Garden Guy: It’s spring! Time to plant trees


Here is some good advice that will save you trouble down the road.

When planting trees, never plant them so high the upper roots are exposed. Uncovered roots are susceptible to drying.

On the other hand, burying the trunk, planting too deep, presents other problems.

When trees are planted too deep, they are predisposed to disease. Some trees such as citrus are quite susceptible to trunk or crown rot; some species of trees are somewhat tolerant. Assuming the tree was planted correctly in the container, maintain this same level.

Although a tree could be planted at the proper soil level at the time of planting, it might later sink because of settling of the soil. What happens is an overzealous gardener will dig the planting hole deeper than the height of the container. The loosened soil put back can eventually settle, drawing the trunk down below the soil level.

Actually, the planting hole should be only as deep as is required to accommodate the plant. The sides of the hole may be larger than the original container. Another caution is in low rainfall areas where a sprinkler system is installed, the irrigation water should never be directed to hit the trunk of the tree.

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I was quite distressed to see a jar full of dead carpenter bees in one of your recent columns.

During the past few years, I could count on one hand the number of honey bees I saw in my backyard.

The carpenter bees, however, were busy pollinating my lilikoi, avocado, lychee, Brazilian cherry and citrus trees.

Please do not advocate killing the carpenter bees, unless they are actively drilling holes in a home.

Please do educate people about the good these bees do.

Thank you, Joanne.

Just for the record, I was certainly not advocating the wanton killing of carpenter bees.

The comments were sent in from a reader who was able to devise a trap which would collect the bees, as the reader stated, “… in keeping the bees from drilling into my house lumber.”

I included a picture to accompany this column of what these bees did to a beautiful ohia post that supports my home; they can be quite damaging and repairs are costly.

On the other hand, carpenter bees do perform an efficient pollination service in passionflower, blueberries, greenhouse tomatoes and greenhouse melons.

They are also important pollinators of cotton in Pakistan, India and Egypt.

In Israel, the night-flowering cactus Cereus repandus is pollinated by a carpenter bee.

Point of interest: the total value of insect pollination for worldwide agricultural production is estimated at $209 billion (2005); this represents 9.5 percent of the value of the world agricultural production used for human food consumption.

And lastly, the traps are “live traps” and, if desired, bees can be taken on a “relocation program.”

••••

Heavy rains leaching nutrients

This past winter and early spring, we experienced a number of storms with high volumes of rainfall.

Some nutrients, nitrogen in particular, almost certainly leached deep into the soil. Nitrogen fertilizers are water soluble and leach quite easily.

An ideal time to apply nitrogen to the soil is after heavy rains.

Potassium, although not as soluble as nitrogen, will also leach.

Phosphorous, the third major plant nutrient, does not move with the soil water.

Yet, this element is often lacking in availability in many Hawaiian soils.

If an application of a complete fertilizer (containing nitrogen–phosphorus-potassium, N-P-K) has not been made this year, now would be a good time to do so.

••••

Mark your calendar for the morning of June 14.

I will be teaching a class about the care of tropical fruit trees, a first-time offer. Call the College of Continuing Education and Community Service at 974-7664 to reserve a seat.

 

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