Safe Use of Agricultural Chemicals
Consider the weather conditions.
Spraying in very hot, wet, humid or windy conditions can be more dangerous. Chemicals move more under such conditions and end up in places where you might not want them; on other plants, in neighbouring areas or even on or into the human body. In wet conditions chemicals can be washed away from the places where they have been applied so that they are not very effective against whatever pest or disease that they are being used to control, or they may be washed into areas where they may cause damage to other plants or animals, for example, onto lawns or into fish ponds.
Hitting the target
Make sure the fertilizer or pesticide goes where you want it and stays there. Use a screen or temporary barrier of some sort (ie: plastic sheeting is useful) to stop spray from drifting, and put fertilizer into holes punched in the ground rather than spreading it over the surface, particularly on sloping ground where it can be easily washed away.
Don't overuse chemicals
Overuse can harm beneficial insects or animals (eg. lady birds, stick insects, birds). Overuse of pesticides can build resistance within the things we spray, and can result in the build up of dangerous residues in the environment. Overuse of fertilizers can leave toxic residues that may damage plant growth, change soil pH, or can result in excess nutrients being washed or leached away into streams, dams, lakes, ground water, and eventually oceans often resulting in such problems as algal blooms. Overuse of such chemicals is also simply wasting your money. Carefully read the manufacturers instructions on what amounts to use, how often to use it, and when to use it.
Be careful not to burn plants
Sprays or fertilizers which are normally useful on plants can cause foliage burn if overused or when sprayed in the wrong climatic conditions or at the wrong time of day.
Store chemicals properly
Avoid leaky sprays, bags or bottles with holes, and keep in a locked shed or cupboard away from children. Store chemical in correctly, labelled containers. Dispose of used pesticide containers, and residues from washing out containers or application equipment according to manufacturers instructions or ring your local council Health Department, state Environment Protection Agency (or similar body), or Agriculture Department for advice.
Handle all chemicals safely
Chemicals which are thought to be safe today may be found to be dangerous tomorrow. Wear protective gear (eg. rubber gloves, a respirator, gum boots, long sleeves and trousers). Don't breath in fumes. Don't dump excess chemicals either in the garden or elsewhere (ie: drains, sewers). Think about what you really need before you buy or make it up, and you shouldn't have any excess.
To prevent contamination and possible damage to your plants, you should use one sprayer for weedicides and another one for insecticides, fungicides and fertilisers. All equipment should be washed out thoroughly after use, and the washings must be disposed off in a safe manner. It is also a good idea to have the phone number for your local poisons information service written down in a prominent position near your phone in case of problems. Such numbers are listed normally in the information sections at the front of your phone directory.
For your own safety and the environment, vary what you use
Alternate several different types of fertilizers and several types of pesticides, so problems don't compound over time as one particular chemical builds up in the body or the environment. The alternating use of pesticides also helps prevent the build up of resistance of pests to a particular pesticide.