07/06/2013 - Diseases and Disorder Unit 27208

The class was conducted by Lisa Burton on Control Measures / Options. The common option for management of the diseases fall into three categories. 

1. Chemical control / options  - the use of chemicals, be it conventional or organic for pest management.

2. Cultural controls / options - the use of a range of options that minimise infection etc.

3. Biological controls / options - the use of natural organisms - mainly pathogens for disease 

    management.

Some examples of other disorders, due to poor management are :

• Herbicide damage - often typified by "up cupped" leaves with prominent veins.
• Pesticide damage - can result under slow drying conditions and often leaves scorch marks.
• Storage disorders - due to low humidity, low temperatures, incorrect oxygen and carbon dioxide levels.

There are a range of control options available to you. Today, its better to think of the control measures as management options. There is a considerable trend toward the use of both cultural and biological control / options, where possible, to minimise the use of agrochemicals. Often these options are considered first, before considering the agrichemical options.

Chemical Controls / options -  Fungicides and Bactericides 

Falls into two groups such as protectants which protect the plant from infections entering the plant, but must be applied before they arrive.

Eradicants the act to eradicate infections that have already started, but generally are only effective if applied up to 96 hours after germination sometimes referred to as "kickback".

Resistance to pesticides is preventing resistance to fungicides is to apply products according to the label and to consider the rotation of the products applied.  A good spray programme is one that incorporates several protectant fungicides and uses eradicants only where an infection occurs.

Cultural Controls / options -  Most diseases prefer humid conditions, so if we can change these favourable conditions to unfavourable we can discourage or stop these disease. To decrease humidity by increasing airflow through a canopy by pruning and spacing the plants. Do not water the canopy leaves, water the soil. In the greenhouse try to increase the ventilation. By providing drainage or locating plants in drier area possible.

Provision is good growing conditions to maintain good plant health and resistance. It is by creating s less favourable environment for pests and diseases have, you can prevent these from occurring. 

Crop rotation by rotating crops to prevent pest or disease build ups, or a carry over. The same plant type is not planted back in the same area each seasons. This is not always possible or effective, but an option none the less. Try to remove alternative plants if possible. The manipulate sowing dates to periods that are less susceptible to disease damage considering the life cycles of diseases.

For soil cultivation and drainage can make the soil less wet and discourage soil / root diseases. the hygiene is vital. It comes in many forms from removing diseases by burning pruning, using clean tools, keeping area clean, picking off diseased plants part. Apart from that is physical controls include soil disinfection, hot water treatment of seeds and bulbs.

Biological Controls / option - 

The control of the plant diseases using pathogens. May be naturally occurring or introduced. A bacterium Agrobacterium radiobacter applied to cutting or seedling prevents the plants from becoming infected with a disease called crown gall.

A commercial preparation is available called Dygall. A fungus Trichoderma viride is commercially available in a variety of forms. It is antagonistic to fungus that causes silver leaf. It may also inhibit other fungus. Trichoderma products include Trichopel.