Rhs year 2 week 19 presentation

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  • 1. RHS Level 2 Certificate Year 2 Week 19 – Plant Pests, their biology and control.
  • 2. Learning objectives
    • 2.6 Describe how the types of weed described in 2.4 relate to horticultural situations, including recently cultivated soil; herbaceous perennial borders; woody perennial plantings; and lawns.
    • 2.7 State the botanical names of TWO weeds associated with EACH of the situations described in 2.6.
    • 3. Know the problems posed by pests in horticulture and ways in which these can be minimised.
    • 3.1 Define ‘plant pest’.
    • 3.2 Describe the damage caused by rabbits, cabbage white butterfly larva, black bean aphid, two-spotted spider mite, glasshouse whitefly, vine weevil, slugs, snails, and stem (or bulb) eelworm.
    • 3.3 Describe in outline the life-cycles of cabbage white butterfly, black bean aphid, glasshouse whitefly and vine weevil.
    • 3.4 Describe TWO different methods of reducing the effects of EACH of the plant pests named in 3.2; methods should be selected from more than one of the control options (chemical, physical, cultural or biological) available.
    • 3.5 Describe how a knowledge of the life cycles of the cabbage white butterfly, black bean aphid, glasshouse whitefly and vine weevil contribute to the success of their control.
  • 3. Quiz
    • 10 questions – 15 minutes
    • Test conditions please
  • 4. Quiz answers (1)
    • 1. (a). 2. (i) Encourage natural predators. (ii) Avoid over fertilizing (iii) Use controls that do not harm predators (iv) tolerate some damage.
    • 3. Possible answers include – ‘Resistafly F1’ Carrots – carrot root fly and ‘Sarpo Mira’ Potato – late blight.
    • 4. Chemical, biological, cultural and physical
    • 5. Benefit – timing of control precise, Limitation – resistance of some insects
    • 6. Vine Weevil
    • 7. One that produces several generations a year – e.g. Cardamine hirsuta
  • 5. Quiz answers (2)
    • 8 . (i) they reproduce vegetatively (ii) they have extensive root systems.
    • 9. Glyphosate – translocated or systemic.
    • Dicamba – selective
    • Diquat – contact
    • Metosulam – residual
    • 10. (i) they compete with cultivated plants for nutrients, water and light. (ii) they are unsightly (iii) They can be hosts for pests, diseases and viruses
  • 6. Typical weeds in the garden
    • Newly cultivated soil – ephemeral and annual weeds, e.g. Stellaria media and Cardamine hirsuta . Seeds exposed to light by cultivation will germinate.
    • Herbaceous perennial borders – ephemerals and annuals can arise, but also perennials e.g. Aegeopodium podagraria and Gallium aparine.
    • Woody perennial planting – the soil may be infrequently cultivated so perennials like Brambles Rubus fruticosus and Bindweed Calystegia sepium may become established
    • Lawns – mowing controls the height of the grass but allows broadleaf weeds such as Taraxacum officinale (dandelion) and Plantago major (Greater Plantain) to thrive
  • 7. Plant pests
    • Definition: any insect or animal that causes unacceptable levels of damage to cultivated plants, making them unsuitable for the purpose for which they are grown.
  • 8. Pest Lifecycles and why they matter
    • Two basic lifecycles for insect pests.
    • One is a complete metamorphosis. That is Egg -> larvae -> pupa -> adult
    • The other is called incomplete metamorphosis. That is Egg -> Nymph (an immature adult) -> adult.
    • Some pests are most effectively controlled at one stage of their life cycle. For example Vine Weevil are generally controlled as larvae, as the adults are hard to find and the eggs and pupae are not affected by controls.
  • 9. Rabbits
    • Damage – nibbled plants and damage to bark of woody plants and trees
    • Control – trapping (must be done humanely); physical barriers; repellent sprays.
  • 10. Cabbage White Butterfly
    • Caterpillars do the damage – large holes in leaves, Small Cabbage White caterpillar also tunnels the hearts of cabbages.
    • Full metamorphosis – adults, eggs and pupae are hard to control, caterpillars are vulnerable.
    • Controls – physical barriers to prevent egg laying (e.g. fine net); biological control - Steinernema carpocapsae; chemical control – pyrethrum or deltamethrin.
  • 11. Black Bean Aphid
    • Clusters of fat black insects at the growing tips and in the leaf axils of plants.
    • Life cycle – eggs laid on Euonymous europaeus and related plants, young hatch and mature there, feeding on new growth. Winged adults migrate in May/June to legumes.
    • Damage – weaken the plant, excrete honeydew, spread viruses.
    • Controls – Fatty acid or pyrethrum sprays; autumn sowing of Broad Beans ( Vicia faba ) and pinching out tips in late May. Ladybirds and their larvae.
  • 12. Two Spotted Mite
    • Tiny eight legged mite, two darker spots on its back. Overwintering females turn red.
    • Life cycle: Egg -> Nymph (3 nymph stages) -> adult. 7-14 days to complete.
    • Damage: white speckles on leaves that gradually taken on a bronzed appearance; webs or groups of mites visible beneath in severe infestations.
    • Controls: increase humidity; Fatty acid sprays on food crops; abamectin on ornamentals; Phytoseiulus persimilis is the biological control under glass.
  • 13. Glasshouse White Fly
    • Tiny white sap sucking winged adults and scale like nymphs.
    • Lifecycle: Egg -> Nymph (forms a legless scale) -> adult.
    • Damage: spreads virus, excretes honeydew.
    • Controls: no effective chemical control other than fatty acid spray. Encarsia formosa is the biological control under glass.
  • 14. Learning outcomes
    • 2.6 Describe how the types of weed described in 2.4 relate to horticultural situations, including recently cultivated soil; herbaceous perennial borders; woody perennial plantings; and lawns.
    • 2.7 State the botanical names of TWO weeds associated with EACH of the situations described in 2.6.
    • 3. Know the problems posed by pests in horticulture and ways in which these can be minimised.
    • 3.1 Define ‘plant pest’.
    • 3.2 Describe the damage caused by rabbits, cabbage white butterfly larva, black bean aphid, two-spotted spider mite, glasshouse whitefly, vine weevil, slugs, snails, and stem (or bulb) eelworm.
    • 3.3 Describe in outline the life-cycles of cabbage white butterfly, black bean aphid, glasshouse whitefly and vine weevil.
    • 3.4 Describe TWO different methods of reducing the effects of EACH of the plant pests named in 3.2; methods should be selected from more than one of the control options (chemical, physical, cultural or biological) available.
    • 3.5 Describe how a knowledge of the life cycles of the cabbage white butterfly, black bean aphid, glasshouse whitefly and vine weevil contribute to the success of their control.