Horticulture: Pears

Research efforts in pears have been focused on orchard systems, factors affecting fruit production, cultivars, and growth regulators. Rootstock research has been focused on the development and/or identification of rootstocks, which induce smaller tree size, precocity, early production, high quality, and large-sized fruit. Rootstocks developed in the United States, England, Germany, Italy, and South Africa are currently under evaluation. While no truly dwarfing rootstock has yet to be identified, rootstocks have been identified which increase the production of larger crops or larger sized fruit at an earlier age.

Training systems have been shown to increase the production of earlier crops of larger sized fruit on Bartlett and d'Anjou pears, while increasing orchard profitability. Hail damage was shown to not be affected by different training systems.

Physiological factors affecting pear production have focused recently on the development of a non-specific failure in red d'Anjou trees. First symptoms include the appearance of small reddish leaves. By the time the leaves begin to collapse, the root system is already dead. There is no biotic factor evident. Factors being explored which may influence the problem are heavy production, cold winter temperatures, and water stress. Root systems under trees with red d'Anjou tops have less starch than roots from trees with green d'Anjou tops. Russet development in d'Anjou pears has been studied for a number of years. There is no magic bullet which will reduce or eliminate the problem in all years. Factors affecting russet include bloom and post bloom moisture, pear rust mite, bacteria, and fungi. These factors contribute differently in different years.

Growth regulators in pears have focused on the control of tree size and increasing precocity and early fruit production. A number of chemicals, which initially demonstrated promise have been eliminated due to physiological problems. Currently a very promising material which controls both growth and reduces the chance of fire blight infection is under evaluation.

January 15, 2008