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  • Author or Editor: A.A. Csizinszky x
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The impact of two insecticide spray application schedules (weekly or on demand), three N and K rates [1x, 1.5x, and 2x; 1x = (kg·ha-1) 130N-149K], and two transplant container cell sizes [small, 21 mm wide × 51 mm deep (7.5 cm 3), and large, 38 mm wide × 70 mm deep (33.7 cm”)] on `Market Prize' cabbage (Brassica oleracea L. Capitata group) yield was investigated in Fall and Winter 1982-83 and Spring 1983. Fenvalerate was sprayed at 0.112 kg·ha-1. For the weekly schedule, 10 sprays were applied in fall and winter and nine in spring; for the on-demand schedule, two sprays were applied in both seasons. There were more insect-damaged heads in both seasons in the plots sprayed on demand than in those sprayed weekly. In fall and winter, the combination of a weekly schedule with 1.5x and 2x N and K rates increased marketable yields over those of the on-demand schedule. Marketable yields at the 1.5x and 2x N and K rates were similar for plants in small or large transplant container cells, but the lx N and K rate applied to plants in small cells reduced yields. In spring, both application schedules produced similar yields, but yield increased with increasing N and K rates and large transplant container cells. Insecticide application schedule and cell size did not affect leaf nutrient concentration significantly, but increasing N and K rates resulted in higher N, P, and K leaf concentrations. Concentrations of N and K in the soil at 42 days after transplanting (DAT) were higher with increasing N and K rates. At harvest (86 DAT), only K concentrations had increased with N and K rates. Chemical name used: cyano (3-phenoxyphenyl) methyl 1-4 chloro-alpha-(1-methylethyl benzeneacetate) (fenvalerate).

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Field studies were conducted for three seasons, Fall 1994, Spring 1995, and Fall 1995 on the effect of UV-reflective films (mulches) on fruit yields and on the silverleaf whitefly [Bemisia argentifolii (Bellows and Perring)] of staked, fresh-market tomatoes (Lycopersicon esculentum Mill). The UV-reflective mulches were metallized aluminum (ALU) and painted aluminum (PAL) on either black or white plastic film. The AL and SL mulches were evaluated with and without a white (fall) or black (spring) 25-cm-wide painted band in the bed center. Controls were the conventional white (fall) or black (spring) polyethylene mulches. Highest reflected energy (μmol·m–2·s–1) to the plants at 25 cm from the mulch surface was measured on the ALU without white painted band or on PAL on white or black mulch with white painted band. Lowest energy was reflected from the white or black controls. Whitefly populations in the fall were lower on the ALU than on the PAL mulches. In the spring, when whitefly populations were low, number of whiteflies on tomato leaves were similar with all treatments. The proportion of plants with symptoms of the silverleaf whitefly transmitted tomato mottle virus (TMoV) were highest on controls. Yields in the fall were similar with UV-reflective or with white mulch. In the spring, fruit size and marketable yields were greater (P < 0.05) on plants with PAL on white plastic film without black band than on black control.

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Two insecticidal spray frequencies, 0 and 3x per week, against the sweetpotato whitefly, Bemisia tabaci Gennadius, were evaluated at three K rates, 190, 380 and 760 kg.ha-1, for their effect on whitefly population, fruit yield and incidence of irregular ripening on tomato, Lycopersicon esculentum Mill., cv. Sunny. Whitefly populations were reduced with three weekly sprays, but not by K rates. Early yields were best with three weekly sprays and with the highest K rate. For the season, yield of extra large (≥ 70 mm diameter) fruit was reduced with three weekly sprays and with increasing K rates. Proportions of irregularly ripened fruits were similar with either spray frequency, but were reduced at the highest K rate.

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Field studies were conducted for three seasons, Fall 1994, Spring 1995, and Fall 1995, on the effect of ultraviolet (UV)-reflective films (mulches) on the silverleaf whitefly (Bemisia argentifolii Bellows and Perring), the incidence of tomato mottle virus (ToMoV), and on fruit yields of staked, fresh-market tomatoes (Lycopersicon esculentum Mill.). The UV-reflective mulches were metallized aluminum (aluminum) and painted aluminum (silver) on either black or white plastic film. The aluminum and silver mulches were evaluated with and without a white (fall) or black (spring) 25-cm-wide painted band in the bed center. Controls were the conventional white (fall) or black (spring) polyethylene mulches. Highest reflected energy (μmol·m–2·s–1) to the plants at 15 cm from the mulch surface was measured on the aluminum mulch with or without a white painted band. Lowest energy was reflected from the white or black controls and from silver on black mulches with or without a black painted band. Whitefly populations in the fall were lower (P ≤ 0.05) on the aluminum than on the silver mulches. In the spring, when whitefly populations were low, whiteflies were more numerous on the black control and silver on white, than on the aluminum mulches. In the fall seasons, the proportion of plants with symptoms of ToMoV transmitted by the silverleaf whitefly were higher on the controls than on the aluminum mulch. In the spring, the proportion of plants with symptoms was not affected by mulch treatments. Yields in the fall were similar with UV-reflective or white control mulches. In the spring, fruit size and marketable yields were greater (P ≤ 0.05) on plants with silver on white mulch than on the control black mulch.

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Field studies were conducted for three seasons, Fall 1988, and Spring and Fall of 1989 on the effect of six mulch colors: blue, orange, red, aluminum, white or black (fall or spring), and yellow on fruit yields and on insect vectors of `Sunny' tomato, In Fall 1988, in a single harvest, fruit size was greater and total marketable yields were higher with blue than with aluminum and yellow mulches. In Spring 1989 early yields of large (> 70 mm) and marketable fruit were higher with aluminum and red than with yellow and blue mulches. In Fall 1989 early yield of large fruit was higher with white than with yellow mulch. Early marketable yields were highest with white and aluminum mulches. Total yields of large fruits were highest with orange and blue mulches but marketable yields were similar with all six mulch colors. The fewest number of aphids, thrips and whiteflies were trapped on aluminum mulch. Blue mulch attracted the largest number of aphids and thrips. Red mulch attracted whiteflies. The three insects are important vectors of several virus diseases.

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Abstract

Fifty plant introduction lines of pepper were screened for resistance to curly top virus using the vector Circulifer tenellus Baker and a strain of virus known to be pathogenic on peppers Inoculations were done by caging either 3 or 15 viruliferous leafhoppers onto a leaf at the 4-true-leaf stage of growth. Four lines (PI 257053, PI 281297, PI 288938, and PI 357522) showed apparent resistance when inoculated by 3 leafhoppers, but non appeared resistant for more than a few days when inoculated by 15 leafhoppers. No correlation was found between leafhopper longevity on a plant and that plant’s resistance to the virus.

Open Access

Optimum economic yield is produced when nutrients in the proper amounts are supplied to the crop. Crop nutrient requirements (CNR) of essential elements have been determined for the major vegetables produced in Florida. However, for minor crops, such as muskmelon, little research has been conducted to determine the CNR, especially potassium. In many vegetables, yield has responded to increasing K rates when other elements were not limiting. Our objective was to determine the K fertility requirement for optimum yield of muskmelon and to evaluate the Mehlich-1 soil test calibration for soil testing low in K (<20 mg·kg–1). Experiments were conducted in the spring and fall seasons of 1995. Potassium at five rates (0, 56, 112, 168, and 224 kg·ha–1) was injected weekly, approximating the growth curve of `Galia' and `Mission'. There were significant yield responses to K fertilization for both cultivars during both seasons. During spring, average marketable yield was 14.5, 26.1, 31.9, 31.5, and 36.3 Mg·ha–1 and for fall, average marketable yield was 15.8, 32.9, 37.8, 37.2, and 36.4 Mg·ha–1 for the previously described K treatments, respectively. The cultivar response for both seasons was described by a linear-plateau model. In spring, yield was maximized with K at 116.8 and 76.3 kg·ha–1 for `Galia' and `Mission', respectively. In fall, K at 73.3 and 68.3 kg·ha–1 produced the peak response for the same cultivars. These results indicate that maximum yield of muskmelon in Florida can be obtained at considerably less K than the current recommendation of 140 kg·ha–1.

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Abstract

First introduced for strawberries in the late 1950s, polyethylene mulch has been used widely for vegetable culture in Florida (4, 5). Currently, about 40,000 ha of vegetables are produced in Florida using polyethylene ground mulches. A full-bed mulch system is used for most of the tomato, pepper, and strawberry crops in Florida (2, 3).

Open Access

Tomato (Lycopersicon esculentum Mill.) was grown with polyethylene mulch at five locations during a total of nine seasons to evaluate the effects of K source and K rate on fruit yield and leaf K concentration with drip and subsurface irrigation. K sources evaluated were KCl, K2SO4, and KNO3, and K rates varied from 0 to 400 kg·ha-1. Preplant soil K concentrations by Mehlich-1 extraction on the sandy soils and loamy sands used in the study varied from 12 mg·kg-1 (very low) to 60 mg·kg-1 (medium). In seven of the eight studies, K source did not significantly influence fruit yield or leaf K concentration. In the other study with subsurface irrigation at Bradenton in Spring 1992, marketable yields were significantly higher with KNO3 than with KCl as the K source. Tomato fruit yield responded to the application of K in all studies. At Gainesville, Quincy, and Live Oak, with drip irrigation on soils testing low to medium in K, maximum yields were produced with 75 to 150 kg·ha-1 K where the K was broadcast preplant. These rates were 25% to 30% higher than those predicted by soil test. At Bradenton and West Palm Beach on soils testing low to very low in K, where all or part of the K was applied in double bands on the bed shoulder with subsurface irrigation, yield responses were obtained to 225 to 300 kg·ha-1 K. These rates exceeded the maximum recommended K rate of 150 kg·ha-1. Tomato leaf tissue K concentrations increased linearly with increased rates of K application, but were not influenced by K source. These data suggest that the recommendation for K on soils testing low in K be increased from 150 to 210 kg·ha-1 and that this increase should suffice for tomatoes grown with either drip or subsurface irrigation.

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Abstract

Field studies were conducted over three seasons to determine the effect of N and K on susceptibility of tomato to bacterial spot. A factorial randomized complete block design consisting of four rates of N (167, 334, 501, and 668 kg·ha–1) and three rates of K (334, 668, and 1335 kg·ha–1) were used. Liquid fertilizer was injected via trickle irrigation. Increasing N rates reduced disease severity, whereas the effect of increasing K was inconsistent from season to season. The concentration of N in leaf tissue showed a significant negative correlation with disease severity, whereas the concentration of Ca in leaf tissue exhibited significant positive correlation with disease severity and negative correlation with N rate during two seasons of data collection.

Open Access