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Three different types of pickling cucumber (Cucumis sativus) were planted in the field with 4 replications in a randomized complete block design. The cultivars selected were standard leaf, “little leaf”, and standard X “little leaf” crosses. The growth of populations of cucumber fruit from each of the three types was measured over a 14 day period which included the optimum harvest date for mechanically harvesting the fruit. A plant sample one m2was randomly selected, the population of fruit diameter and length in each sample was measured daily. The standard leaf types were the first to reach a harvest date. The standard X “little leaf” crosses were next, followed by the “little leaf” cultivar. The differences in days to harvest could be 14 days or more between the standard and “little leaf types. The distribution of fruit by number and volume will be presented. Using this information a harvest date for maximum economic return can be predicted for each of the cultivars.
Pickling cucumber production has steadily shifted to machine harvest as availability and cost of labor have become limiting factors. In a once over harvest, one needs to schedule harvest for optimum yield and economic return. This becomes a critical factor when one is scheduling both equipment and planting schedules. To predict the time for mechanical harvest of pickling cucumbers, one needs to know the relative fruit growth rates. Previously two cultivars were grown in the greenhouse and they were Calypso and H-19, a little leaf cultivar. Growth rates of individual fruit and combinations of two fruit at adjacent nodes were measured. The cultivar H-19 had overall slower growth rates than Calypso but the competition from adjacent fruit was less in H-19 than Calypso. The experiment was repeated with plants in the field and similar results were obtained. Data will be presented showing the growth rates of field grown fruit for individual and combinations of adjacent fruit. Growth rates were recorded for a population of fruit within a square meter. This data will be compared to the growth rates for individual fruit.
Pumpkin cultivar trials were held in 2003 and 2004 at the Agricultural Experiment Station Fayetteville, AR. 18 cultivars were direct seeded the 4th week of June. Plots 8 plants each, spaced 3 ft apart, 12 ft between rows were randomly replicated 6 times. Pumpkin fruit were harvested October 1 and evaluated for number, size shape, and quality. Plots were irrigated by drip irrigation and standard production practices were followed. During 2004 the same practices were followed except plots were planted during the second week of July. In 2003 large fruited pumpkins yielded 700 to 1950 fruit per acre. Howden, the industry standard yielded 700 fruit, averaging 16 lb each, with a gross return of $700/acre. Cultivar fruit size ranged from 15 to 27 lb, and yields ranged from 10200 to 52000 lbs to the acre. Based on the 1 Oct. 2003 prices from USDA AMS, gross returns ranged from $744 to $1760 per acre. Specialty types Jack be Quick, Rouge, and Long Island Cheese yielded 15700, 1800, and 1470 fruit per acre valued at $2100, 1950, and 3400 respectively. Excessive rain in June 2004, and cooler that normal weather during July and early August significantly affected quality and yields of pumpkin fruit. Fruit number and size per plot were reduced up to 75%. Yields ranged from 10% to 20% of 2003 yields. Fruit quality was significantly affected making most of the fruit harvest unmarketable due to immaturity and size.
Abstract
The leaf roll-necrosis disorder has been identified in collections of lilac (Syringa vulgaris L.) in or near the cities of New York, Philadelphia, and Boston. Observed symptom differences among lilacs at 6 sites were largely quantitative, indicating the occurrence of incitants common to all locations. Activated charcoal and 4,4’-dioctyldiphenylamine filter chambers applied to branches reduced injury and provided corroborating evidence that air pollutants, including oxidant-type, were causal factors. Monitoring data from New York City and Philadelphia revealed progressively decreasing pollutant levels in recent years that coincided with decreases in severity of the disorder. Fluoride was not a causal agent, based on low levels in leaves. In experimental fumigations of lilac clones, although the results were inconclusive regarding identification of causal pollutants, ozone and sulfur dioxide induced some symptoms of the disorder. The occurrence of additional field symptoms suggested the involvement of other, as yet unidentified, phytotoxic pollutants.
Scientists have sought to stimulate plant growth using carbonated irrigation water for more than 100 years. The mechanisms by which carbonated water may increase plant productivity and the influence of environmental and cultural growing conditions on those mechanisms are not completely understood. Several greenhouse and field studies have demonstrated that carbonated irrigation water can increase crop yield significantly while others have shown that carbonated irrigation water does not influence plant productivity. It is unlikely that carbonated irrigation water will be recommended commercially until the conditions are delineated under which a positive and economically advantageous growth response is ensured.
Southernpea [Vigna unguiculata (L.) Walp.] is the main source of protein in humid and subhumid tropics, but production is limited by low and erratic rainfalls. This potential calls for greater management of water deficit stress through timely irrigation and greater understanding of crop response to adverse environmental conditions. The objectives of this study were to: identify growth stages of southernpea sensitive to water deficit, estimate critical length of water deficit detrimental to southernpea during each stage, and describe physiological and morphological responses of southernpea to water deficit stress. In this study, two southernpea cultivars, `AR.91-285' and `Coronet', were used to examine the effect of water deficit stress on seed yield, number of pods per plant, number of seeds per pod, pod length, and hundred seed weight during three stages of growth. The greenhouse and field results for these parameters indicated that the vegetative stage was the least sensitive to water deficit stress, followed by podfilling and flowering stages. However, pod filling stage was found to be less sensitive than vegetative stage beyond 21 days of stress. The critical length of water deficit causing yield reduction appeared to be 7 days for flowering and pod filling stages and 14 days for vegetative stage. `Coronet' was less sensitive to water deficit stress than `AR.91-285'. Reduced plant size, change in leaf color, and wilting were plant responses during the vegetative stage. Leaf senescence, flower abscision, fewer and shorter pods, and early pod maturity were observed plant responses during the reproductive stages. We observed a general decline in stomatal conductance and net CO2 assimilation with increasing days of stress. After 7 and 14 days of water-deficit-stress vegetative growth, stomatal conductance and net CO2 assimilation returned to the levels of control.
Growth of Pythium aphanidermatum, Pythium ultimum, Pythium irregulare, Phytophthora nicoctianae, Phytophthora cinnomomi, Fusarium oxysporum, Rhizoctonia solani and Thielaviopsis basicoli was inhibited in vitro when grown in a clarified V-8 nutrient solution containing 10% garlic extract. After exposure to 10% garlic extract for 3 days, all fungi and fungal-like organisms failed to grow after being washed and transferred to fresh cornmeal agar nutrient medium without garlic extract. When Sphagnum peat was inoculated with P. aphanidermatum and drenched with solutions containing varying concentrations of garlic extract, a single drench of 35% garlic extract or two drenches of 15% garlic extract were required to rid the substrate of viable P. aphanidermatum. In sand, a single application of 25% garlic extract or two applications of 10% garlic extract were required to rid the sand of viable P. aphanidermatum Thus, Sphagnum peat appeared to partially inactivate the components in garlic and did so to a greater extent than sand. Therefore, efficacy of garlic extract as a soil drench fungicide will be affected by the type of substrate or soil to which the garlic extract is applied.
Pythium aphanidermatum, Pythium irregulare, Pythium ultimum, Phytophthora cinnomomi, Phytophthora nicotianae, Rhizoctonia solani, Fusarium oxysporum, and Thielaviopsis basicoli grew and eventually covered petri plates containing a nutrient solution alone, but they failed to grow in nutrient solutions containing 10% or higher levels of garlic extract or a fungicide control. When plugs containing the fungal organisms exposed to 10% garlic (Allium sativum) extract solution for 48 h were washed and transferred to fresh cornmeal agar (CMA) growth medium, only F. oxysporum displayed growth. However, growth of F. oxysporum was limited to no greater than 2 mm from the original inoculum plug. After a single application of a solution containing at least 35% garlic extract or two applications containing 25%, viable P. aphanidermatum could not be recovered from a peat-based root substrate. By contrast, after a single application of a solution containing 25% garlic extract or two applications of 10%, we were unable to recover viable P. aphanidermatum from a sand substrate. When peat treated with increasing concentrations of garlic extract was placed on CMA inoculated with P. aphanidermatum, the first visual sign of a zone of inhibition occurred for peat saturated with 30% garlic extract solution and the zone increased as the garlic extract concentration increased. By contrast, when sand treated with increasing concentrations of garlic extract was placed on CMA inoculated with P. aphanidermatum, the first visual sign of a zone of inhibition occurred when saturated with 10% garlic extract solution. Therefore, the garlic extract was found to be fungicidal against a broad range of soilborne fungal organisms, but the concentration required to kill the organisms varied depending on root substrate.
Abstract
The enzyme-linked immunosorbent assay (ELISA) was used for the detection of tobacco ringspot virus (TRSV) in crude leaf extracts of geranium (Pelargonium × hortorum Bailey). An ELISA test protocol using a coating antibody concentration of 10 μg/ml, a 1000-fold dilution of antibody-enzyme conjugate, a substrate reaction time of 30-45 minutes, and a leaf test sample prepared in 20 volumes of phosphate buffer provided the best compromise between test reliability, conservation of reagents, and convenience. Using this protocol, significantly positive absorbante values (A405nm) were obtained with extracts from geraniums latently-infected with TRSV whereas color development form noninfected geraniums was negligible. Potentially, the ELISA represents a rapid, reliable, economical, and convenient method for virus-indexing geraniums commercially.
Alternative approaches to strawberry production that rely on cultural practices, biological controls, or natural products to reduce or replace off-farm chemical inputs are needed. Driving this growing interest are environmental concerns and rising production costs. Corn gluten meal (CGM), a byproduct of corn wet-milling, has weed-control properties and is a N source. The weed control properties of CGM have been identified in previous studies. The hydrolysate is a water-soluble, concentrated extract of CGM that contains between 10% to 14% N. Our objective was to investigate corn gluten hydrolysate as a weed control product and N source in `Jewel' strawberry production. The field experiment was a randomized complete block with a factorial arrangement of treatments and four replications. Treatments included application of granular CGM, CGM hydrolysate, urea, urea, and DCPA (Dacthal), and a control (no application). Granular CGM and urea were incorporated into the soil at a depth of 2.5 cm at rates of 0, 29, 59, and 88 g N/plot. Plot size was 1 × 3 m. The field experiment was conducted from 1995-1998. The source of nitrogen showed few effects for all variables measuring yield and weed control for all years. In general, the rate of nitrogen had little or no effect on total yield. However, the rate of nitrogen at 88 g N/plot showed an increase in average berry weight, leaf area, leaf dry weight, and weed control.