Search Results
Two-year-old highbush blueberry bushes (Vaccinium corymbosum L. `Collins') were treated in Mar. 1985 with diuron or simazine at 2.2 or 4.5 kg a.i./ha. No residues were detected by reverse-phase high-performance liquid chromatography-ultraviolet absorbance detection (HPLC-UV) from treated berries that were harvested in June. Methiocarb was applied in May 1986 at 0.84 and 3 kg·ha-1 over the top of 3-year-old `Collins' when the berries began to ripen. Reverse-phase HPLC-UV of berries treated with methiocarb at 3 kg·ha-1 had combined residues of methiocarb and its sulfone and sulfoxide metabolites of 13.1 ppm from unrinsed and 7 ppm from rinsed berries harvested on the day of treatment; 4.9 ppm from unrinsed and 4 ppm from rinsed berries harvested 4 days after treatment; and 2.4 ppm from unrinsed and 2.5 ppm from rinsed berries harvested 8 days after treatment. Unrinsed berries treated with methiocarb at 0.84 kg·ha-1 had 5.7 ppm residue on the day of treatment and 1 ppm 8 days later. Residues from berries treated with methiocarb at 0.84 or 3 kg·ha-1 were below the legal tolerance level of 5 ppm after the required 7-day waiting period. Chemical names used: n'-(3,4-dichlorophenyl)-N,N -dimethylurea (diuron); 6-chloro- N,N' -diethyl-1,3,5-triazine-2,4-diamine (simazine); 3,5-dimethyl-4-(methylthio)phenol methylcarbamate (methiocarb).
The southern highbush (Vaccinium mostly corymbosum) blueberry cultivars Jubilee, Magnolia, and Pearl River, released by the USDA in 1994, were compared with `Premier' and `Climax', two widely planted rabbiteye (V. ashei) cultivars, on the basis of flowering and harvest dates, yield, and physical and chemical quality parameters. The southern highbush cultivars flowered later and ripened at least 1 week before `Climax', one of the earliest rabbiteyes. `Pearl River' berries had less waxy “bloom” and appeared almost black when fully ripe; they had significantly less anthocyanins than the other cultivars compared. `Premier' was lower in titratable acidity and higher in sugars than the southern highbush cultivars. Although data analysis indicated statistical differences in glucose and fructose concentrations among the other four cultivars, these differences were not pronounced. Based on the quality factors used in this study, the southern highbush cultivars compared acceptably to the rabbiteye cultivars.
Four greenhouse leaf inoculation methods for screening Japanese plum (Prunus salicina L. and hybrids) for resistance to Xanthomonas campestris pv. pruni (Smith) Dye were compared for repeatability, ability to differentiate among plant genotype responses, and correlations with field ratings. Clonally propagated trees were inoculated artificially in a greenhouse by immersing leaves in 2.5 × 108 cfu/ml inoculum (DIP), rubbing the adaxial side of leaves with a slurry of 2.5 × 108 cfu/ml inoculum and Carborundum powder (CARB), infiltrating leaves with 5 × 105 cfu/ml inoculum using a needle-less syringe (INFS), and infiltrating with 5 × 106 cfu/ml inoculum (INF6). No greenhouse method was superior in all assessment categories. The CARB method was most repeatable (t = 0.78) but had a low Spearman's correlation (rs = 0.29), indicating that greenhouse rankings did not correspond closely with field rankings. The INF6 method was unsuitable because it did not differentiate between plant genotypes. The DIP method appeared most suitable, having moderate repeatability (t = 0.46) for four observations per leaf and moderate Spearman's correlation with field performance (rs = 0.56). The INF5 method may be appropriate for identifying bacterial spot resistance that is associated with resistance in the leaf mesophyll.
Vegetative and fruiting characteristics were measured for a spur mutant of `McIntosh' apple (Malus × domestics Borkh.). Nine-year-old `MacSpur' trees in an orchard in New Brunswick, Canada, were grouped according to three degrees of spurriness. Reduced terminal growth, fewer limbs per tree, more flowering spurs per unit length of 2- and 3-year-old wood, less yield, and lower yield efficiency were associated with the highest degree of spurriness. The variability suggests that `MacSpur' may be an unstable periclinal chimera.
`Inca Yellow' marigolds (Tagetes erects L.) were planted in polyethylene bags containing coal bottom ash (CBA), pine wood peelings (PWP), a mixture of 1 CBA: 1 PWP (v/v), and loose Grodan rockwool (RW) and grown in a circulating nutriculture system. Three fertigation frequencies of 12, 6, or 4 cycles per 12-hour light period were set with a duration of 5 minutes each. Flower diameters of marigolds grown in CBA, PWP, and CBA-PWP exceeded flower diameters of RW-grown marigolds, and days from planting to harvest were less in CBA and CBA-PWP than in the other two media. There was no interaction between medium and fertigation frequency. Foliar analysis showed no significant differences in plant elemental composition among root media or fertigation frequencies. Postharvest PWP water extracts contained higher P levels than extracts of other media, and CBA-PWP water extracts contained higher K, Ca, and Mg. In the CBA-PWP mixture, decomposition products from PWP may have increased P volubility and solubilized the K, Ca,-and Mg-in CBA.
Five different statistical methods were used to estimate optimum plot size and three different methods were used to estimate optimum number of replications with short-day onions (Allium cepa L.) for yield, seedstem formation (bolting), purple blotch and/or Stemphylium (PB/S), botrytis leaf blight (BLB), and bulb doubling with a basic plot size unit of 1.5 × 1.8 m (length × width). Methods included Bartlett's test for homogeneity of variance, computed lsd values, maximum curvature of coefficient of variation plotted against plot size, Hatheway's method for a true mean difference, and Cochran and Cox's method for detecting a percent mean difference. Bartlett's chi-square was better at determining optimum plot size with transformed count and percent data compared with yield data in these experiments. Optimum plot size for yield of five basic units (7.5 m length) and four replications is indicated using computed lsd values where the lsd is <5% of the average for that plot size, which was the case in both years of this study. Based on all the methods used for yield, a plot size of four to five basic units and three to five replications is appropriate. For seedstems using computed lsd values, an optimum plot size of four basic units (6 m length) and two replications is indicated. For PB/S two basic units (3 m length) plot size with four replications is indicated by computed lsd values. For BLB a plot size of four basic units (6 m length) and three replications is optimum based on computed lsd values. Optimum plot size and number of replications for estimating bulb doubling was four basic units (6 m length) and two replications with `Southern Belle', a cultivar with a high incidence of doubling using computed lsd values. With `Sweet Vidalia', a cultivar with low incidence of bulb doubling, a plot size of four basic units (6 m length) and five replications is recommended by computed lsd values. Visualizing maximum curvature between coefficient of variation and plot size suggests plot sizes of seven to eight basic units (10.5 to 12 m length) for yield, 10 basic units (15 m length) for seedstems, five basic units (7.5 m length) for PB/S and BLB, five basic units (7.5 m length) for `Southern Belle' doubling, and 10 basic units (15 m length) for `Sweet Vidalia' doubling. A number of plot size-replication combinations were optimum for the parameters tested with Hatheway's and Cochran and Cox's methods. Cochran and Cox's method generally indicated a smaller plot size and number of replications compared to Hatheway's method regardless of the parameter under consideration. Overall, both Hatheway's method and computed lsd values appear to give reasonable results regardless of data (i.e., yield, seedstems, diseases etc.) Finally, it should be noted that the size of the initial basic unit will have a strong influence on the appropriate plot size.
Abstract
Intact roots of 109 radish (Raphanus sativus L.) cultivars were analyzed for glucosinolates (GS’s) and found to contain primarily 4-methylthio-3-butenyl-GS with small amounts of 4-methylsulfinylbutyl-, 4-methylsulfinyl-3-butenyl-, and 3-indolylmethyl-GS’s. Cultivars included oil radishes (ssp. oleifera) and food radishes (ssp. radicola) available in European, European-American, Japanese, and Korean markets. Regarding total GS’s, 80% or more of the red European-American radishes had 100-199 pmole/100 g, the Korean 100-299, and the Japanese 200-399. No correlation was found between root size and 4-methylthio-3-butenyl-, 3-indolylmethyl-, or total GS’s. Japanese radish peelings contained significantly greater concentrations of these 3 constituents than did the peeled root.
Abstract
Length of the fruit development period in Florida breeding populations of low-chilling peach (Prunus persica L. Batsch) had estimated heritability values of 0.73 to 0.98. High genetic correlations were found between leaf color classes and length of fruit development periods.
`Umatilla Russet' and `Russet Legend', two newly released potato (Solanum tuberosum L.) cultivars were compared with four established cultivars (`Russet Burbank', `Shepody', `Frontier Russet', and `Ranger Russet'). Potatoes were grown under four, season-long, sprinkler irrigation treatments in three successive years (1992-94) on silt loam soil in eastern Oregon. At each irrigation, the full irrigation treatment received up to the accumulated evapotranspiration (ETc) since the last irrigation. Three deficit irrigation treatments had progressively less water. The new cultivars `Umatilla Russet' and `Russet Legend' performed as well as or better than the other cultivars in the full irrigation treatment, with `Umatilla Russet' showing a higher yield potential at the higher water application rates than `Russet Legend'. All cultivars produced more U.S. No. 1 tubers than `Russet Burbank', except in 1993, an unusually cool and wet year. `Russet Legend' was the only cultivar showing a tolerance to deficit irrigation. In two out of the three years, `Russet Legend' was as productive of U.S. No. 1 yield over most of the range of applied water as `Shepody', `Frontier Russet', and `Ranger Russet' were at the higher end of the applied water range. Chemical names used: 0,0-diethyl S-[(ethylthio) methyl] phosphorodithioate (phorate); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); and 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1methyl-ethyl) acetamide (metolachlor).
Bacterial canker (BC), caused by Pseudomonas syringae pv. syringae van Hall, is a serious disease of stone fruits that occurs most commonly in young orchards. Many factors can predispose or increase the risk that trees develop BC such as sandy or compacted soils, low soil pH, inadequate tree nutrition, frost or cold injury, genetic susceptibility, and presence of ring nematode, Criconemella spp. However, questions still remain about how these factors influence disease incidence in `French' prune, Prunus domestica L. In 1991, we established a 3.64-ha plot in Winters, Calif., to determine the effects of nitrogen (N) fertigation on growth responses and yield of young prune trees. N was applied through a surface drip system at 0, 0.11, 0.23, and 0.45 kg actual N/tree per year as UN32 urea (Unocal, Sacramento Calif.) with 1/10th of the total amount delivered per application every other week from May through September starting in 1992. Two other treatments were also included: 0.064 kg N/tree per year through surface drip if % leaf N dropped below 2.3%, and 0.23 kg N/tree/year delivered in small amounts every irrigation via an automated buried drip system. Symptoms of BC began appearing primarily in the 0- and 0.064-N treatments in 1993. During 1995 and 1996, we demonstrated highly significant relationships between low N status measured in leaves and increased incidence of BC. Furthermore, we determined levels of N application via drip irrigation, which resulted in good yields, vigorous growth, and lack of BC in our test plots, but also minimized N use and potential for nitrate leaching into groundwater. These and additional results will be presented.