54 WORKSHOP 7 Alternative Production and Protection Practices for Tree Nut Crops
Richard P. Buchner
Mark V. Coggeshall
purchased from individuals through a system of 250 hulling stations distributed across 17 different states (B. Hammons, personal communication). Without question, the greatest constraint associated with the growth of black walnut as a nut crop for the
Shawn A. Mehlenbacher
Disease resistance is an objective of most breeding programs for small fruits, tree fruits, and nuts. Often a moderate level of resistance is adequate, and must be combined with many other desirable horticultural characteristics. Classical methods (a segregating population of the host plant is inoculated with a virulent isolate of the pathogen under environmental conditions appropriate for disease development) have been used with great success and have incorporated both horizontal and vertical resistance. Molecular approaches offer new opportunities and are likely to be appropriate and cost-effective in a few situations. Transformation is not yet routine in fruit and nut crops, and there is a shortage of useful genes. Genetic maps are being constructed using RFLP and RAPD markers in several species, allowing determination of number and location of important genes as well as indirect selection based on linked markers. This presentation will include examples of both classical and molecular approaches as they are used in the genetic improvement of fruit and nut crops with an emphasis on fungal and bacterial diseases.
Naomi Hirsch and Louise Ferguson
For California pomology, it is ideal to communicate and disseminate information electronically because of its large size and diversity of fruit and nut crops. In support of statewide extension, the Fruit & Nut Research and Information Center's World Wide Web site 9 http://pom44.ucdavis.edu) focuses on providing information and links for temperate, subtropical and tropical fruits and nuts and keeping all interested persons well informed about University of California research and outreach activities. The Internet has been proven ideal for its user friendliness and rapid dissemination of current information. The Center supports this electronic change for growers and industry by collaborative projects with industry and involving Internet education and demonstrations at short courses, symposia, and educational days throughout the state. By this outreach to fruit and nut crop industries, the needs of the growers can be addressed. Also, it is important to address interdisciplinary cooperation and efficiency in the Agricultural Experiment Station and Cooperative Extension programs, especially in view of the recent reduction in staff and resources. By creating electronic listserv groups for each crop through the Center, extension specialists and farm advisors have the ability for increased communication. A more visible and active focal point —both within and outside the University—for research and outreach activities related to fruit and nut production, handling, processing, marketing and consumption has been created since the Center was established in Dec. 1995.
A course entitled “Plantation, Beverage, and Tropical Nut Crops” was developed in order to expand the content and diversity of the horticulture curriculum at Louisiana State University. The course was designed for both upper division undergraduates and graduate students in the plant sciences. The course was intended to broaden the exposure of both domestic and international students to the world's most important plantation, beverage, and tropical nut crops. These crops are generally not commercially grown in the United States, but include some of the world's most economically significant commodities. The selected crops are typically not covered in existing horticulture or agronomy classes. Details of the individual crop cultural practices, harvesting methods, postharvest care, agro-processing, and international marketing are provided. The instructional materials were formatted for delivery via compressed video and transmitted to off-campus sites to afford the opportunity of long-distance learning to nontraditional students. The course was successful in attracting nonhorticulture students and facilitated interdisciplinary interaction among students from diverse curricula.
Bruce W. Wood
Excessive fruit drop (i.e., June drop) can limit orchard profitability of certain pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars. The present study examines efficacy of aminoethoxyvinylglycine (AVG; formulated as ReTain®; Valent BioSciences, Libertyville, IL), a natural ethylene inhibitor, for increasing nutmeat yield in a commercial ‘Desirable’ pecan orchard over a 2-year period. The 30-ha experiment consisted of two treatments (nontreated versus ReTain) in the first year, an “off” year in the orchard's alternate bearing cycle. The second year's study, an “on” year, consisted of four treatments (i.e., “08 nontreated + 09 nontreated,” “08ReTain + 09 nontreated,” “08 nontreated + 09 ReTain,” and “08ReTain + 09 ReTain”). AVG, as ReTain [132 mg·L−1 a.i. (11.7 oz/acre)], was applied as two post-pollination canopy sprays (937 L·ha−1) 2 weeks apart in both years. During the “off” year, ReTain increased nut yield parameters with ReTain increasing kernel yield by 36% (704 kg·ha−1 versus 516 kg·ha−1) over that of nontreated trees. In the subsequent “on” crop year, the trees exhibiting a ReTain-associated previous year yield increase of ≈36% exhibited a reduction in yield of ≈25%, thus largely negating the previous season's yield increase over a 2-year alternate bearing cycle. Additionally, ReTain-treated trees during the “on” year failed to exhibit an increase in yield parameters over that of the nontreated control. As a result of a lag effect on subsequent year yield parameters, ReTain offers potential as a crop-load management tool for ‘Desirable’ orchards in “off” years such as a year of relatively high nutmeat price followed by a year of relatively low price. There appears to be no positive effect on yield when used in a heavy crop-load “on” year of an alternate bearing cycle. Thus, ReTain might have benefit for stabilizing alternate bearing in ‘Desirable’ pecan orchards. Kernel quality (defined as percentage of nut weight as kernel) of individual nuts from “on” year trees was not as sensitive to units of yield increase as for individual nuts of “off” year trees, thus implying that the rate of assimilate partitioning to individual reproductive structures in “off”-year trees is not as great as that in “on”-year trees.
John M. Capik, Megan Muehlbauer, Ari Novy, Josh A. Honig, and Thomas J. Molnar
blight of European hazelnut: It’s becoming a manageable disease Plant Dis. 80 1308 1316 Johnson, K.B. Pinkerton, J.N. 2002 Eastern filbert blight, p. 44–46. In: Teviotdale, B.L., T.J. Michailides, and J.W. Pscheidt (eds.). Compendium of nut crop diseases