Abstract
Elemental content was determined for ash of Prunus serotina J.F. Ehrh. (black cherry), Celtis occidentalis L. (hackberry), Quercus rubra L. (red oak), and Q. alba L. (white oak), plus a mixture of species containing Pinus (pine), Picea (spruce), and Malus spp. (apple). Ash from the 4 species averaged 26% Ca, 7.0% K, 1% P and smaller amounts of Mg, Mn, Fe, B, Cu, Zn, Pb, Cd, Ni, Cr, Al, and Na. The species mixture was lower in Ca and K but higher in most of the other elements. The effective calcium carbonate equivalent (total neutralizing power or TNP) of the wood ash ranged from 83% (mixed species) to 116% (red oak). Increased rates of application of wood ash increased soil pH. No significant effects of wood ash applied to soil were found on germination, leaf area, leaf number, plant height, fresh weight, dry weight, yield, or leaf tissue elemental analysis of snapbean (Phaseolus vulgaris L.) at 2400-9700 kg/ha.
Abstract
‘Harrow Beauty’ is a very attractive, medium-sized, firm-fleshed, cold hardy, freestone peach [Prunus persica (L.) Batsch] that ripens between ‘Canadian Harmony’ and ‘Loring’. It was introduced in 1983 for the Ontario fresh market as a possible replacement for ‘Loring’ which is marginally adapted to all but the best peach sites in Ontario. The tree is of medium vigor, cold hardy, productive, and appears to have moderate field tolerance to perennial canker (Leucostoma spp.). The fruit seem resistant to bacterial spot [Xanthomonas campestris pv. pruni (Smith) Young et at.], brown rot [Monilinia fructicola (Wint.) Honey], split pits, preharvest drop, and flesh oxidation. The fruit are well suited for the fresh market including local sales and shipping. ‘Harrow Beauty’ is performing well in regional trials in Ontario and is adapted to regions where ‘Redhaven’ is successfully grown.
Japanese plum (Prunus salicina Lindel. `Casselman') trees exposed to three atmospheric ozone partial pressure treatments were sprayed with a summer application of Volck Supreme oil (1% aqueous solution) to control an outbreak of spider mites (Tetranychus spp.). Phytotoxic effects were observed on the foliage of trees in the plots exposed to ambient or higher atmospheric ozone partial pressures 5 days following spray application. Foliage on trees exposed to 0.044 and 0.081 μPa·Pa-1 ozone [12-h mean (8 Apr. to 12 June 1992)] partial pressures developed water spotting and more foliage abscission than trees exposed to charcoal-filtered air (0.024 μPa·Pa-1 ozone). Thus, ozone air-pollution stress may predispose plants to increased phytotoxicity from summer oils.
Abstract
The effects of irrigation and tree density on peach [Prunus persica (L.) Batsch cv. Harken/Siberian C] production were investigated over 11 years. Irrigation improved growth of peach trees, lowered levels of winter injury and perennial canker (Leucostoma spp.), and promoted tree survival. Annual and cumulative marketable yields were increased, especially in the later years. Tree density did not affect perennial canker, winter injury, or tree survival. Reducing tree spacing increased resulted total growth per hectare and annual and cumulative marketable yields. Irrigation and density treatments usually did not interact and had an additive effect on growth and fruit production. The most productive management system (a combination of 50% available soil moisture and 536 trees/ha) resulted in accumulated yields over 8 years of 179 tonnes (t)/ha comparted with only 74 t/ha for the check treatment (no irrigation and 266 trees/ha).
Bahiagrass (Paspalum notatum Flugge cv. Paraguayan-22) growing under newly planted peach [Prunus persica (L.) Batsch.] trees severely stunted the trees. Neither supplemental fertilizer nor irrigating with two 3.8-liters·hour-1 emitters per tree eliminated tree stunting emitters were controlled by an automatic tensiometer set to maintain 3 kpa at a depth of 0.5 m under a tree in bahiagrass. Preplant fumigation with ethylene dibromide at 100 liters·ha-1 increased tree growth, but not tree survival. Fenamiphos, a nematicide, applied under the trees each spring and fall at a rate of 11 kg-ha -1 had no positive effect on tree survival, tree growth, or nematode populations. Bahiagrass tended to suppress populations of Meloidogyne spp. under the trees., Meloidogyne spp. were the only nematodes present that had mean populations > 65 per 150 cm3 of soil. Leaf concentrations of several elements differed between trees growing in bahiagrass sod and in. bare ground treated with herbicides. Leaf Ca was low for all treatments in spite of a soil pH near 6.5 and adequate soil Ca. The severe stunting of trees grown in bahiagrass, irrespective of the other treatments, demonstrated that bahiagrass should not be grown under newly planted trees. The low populations of parasitic nematodes in bahiagrass showed that bahiagrass has potential as a preplant biological control of nematodes harmful to peach trees. Chemical name used: ethyl 3-methy1-4-(methylthio) phenyl (1-methylethyl) phosphoramidate (fenamiphos).
Abstract
Procedures were developed for screening Prunus spp. and related genotypes for resistance/tolerance to the root lesion nematode Pratylenchus vulnus Allen and Jansen in the field and greenhouse. Inoculum rates tested were 150 and 1500 nematodes per 375-cm3 pot in the greenhouse and 300 and 3000 nematodes per planting site in the field. Nematodes per gram of root was a reliable indication of the relative resistance of a genotype to initial invasion and establishment of P. vulnus at 122 days after treatment (DAT). At 122 DAT, more distinct differences between genotypes were seen at the low inoculum rate than at the high rate. The most sensitive growth measurement in the field appeared to be the relative diameter increase at 175 DAT. Significant reductions in Ca++ and Mg++ in new rootlets were also a reliable indication of nematode effects on a genotype in both the field and the greenhouse. Using these criteria, Pistacia atlantica Desf. was classified as resistant, ‘Nemaguard’ peach [Prunus persica (L.) Batsch] as susceptible, and P. besseyi Bailey, ‘Royal’ apricot (P. armeniaca L.), and ‘Myrobalan 29C’ plum (P. cerasifera Ehrh) as tolerant in decreasing order of tolerance.
In Spain, water for agricultural use represents about 85% of the total water demand, and irrigated crop production constitutes a major contribution to the country's economy. Field studies were conducted to evaluate the potential of multispectral reflectance and seven vegetation indices in the visible and near-infrared spectral range for discriminating and classifying bare soil and several horticultural irrigated crops at different dates. This is the first step of a broader project with the overall goal of using satellite imagery with high spatial and multispectral resolutions for mapping irrigated crops to improve agricultural water use. On-ground reflectance data of bare soil and annual herbaceous crops [garlic (Allium sativum), onion (Allium cepa), sunflower (Helianthus annuus), bean (Vicia faba), maize (Zea mays), potato (Solanum tuberosum), winter wheat (Triticum aestivum), melon (Cucumis melo), watermelon (Citrillus lanatus), and cotton (Gossypium hirsutum)], perennial herbaceous crops [alfalfa (Medicago sativa) and asparagus (Asparagus officinalis)], deciduous trees [plum (Prunus spp.)], and non-deciduous trees [citrus (Citrus spp.) and olive (Olea europaea)] were collected using a handheld field spectroradiometer in spring, early summer, and late summer. Three classification methods were applied to discriminate differences in reflectance between the different crops and bare soil: stepwise discriminant analysis, and two artificial neural networks: multilayer perceptron (MLP) and radial basis function. On any of the sampling dates, the highest degree of accuracy was achieved with the MLP neural network, showing 89.8%, 91.1%, and 96.4% correct classification in spring, early summer, and late summer, respectively. The classification matrix from the MLP model using cross-validation showed that most crops discriminated in spring and late summer were 100% classifiable. For future works, we would recommend acquiring two multispectral satellite images taken in spring and late summer for monitoring and mapping these irrigated crops, thus avoiding costly field surveys.
Whole-shoot water potential, osmotic potential of the xylem fluid, and bark water potential were examined from late winter through early spring for six peach [Prunus persica (L.) Batsch.] cultivars varying in relative susceptibility to Leucostoma canker. There were significant differences among cultivars for whole-shoot water potential on all 11 dates tested in 1986, but not in 1985. The date effect was not consistent among cultivars, although when averaged across dates, the whole-shoot water potential of `Loring' was significantly more negative than that of `Candor' or `Garnet Beauty'. There were significant differences among cultivars for xylem fluid osmotic potential on one of five dates tested in 1985 and three of 11 dates tested in 1986, although cultivar differences were not consistent between years. Cultivars exhibited differences in bark water potential on three of five dates tested in 1985, with `Loring' exhibiting the least negative values when averaged across dates. There were only occasional significant correlations of the water status characteristics with relative susceptibility to Leucostoma canker or suberin accumulation. Measurements of plant water status among cultivars or genotypes in peach do not appear to be reliable indicators of susceptibility to Leucostoma spp. or wound response.
Abstract
‘Harson’ is an attractive, high-quality, yellow-fleshed, freestone peach [Prunus persica (L.) Batsch] that ripens in the midseason 2 days before ‘Redhaven’. It was introduced in 1982 for the Ontario fresh market to advance the season of ‘Redhaven’-type peaches by 2 days and reduce the gap in harvest sequence between ‘Sunhaven’ and ‘Redhaven’. The tree is of medium vigor, cold hardy, productive, and appears to have moderate field tolerance to perennial canker (Leucostoma spp.). The fruit appear to be resistant to bacterial spot [Xanthomonas pruni (E. F. Sm.) Dows.], brown rot [Monilinia fructicola (Wint.) Honey], split pits, preharvest drop, and flesh oxidation. They are wellsuited for the fresh market, including local sales and shipping, and for preservation at home, especially as canned halves and frozen slices. Research and grower cooperators in southern Ontario and near Annapolis Royal, Nova Scotia report that ‘Harson’ is performing well in their trials compared with other midseason cultivars and encouraged its introduction. This new cultivar is likely to be adapted to most regions where ‘Redhaven’ is grown successfully. The name ‘Harson’ honors T.B. Harrison for his many years of service to the Western Ontario Fruit Testing Association and the fruit industry of Ontario.
Abstract
‘Harcrest’ is a cold hardy, productive, attractive, firm-fleshed freestone peach [Prunus persica (L.) Batsch] that ripens 2-3 days after ‘Cresthaven’ and ‘Redskin’ in the late season. It was introduced in 1983 for the Ontario fresh market to extend the ‘Cresthaven’ and ‘Redskin’ season with a similar type of peach and is considered a potential replacement for ‘Redskin’. The tree is vigorous and appears to have moderate field tolerance to perennial canker (Leucostoma spp.). Leaves and fruit are moderately resistant to bacterial spot [Xanthomonas campestris pv. pruni (Smith) Young et al.] while flowers and fruit are resistant to brown rot [Monilinia fructicola (Wint.) Honey]. Fruit are resistant to split pits but subject to preharvest drop if hot, dry conditions prevail just before harvest. The yellow flesh does not brown readily on exposure to air. ‘Harcrest’ is well suited for the fresh market including local sales and shipping and is suitable for preservation at home by canning or freezing. ‘Harcrest’ is performing well in regional trials in Ontario, and is adapted to regions where ‘Redhaven’ is successfully grown.