Integrated Pest Management Midterm

What is a pest?
a pest is any organism that interferes with the activities and desires of humans
Name 3 arthropod classes
1. Arachnida; Ex. spiders
2. Crustacea; Ex. crabs
3. Diplopoda; Ex. millipedes
4. Chilopoda; Ex. centapedes
5. Insecta or Hexopoda (insects)
3 characteristics of invasive plants
1. Introduced from other regions
2. Show a tendency to spread out of control.
3. Outcompete native plants, producing a monoculture that discourages the growth of other plant varieties.
2 types of insect development
no metamorphosis
gradual metamorphosis
What is a weed bud bank and what is its typical longevity?
A budbank is the total accumulated meristems (buds) on vegetative reproductive structures of weeds such as nutsedges, johnsongrass and field bindweed. Each bud can make a new plant.
Typical longevity of a budbank 2 to 10 years.
2 ways weeds can disseminate to new locations
wind
passing through the digestive tracts of herbivores and omnivores.
What are pheromones?
A pheromone is a chemical an animal produces which changes the behavior of another animal of the same species (animals include insects)
What pest organisms can enter a state of cryptobiosis when suitable environmental conditions deteriorate?
nematodes
What does it mean when an arthropod pest is said to have a delayed voltine seasonal cycle?
life cycle requires more than 1 year for completion
What is the definition of IPM?
IPM is a sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health, and environmental risks.”
What does the term monitoring mean as used in IPM efforts and list 2 benefits of this activity
Monitoring means capturing samples of pest organisms in order to record phenological timelines and extrapolate pest populations in an agroecosystem.
1. Monitoring provides information on spatial patterns of pests so that any pest management actions will be more accurately targeted.
2. Monitoring provides information on population size and thus can influence the decision to take action or not, such as whether to spray or not to spray.
What is the disease pyramid?
What is the disease pyramid?
the existence of a disease caused by a biotic agent absolutely requires the interaction of a susceptible host, a virulent pathogen, and an environment favorable for disease development (1,6). Conversely, plant disease is prevented upon elimination of any one of these three causal components.
What is a facultative saprophyte?
an organism that is usually parasitic but may live as a saprophyte having the ability to be a parasite.
What is cultural control?
making the environment less suitable for the pests
how are cultural tactics different from physical and mechanical tactics?
all cultural control tactics are mediated through the crop or crop environment, such as changes to the microclimate or crop canopy
Do cultural controls affect pest directly or indirectly
indirectly
are cultural controls fast acting or slow acting?
slow acting
Are cultural controls good for a sudden infestation?
no, for taht you need direct controls like chemical spraying
how do cultural controls work? do they eliminate the pest?
Cultural controls seek to keep the pest below the economic injury level
do cultural controls change the ecosystem carryign capacity for the pest?
no
can a pest bounce back if cultural controls are relaxed to a economically damaging level?
yes
Can cultural controls be stopped and started as needed or do they need to be continuous
cultural controls need to be continuous
Do cultural controls require high inputs?
no they generally require low inputs and have minimal environmental impact
Do cultural controls need sophisticated equipment?
no
What resources to cultural controls require most?
extra expertise and time on the part of managers, more human training needed
Are cultural controls often specific to a region?
yes
How can pests enter a crop? 7 things
1. animals
2. equipment
3 soil
4. in the crop seed itself
5. weeds
6. nematodes
7. insects
how can animals put pest in a crop?
they can transport weeds, nematodes, pathogens, insects and mites on their bodies
how can equipment put pests in a crop field?
on the tires or tools, equipment needs to be cleaned before moved to a new place, all surfaces with plant or soil debris
Do farmers generally have a good practice of cleaning their equipment or not?
no
how can soil transport pests?
soil can contain lots of insect eggs, pathogens, fungi and weed seeds
how can crop seeds transmit pests?
infected transplants, infected seed, infected propagule material.
can viruses ever be seed borne?
yes
how do you ensure that seeds or propagule material is not infected
get certified disease free material
is grain and grass crop seed infected with weed seeds?
yes
What kind of planting materials are nematodes expecially a problem for?
nematodes are particularly problematic with corms, bulbs and tubers
How much of a problem is contamination of seed by insects?
less of a problem, can be traeted by treating seeds with insecticides or fumigants
How about insects in cuttings or roots used in vegetative propagation?
Insects are more of a problem in vegetative propagation, for example lepidopterous borer larvae in sugar cane pieces
What is a limitation of certified seed?
it is more expensive
What is the role of sanitation in agriculture?
removing crop and other plant debris that may be harboring pests, decreasing likelihood of pest carryover from season to season
how does sanitation conflict with no-till farming?
no-till leaves a ground cover, but this can create shelter for pests
Does sanitation have any application to weed management?
no
example of overwintering pathogens
apple scab on the dead leaves overwintering around an apple tree
what is the key IPM tactic for apple scab fungus on the leaves?
till the leaves into the ground or add nitrogen fertilizer to speed leaf decomposition to decrease apple scab inoculum
where does brown rot disease of peaches overwinter?
on infected fruit mummies on the ground
What is done with palms infected with red ring of coconut?
they are cut down and burned to ensure that weevil vectors do not emerge from the diseased bole and infect new palms
What non-insect pest animals are take shelter under debris?
mollusks snails and slugs
How is the navel orange worm pest controlled in almonds?
the mummy or sticktight nuts must be removed from trees and from the ground because they contain the pupae of the navel orange worm
What is the main control tactic for cotton insect pests?
destruction of the stubble by cultivation or plowing
how are overwintering corn borers killed?
by shredding the corn stalks
how are overwintering codling moths killed on pear trees
left over fruit is collected and destroyed.
What is the most important factor for controlling pest mammals such as squirrels, gophers, and field mice?
removing vegetative cover
what are disadvantages to sanitation
conflicts wtih no-till, that is the only disadvantage
what are host free periods?
times where the host crop or alternative crop is not planted so there is no host for the pest
where are host free periods not possible?
where the climate keeps host plants or alternative host plants growing all the time because overlapping crops permits the pest to move to each succeeding crop
which pests or pathogens is the host free period most important for?
host free most important for controlling fastidious pathogens vectored by arthropods, including phytoplasmas, some bacteria and all viruses
how long is needed for host free periods to stop viruses?
a few weeks
what is the host free month for lettuce mosaic virus in Salinas valley?
December
What does the timescale for host free periods for nematode control depend on?
the death rate of nematodes without a host, usually several years rather than a few weeks as for viruses.
What kind of nematodes are able to live for 6 to 10 years and why?
cyst-nematodes, as eggs in cysts for 10 years or more
what can long host free periods select for in nematodes?
nematode races taht are longer lived and can survive long rotations
what is the cotton free period in the Central Valley in California?
January to March
What an obligate alternative host?
a second host that is needed for a pathogen to survive, such as the cereal rust fungus
Is “host free periods” relevatn to weed management?
no, but weeds can provide alternative hosts to pathogens or insects
What is a major problem in host free periods for nematodess
controlling alternative hosts in neighboring areas
why is the control of alternative hosts a double edged sword in relation to arthropod management?
because those alternative hosts may also be hosting beneficial insects
What is area wide insect management?
controlling insects on vegetation external to crop fields
What is the obligate alternative host for lettuce root aphids?
poplar trees
how do alternative hosts relate to vertebrate animals?
alternative hosts can serve as food for ground squirrels and meadow mice Removal of noncrop host vegetation for reducing populatiosn
what is the major limitation of alternative host removal?
depends on implementation at the regional level
How does rotation work as a cultural control?
it changes the associated pest complex
What can make rotation to non-host crops ineffective?
if alternative host weeds are permitted to grow
How can rotation help control weeds?
an herbicide can be used in a rotation crop that could not be used in the previous crop
Which two root parasitic weeds are controlled by rotation to non-host crops?
root parasitic weeds in the genera striga and orobanche
What kind of pest is rotation the standard recommendation for?
nematodes to manage sugar beet cyst nematode
how often can sugar beets be planted on soil infested with sugar beet cyst nematodes
not more often than every three or four years
What can negate the effects of crop rotation for nematode control?
weeds in the crops, because some nematodes have wide host ranges Pigweed in corn can maintain root-knot nematodes even though corn is not a host
how is rotation for insect pests?
rotation works for insect pests with a non-mobile soil dwelling stage in their life cycle
How is rotation used with corn and soybeans for the corn root worm
2 year rotation to soybeans almost eliminates the corn rootworm
How did the western corn rootworm adapt to rotation?
Western corn rootworm evolved strains that spend 2 years diapausing eggs in soil and other strains have adapted to ovipositing in soybean fields.
What can an incorrect choice of crop sequence result in?
an elevated insect problem, such as wireworms in potatoes following red clover or sweet clover
what is the major limitation of rotation?
the best crop for pest management reasons may not be the the best crop economically
why do lots of midwest farmers not us a corn-soybean rotatioN?
because the risk of corn rootworm is outweighed by the price of corn — the risk is worth it
what is an advantage of fallow rotation?
pest control tactics can be used that are not feasible when crops are present, such as tillage and desiccation
how does fallow reduce weed seedbanks?
light tillage to kill each flush of seedlings or deplete underground root reserves of perennials
what is the limitation of fallowing?
no money is made
How are planting dates used as a cultural control?
The pest can be avoided or the pest impact can be reduced
What factors in usnig planting dates as a cultural control 3 factors?
1. Climatic region
2. type of crop
3. Nature of the pest
how cn planting dates reduce pathogen problems?
1. avoid seasons where pathogen vector activity peaks
2./ maximize crop and growth rates in relation to pathogen activity
3. avoid seasons when pathogen inoculum is at its greatest
How can planting dates help fight weed infestations?
it is possible to time planting of a crop that favors the crop growth and not the weed growth. Planting cereals in the spring can minimize impact of downy brome, wild oats and other weed grasses taht grew during the winter because htye can be killed before the crop is planted
Why is alfalfa planted in late winter in Central Valley California?
to escape summer and winter weeds
What does poikilothermic mean?
A poikilotherm is an organism whose internal temperature varies considerably
how can changing planting dates reduce nematode problems
nematodes less active in cool soil, plant in cool soil
how is planting date used for sugar beet against sugar beet cyst nematode?
Sugar beets planted early spring allows for beets to establish but discourages nematode attack until after beets have grown somewhat
How were carrots protected from root-knot nematode in California with planting dates?
Carrots were planted in the fall in CA to reduce galling and forking damage by root-knot nematodes
What is phenology?
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate.
How are plants and pest insects related with phenology?
many host specific insects require perfect synchronization of their life cycles with the life cycles of the host plant.
How are sugar beet plantings timed in the Central Valley California?
sugar beets are planted only after the annual flights of the green peach aphid to avoid transmission of yellows viruses
what factors are conflicting in planting dates for sugar beets?
yellows virus date versus nematode date
how is timing used to foil the boll weevil for cotton? 3 things
1. Cotton planted early
2. Short season variety
3. Defoliated early before boll weevil populations reach damaging levels
When is late planting a good idea?
to let overwintering insects starve to death
What are the limitations of manipulating the planting date?
1. missing the best market price
2. weather conditions may prevent early planting
3. pest evolved with crop; conditions unfavorable for pest are often unfavorable for the crop
What does crop density help with?
weeds
How can higher densities help with pathogen problems? How can they hurt?
Seedling diseases can be offset with higher seeding rate. however, higher density can also lead to more spread of diseases
What kind of crops is density for weed control most significant?
broadcast crops such as cereal and alfalfa
How does reducing row spacing and closing the canopy sooner impact arthropod management?
Predators prefer to hunt pest insects under a closed canopy. Also, pest insects such as corn earworm moths often prefer to oviposit in open canopy fields
how can density help with vertebrates?
seedling densities can offset damage from birds
Limitations of density solution
1 Higher cost of seed
2. crop density that is above optimum for root crops such as carrots and sugar beets can reduce marketable yields
what is the advantage of priming or pregerminating the crop relative to pest insects and pathogens?
reduces the time the crop is exposed to pests associated with stand establishment
what is the advantage of priming or pregerminating the crop relative to weeds?
rapid germination and emergence allows a crop to establish faster than weeds
what is a limitation of priming seed?
seed becomes more difficult to handle, if the radicle has emerged it must not be broken off it is expensive compared to conventional seeding
what is the advantage of deep planting? disadvantages?
birds can’t get the seed. however, seedlings are weaker and emerge slower which is a problem for other reasons
Advantages of transplanting?
1. more uniform crop stand
2. reduced seed cost
3. earlier harvest for market and avoiding late season pests
Transplants in regard to diseases of germinating seeds?
transplatns are beyond diseases of germinating seed such as damping off.
disadvantage of transplanting?
can damage the roots, opening up entries for pathogens
mechanical spread of virus such as tobacco mosaic virus
advantages of transplanting over nematodes
delays nematode infection, larger plants better able to sustain nematode attack
advantage of transplanting over weeds
1 transplanted crop is much larger than germinating weeds and thus has a competitive advantage.
2 also allow for piling soil into crop row for weed management
3. transplanted crops can be grown without use of herbicides
4. trifluralin herbicide can be used on transplanted tomatoes but not on direct seeded tomatoes
transplantation regards mollusks/arthropods
established root systems and top growth reduces damage from cutworms and slugs
limitations of transplanting
labor intensive/need greenhouse/not for root crops
what two aspects of soil can be changed for cultural control?
moisture and pH
how can moisture of soil affect pest management?
drown the pests or dry them out, such as with rice cultivation
how can altering pH of soil help?
alter ability of microorganisms to survive and attack the host
Pathogens — soil moisture
wet soil can increase pathogen attack, many soil borne pathogens have a motile stage in their lifecycle such as the zoospores of Phytophthora needs free water to swim to the host
soil pH — pathogens
changing the soil pH can change the suitability for of soil environment for many microbial organisms clubroot pathogen only infects if soil is below pH of 7.0 (acidic)
how is potato scab streptomyces affected by soil pH?
acidifying the soil to pH of 5.0 controls potato scab
soil moisture – weeds
some weeds such as canary grass and wild oats do better in wet soil
can soil compaction favor weeds? how
yes, knotweed and some spurges can grow well in compacted soil while crops do not thrive in it
moisture — nematodes
nematodes can be drowned
how does pH affect sorghum?
acidic soil extends the whorl stage of sorghum, which benefits the armyworm which eats the whorl stage of sorghum
what kind of fertilization is best for pest managmeent
optimally fertilized crops resist pests the best
overfertilization and pathogens and weeds
overfertilized crops are very lush — increase pathogens and weeds