Plant Science Final

• Xylem transports water and minerals from roots to shoots, while phloem transports sugars produced by photosynthesis throughout the plant.
• The endodermis is the innermost layer of cells surrounding the vascular tissue.
• Parenchyma tissue provides support and storage functions within plants.
• Chemical Pest Management

  • Disinfectants
  • Fungicides
  • Nematicides
  • Bactericides
  • Insecticides
• Metamorphosis


  Always damaging the plant
• Butterflies are not complete
• Integrated Pest Management (IPM)


  • Concept that pests are always present
  • Objective is to keep the pest populations low
  • Integrates a variety of management approaches
  • Goal: cost-effective and environment-friendly
• Pest Management

  • Cultural-Crop rotation, irrigation/fertilization, and sanitation
  • Biological-Beneficial insects, disease-resistant bacteria, green manure, and plant chemicals
  • Mechanical-Handpicking, trapping, and tillage
  • Genetic-Pest-resistant crops
• Viruses


  • Small simple pathogens
  • Need wounds for transmission
  • Symptoms include stunting, tissue deformities, chlorosis, and vein clearing
  • Management includes using virus-free seed, sanitation, and resistant varieties
• Nematodes


  • Microscopic roundworms
  • Feed on plants using stylet
  • Symptoms include stunting, wilting, and chlorosis
  • Management includes crop rotation, resistant varieties, or fumigants
• Insects


  • Small invertebrate animals
  • Life cycles include metamorphosis, incomplete metamorphosis, and no metamorphosis
  • Feeding habits can be chewing or piercing and sucking
  • How they damage the plant?
  • What the producer does to prevent them?
• Plant Pathogens


  • Fungi
  • Bacteria
  • Viruses
  • Nematodes
  • Parasitic plants
• Fungi


  • Composed of filamentous threads
  • Enter by natural openings, injuries or wounds, or direct penetration
  • Symptoms include leaf spots, blights, wilts, rots, and cankers
  • Managed by crop rotations, planting disease-free seed, removing debris, and fungicides
• Bacteria


  • Microscopic, single-celled organisms
  • Present on plant surfaces; survive on plant exudates
  • Symptoms include leaf spots, wilts, stunting, and yellowing
  • Management includes disease-resistant varieties, crop rotation, and sanitation
• Plant disease occurs when a pathogen, a susceptible host, and a favorable environment are present
• Pathogens include fungi, bacteria, nematodes, viruses, and others
• Insects can damage crops in fields and in storage facilities
• Integrated pest management integrates multiple approaches
• Pest management includes cultural, biological, mechanical, genetic, and chemical practices
• Plant disease is a progressive deviation from plant's normal development, appearance, or function
• Plant disease requires a susceptible host, pathogen, and favorable environment
• Plant diseases can be biotic or abiotic
• Weed


  Plant out of place
• Classifying weeds


  • To know how to manage them
  • Based on environment they grow in
  • Based on life cycles
  • Based on taxonomy
• Weed classifications


  • Annuals
  • Biennials
  • Perennials
• Annuals


  • Thrive on frequently disturbed sites
• Biennials


  • Persist in permanent pasture
• Perennials


  • Survive under diverse conditions
  • Difficult to control once established
• Weeds

  • Light requirement sometimes hard to penetrate the soil
• Weeds


  • Reduce yield by competing with crops
  • Increase production costs
  • Can be allelopathic (release chemicals that inhibit other plants)
  • Can be parasitic
  • Devalue primary crop
  • May contain toxins
  • Compete for water, nutrients, harvest equipment
• Weeds can affect the intake of MILK and yield of plants
• Traits of some weeds

  • High seed production
  • Seed dormancy (long seed bank dormancy period)
• Weed prevention methods

  • APHIS (Animal and Plant Health Inspection Service)
  • State government
  • Farmers
• Herbicides


  • Chemicals used to kill weeds
  • Primary method of weed control
• Herbicides


  • Advantages: reduced cost, greater flexibility, effective, can be persistent
  • Disadvantages: can kill non-targets, contamination, herbicide resistance
• Herbicide-tolerant crops


  • Genetically engineered resistance to glyphosate (low-cost, non-selective herbicide)
  • Used with conservation tillage
• Herbicide types


  • Mode of action (growth regulators, inhibitors, desiccants)
  • Time of application (pre-plant, pre-emergence, post-emergence)
• Herbicides make up about 60% of pesticides used in agriculture
• Cotton and soybean are somewhat resistant to herbicides
• Cultural weed control practices

  • Crop rotation
  • Plant population
  • Cover crops
  • Companion crops
  • Planting date