Making older trees ‘ladderless’ might kill them

Q: I watched your videos about pruning your peach trees for a lateral orchard. We planted some bare-root plum and peach trees last Saturday. I want to do a lateral orchard but there are no branches down at knee level. They are at about hip level. Would I still cut the trunk off at knee level? Would branches or buds form down lower if I did that or would it just kill my trees?

A: It should be a ladderless orchard since what you are trying to accomplish is to keep the trees close enough to the ground so you do not have to use ladders for pruning or harvesting the fruit. I could see how listening to the word ladderless on a video might be heard as lateral.

If a peach or plum has been in the ground for a while, I would not recommend cutting the trunk at knee height. You will run the risk of severely damaging or even killing the tree. It depends on the tree, but with plum or peach it would be very risky to cut an older part of the tree to re-establish the scaffold limbs. Now, if your tree was an almond, then you could cut larger diameter wood and it will regrow below the cut.

You will have to work with the tree structure that you have. Maybe you will not be able to keep it at 6½-7 feet tall but you certainly could keep it less than 10 feet tall and still have a sizable harvest. My videos are available on Youtube by searching for Extremehort. I will be posting some new ones next week.

Q: In my backyard in 2010, I planted a semidwarf early Elberta peach tree and a Katy apricot. I hand-watered them and left their tree wells uncovered until I completed the irrigation system around April 2011. Now, each tree has drip emitters. I put a thick layer of Dr. Q's Pay Dirt potting soil on top of each tree well and then covered the potting soil over with a layer of the ruby red stone that I have throughout the floor of my backyard. Both trees are doing very well and I want to be sure to do everything I can for their long-term health.

Per your article in View, should I move the red stone back off the top of the tree wells to a radius of 6 feet away from each tree, and then cover each tree well with a layer of wood mulch instead?

A: One problem we have when growing fruit trees in our desert is the small amount of organic matter in our soil. This miniscule amount of organic matter is not enough for nearly all plants, including so-called desert plants.

Fruit trees, and nearly all other plants, perform much better if organic matter (compost preferably) is added to the soil surrounding the roots. I hope that you added a lot of amendments to the soil at the time of planting, not just to the surface.

I have compared two application methods when compost is applied to fruit trees: mixing it only to the soil at the time of planting and adding it only to the soil surface after planting. Adding it to the soil, not just the soil surface, dramatically improves plant growth .

The best amendments to use to increase organic matter in our soil are homemade composts. Commercially made composts, available in bags or bulk and extremely variable in quality, would be next. The good ones (there are good ones out there now thanks to the explosion in organic gardening) are expensive. The cost of enough good quality compost, added to the hole at planting time, in some cases might rival the cost of the plant itself.

If trees are planted in amended soil and the surface covered with rock, then, over time, the organic matter in the soil is "used up," so to speak, by soil microorganisms. When the majority has been used up, we say the soil has become "mineralized." Without addition of organic matter to the soil surface every two to three years, the soil slowly reverts back to its previous desert condition.

From my observations of fruit trees and nondesert landscape plants growing in our desert soil amended only at the time of planting and mulched with rock, the soil is typically "mineralized" by the fourth or fifth year. Cacti and desert plants are much more tolerant of mineralized soil but still grow better in amended soil.

By placing wood mulch on the soil surface where it is wet, the mulch slowly decomposes. Through its decomposition it adds organic matter to the soil.

Through their decomposition, mulches add a lot of organic activity, such as beneficial microorganisms and earthworms, leading to improved plant health. Rock mulch cannot add organic matter, so in a few years none of the benefits of organic mulches will be present.

I am guessing your trees will be fine for several years with rock mulch covering the soil surface. But what may happen in the fourth through the sixth years, as the soil becomes mineralized, is that they may begin to decline in health. The trees may become more and more yellow, leading to leaf scorch, followed by branch dieback and attacks by insects such as borers.

Borers come into play due to a decline in tree health. Decreased plant health causes a thinning of the tree canopy leading to an increased amount of sunburn damage to the limbs. Sunburn damaged areas are ideal locations for borer damage to occur.

It is best for the trees if you can put wood mulch in the wet areas under the trees. If you can do this, then it will probably not be a problem. The wood mulch will not decompose in the drier areas under the tree.

Q: Several months ago, you answered my question as to what was causing the loss of all my almonds in my almond trees. You said I should apply the insecticide Sevin for pest control. But when do I apply the Sevin? My almonds are doing well now but they always do well now, and then later I see something oozing out of the nuts and a yellowish design on the inside. Then the nuts drop from the tree. So when do I spray with this insecticide?

A: If I told you to apply Sevin insecticide, I must have thought you had leaffooted plant bug in your almonds. My personal philosophy is to use pesticides as a last resort for insect control whenever possible. This would be the only reason I would recommend the use of a pesticide in almonds.

You would apply it when you see the insect present on the leaves. This insect has wintered in your or your neighbors' landscape plants. I have seen them winter in our climate in these locations. When leaves emerge, this insect will begin feeding and laying eggs.

The first thing you will see are herds of the immature, called nymphs, on the undersides of leaves. You might see some adults as well but the babies are much more numerous. You should start to see them around late April or early May so start looking then. When you see them, begin spraying immediately according to the label mixing rate. Wear protective clothing.

Bob Morris is a horticulture expert living in Las Vegas. Visit his blog at xtremehorticulture.blogspot.com.