Q: Our pear trees have a lot of fruit on them this year. What is the best way to store them for future use? A: Pick them when fully mature but still hard and green and store them immediately at 60 degrees to 65 degrees F. Keiffers will ripen in two to three weeks, Bartletts somewhat sooner. After ripening, put them in the refrigerator as close to 31 degrees F. as possible. Q: I planted bluegrass seed in my lawn nearly four weeks ago and there is no sign of new grass. Does it mean the seeding was a complete failure? A: In early to mid-fall, Kentucky bluegrass seeds can be expected to germinate in 14 to 28 days, provided they were planted properly and kept moist. The seeds need light in order to germinate and should have been planted about 1/4" deep and lightly covered with soil. They should be kept moist until they germinate, which may involve light sprinkling once or twice a day. If the seeds were not seriously damaged they may still germinate. Q: I have had a white birch for three years. It has been beautiful, but now it's dying. Is there any way to save it? A: Outside its natural range, the white birch is very susceptible to attack by bronze birch borers. The borers over-winter as larvae under the bark of the tree, emerge as adults in early May and lay eggs soon afterwards. Preventive spraying should be done in late May and in early, mid- and late June. Spray the entire tree.However, when the tree has been badly damaged, it's too late to save it. Q: My two-year-old rambler rose seems healthy but had only two flowers this year. What could be wrong with it? A: Lack of sunlight is the usual reason, also severe pruning, too much competition from other plants, variety not suited to location, damage from Japanese beetles and other insects, too much or too little water, too much or too little fertilizer. Q: I have a black walnut tree that had its first bearing this year: two nuts. The tree is about 20 feet tall and beautiful with its sprawling branches, but I think it should be pruned. When and how should it be done? A: Walnut trees old enough to bear nuts can be pruned during the winter dormant period. Prune in moderation.Cut out deadwood, and thin out crowded or crossing branches, or any that are lower than desired. Avoid cutting off the short twigs that grow on the limbs; their leaves nourish and shade the limbs, and their removal could result in weak, sunburned limbs that become riddled by boring insects. Avoid cutting branches much larger than four inches in diameter, since large wounds are slow to heal. Q: Our rhododendrons bloom heavily one year and hardly at all the next year. What is wrong? A: It may be that if the faded flowers are removed promptly to prevent energy from being used to produce seed, there may be more flowers the following year. One rhododendron specialist says that forming seed pods uses up seven times as much energy as forming flower buds.