5.0 AQUATIC AND MOSQUITO (PART 4 OF 4)
Name the primary goal of pest management - Answer -The primary goal of a pest
management program is to keep the pest population from exceeding a tolerable level.
List some of the key ideas and goals of Integrated Pest Management. - Answer -
Integrated Pest Management (IPM) is a coordinated and systematic approach to pest
control. It is a system where you try to control pests with all available and practical
techniques and rarely relies on a single management tactic. Site-specific
recommendations that rely on preventive tactics act as a first line of defense.
You may want to establish a set of guidelines for when control is needed in the different
situations you are likely to face. For example, the acceptable levels and types of weeds
and insects will likely be different in different places (an often-used park, lake or back
yard compared to places little used, for example). By developing a rough idea of when
control is necessary (i.e., an action threshold) in different situations, you can begin to
formulate pest management plans for each situation. Each plan should include a goal
as well as all appropriate control methods (discussed later) to meet that goal.
In an IPM system, you use a wide range of pest control methods (e.g., cultural,
biological, mechanical, and chemical) or tactics such as sanitation and exclusion. The
goal of this strategy is to prevent pests from reaching damaging levels with the least risk
to the environment.
List some of the benefits of IPM. - Answer -1: IPM helps preserve a balanced
ecosystem
Every ecosystem, made up of living things and their nonliving environment, has a
balance: the actions of one kind of organism usually affect other species. Introducing
chemicals into the ecosystem can change this balance, destroying certain species and
allowing other species (sometimes other pests) to dominate. Unfortunately, pesticides
can kill beneficial insects that consume pests, leaving few natural pest control
mechanisms.
2: Pesticides can be ineffective
Chemical pesticides do not always work. As we discuss in the chapter, "Resistance,"
many pests have devel- oped a resistance to pesticides. Furthermore, pests may
survive if the chemical does not reach them, is washed off, or is applied improperly.
3: IPM can save money
A good IPM program can prevent loss of wanted plants and landscape or structural
damage caused by pests. IPM may also avoid the cost of purchasing unnecessary
pesticides.
4: IPM promotes a healthy environment
,Using IPM strategies helps reduce environmental impact. Using fewer pesticides lowers
the risk that persistent chemicals may harm living creatures and contaminate
groundwater. It also lessens the need to dispose of containers and unused pesticides.
5: IPM helps maintain a good public image
IPM is a well-known strategy that is requested (and sometimes mandated) in many
areas of society—especially schools. IPM is used to grow food, manage turf and
ornamentals, protect homes and businesses, man- age school grounds, and safeguard
the health of humans, pets, and wildlife.
Describe when in a plant's life cycle it is best to apply chemical controls and why. -
Answer -Timing of treatment (in relation to a plant's life cycle) is very important. In
general, herbicides are more effective on young, vigorously growing plants. Such plants
absorb water and nutrients faster to maintain their growth. As a result, they absorb
herbicides faster, too. Most plants will be less susceptible when they reach maturity and
have gone to seed.
Explain how to prevent significant oxygen depletion when using aquatic herbicides. -
Answer -One more advantage to treating younger plants is the reduced risk of
significant oxygen depletion. In spring and early summer when plants are actively
growing, the water is cooler—cooler water can hold more oxygen. Also there will be less
dead plant material for decay organisms to feed on. Decay organisms (such as
bacteria) use oxygen as they break down dead plant material and can severely deplete
the amount of oxygen in the water when there is a lot of dead plant matter for them to
consume.
List factors that affect the performance of aquatic herbicides. - Answer -A variety of
environmental factors are important to the performance of herbicides. One of the most
critical is water temperature. Many herbicides require a specific water temperature to be
effective on various plant species. Try not to apply herbicides when water temperature
is less than 60°F because plants will be less active and may not take up enough
herbicide. Check the label for temperature information. Green plants need sunlight to
grow. If effective treatment with a particular herbicide requires actively growing plants,
adequate sunlight may be critical.
Explain why one herbicide application is sometimes not enough to manage nuisance
aquatic plants. - Answer -Most aquatic herbicides are contact products (and not
systemic) with relatively little persistence. While this is good because it allows for fairly
short-lived water use restrictions, it also means that re-treatment may be necessary
during the growing season. This is because the herbicides will not prevent seeds from
germinating or perennial plants from reproducing vegetatively.
Algae often must be retreated several times per season, whereas flowering plants
usually only need a follow-
up treatment to catch missed or late-sprouting plants. Re-treatment in subsequent years
is usually required if seeds or vegetative structures are sufficiently plentiful to recreate
the original problem.
, However, a second treatment is not always aimed at the same plants. Sometimes, the
first treatment opens the way for a new weed problem that calls for another treatment.
An example of such a weed shift is when Chara appears after submerged flowering
plants are controlled. Other times, different plants become problems at different times of
the year, and treatments to control them are not related to each other.
Describe the characteristics of the pesticide rotenone. - Answer -Rotenone Use
Rotenone is classified as a restricted-use pesticide. This means only certified
applicators may use rotenone. Rotenone is available in powder form, but all use in
Wisconsin is limited to the liquid emulsifiable formulation.
Fish kill in warm water takes place rapidly, usually shortly after treatment is started. The
rate of mortality increases as water temperature increases. Fish actively moving in
warm water tend to avoid rotenone and seek springs or feeder streams containing
untreated water. Bullheads may dive into bottom muds to survive the warm water
treatments. Fish will recover if they are not exposed to adequate concentrations of
rotenone for a sufficient time (e.g., if rotenone is detoxified rapidly).
Rotenone is absorbed by aquatic vegetation, algae, and suspended solids. So, its
effectiveness in highly turbid (cloudy) waters, particularly where large numbers of
APPlicAtion Methods AB1c15
Chemical Fish Management
SECTION VII Applying Pesticides
carp or bullheads are actively feeding, is greatly reduced. Natural detoxification ranges
from 2 to 8 weeks in the summer and from 3 to 4 months in ice-covered waters. High
alkalinity and water temperatures, turbidity, abundant light and oxygen all speed
detoxification.
Outline the factors that determine the best time for a chemical treatment for fish. -
Answer -Choosing the correct season to carry out chemical rehabilitation is vital to the
success of your projects. This is particularly true for treatments near residential areas
and those involving streams or drainage lakes. Consider the following in selecting the
time of treatment:
● The lowest water levels usually occur in midsummer or winter.
● Thorough dispersion of chemicals is easiest during turnover periods.
● Many fish species congregate or have predictable movement patterns during certain
seasons or when certain conditions occur, such as changes in water level or
temperature.
● The lower the water temperature, the longer the period of chemical toxicity.
● Dense vegetation can hinder the dispersion of chemicals and cause rapid and wide
fluctuations in pH. High pH and water temperature reduce the period of toxicity and
necessitate the use of higher labeled concentrations of pesticides.
● Thick ice can reduce the volume of water to be treated and, in shallow areas, water
may freeze to the bottom making treatment unnecessary. On the other hand, ice cover
prevents effective observation of treated water areas, treatment progress, and fish kill.
● Public use of most waters is minimal in the fall so dead fish removal may not be as
critical at this time, especially in waters away from residential areas.
Name the primary goal of pest management - Answer -The primary goal of a pest
management program is to keep the pest population from exceeding a tolerable level.
List some of the key ideas and goals of Integrated Pest Management. - Answer -
Integrated Pest Management (IPM) is a coordinated and systematic approach to pest
control. It is a system where you try to control pests with all available and practical
techniques and rarely relies on a single management tactic. Site-specific
recommendations that rely on preventive tactics act as a first line of defense.
You may want to establish a set of guidelines for when control is needed in the different
situations you are likely to face. For example, the acceptable levels and types of weeds
and insects will likely be different in different places (an often-used park, lake or back
yard compared to places little used, for example). By developing a rough idea of when
control is necessary (i.e., an action threshold) in different situations, you can begin to
formulate pest management plans for each situation. Each plan should include a goal
as well as all appropriate control methods (discussed later) to meet that goal.
In an IPM system, you use a wide range of pest control methods (e.g., cultural,
biological, mechanical, and chemical) or tactics such as sanitation and exclusion. The
goal of this strategy is to prevent pests from reaching damaging levels with the least risk
to the environment.
List some of the benefits of IPM. - Answer -1: IPM helps preserve a balanced
ecosystem
Every ecosystem, made up of living things and their nonliving environment, has a
balance: the actions of one kind of organism usually affect other species. Introducing
chemicals into the ecosystem can change this balance, destroying certain species and
allowing other species (sometimes other pests) to dominate. Unfortunately, pesticides
can kill beneficial insects that consume pests, leaving few natural pest control
mechanisms.
2: Pesticides can be ineffective
Chemical pesticides do not always work. As we discuss in the chapter, "Resistance,"
many pests have devel- oped a resistance to pesticides. Furthermore, pests may
survive if the chemical does not reach them, is washed off, or is applied improperly.
3: IPM can save money
A good IPM program can prevent loss of wanted plants and landscape or structural
damage caused by pests. IPM may also avoid the cost of purchasing unnecessary
pesticides.
4: IPM promotes a healthy environment
,Using IPM strategies helps reduce environmental impact. Using fewer pesticides lowers
the risk that persistent chemicals may harm living creatures and contaminate
groundwater. It also lessens the need to dispose of containers and unused pesticides.
5: IPM helps maintain a good public image
IPM is a well-known strategy that is requested (and sometimes mandated) in many
areas of society—especially schools. IPM is used to grow food, manage turf and
ornamentals, protect homes and businesses, man- age school grounds, and safeguard
the health of humans, pets, and wildlife.
Describe when in a plant's life cycle it is best to apply chemical controls and why. -
Answer -Timing of treatment (in relation to a plant's life cycle) is very important. In
general, herbicides are more effective on young, vigorously growing plants. Such plants
absorb water and nutrients faster to maintain their growth. As a result, they absorb
herbicides faster, too. Most plants will be less susceptible when they reach maturity and
have gone to seed.
Explain how to prevent significant oxygen depletion when using aquatic herbicides. -
Answer -One more advantage to treating younger plants is the reduced risk of
significant oxygen depletion. In spring and early summer when plants are actively
growing, the water is cooler—cooler water can hold more oxygen. Also there will be less
dead plant material for decay organisms to feed on. Decay organisms (such as
bacteria) use oxygen as they break down dead plant material and can severely deplete
the amount of oxygen in the water when there is a lot of dead plant matter for them to
consume.
List factors that affect the performance of aquatic herbicides. - Answer -A variety of
environmental factors are important to the performance of herbicides. One of the most
critical is water temperature. Many herbicides require a specific water temperature to be
effective on various plant species. Try not to apply herbicides when water temperature
is less than 60°F because plants will be less active and may not take up enough
herbicide. Check the label for temperature information. Green plants need sunlight to
grow. If effective treatment with a particular herbicide requires actively growing plants,
adequate sunlight may be critical.
Explain why one herbicide application is sometimes not enough to manage nuisance
aquatic plants. - Answer -Most aquatic herbicides are contact products (and not
systemic) with relatively little persistence. While this is good because it allows for fairly
short-lived water use restrictions, it also means that re-treatment may be necessary
during the growing season. This is because the herbicides will not prevent seeds from
germinating or perennial plants from reproducing vegetatively.
Algae often must be retreated several times per season, whereas flowering plants
usually only need a follow-
up treatment to catch missed or late-sprouting plants. Re-treatment in subsequent years
is usually required if seeds or vegetative structures are sufficiently plentiful to recreate
the original problem.
, However, a second treatment is not always aimed at the same plants. Sometimes, the
first treatment opens the way for a new weed problem that calls for another treatment.
An example of such a weed shift is when Chara appears after submerged flowering
plants are controlled. Other times, different plants become problems at different times of
the year, and treatments to control them are not related to each other.
Describe the characteristics of the pesticide rotenone. - Answer -Rotenone Use
Rotenone is classified as a restricted-use pesticide. This means only certified
applicators may use rotenone. Rotenone is available in powder form, but all use in
Wisconsin is limited to the liquid emulsifiable formulation.
Fish kill in warm water takes place rapidly, usually shortly after treatment is started. The
rate of mortality increases as water temperature increases. Fish actively moving in
warm water tend to avoid rotenone and seek springs or feeder streams containing
untreated water. Bullheads may dive into bottom muds to survive the warm water
treatments. Fish will recover if they are not exposed to adequate concentrations of
rotenone for a sufficient time (e.g., if rotenone is detoxified rapidly).
Rotenone is absorbed by aquatic vegetation, algae, and suspended solids. So, its
effectiveness in highly turbid (cloudy) waters, particularly where large numbers of
APPlicAtion Methods AB1c15
Chemical Fish Management
SECTION VII Applying Pesticides
carp or bullheads are actively feeding, is greatly reduced. Natural detoxification ranges
from 2 to 8 weeks in the summer and from 3 to 4 months in ice-covered waters. High
alkalinity and water temperatures, turbidity, abundant light and oxygen all speed
detoxification.
Outline the factors that determine the best time for a chemical treatment for fish. -
Answer -Choosing the correct season to carry out chemical rehabilitation is vital to the
success of your projects. This is particularly true for treatments near residential areas
and those involving streams or drainage lakes. Consider the following in selecting the
time of treatment:
● The lowest water levels usually occur in midsummer or winter.
● Thorough dispersion of chemicals is easiest during turnover periods.
● Many fish species congregate or have predictable movement patterns during certain
seasons or when certain conditions occur, such as changes in water level or
temperature.
● The lower the water temperature, the longer the period of chemical toxicity.
● Dense vegetation can hinder the dispersion of chemicals and cause rapid and wide
fluctuations in pH. High pH and water temperature reduce the period of toxicity and
necessitate the use of higher labeled concentrations of pesticides.
● Thick ice can reduce the volume of water to be treated and, in shallow areas, water
may freeze to the bottom making treatment unnecessary. On the other hand, ice cover
prevents effective observation of treated water areas, treatment progress, and fish kill.
● Public use of most waters is minimal in the fall so dead fish removal may not be as
critical at this time, especially in waters away from residential areas.
