Chapter 11: Plant Health Care Flashcards
pesticides
any chemical used to control or kill unwanted pests such as weed, insects, or fungi
Plant Health Care
PHC; comprehensive program to manage the health, structure, and appearance of plants in the landscape; approach to managing trees that recognizes that tree health problems are often the result of many factors, not just a single agent; holistic approach to make management decisions that focus on plants and their interactions with the living and nonliving elements of the landscape; attempts to prevent problems before they start; proactive and cost-effective approach to manage plant health; involves proper planning, plant selection, and a wide range of cultural practices aimed at improving site and soil conditions; a philosophy, an educational process, and a decision-making process
Competition with trees above and below ground
above - light
below - water, minerals, and space
elements of a landscape includes?
soil, shrubs, herbaceous plants, turfgrass, and hardscape; arborists cannot view trees in isolation
What kind of different contractors might a property owner hire?
tree service for maintenance of trees, lawn care company to manage lawn, and landscape company maintenance firm to care for the other elements of the landscape
Where does PHC begin?
with the design of the landscape and selection of plants
What constitutes a healthy plant?
free of disorders and pests and has sufficient ability to resist stress
vitality
overall health; ability of a plant to deal effectively with stress and thrive in a given environment
vigor
overall health; capacity to grow and resist stress, sometimes limited in reference to genetic capacity; plant’s inherit genetic capacity to resist stress
What define’s a plant’s vigor?
tolerance of various soil types, moisture conditions, cold or heat, and other factors
How to manage plant vigor?
select plants well suited for the environment and resistant to pests
resource allocation
in plant physiology, distribution and use of photosynthates for various plant functions and processes; in management, distribution of materials or other assets to accomplish objectives
What are the four primary functions for photosynthesis?
maintenance (including reproduction), growth, storage, and defense
What influences energy allocation to each primary function?
tree age and health, seasonal and environmental conditions, stress factors, cultural practices, and even by ecological strategies
What does photosynthesis require?
light, water, CO2, chlorophyll, and a few essential minerals
stress factor
any condition that limits a plant’s ability to obtain or use these key resources (or that leads to excessive amounts); often directly related to soil quality or other environmental conditions and may be attributed to human activity
“survival mode”
when a tree is stressed and redirects resources away from growth, storage, and defense, and toward reproduction and maintenance
physical defense mechanisms
thorns, spikes, tiny hairs on the leaves, or leaves with thick, toughened cuticles
cellulose
complex carbohydrate found in the cellular walls of the majority of plants and algae and certain fungi
lignin
organic substance that impregnates certain cell walls to thicken and strengthen the cell to reduce susceptibility to decay and pest damage
How do cellulose and lignin serve as a cellular defense mechanism?
because many herbivores, and even some pathogens, cannot digest these compounds
Is the compartmentalization process an anatomical or chemical defense mechanism?
both, because it resists insect damage and disease spread
allelochemicals
substance produced naturally by plants as part of a defense against pests and other plants; may adversely affect the growth and development of other plants; compounds that have toxic or deterring effects on certain herbivores
tannins
organic substance produced by trees; believed to be involved in a tree’s chemical defense process
phenols
naturally produced organic alcohol with acidic properties; one of several chemical defense compounds in trees
herbivores
an animal that feeds primarily on plants
Examples of natural insecticides
nicotine, pyrethrin, neem, and rotenone
What effect does moderate drought stress have on allelochemical levels?
can increase the levels of allelochemicals, perhaps boosting a tree’s defense system
Is a rapidly growing tree always a healthier tree?
No, photosynthates may be diverted from defense compound production to increased growth of succulent tissues; increased growth without a corresponding increase in photosynthetic rate of individual leaves may stress the plant
How may a tree react if water is limited?
close stomata, levels of dissolved substances in cells may change to maintain turgor pressure, and the root:shoot ratio may increase; long term moisture stress may trigger more dramatic responses like leaf drop
How may a tree react to low light levels?
increase shoot growth toward the light source and adjust leaf size and thickness to maximize photosynthesis
How may a tree react to nitrogen deficiency?
decrease shoot growth and increase root growth to maximize mineral uptake and availability for existing foliage; produce smaller and thicker leaves
mortality spiral
sequence of stressful events or conditions causing the decline and eventual death of a tree
resource allocation in young trees vs. mature trees
young trees can afford to allocate more energy to growth than to defense; defense is more critical than growth to mature trees
appropriate response process
ARP; method of systematically assessing plant health and client needs to determine which course of action, if any, is recommended; process of gathering information, assessing the severity and implications of the problem, determining client expectations, formulating options, and deciding on a course of action
thresholds
in Integrated Pest Management, pest-population levels requiring action; in hazard assessment, risk assessment, and risk management, levels of risk requiring action
Integrated Pest Management
IPM; method of controlling plant pests by combining biological, cultural, mechanical, physical, and/or chemical management strategies; a component of PHC
What criteria defines a pest?
- ) it competes with desirable plants for resources
- ) it threatens the health, structural integrity, or appearance of desirable plants
- ) it diminished personal enjoyment, utility, or safety in the landscape
focus of PHC with pests
pest prevention and suppression rather than eradication
What will an appropriate IPM strategy do?
- ) avoid harmful effects on beneficial and nontarget organisms (people, animal, beneficial insects, and plants)
- ) cause minimal disturbence in the built and natural environments
- ) promote plant health, structural integrity, and appearance
- ) achieve the goals of the client in a cost effective manner
monitoring
keeping a close watch; performing regular checks or inspections; programming of regular landscape inspections to make observations and collect information to aid in making decisions about the management of pests and other disorders
What three types of information should be collected during a landscape inspection?
site information, plant information, and disorder information
Valuable site information includes?
recent weather trends, landscape management practices, changes in drainage or land contour, addition or removal of nearby plant material, and hardscape construction or repair
Valuable plant information includes?
leaf number, size, and color; twig growth; symptomatic reactions; and/or any signs of disorders