2009 Annual Report
1a.Objectives (from AD-416)
Develop pest management technologies that reduce the dependence on conventional synthetic pesticides by integrating new biocontrol and alternative and environmentally benign insect control programs into the tree fruit production systems. Develop knowledge and strategies to improve nutrient and water use efficiencies of production systems. Characterize the physiological basis of environmental and genotypic interactions for fruit bud initiation and root plasticity. Develop systems that integrate traditional management of the tree and soil with novel techniques to manage fruit, shoot and root growth and minimize pest damage. Develop automation systems for production and post harvest practices of deciduous tree fruits to improve fruit quality, labor productivity, and reduce costs.
1b.Approach (from AD-416)
Orchard management practices will be altered to increase biological and bio-based control of pests and ensure sustainable production. Particle film and other developing technologies will be incorporated into production system to reduce the use of synthetic pesticides and mitigate the effects of environmental stresses. Natural products will be evaluated for pest control. Establish an insect rearing facility for natural and beneficial insect predators. Develop means of dispersing beneficial insects. Study insect behavior to develop attract and kill strategies, biological control, and the use of natural environmentally benign substances for integration into an orchard ecosystem. Different green and organic mulches will enhance the habitat for predatory and parasitic arthropods, manage weeds, modify root growth and distribution, and improve nutrient and water use efficiency, and fruit quality. Sod, shading, and reflective ground covers will be used to regulate carbon allocation to fruit bud development. Root distribution and morphology, phytohormone levels, and response to competition will be measured in apple and peach cultivars. Carbon allocation will be modeled in fruit bud and root tissues. Senor and sensor systems will be developed to determine fruit location in a canopy and differentiate fruit quality. Fruit quality is defined as either maturity or defect aspects. Developed sensors will be utilized in automated harvesting and post harvest sorting systems that will lead to consistent and uniform fruit quality and will allow to improve labor productivity and reduce costs.
During the past year experiments were completed in which peach trees with different shoot and root growth habits were evaluated for leaf nitrogen (N) and phosphorus (P) concentrations after fertilizer applications in the greenhouse and field. Compact peach trees were determined to have more fibrous roots systems that provided an advantage to absorb nutrients such as P when it is present in low concentrations in the soil. However, under conditions of high soil fertility, the fibrous root systems of Compact trees did not improve nutrient uptake and Pillar trees that had greater water movement capacity had greater nutrient uptake. Carbon allocation to fine feeder roots were determined to be greater in Compact growth habits of peach, providing a potential opportunity for improved resource utilization and orchard efficiency.
A long-term field experiment was concluded that determined growth and yield in peach trees that were managed with different pruning methods and levels of grass competition in young and mature orchards. Grass competition dwarfed and reduced yield of individual peach trees but the reduction in tree size should reduce pruning costs and enable greater tree density which may increase economic returns per hectare. It was concluded that orchard efficiency and weed management could be improved by high density plantings with peach tree size regulated through managed ground cover competition.
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 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. Treatments of Surround plus irrigation had the lowest WUE compared to the Control non-irrigated treatment, likely due to increased stomatal conductance from lower canopy temperature and increased canopy PAR diffusion that drove increased photosynthesis. In 'Empire' apple, photosynthesis and productivity can be increased with Surround and irrigation treatments but at the cost of decreased WUE.
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.
Root system characteristics that improve peach tree nutrient uptake are identified. Adequate mineral nutrition is critical for high fruit quality and sustained yield of fruit trees and root systems must compete for nutrients such as nitrogen (N) and phosphorus (P), which are often present in low quantities in the soil. Compact peach trees with fibrous roots systems were shown to have an advantage in absorbing nutrients such as P when it is present in low concentrations in the soil. However, under conditions of high soil fertility the greater water movement capacity of Pillar trees supported greater nutrient uptake. Genetically-determined peach tree root growth habit affects nutrient absorption and therefore it could be a selection factor in breeding programs and soil management plans.
Tworkoski, T., Glenn, D.M. 2008. Orchard floor management systems. In: Layne, D.R., Bassi, D., editors. In the Peach, Botany, Production, and Uses. Cambridge, MA: CBI. p. 332-350.
Tworkoski, T., Glenn, D.M. 2008. Response of Young Apple Trees to Grass and Irrigation. International Journal of Fruit Science. 8:89-108.