What is the horticultural history of the plant?
This inquiry involves a whole series of important questions, some of which can be answered only by others, some of which you can determine from evidence at hand. For example, what is the plant’s transplant history? Looking at a declining 40-foot tree can be a puzzle that is pretty easily put together when you discover the tree was transplanted two years previously. On younger plants, transplant history is often quite evident. A declining rhododendron that has branches growing out of the ground and is planted 6 inches deeper than the root ball grade tells a great deal about the causes of decline. Apply the axiom: “plant them low, never grow; plant them high, watch them die; plant them right, sleep at night.”
The same combination of questions to ask and clues to look for applying to horticultural practices such as fertilization, mulching, pesticide spray programs, plant hardiness, use of girdling wires and the source of plant material. You can ask about fertilization rates, but you can often find telltale signs that help ask more pointed questions, such as an excessive pile of granular fertilizer on the ground or on mulch.
Check the depth of organic mulches. The recommended amount is 2 inches to 2½ inches, although more commonly
6 inches to 8 inches (or even more) is applied, or mulch piles up over the years with reapplication exceeding breakdown. Additionally, mulch is often piled up against the trunk of a tree or base of a plant. The result of this over-mulching may be the reduction of oxygen availability to feeder roots, especially on young plants, and excessive moisture retention may potentially lead to crown and root rots. Mulch mounded against the base of the crown can also provide a perfect protected location for rodents in winter, which can severely damage or kill young, thin-barked trees and shrubs.
Again, consider the always-important question of timing. An irrigation system that is present and seemingly functional may not have been working during the hottest portion of the summer when observed damage really was caused. Conditions may be cool and non-stressful in September, but what if a large tree was transplanted on a 100-degree day in July?
The same combination of questions to ask and clues to look for applying to horticultural practices such as fertilization, mulching, pesticide spray programs, plant hardiness, use of girdling wires and the source of plant material. You can ask about fertilization rates, but you can often find telltale signs that help ask more pointed questions, such as an excessive pile of granular fertilizer on the ground or on mulch.
Check the depth of organic mulches. The recommended amount is 2 inches to 2½ inches, although more commonly
6 inches to 8 inches (or even more) is applied, or mulch piles up over the years with reapplication exceeding breakdown. Additionally, mulch is often piled up against the trunk of a tree or base of a plant. The result of this over-mulching may be the reduction of oxygen availability to feeder roots, especially on young plants, and excessive moisture retention may potentially lead to crown and root rots. Mulch mounded against the base of the crown can also provide a perfect protected location for rodents in winter, which can severely damage or kill young, thin-barked trees and shrubs.
Again, consider the always-important question of timing. An irrigation system that is present and seemingly functional may not have been working during the hottest portion of the summer when observed damage really was caused. Conditions may be cool and non-stressful in September, but what if a large tree was transplanted on a 100-degree day in July?
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