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- Author or Editor: Matthew K. Rogoyski x
A decision support system has been developed to help Colorado fruit growers with apple (Malus domestica Borkh.) thinning. This system can also be used as a teaching aid and as a tool for generating research hypotheses. The system determines if fruit thinning is needed by identifying catastrophic events that would eliminate the need for thinning. The major function of this decision support system is determination of tree responsiveness to chemical thinning agents. This is accomplished through analysis of the user's answers to questions related to the physiological status of the trees, environmental data, bearing history, and the apple variety in question. On the basis of the above analysis, two sets of recommendations are presented: general recommendations based on the variety selected, and specific ones for that variety based on growth stage and tree responsiveness to thinners. The user also is provided with the rationale for the recommendations.
Abstract
A disorder of red raspberry (Rubus idaeus L.) in an area exposed to high temperature and solar radiation has been identified as a form of solar injury. Specific fruit maturity stages were defined and susceptibility to injury was found to rapidly increase as fruit matured from the “green” to the “white” to the “pink” stage. Appreciable injury (more than two unpigmented drupelets per fruit) only occurred at 42C and higher with 4 or more hours of UV radiation at the fluence level used. While the injury at 42C was proportional to UV exposure, the radiation environment in the laboratory was not designed to simulate solar radiation. Therefore, no quantitative function relating injury to fruit temperature and UV radiation is presented. The results indicated that attenuating UV absorption alone, without lowering temperature, is likely to protect raspberries in the field.
Reduction of heat stress disorders of `Golden Delicious' apples, such as sunburn, has been accomplished with cellulose fibers that modify reflective fruit surface properties. Incidence of sunburn on apples, directly exposed to sunlight, was decreased from 38% for untreated fruit to 12.5% for apples treated with cellulose fibers and binding agent and to 25.1% for apples treated with the binding agent only. Field stability of the binding agent (1% colloidal suspension of corn starch) was improved over the formulation used during the previous growing season. It was found that heating the starch suspension to 121C for 15 minutes increased its stability as a binding agent. A cumulative total of 3 cm (over three events) removed enough fibers to necessitate reapplication of the reflectant. The cellulose fiber/binder residue remaining at harvest was readily removed from fruit surface with water and a brush. Specialized sprayer was developed to deliver long fiber cellulose formulations that conventional sprayers are not capable of dispensing.