1a. Objectives (from AD-416)
1. Develop and integrate sustainable pest control technologies into deciduous tree fruit production systems. 2. Develop and integrate new horticultural technologies and strategies into deciduous tree fruit production systems to improve apple and peach fruit quality. 3. Develop and integrate new automation and mechanization technologies into deciduous tree fruit production systems to improve apple and peach production efficiency.
1b. Approach (from AD-416)
This project proposes the development and integration of entomological, horticultural, and engineering technology to solve major problems affecting temperate tree fruit production, the sustainability and environmental impact of tree fruit production, and consumer acceptance of tree fruits. Novel arthropod management techniques will be developed through the evaluation of insect behavioral manipulation strategies, identification of insect-resistant fruit tree accessions, and manipulation of the orchard floor vegetation to encourage beneficial insects and arthropods. Improved light, water, and pest management will be developed through new irrigation and vegetation manipulation of the orchard floor and through improved understanding of hormones and growth habit on carbon partitioning, tree development, and water use efficiency. Novel crop load management will be developed through new chemical and mechanization approaches. Future mechanization of orchard operations will be facilitated by newly developed tree management systems to improve light penetration in novel tree growth habits and by computerized visualization of tree branches and fruit. The broad base of expertise in the research program will integrate the most appropriate technologies to solve the key problems of tree fruit production. Productive and sustainable tree fruit production systems will benefit both consumers and global competitiveness of U.S. growers.
3. Progress Report
During 2009 progress was made toward improved management of insect pests in orchards with techniques that require reduced use of synthetic pesticides. A bioassay that used detached insect antennae was developed to identify volatile chemical signals that disrupt breeding in plum curculio. Traps for attracting and killing apple maggots were improved with food-based cues in combination with a novel toxicant delivery system. The new traps were field tested with apple growers in four states. Trials were conducted in commercial apple orchards to evaluate the ability of pheromone and repellant formulations to disrupt mating of dogwood borer. Field trials were completed to determine insect population variability and sampling needed to precisely characterize predator and herbivore populations in orchards. These statistics are critical to determine pest and natural enemy populations responding to diverse spatial arrangements of flowering plants in orchards. Apple germplasm with resistance to codling moth was identified. Larvae were suppressed when codling moth fed on fruit of M. tschonoskii and M. x soulardii and laboratory assays suggested phenolic compounds were agents for resistance. In the past year greenhouse experiments were completed that characterized effects of surface and subsurface irrigation on young apple trees grown with grasses that have different rooting depths. It was determined that grass ground cover and subsurface irrigation may be combined to manage fruit trees while suppressing weeds. Water use efficiency (WUE) was measured with whole canopy gas exchange chambers and using stable isotope discrimination analysis from 2003 to 2007, demonstrating that seasonal water use of apple is better evaluated with stable isotope discrimination. Apple trees with the particle film, Surround, plus irrigation had the lowest WUE but highest photosynthesis and productivity compared to the Control non-irrigated trees, likely due to favorable temperature and light conditions in the tree canopy that were Surround-generated. In a newly planted apple orchard reflective groundcover mulches were compared to conventional weed-free herbicide management, demonstrating a number of benefits from mulch including: improved growth, yield, fruit color, and over 50 percent reduction of spirea aphid infestations. Studies continued with the natural product, eugenol, to thin apple and peach blossoms. Low concentrations of eugenol were comparable to commercial thinning sprays or hand thinning for peach. A new high-density peach orchard was established using novel peach growth habits with different training systems to identify potential benefits for cultural management efficiency and adaptability to mechanical thinning. A new self-propelled mobile platform was designed to carry and operate a re-designed single spiked-drum shaker mechanism for peach bloom and green fruit thinning. The shaker was tested in commercial orchards on high-density peach trained to a perpendicular system and reduced bloom density up to 20 percent and green fruit crop loads up to 50 percent.
1. Mechanical peach thinning equipment is developed. Peach normally sets many more fruit than it can develop to acceptable market quality standards. Peaches currently require laborious and costly hand thinning. A spiked-drum shaker mechanism has been developed as a mechanical supplement for hand thinning in peaches. The equipment can bloom thin or thin at the normal green fruit thinning stage. Saving of 30 percent to 50 percent in hand thinning costs has been demonstrated for high-density peach production systems.
2. Increasing plant diversity increases ecosystem services in orchards. Orchard-level management experiments that evaluate pesticides often do not consider effects beyond the targeted pests, missing potentially important effects on ecosystem services provided by the orchard. Biological control in apple and peach orchards was evaluated with and without flowering plants and interplanting of peach trees with apple trees. Although biological control of targeted aphids and bud moth did not increase, population levels of other pests and percent fruit damaged by several insect pests were reduced by increasing plant diversity of the orchard ecosystem. Increased diversity of the orchard vegetation structure suppressed pest damage through complex functional interactions and not only by direct predator-prey or parasitoid host interactions. The ecosystem service of pest regulation was achieved indirectly through subtle changes in ecosystem processes, but this was only detected by using a holistic approach to evaluating orchard-level experiments.
3. Particle film materials reduce heat stress and increase apple productivity. Heat stress is a limiting factor of plant productivity throughout the world and kaolin-based particle films (PF) have demonstrated that the reflective nature of the resulting plant surface can increase plant productivity primarily by reducing temperature in fruit, leaf, and canopy but the underlying plant responses are not clear. Water use efficiency (WUE) was measured with whole canopy gas exchange chambers and using stable isotope discrimination analysis from 2003 to 2007 and demonstrated that seasonal water use (SWUE) of apple is better evaluated with stable isotope discrimination integrating seasonal variation, rather that the use of whole canopy gas exchange measurements that measure WUE for brief periods of time. A 3 percent Surround irrigated treatment had the lowest WUE compared to the Control non-irrigated treatment due to increased stomatal conductance from lower canopy temperature and increased canopy PAR diffusion that increased photosynthesis. In ‘Empire’ apple, photosynthesis and productivity can be increased with PF and irrigation treatments but at the cost of decreased WUE.
Schupp, J., Baugher, T., Miller, S.S., Harsh, R.M., Lesser, K.M. 2008. Mechanical thinning of peach and apple trees reduces labor inputs and increases fruit size. HortTechnology. 18:660-670.