Search Results
Euonymus fortunei (Turcz.) Hand.-Mazz. is susceptible to anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. Fungicides have provided little control of anthracnose on E. fortunei in past studies. Identification of cultural practices that reduce disease incidence would be beneficial to the nursery industry. Containerized E. fortunei `Emerald'N Gold' plants were placed either on gravel beds or black plastic-covered gravel beds. Half of the beds in each bed treatment were sprayed with a 10% bleach solution monthly to attempt to reduce the presence of C. gloeosporioides inoculum. Plants were rated monthly from May (initial rating) through October for disease severity. A covariate analysis was performed using initial ratings as the covariate for ratings from all other months. Bleach did not affect disease ratings at any time. Disease ratings of plants on plastic-covered beds were lower than those of plants on gravel beds. Disease ratings decreased linearly as the growing season progressed.
A survey of commercial nursery growers was conducted to identify cultural practices used in wintercreeper euonymus (Euonymus fortunei) production. Growers that have or have not experienced anthracnose incited by Colletotrichum gloeosporioides on wintercreeper euonymus participated in the survey. Nurseries reported using a variety of practices to produce quality plants for sale. Plant culture appeared similar between nurseries with anthracnose problems on wintercreeper euonymus and those without anthracnose problems.
Abstract
A study of peach (Prunus persica (L.) Batsch) seedlings which became stunted in soil fumigated with methyl bromide-chloropicrin indicated that poor growth was associated with a major deficiency of P aggravated by marginal levels of Cu and Zn. The concentrations of K, Ca, and Mg were also lower in stunted plants. Where stunting occurred, mycorrhizal root colonization was very poor and viable inoculum was low. These results indicate that elimination of mycorrhizal fungi is the primary factor in fumigation-induced stunting of peach, and also suggest that a reduction in Cu uptake in combination with previously recognized P and Zn deficiencies may contribute to poor growth.
Plants of Euonymus fortunei `Emerald Gaiety', `Emerald 'n Gold' and `Canadale Gold' were sprayed to runoff weekly at two sites with one of three fungicide treatments or water (control) to determine fungicide effectiveness in controlling anthracnose caused by Colletotrichum gloeosporioides. Copper sulfate pentahydrate was applied at 0.4 or 0.6 g·L-1 a.i. or mancozeb was applied at 1.8 g·L-1 a.i.. Plants were rated for disease incidence approximately monthly. No interaction occurred between fungicide and cultivar. Differences among fungicide treatments were not apparent until weeks 18 or 20 depending on the site, when plants treated with mancozeb had lower disease ratings than plants receiving any other treatment. Cultivars differed at almost every rating date at both sites. Poison agar experiments were conducted to determine mycelial inhibition by copper sulfate pentahydrate or mancozeb.
Research is described on the development of an automated inspection system which uses digital images and artificial intelligence techniques. Procedures have been developed for evaluating size, shape, and color of apples, potatoes, and mushrooms. Current emphasis is being placed on developing algorithms for detection of surface defects. A major effort will also be expended toward the development of an overall “quality” score for automated inspection of fruit and vegetables. The automated results are compared with those obtained using conventional manual inspection methods. Apples, potatoes, and mushrooms are the primary crops being inspected although the algorithms and techniques are applicable to many different fruits and vegetables. Color and monochromatic image processing components in “MS-DOS” and “Macintosh” computers are being used in this study.
The objective of this research was to determine the response of soil properties and plant growth to the application of various tree-based mulches and provide information specifically regarding attributes of eastern redcedar mulch (Juniperus virginiana). Eastern redcedar mulch, cypress mulch (Taxodium distichum), pine bark nuggets [southern yellow pine (Pinus sp.)], pine mulch (southern yellow pine), hardwood mulch [maple (Acer sp.), oak (Quercus sp.)], red-dyed mulch [maple, poplar (Populus sp.)], and grand eucalyptus mulch (Eucalyptus grandis), as well as two nonmulched controls (with and without chemical weed control) were tested. Volumetric soil moisture, soil nutrients, soil temperature, weed growth, and growth and survival of planted annuals and trees were measured. Compared with nonmulched controls, mulch treatments generally increased growth of annuals and trees and decreased weed growth, but few differences in measured variables were noted among mulch types. Mulched plots had greater volumetric soil moisture than nonmulched plots during extended periods without rainfall. Mulched plots had more moderate diurnal soil temperatures than nonmulched control plots. Soil pH and soil potassium increased with hardwood mulch during the 2 years of the study. These results indicate tree-based mulch benefits plant growth and survival by maintaining greater soil moisture, decreasing competition from weeds, and moderating soil temperatures compared with not using mulch. Eastern redcedar mulch provides similar benefits as other common wood mulches and is a viable forest product.
Abstract
Fruit production and tree size were measured and yield efficiency was computed for 11-year-old trees of ‘Washington’ navel and ‘Olinda Valencia’ oranges [Citrus sinensis (L.) Osbeck], ‘Minneola’ tangelo (C. paradisi Macf. × C. reticulata Blanco), and ‘Lisbon’ lemon (C. limon Burm. f.) on 21 rootstocks in the San Joaquin Valley of California. Performance of most rootstocks was similar over all scions, and several rootstocks produced trees with higher yields than ‘Troyer’ and ‘Carrizo’ citranges [C. sinensis × Poncirus trifoliata (L.) Raf.], the current standard rootstocks. ‘Yuma Ponderosa’ lemon (× C. limon) had the highest yields, but several trees on this rootstock died or were declining. Trees on ‘C-32’ citrange (C. sinensis × P. trifoliata) were largest, and yielded nearly as much as those on ‘Yuma Ponderosa’ lemon. ‘C-35’ citrange (C. sinensis × P. trifoliata) produced smaller trees with excellent yield efficiencies, and should be suitable for higher-density plantings with most scions, except perhaps navel orange, because this combination yielded poorly at other locations. ‘Rangpur’ lime (C. limonia Osbeck) was promising only with lemon scion, and ‘Swingle’ citrumelo (C. paradisi × P. trifoliata) only with ‘Minneola’.