Longer irrigations will flush out pines

I will be conducting a pruning seminar at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas detailing how to prune fruit trees for small spaces Saturday at 10 a.m. This seminar will cover how to prune multiple fruit trees planted in a single hole as well as espalier pruning.

For directions to the orchard, please call the master gardener help line at 257-5555.

You should start seeing the first fruit trees in bloom sometime this week and even earlier if they are planted in a warm microclimate . Remember do not spray fruit trees with anything while they are in bloom; but you may resume as soon as flowering is over.

If you have not applied dormant oils yet to your fruit trees, an excellent time to apply is just after bloom and as the new leaves are emerging. The reason it is a good time is because overwintering insects will be leaving their hiding places and invading the new leaves and new growth as they emerge. They are fully exposed at this time and at a stage when they are easy to control before they begin reproducing.

These types of dormant oils would be correctly classified as "summer" oils, even though they are termed dormant oils due to their viscosity or density and will not damage most plants with young, new foliage. They are given the classification of dormant oil because the normal time for application is when trees are dormant or "sleeping" through the winter months.

Fertilizers for most fruit and ornamental trees and shrubs should be applied now as new growth is emerging. If you have had problems with leaf yellowing in past years, then make sure you apply an iron fertilizer called a chelate that contains the acronym EDDHA in the ingredients.

Q: I have pines which are just under 20 feet tall and must have always been held back because of the frequent and shallow watering they have received.

Even now it's twice a day for 10 minutes. We have lived here for four months now. Do you suppose if we go ahead and alter the watering schedule now to more infrequent but longer times, that this would have an effect on their appearance?

A: Yes. If you begin to give them more water, they will begin to become more full and lush. This will not happen right away but you should start to see a difference beginning next year and in progressive years they will become more dense until about the third year when they will probably be at their maximum visual density.

Needles are retained on branches for around three to five years. Wood that is older than this, in many pines, will drop their needles. A healthy pine tree should produce about 10 inches of new growth each year. If there is not enough water for the tree, then it will only produce a couple of inches of new growth each year.

If a pine tree, for example, retains needles for five years and it only produces 2 inches of growth each year, then needles in the canopy will be on only 10 inches of growth on each branch. If it is healthy, then needles will be on five years of growth times 10 inches or 50 inches of growth on each branch.

So the pine tree that is receiving more water will be five times more dense than the one struggling with water. The down side is that well-watered pine trees get larger and more dense, which equals higher water consumption.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.