Unit 260 Maintaining plants outdoors
How to check and report signs of damage or threats to health of plants
As part of general duties the horticultural worker should always be on the lookout for threats to the health of the plant they are looking after. This might come from
(i) pests
(ii) diseases
(iii) disorders
(iv) unfavourable conditions
(v) competing growth.
The symptoms will range from visible presence of pests such as aphids on roses, the results of pest attack such as saw fly damage, right through to general stunting of growth due to lack of soil nutrients. In general terms problems can be noted when there is a lack of growth, discoloration or plants, dropping or wilting of leaves.
Some common problems might be
Pests such as
Aphids (Greenfly) Sawfly damage
Diseases such as
Black spot on rose Powdery mildew
Disorders and unfavourable conditions such as
Water logged soil Lack of water
Lack of nutrients such as nitrogen
Competing growth (weeds stealing light, water and nutrients from the soil)
How seasonal weather conditions affect plant growth and health.
Although there is a natural growth cycle for every plant, the vegetative and flowering stages of growth are directly influenced by light. Light gives food and energy to plants through photosynthesis. Therefore as day light is less in the autumn and winter many plants reduce their growth at this time of the year.
Plant growth is at its maximum when the soil is warm and moist and the day light is long. Therefore the period of most growth is spring and early summer. This will also be the times of the year when most weeds will germinate.
During extreme heat and cold plant growth is also inhibited as heat often means water is in short supply and plants need water to move nutrients around their systems and to photosynthesis and make new cells. In extreme cold plants shut down as it can be hard to obtain water from the soil (due to it been frozen). Extreme frost can severely damage a wide range of plants as the water in the plants cells freezes and expands breaking the cell walls, this then leaves plants open to attack from disease.
Why do we carry out feeding of plants?
We apply fertilisers to plants to keep them growing healthily; plants absorb through their roots about 30 different nutrients and minerals dissolved in water. The three most important are nitrogen (N), phosphorus (P) and potassium (K) – the letters in brackets are their chemical symbols. In nature, as leaves fall and plants die, they decompose and return nutrients to the soil, maintaining the natural balance. However in gardens we remove clippings and other plant material when mowing, weeding and tidying and by removing the plant ‘bits’ that would naturally rot down, we are actually depleting the soil of its nutrient reserves. Correct feeding of plants will ensure good growth and floral displays
Why do we carry out watering of plants?
There is nothing 'in' water that helps it to grow. It is the water itself that the plant uses for growth. There are some minerals dissolved in water which help the plant to grow, but they aren't as essential as the water itself.
During photosynthesis, the plant uses an input of energy (light) to converts water molecules and Carbon Dioxide molecules into Glucose molecules (sugar).
Why do we carry out surface cultivation?
Improving soil quality with good soil cultivation is an important part of any gardening program and weed control or surface cultivation is crucial. Surface cultivation
a. Removes weeds
b. Opens up the soil letting in water and air
c. Breaks up the soil letting plant roots move down into the soil.
However it also disturbs the soil bring new weed seeds to the surface where they germinate.
Why do we carry out mulching?
Many different materials can be used to cover the soil’s surface, including bark chippings, leaf mould, and well-rotted farmyard manure or crushed shells.
Mulching has many benefits. It can provide nutrients for plants, lock in moisture, form a barrier against weeds and can help to insulate the roots of vulnerable plants from winter cold. Mulches can also be used for decorating the tops of pots.
When to mulch
· In the autumn, spread a ring of mulch around newly planted trees, shrubs or herbaceous perennials. In early winter, tender plants like Verbena bonariensis or dahlias will benefit from thick mulch. It will help protect roots and the crown of the plant from frost.
· The best time to mulch entire beds or borders is in late-winter or early spring. This will trap in moisture from wet weather and ensure beds don’t dry out quickly in the heat of summer.
The effects of soil condition on plant growth.
For plants to grow well they must have good soil conditions and in general this means
a. The soil is well drained to stop water logging
b. The soil is not compacted so roots can work down into the soil
c. The soil has enough nutrients and organic matter (to supply plants with the food they need).
d. The soil is not too light which would result in a problem with the plants been able to obtain the water they need
Reasons why watering regimes vary for different soils and plants.
Light sandy soils will require more water than heavy clay soils. This is because there are large spaces between the particles of sand so water drains quickly, in clay soils the particles are very closely packed together due to their size and drain slowly also due the greater surface area of the soil more water is held on the clay particles
Methods of dealing with threats to plant health
There are 3 main methods that can be used
Physical methods of dealing with threats to plant health
This is to physically attack/deal with the conditions causing the problem, for example a. By pruning off areas of diseased plant tissue.
b. by crushing slugs
Cultural methods
This means changing the environment around the plant. For example
a. if we add organic matter to the soil we may overcome a growth problem caused by lack of water on a light sandy soil
b. We might grow plants that discourage some insect pests by the chemical they release
Chemical methods
The range of threats that are dealt with by chemical means tend to be
Weeds- to control weeds we use herbicides
Pests- For insect pests we use insecticides
Diseases- For the control or prevention of diseases we use fungicides
This should normally be seen as a last resort as chemicals are expensive and have the potential to cause harm to the environment
How the use agrochemicals/ pesticides can improve plant health.
Used correctly pesticides can work quickly and effectively to deal with a problem. They can ensure that an attack by for example pests such as aphids can be reduced to a level where natural predators can control the problem
However if used incorrectly they can damage plants (scorch the leaves, stunt growth or even kill plants). Before using pesticides the label must be studied carefully and obeyed fully taking into account the time of the year and the weather conditions
Describe how environmental damage can be minimised when maintaining plants
Damage to the environment can be avoided by a number of means e.g.
Calibrating sprayers so only the required amount of pesticide is used
Recycling grass clipping etc. on a compost pile rather than send to landfill
Not using fertiliser near to water courses (streams etc.)
The correct methods for disposing of organic and inorganic waste.
Non-hazardous waste e.g. grass clippings, these can be recycled by composting.
Hazardous waste e.g. empty pesticide containers should be rinsed and the rinses should be added to the sprayer tank. Once rinsed the empty container should be stored in a safe locked container for approved contractor disposal.
Current health and safety legislation and code of practice which applies to this area of work
The Health and Safety at Work Act (HASAWA)
The is probably the most important legislation it is quite complex but has the following main aims
To protect workers and other people on the work site.
1. Employers must
a. Take steps to ensure safety of their work force
(It is for the above reason that risk assessment is required. Risk assessment requires that the employer assesses the risks of all work place operations and then takes steps to remove or reduce those risks).
b. Take steps to ensure safety of visitors, customers and the public who enter the work place
2. Employees (you) must
a. Take reasonable steps to protect themselves at work
b. Take reasonable steps to protect others at work (work mates, public etc.)
c. Not interfere with any equipment provided for their safety
d. Co-operate with management to help ensure H/S is maintained.
Noise at work regulations 1989
These regulations are aimed at protecting the hearing of workers.
They place a responsibility on employers to provide free ear hearing protection is noise reaches a set level.
85dB Employees can request free hearing protection
90dB Employees must wear hearing protection
140dB Employees must not be exposed to this level of noise, as no protection will work
As a rough guide a strimmer is approx. 108 dB.
Manual Handling Regulations 1992
These regulations are aimed at preventing injuries caused by lifting, moving heavy of awkward objects.
Employers must
a. Assess the risks of such lifting, moving operations
b. If possible eliminate the operation (i.e. by using a forklift etc.).
c. If required train staff in the safe lifting and handling of objects.
Provision and use of Work Equipment Regulations 1998 (PUWER).
Set of regulations that require employers ensure all tools and equipment used at work (from a hammer to a mower) are
a. Suitable for intended use
b. Safe for use
c. Maintained correctly
d. Carry appropriate warning labels