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Level 3 Question on Plant Growth
by Janet Prescott - Sunday, 13 May 2018, 9:08 PM

From R3013 Feb ‘17

Q2 a) Name TWO perennial weeds that could be found in a border in a public park (2 marks)

b) Describe integrated control methods for ONE of the weeds NAMED in a) (8 marks)

This question relates to the following part of the syllabus:

1.1 Describe symptoms and damage caused by a range of pests, diseases and weeds in specific horticultural situations

Weeds: couch, annual meadow grass, dock, Japanese Knotweed, bindweed, hairy bittercress

2.1 State a range of appropriate methods for control of pests, diseases and weeds.

To include: physical, cultural, chemical (including partial sterilisation of soils and other media), biological for each of the pests, diseases and weeds.                   

Sources of information e.g. current UK Pesticides Guide.

Define Integrated Pest Management. 

Review the use of Integrated Pest Management in horticultural situations:

Explain what is meant by ‘Economic Damage threshold’ 

Appropriate selection of integrated control methods for pests, diseases and weeds listed in 1.1.

Part a) needs two suitable names of weeds. Although there are common names in the syllabus, you need to follow the instructions at the start of the exam paper and use full botanical names. It is also important to read the question well and make sure your examples are both perennial weeds and commonly found in borders.

Examples of suitable weeds in the examiner’s comments are: Aegopodium podagraria and Taraxacum officinale.

Others that are on the syllabus could be Elymus repens (couch grass), Rumex obtusifolius (dock), and Calystegia sepium (hedge bindweed).

A longer answer is required for part b) as you are asked to ‘describe’. You should state the weed example first, and the rest of the answer needs to be relevant to your choice of weed. For this question you need to understand what integrated control means. It is crucial for integrated control methods that the least harmful methods are used first. It is important to structure your answers well and write the points in the correct order for this type of question.

The examiner’s comments pointed out that marks were lost if chemical methods were described first, and suggest the following:

Good answers to this question evidenced an understanding of the requirement to seek to control the weed through cultural, physical and environmental methods before resorting to chemical control. Marks could be gained for describing the following techniques:

·        plant inspection prior to planting

·        digging by hand to remove all of the root system

·        digging up a plant infested with weed in order that all of the weed can be removed

·         the use of mulch and physical barriers and covering ground for a year or more with a black plastic membrane to exclude light and so weaken the weed.  

Having outlined a number of the above controls a candidate should then describe the use of a translocated herbicide such as Roundup and also consider the use of residual herbicides.

An important general point for this unit is to check that you are using up to date examples of any pesticides. These can be checked on the RHS Advisory leaflets for home gardeners, and also on the HSE Pesticides Register of UK Authorised Products.