, and a water control). There were two plantings. Only red fruit was harvested. For both plantings, there was more gold flecking in the control than any of the insecticide treatments. There were no differences among the insecticides. For the early planting, `Mountain Fresh' had more gold fleck than the other cultivars. In the late planting, there were no differences between cultivars. This study demonstrates that Asana was not responsible for gold flecking and actually reduced it compared to the control. These results also suggest that insects may play a role in gold flecking.

Tomato Growth and Yield Response to Cover Crop and Fertilizer Nitrogen

The goal of this study was to evaluate how tomato yield, vegetative dry matter, leaf area index (LAI), and photosynthesis (Pn) responded to winter cover crop and recommended fertilizer N rates. The following winter/spring fertility treatments were applied using randomized complete block design with four replications: 1) 0 N winter /0 N spring, 2) 0 N winter/90 kg·ha–1 N spring, 3) 0 N winter/180 kg·ha–1 N spring, 4) 0 N winter + abruzi rye/0 N spring, 5) 0 N winter + hairy vetch/0 N spring, and 6) 0 N winter + crimson clover/0 N spring. In Spring 1997, `Mountain Pride' tomatoes were transplanted in all plots. Whole plant dry matter, LAI and Pn were measured at flowering, fruiting and prior to senescence, while seasonal yield was compiled over 6 weeks. Tomatoes preceded by Vetch produced highest plant dry matter (243.0 g/plant) prior to senescence, highest LAI (3.07) at fruiting and highest P (8.98 μmol CO2/m2 per s) during flowering. Total yield were highest (60.9 Mg·ha–1) at 180 kg·ha–1 N and lowest (35.3 Mg·ha–1) in control. Supplemental N from legume and grain cover crops affected plant dry weight, LAI, Pn, and yield comparable to those receiving synthetic N. Results of this study indicate that cover crop treatments were as effective as N fertilizer in supporting tomato yield, vegetative growth, LAI, and photosynthesis.

Winter Legume Cover for Sustainable Tomato Production

The purpose of this study was to compare the efficacy of winter cover cropping with legumes for replacing synthetic N fertilization in tomato production. The following winter/spring fertility treatments were applied: 1) 0 N winter/ 0 N spring, 2) 0 N winter/90 kg·ha-1 N spring, 3) 0 N winter/180 kg·ha-1 N spring, 4) 0 N winter+rye/0 N spring, 5) 0 N winter+hairy vetch/0 N spring, and 6) 0 N winter+crimson clover/0 N spring. In the spring of 1996, tomato cultivar `Mountain Pride' was planted in all plots. The effects of different treatments on plant dry weight and fresh fruit yields were determined. Tomato following legumes or supplied with 90 kg·ha-1 fertilizer N produced highest plant dry weight, while 0 N winter/0 N spring and 0 N winter+rye/0 N spring produced plants with least dry weights. Treatments differed in a similar fashion also for fresh fruit yields. The results suggested that winter legumes were at par with commercial N fertilizer in supplying needed inorganic N to the succeeding tomato crop soil.

Effect of N Source on Photosynthesis and Plant Dry Matter Yield of Tomato

The objective of this study was to determine if winter legume or grain cover could support net photosynthesis (Pn) and plant dry matter production comparable to recommended rate of synthetic N. The following winter/spring fertility treatments were applied: 1) 0 N winter/0 N spring, 2) 0 N winter/90 kg·ha–1 N spring, 3) 0 N winter/180 kg·ha–1 N spring, 4) 0 N winter+abruzi rye/0 N spring, 5) 0 N winter+hairy vetch/0 N spring, and 6) 0 N winter+crimson clover/0 N spring. `Mountain Pride' tomato was planted in all plots in spring. Plant dry weight and Pn were measured at flowering, fruiting and prior to senescence. The highest Pn (22.78 μmol CO2/m2 per s) and leaf dry weight (115.2 g/plant) were obtained at fruiting, while highest branch dry weight (194.5 g/plant) occurred prior to senescence. There was significant increase in plant dry weight during reproductive growth phase. Tomato plants receiving supplemental N from crimson clover or hairy vetch had Pn and plant dry weight comparable to those receiving synthetic N. The results of this study indicated that legume cover crops were as effective as commercial N fertilizer for supporting photosynthesis and vegetative growth of tomato.

Yield and Nitrogen Concentration of Tomato following Winter Cover Crops

Our objective was to determine the effect of winter cover crops on the yield and N concentration of the following crop of tomato. No commercial fertilizer was applied to the tomato crop. Cover crops were planted in fall in a randomized complete-block design with control (fallow), rye, hairy vetch, and crimson clover treatments. `Mountain Pride' tomato was planted in spring after incorporating cover crops into the soil. Soil inorganic N content during the tomato growing season was significantly affected by the nature of cover crops planted during winter. Tomato planted after legumes had significantly greater amounts of inorganic N available for uptake compared to nonlegume or control. A rye cover crop did not have any effect on the yield of the ensuing tomato crop. On the contrary, a 15% increase in tomato fruit yields resulted from cover cropping with legumes. The N concentration in fruit in all treatments was similar. However, tomato grown after rye had significantly lower vegetative N concentration. Total N uptake was significantly greater in tomato succeeding legumes compared to nonlegume or fallow. It was concluded that by adding inorganic N into the soil, legumes increased the fruit yield and N uptake of the succeeding tomato crop.

Gas Exchange in Tomato in a Cover Crop–Tomato Cropping System

Our objective was to determine the effect of cover crops on the gas exchange activities of a succeeding crop of tomato. No commercial N fertilizer was applied, and the mineralization of cover crops provided the sole source of supplemental N for the tomato crop. Cover crops were planted in randomized complete blocks on 8 Sept. 1994, with treatments consisting of control (fallow), rye, hairy vetch, and crimson clover. A tomato cultivar Mountain Pride was transplanted in the field on 18 Apr. 1995. The gas exchange rate of tomato was measured at flowering (6 June), fruiting (13 July), and senescence (10 Aug.) with infrared gas analyzer using a steady-state gas exchange system. The highest stomatal conductance (gs) and CO2 exchange rate (CER) was obtained during flowering and fruiting, respectively. The tomato plant following a legume cover crop conducted water vapor at a significantly higher rate than those preceded by rye or fallow. The CER of tomato planted behind a legume cover crop was also higher compared to those following rye or fallow. The gs ranged from 384 to 1146 mmol·m–2·s–1, and CER varied from 5.7 to 17.8 mol·m–2·s–1 depending on the preceding cover crop and the stage of growth of the tomato plant. From the results of this study, it was apparent that, while legume cover crops increased the gas exchange activities of the ensuing tomato crop, nonlegumes had no such effect.

Control of Tomato Pinworm in South Florida, Spring 1995

Abstract ‘Mountain Pride’ tomato were transplanted on to Rockdale soil in Homestead, FL on 15 March 1995. Plant beds were 3 ft. wide and covered with 1.5-mil thick black polyethylene mulch. Beds were fumigated with 240 lb./acre of 67% methyl bromide – 33% chloropicrin 6 d before planting. Plant spacing was 1.5 ft along the center of the bed and 6 ft in between the beds. Plants were irrigated twice weekly using sprinkler system delivering about 2 inch each time. Fertilizer was applied at 200-50-240-40 lb./acre N-P-K-micronutrient mix. Treatment plots were 20 ft by two rows arranged in RCB design with four replications. Treatments evaluated were: 1) Fenoxycarb (0.6 lb. [AI]/acre), 2) CGA-215944 (0.1 lb. [AI]/acre), 3) combination of treatments 1 & 2, 4) oxamyl (0.5 lb fAI]/acre), 5) Lannate (0.5 lb. [AI]/acre); 6) Baythroid (2.8 oz./acre); 7) ABG 6347 (1.0 lb./acre), 8&9) Larvin (0.25 & 0.40 lb. [AI]/acre), and 10) a nontreated control. Treatments were applied on 13, 19, and 28 May, and 5 June 1995 using a backpack sprayer with two nozzles per row at 30 psi. delivering 100 gallons/acre. Evaluation of insecticides was made by counting total numbers of pinworms on randomly collected 20 leaves, 2 leaves per plant, in treatment plot 24 h after each application.

Development of a Polyethylene Mulch System that Changes Color in the Field

A polyethylene mulch system that changes its predominant surface color from black to white in the field has been developed and used to grow tomatoes (Lycopersicon esculentum Mill. cv. Mountain Pride) and squash [Cucurbita pepo var. melopepo (L.) Alef. cv. Dixie Hybrid]. The system uses a black photodegradable polyethylene mulch placed on top of a white nondegradable polyethylene mulch (photodegradable mulch overlay system). As the black photodegradable mulch degrades with increasing exposure to radiation, the white mulch surface is exposed. Differences among plastic systems in the percentage that breaks down may be explained by differential shading of the mulch by the vegetative growth of the crops. None of the formulations of the Plastigone brand photodegradable mulches in the photodegradable mulch overlay system had an effect on tomato or squash production. As the color of the system changed from black to white, soil temperatures under the mulch decreased. Tomato production remained unaffected in one of the two years as long as the mulch remained black for at least the first 20 days during that season. In year 2, the controlled mulch system color change affected neither tomato nor squash production relative to nondegradable white and black mulches used as controls.