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Kentucky is one of seven states in the southeast evaluating 13 Asian pear cultivars for suitability to the region. The cultivars were planted on a (20′ × 10′) spacing in 1989 at three separate locations. Data on time of bloom, tree growth, fire blight susceptibility and fruit quality and yield were collected. This study demonstrates the variability seen in Asian pear cultivars in response to site. There was a significant site by cultivar interaction for fire blight. The Princeton site had significantly more fire blight than either Lexington or Quicksand. Four cultivars, Niitaka, Shin Li, Shinko and Shinseiki had low fire blight ratings which were not significantly different between the three sites. Asian pear growth rates were significantly different between the three sites, but cultivar growth rates were not. Tree growth rate showed a significant negative correlation to fire blight rating. That is infected trees did not grow much. Initial findings show Shinko, Shinseiki and Niitaka to have some tolerance to fire blight spread and to produce good yields of attractive fruit. However, Niitaka had a very tough skin with a tendency towards fruit cracking. The cultivar Shin Li which also had fire blight tolerance did not produce fruit or flowers.
Abstract
The sweet, juicy, red flesh of watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] is a popular dessert in Australia, while the bland, white, firm-textured flesh of pie-melons, also Citrullus lanatus (Thunb.) Matsum. and Nakai, is used in jam making. Red flesh color of watermelon is a monogenic trait and recessive to white (7). Both bitter and sweet forms of C. lanatus occur and are naturalized in inland areas of tropical and subtropical Australia (3, 9). Bitter fruit of commercial watermelon occasionally have appeared in markets in Australia. A mutation within a commercial cultivar has been considered as the source of plants producing bitter fruit (1,3,6). The nonbitter characteristic of fruit in commerce is conferred by a single recessive gene (1, 7). However, in bitter fruit of C. lanatus, the concentration of Cucurbitacin E glycoside, the principal compound sensed as bitterness (2, 5), is influenced by a modifier gene or genes (1, 7). The concentration of the glycoside in bitter fruit of Accession 242 (a wild type), and of the bitter mutant of the commercial cultivar Hawkes-bury, are 240-590 mg°kg−1 and 1500-2100 mg°kg−1, respectively, and 910-1240 mg °kg−1 in the F1 (1, 2). The concentration of Cucurbitacin E glycoside in nonbitter fruit of C. lanatus is reported to be 0 mg°kg−1 (1) and 60-90 mg°kg−1 (8).
Abstract
Postharvest flower fresh weight of Zinnia elegans Jacq. increased when held in solutions containing 200 mg liter-1 8-hydroxyquinoline citrate (8-HQC) and sucrose and decreased when held in deionized water. Ethylene biosynthesis was enhanced by holding flowers in solutions of 8-HQC + 1, 2% or 3% sucrose compared with deionized water where ethylene release was low initially and remained low. Carbon dioxide evolution declined sharply the first 2 days postharvest and remained low for flowers held in deionized water, but remained at initial levels for those held in 200 mg liter-1 8-HQC + 3% sucrose. Glucose, fructose, and sucrose in ray florets declined to levels barely detectable if flowers were held in deionized water but increased if held in 200 mg liter-1 8-HQC + 3% sucrose. The induction of ethylene biogenesis may be an injury response caused by sucrose.
Abstract
Susceptible tomato (Lycopersicon esculentum Mill.) cultivars in coastal Queensland may suffer substantial losses from bacterial wilt [Pseudomonas solanacearum (Smith 1896) Smith 1914 biovar III] from late spring to autumn (3). Verticillium wilt (Verticillium dahliae Kleb. race 1) can be a major disease from autumn to early spring. A hybrid cultivar, Redlands Summertaste (1), recently was released and is resistant to bacterial wilt, verticillium wilt, and fusarium wilt [Fusarium oxysporum Schlecht, f.sp. lycopersici (Sacc.) Snyder & Hansen race 1 and 2]. However, although this cultivar has high yields (75 to 92 t·ha–1), the jointed fruit attachment and indeterminate growth habit limit returns to growers who have high labor costs. ‘Redlander’ was developed as an inbred cultivar to provide a locally adapted tomato in which resistances to bacterial, verticillium, and fusarium wilts are combined with good fruit quality, jointless pedicel, and determinate growth habit.
Buffalograss [Buchloë dactyloides (Nutt.) Engelm] is a drought-resistant, dioecious species, native to the Central Great Plains, which shows excellent potential as a low-maintenance turfgrass. Although buffalograss can be propagated vegetatively, there is a need for seeded turf-type cultivars. To assist in developing seeded cultivars, heritabilities of turf characteristics were estimated. Heritabilities from maternal half-sib analyses ranged from h2 = 0.04 ± 0.03 for the 1988 uniformity rating to h2 = 0.62 ± 0.26 for the 1989 spring color rating. Heritability estimates calculated from offspring-parent regression were also variable and generally lower than maternal half-sib analysis. The results suggest that some turf characteristics are highly heritable and that growing conditions markedly affect heritability estimates.
Effects of planting methods and rowcover on the production of yellow crookneck squash, Cucurbita pepo L. var. melopepo Alef., were evaluated over 2 years at the E.V. Smith Research Center, Shorter, Ala. Summer squash was direct-seeded or transplanted in the field with or without black plastic mulch and grown with or without rowcover. Yield of transplanted squash was significantly increased over the same squash direct-seeded. Neither plastic mulch nor rowcover had an effect on summer squash production. Transplants matured 8 to 10 days earlier than the direct-seeded plants.
A barrier system for pest control consisting of insect-exclusionary cages covered with three types of mesh material was placed over columnar apple (Malus domestica Borkh.) trees. This system has been shown to provide arthropod control equivalent to insecticides. Light intensity, evaporation, and air and soil temperature were reduced inside the cages. Shoot elongation of columnar apple trees grown inside insect-exclusionary cages was significantly greater than that of trees grown outside the cages. However, this increased shoot growth was not due to etiolation. Tree performance was unaffected by insect-exclusionary cages. Fruit set and fruit soluble solids concentration were not reduced by the cages; however, fruit color intensity was reduced as the degree of shading from the mesh increased. These findings, in conjunction with high levels of arthropod control by insect-exclusionary cages, may allow insect-exclusionary cages to be used for evaluating integrated pest management thresholds, predator-prey relationships, and apple production without insecticides.
Yellow crookneck `Dixie' hybrid summer squash, Cucurbita pepo L. var. melopeop Alef., was evaluated at E.V. Smith Research Center, Shorter, Alabama. Summer squash was grown in single rows spaced 6 feet apart. Plants were seeded 18 inches apart within 20-foot row plots. Treatments were: 1) black plastic mulch (BPM), 2) yellow painted plastic mulch (YPM), 3) white plastic mulch (WPM), 4) bare soil (BS), 5) aluminum painted plastic mulch (APM) and 6) bare soil with Diazinon insecticide (BSI). Aphid traps caught more aphids in BS or BPM plots than those from APM or YPM plots. The onset of mosaic disease incidence of squash infected with the two viruses identified as zucchini yellow mosaic and cucumber mosaic was delayed by as much as three weeks when compared to BSI or BS. Summer squash planted in APM, WPM, YPM and BPM produced 96%, 98%, 75% and 21%, respectively, more total squash yield than that produced on bare soil (control). A higher percentage of green squash (virus infected) was produced from plants grown over BPM (72%), BSI (68%), BS (59%), YPM (57%) or WPM (57%) than from APM (39%)
A factorial experiment begun in 1980 included `Hamlin' and `Valencia' sweet-orange scions [Citrus sinensis (L.) Osb.], and Milam lemon (C. jambhiri Lush) and Rusk citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] rootstocks, tree topping heights of 3.7 and 5.5 m, between-row spacings of 4.5 and 6.0 m, and in-row spacings of 2.5 and 4.5 m. The spacing combinations provided tree densities of 370, 494, 667, and 889 trees ha. Yield increased with increasing tree density during the early years of production. For tree ages 9 to 13 years, however, there was no consistent relationship between yield and tree density. Rusk citrange, a rootstock of moderate vigor, produced smaller trees and better yield, fruit quality, and economic returns than Milam lemon, a vigorous rootstock. After filling their allocated space, yield and fruit quality of trees on Milam rootstock declined with increasing tree density at the lower topping height. Cumulative economic returns at year 13 were not related to tree density.
Combinations of solarized soil (SBS), bare soil control (BS), black plastic mulched soil (BM), row cover (RC), fungicide (chlorothalonil) and biological treatments (Bacillus cereus) were evaluated. SBS vs. BS treatments were main plots, mulch and row covers splitplots and foliage treatments split-splitplots. Application of either foliar treatment was superior to BS. Using a 1/2 rate of fungicide on plants from solarized soil treatments showed equal or comparable reduction of the disease when compared to tomatoes grown in BS with high rates of the fungicide. Combined treatments of solarized + BM, BM with or without RC and low rate of fungicide or biological agent, were the most effective when compared to BS + fungicide, indicating that integration of plasticulture and biological strategies can reduce early blight below the levels of commercial fungicide applied to tomatoes grown on BS.