Early fruit production and control of tree size are important factors in the economic viability of high-density apple orchards. A horticultural tool permitting growers to induce terminal budset should provide greater control over the balance between vegetative growth and reproduction, increasing orchard production and profitability. With this goal, the experimental GA-biosynthesis inhibitor, BAS-125W, is being evaluated for effects on enhancing floral initiation and controlling tree size in young orchards. In nursery stock, the effect of inducing earlier terminal budset is also being studied for influence on storage carbohydrates and performance after planting. Studies in 1996 showed that 250 ppm BAS-125W induced terminal bud set on actively growing second-leaf `Macoun', `Delicious', and `Fuji' trees. Seven application dates from 17 June to 9 Sept. were compared to determine how time of treatment would effect degree and distribution of flowering the following year. Terminal budset typically occurred 2 weeks after application, with shoot growth resuming in 4 to 5 weeks. At two dates, treatment of growing tips only was compared with entire tree application to distinguish the direct effect of GA-inhibition on floral initiation from the effect of redistributing photosynthate. Treatment from 17 June to 29 July significantly reduced total annual shoot growth compared to the untreated controls, while later treatments had no significant effect on shoot length. Treatments of nursery stock with BAS-125W on 1 Sept. accelerated terminal bud set by at least 7 days compared to untreated controls of both `Fuji' and `Golden Delicious'. Effects of treatments on flowering and tree growth in 1997 will be discussed.
Christopher L. Owens and Eddie W. Stover
R. Paul Schreiner, Patricia A. Skinkis, and Amy J. Dreves
The grape rust mite [Calepitrimerus vitis (Acari: Eriophyidae)] is an important pest of grapevines (Vitis sp.) in grape-growing regions around the world. A rapid method for extracting eriophyoid mites was adapted from earlier studies to provide integrated pest management (IPM) consultants and commercial growers with a practical, efficient, and reliable tool to monitor grape rust mites in vineyards and nursery stock vines. The rinse in bag (RIB) method allows quick extraction of mites from young shoots or from leaves using 35% to 70% ethanol or isopropanol in a sealable plastic bag. The RIB method recovered ≈85% of grape rust mites from single leaves in the first rinse. The method is useful to estimate grape rust mites on young shoots (≤10 cm length), although recovery of grape rust mites (average ranging from 35% to 81%) was lower because of a higher density of trichomes on young shoots as compared with leaf samples. The RIB method was not effective to assess grape rust mites within dormant buds, so a separate method using a blender to disrupt tissues and extract mites in alcohol was developed. The RIB method was used to determine grape rust mite abundance with leaf symptoms in commercial vineyards and nursery stock vines. The earliest visible symptom of grape rust mite damage on leaves in the summer was the development of stippling that is distinct from the type of damage caused by other grapevine pests. The stippling is described as numerous clear zones of small diameter (resembling pinholes) that are visible when a leaf is backlit. The severity of stippling was related to the number of grape rust mites present on leaves, with >600 occurring on leaves with severe stippling symptoms. In commercial vineyard case studies, the RIB method was used over two seasons and revealed that grape rust mite populations remained on leaves until postharvest, and foliar applications of wettable sulfur reduced grape rust mite populations on leaves.
Janet C. Cole, Roger Kjelgren, and David L. Hensley
Coordinating Committee (WRCC-58) “The Production, Transition, and Reestablishment of Perennial Nursery Stock.” The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby
Gerald Klingaman and G.L. Wheeler
Eight species of woody nursery stock were grown in 4 liter containers and fertilized with a conventional resin-coated slow release material (at 3.5 g N per container) or composted poultry manure applied as a top dressed or incorporated with nitrogen rates ranging from 1.0 to 11.2 g N per container. In all cases the conventional resin-coated product outperformed composted poultry manure by factors of 2 to 3 times (for height, dry weight and quality score). Although a rate response was observed with the composted, even the highest rate of nitrogen application produced plants with dry weights of 1/2 that of the control. When comparing the sources of composted poultry manure alone, the 4-4-4 product outperformed the 2-2-2 compost, even with equivalent rates of nitrogen, for 3 of the 8 species studied. Incorporation proved superior to topdressing for the 4-4-4 source but topdressing was superior for the 2-2-2 material. These studies are part of a nutrient partitioning experiment being conducted to determine the fate of nitrogen released from composted poultry manure.
L. Nash, W. Fountain, and M. Witt
In a unique partnership. the University of Kentucky Dept. of Horticulture, the Cooperative Extension Service, and the Kentucky State Division of Forestry are teaming up to produce two training packages for “train-the-trainer” workshops throughout the state. The workshops will be open to people interested in urban/community trees and arboriculture.
The first training session will be held in 1993 and will cover five modules: 1) Designing the planting site to compensate for a disturbed environment; 2) Species selection for the existing site; 3) Scientific planting techniques; 4) Post-planting care: and 5) Integrated pest management.
The second training session will be held in 1994 and will cover the following topics: 1) Establishing a scientific management program for the urban forest; 2) Preparation and administration of grants: 3) Fund-raising and efficient use of volunteers; 4) Developing an urban tree inventory; 5) Recognition of hazard trees; and 6) Selecting quality nursery stock.
The training packages will consist of a written manual, videos, and slide sets. Training sessions are open to foresters, county agents, city planners, developers, and others in Kentucky who are interested in returning to their communities and training others on the topics covered.
Roger Kjelgren and Craig Spihlman
Limited root development of nursery stock in root-control bags facilitates harvest but without irrigation may predispose stock to water stress. The effect of bags and irrigation on growth and water relations of field-grown Malus sieboldii var. zumi were investigated following transplanting as large liners into a silty-clay soil. Predawn leaf water potential (ψ), and midday stomatal conductance (gs) and ψ, were measured periodically through the season. Late-season osmotic potential (ψπ), caliper, leaf area, and root growth were also measured. Non-irrigated treatments exhibited water stress during an extended mid-summer drought, as predawn ψ and particularly gs were less than irrigated treatments, resulting in lower vegetative growth and ψπ. For combined bagged treatments water relations did not differ, but leaf area, root growth, and ψπ, but not caliper, were less than non-bagged trees. Growth measurements and ψπ of non-irrigated bagged trees, however, were consistently lower but nonsignificant than the other treatments. Bag-induced root reduction can limit some top growth even with optimum soil water. Moreover, in terms of potential Type-II errors extrapolated over a conventional production cycle, trees grown in root-control bags in normally non-irrigated soils may be more susceptible to water stress and subjected to further cumulative growth limitation.
Michael A. Gold, Mihaela M. Cernusca, and Larry D. Godsey
In 2004, a nationwide survey of chestnut (Castanea spp.) producers in the United States was conducted. Results show that the U.S. chestnut industry is in its infancy. The majority of chestnut producers have been in business less than 10 years and are just beginning to produce commercially. Volume of production is low (<1.5 million lb). U.S. chestnut producers are mainly part-timers or hobbyists with small, manually harvested operations. The majority of respondents sell fresh chestnuts. Demand exceeds supply, and prices often exceed $3.50/lb. Barriers to success in the chestnut business include the lack of information for producers, retailers, and consumers, 5- to 10-year time lag to get a return on investment, and shortage of available chestnut nursery stock of commercial cultivars. There are also concerns related to pest and disease control and market uncertainties. Lengthy quarantines for cultivars from other countries and lack of chemicals registered for use with chestnuts can also be considered barriers to success. Chestnut grower associations, universities, and state and federal agencies must join their efforts to fund and support chestnut research and industry development.
Brian K. Maynard, Richard A. Casagrand, and Roberta A. Clark
The development of a manual and database of recommended trees and shrubs was undertaken as a collaborative effort of the University of Rhode Island, University of Massachusetts Cooperative Extension and regional nursery stock producers. Initial selection was limited to species exhibiting few or no pest and disease problems, and without site requirements or other factors that could lead to higher maintenance in established landscapes. The preliminary list was reviewed by more than 30 representatives of regional arboreta, universities, growers, landscapers and arborists. In its third printing, the manual includes lists of recommended species, excluded species (with explanations), species for particular situations, and a guide to sustainable landscaping. The consortium brought together to create the manual is also developing a point-of-sale logo and poster to advertise recommended plant species and sustainable landscaping. This project has raised important issues about the interface between the industry and academia in promoting new and less readily available plants.
The database is maintained in FileMaker Pro (MAC), and will be made available in several DOS or MAC formats to those supplying a unformatted3.5” DD or HD disk.
Chris Starbuck, Daniel K. Struve, and Hannah Mathers
Two experiments were conducted to determine if 5.1-cm-caliper (2 inches) `Summit' green ash (Fraxinus pensylvanica), and 7.6-cm-caliper (3 inches) northern red oak (Quercus rubra) could be successfully summer transplanted after being heeled in pea gravel or wood chips prior to planting in the landscape. Spring harvested trees of each species were either balled and burlapped (B&B) or barerooted before heeling in pea gravel or wood chips. Compared to B&B `Summit' green ash, bareroot stock had similar survival and shoot extension for three growing seasons after summer transplanting. Bareroot and B&B northern red oak trees had similar survival and central leader elongation for 3 years after summer transplanting. In the third year after transplanting, northern red oak bareroot trees heeled in pea had smaller trunk caliper than B&B trees heeled in wood chips. These two taxa can be summer transplanted B&B or bareroot if dormant stock is spring-dug and maintained in a heeling-in bed before transplanting. This method of reducing transplant shock by providing benign conditions for root regeneration can also be used to extended the planting season for field-grown nursery stock; the method is called the Missouri gravel bed system.
William A. Retzlaff, Ted M. DeJong, and Larry E. Williams
Uniform nursery stock of five almond cultivars (Prunus dulcis Mill., cv Nonpareil, Mission, Carmel, Butte, and Sonora) propagated on peach (P. domestica L. Batsch.) rootstock were planted in open-top fumigation chambers on 19 April 1989 at the University of California's Kearney Ag Center located in the San Joaquin Valley of California. The trees were exposed to three atmospheric ozone partial pressures (charcoal filtered air, ambient air, or ambient air+ozone) from 1 June to 2 November 1989. The mean 12-h (0800-2000 h) ozone partial pressure measured in the open-top chambers during the experimental period averaged 0.038, 0.060, and 0.112 μPa Pa-1 ozone in the charcoal filtered, ambient, and ambient+ ozone treatments, respectively. Leaf net CO2 assimilation and cross-sectional area growth of Nonpareil trees were reduced by increasing atmospheric ozone partial pressures, but Mission trees were unaffected. Foliage of Nonpareil almond abscised prematurely in the ambient and ambient+ozone treatments. The susceptibility of the Butte, Carmel, and Sonora almond cultivars to ozone was intermediate between the Nonpareil and Mission cultivars.