QUESTION: Can I prune pine trees and juniper shrubs during this winter?
ANSWER: Pruning of pine, juniper, cedar, fir, and spruce tree and shrubs should be done during the spring. Pruning is a stressful event for nearly all plants. The mentioned conifers are not growing much if any during the winter season and will have growth start in the spring. Waiting until spring to prune or trim these plants will afford them the opportunity to heal properly because of the strength they will have during the spring push of growth.
QUESTION: What are these fuzzy brown spots about l/8th to 1/4 inch in diameter on the underside of oak leaves? The affected oak trees were planted last spring.
ANSWER: At first it looked like an egg mass of a lepidoptera, that is the moth and butterfly family. After further examination of the sample leaf it was determined to be a gall of the woolly leaf gall caused by cynipid wasp. Other gall forming insect are other wasps, aphids, psyllids or other insect. Most galls are formed as a reaction of the plant to larval feeding or adult egg laying. Most of the time the gall is formed from the reaction of chemicals that the insect secretes which produces mutation of plant cells. This abnormal tissue many times provides cover over the newly laid or hatched eggs. Also many times the inside gall tissue is a food source for newly hatched insects.
QUESTION: Is it all right to have red delicious apple trees blooming now? Why is this happening?
ANSWER: It is not good or normal to have fruit trees blooming this time of year. Those flowers will be frozen and die and not produce any fruit. This is happening because of the weather. There is not anything that can done about it without drastic measures like growing in a temperature controlled greenhouse. The trees have not had proper chilling, that is, not enough hours in the cold. Let me explain. When there is not prolonged low temperatures, that is temperatures between 32 and 59 degrees F., the chill requirement is not fulfilled. Time between these temperatures accumulate chill hours, with 43degrees being optimum. Each hour above 60 degrees negates an hour of chill accumulation. For red delicious apples 1,234 hours of chill are required to overcome dormancy. Other deciduous fruit trees have other total chill requirements. Without this chill requirement normal growth will not occur, flowering can be sporadic, small leaves and fruit, short shoot growth and low yields will result. That is the reason standard apple trees do not grow or produce well in Tucson, Phoenix, Yuma or other warm areas of Arizona. They plant low chill requiring apple trees which do not have the fruit qualities that "normal" chill varieties have. To grow citrus you cannot have too much cold and to grow apples you need to have cold winter weather.