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- Author or Editor: D. J. Schuster x
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.
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.
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).
Response of tomatoes, Lycopersicon esculentum Mill., cv. Flora-Dade, to insecticides applied weekly or on demand and to 3 fertilizer levels, low (1 ×), medium (2 ×), and high (3 ×), was investigated in fall 1979 and spring 1980. Insecticide spray schedules had no effect on fruit size, marketable yield, and number of fruit per ha. The application of fertilizers above the 1 × level (148 kg/ha N, 30 P, 171 K, and 10 Mg) did not improve fruit size or increase tomato yields, but increased residual salt content of soil.
Twenty eight cultivars of Chrysanthemum morifolium Ramat. varied widely in foliar damage by the vegetable leafminer, Liriomyza sativae Blanchard. The total number of leafmines per 5 stems range from 1.3 for ‘Nob Hill’ to 15.5 for ‘Deep Valiant.’ In general, the standardtype cultivars had less leafminer damage than the spray-types. ‘Iceberg,’ a spray-type cultivar commonly grown in Florida, was more damaged than 11 spray and 9 standard cultivars. Foliage of ‘Bright Yellow Tuneful,’ ‘Divinity,’ ‘Pink Marble,’ ‘Nob Hill,’ ‘Albatross,’ ‘Sea Foam,’ and ‘Colonel Comfort’ had less damage in 2 experiments than foliage of ‘Iceberg.’
When cultivars of chrysanthemums, Chrysanthemum morifolium Ramat. were evaluated for resistance to the vegetable leafminer, Liriomyza sativae Blanchard, more differences among mean leafmines occured as each flowered than when biweekly evaluations were made before harvest. Pinched plants at this time also had more leafmines than unpinched plants, probably because of the increased maturation time and, hence, increased exposure to the leafminer population. When cultivars were evaluated simultaneously after they all had flowered, pinched plants had fewer complete leafmines on 2 of 10 cultivars.
Chrysanthemums (Chrysanthemum morifolium Ramat. cv. Manatee Iceberg) were grown in plots in the open or under polypropylene 25% shade cloth covered structures and were either treated with pesticides or untreated. The number of stems damaged by lepidopterous larvae before harvest was reduced and chemical control efficiency increased by pest exclusion. Shade cloth improved flower quality ratings 41% and 26%, respectively. In a second experiment, plots grown as before were treated either weekly or on demand (when larval densities were >1/1.5 m2) for Lepidoptera control. Significantly fewer stems were damaged in enclosed plots with 2 insecticidal applications than with 11 applications in unenclosed plots. Shading improved flower quality ratings 29% and 22%, respectively, for plots treated weekly or on demand.
In Fall 1990 and Spring 1991, the effects of four mulch colors, orange, yellow, aluminum, and white or black (fall or spring) were evaluated in the field on yields of `Sunny' tomato and numbers of insect vectors. In additional treatments, plants on the orange mulch were sprayed weekly with 2% mineral oil, and the yellow mulch was sprayed with soybean oil as needed during the season. In fall, plants were tallest (P ≤ 0.05) on the aluminum and yellow + oil treatments. The largest number of whiteflys (Bemisia argentifolii, Bellows and Perring) and the largest proportion of plants with virus symptoms were found on the white and yellow mulches. Fruit size and marketable yields were best with the yellow + oil treatment. In the spring, insect populations were low and only a few plants had virus symptoms. Plant heights, fruit size, and marketable yields were similar with all treatments.
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.
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.