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DISEASE CONTROL

Thus far, we have discussed the various biotic and abiotic causes of plant disease. In the next section we will discuss methods for disease control.

DISEASE CONTROL - CULTURAL CONTROL

Typically the most common way in which homeowners attempt to control plant diseases is through the use of CULTURAL CONTROLS. Cultural controls involve ways in which you can modify how you grow your plants in order to reduce or eliminate disease. One general area of cultural control is to avoid the pathogen.

AVOIDING THE PATHOGEN.

Pathogen avoidance may seem difficult, but there are several straightforward ways in which you can accomplish this.

BUY SEED FROM A REPUTABLE SOURCE.

Many plant pathogens, particularly viral and bacterial pathogens are carried on seed. Therefore using clean seed to start can help minimize disease problems later on. If possible, buy seed that is certified as disease or pathogen-free. Certification doesn't guarantee that there are absolutely no pathogens in the seed, but does indicate that the seed has been produced in a manner that will minimize the likelihood of pathogens being present. Often certified seed is produced in dry areas (e.g., in the western USA) where pathogens typically don't grow well. Certified seed is also tested for pathogens during the certification process and meets some set of standards for the percentage of seeds that may be infected with a given pathogen. If you buy certified seed, you should ask for information on where the seed was produced, what pathogens it has been tested for and what the testing standards are.

INSPECT PLANTS PRIOR TO PURCHASE

When buying transplants, check before you buy to make sure that the plants look healthy. Do not buy obviously diseased or unthrifty plants. In addition to looking at leaves, stems and branches, try to get a look at the plants’ root systems. Look for root browning that might be an indication of a root rot or nematode problem.

INSPECT PLANTS FOR INSECT PESTS

Insect pests can cause serious damage to plants through their feeding. Also remember that some insects serve as vectors for pathogens.

CONTROL ALTERNATE HOSTS

Many pathogens are able to attack more than one host. If you have chronically had problems with a particular disease, check to see if the causal pathogen has other hosts. Do not plant any host for the pathogen in the affected area of your garden. Also learn about potential weed hosts and keep these under control. Control of alternate hosts will prevent the build-up of a pathogen and can often reduce the time that you need to wait before replanting a desirable ornamental back into a problem spot.

USE NON-CONTAMINATED WATER

Be careful of your water source. Sometimes water that has come into contact with the soil or plant pathogen infected plant material can serve as a source of inoculum for healthy plants. In particular, be careful when using water from a pond or cistern, or recycled water in a greenhouse. Rainwater is typically pathogen-free as long as it has not come into contact with soil or infected plants.