A
November 2001
By Mary Bernard, Master
Gardener
Prevention
is the best remedy when it comes to dealing with most plant diseases. Many diseases cannot be effectively controlled once
symptoms develop or become severe. Fall is a good time
to launch your preventative management program in the home orchard and garden. This includes a combination of strategies involving
sanitation, cultural practices, and seasonal spray applications.
Garden sanitation aims to remove the source of future disease infections by
means of a thorough clean up program. Common fungus
diseases like peach leaf curl, brown rot, apple scab, camellia petal blight,
and black spot on roses will reappear the next season because the fungus spores
survive over winter in dead leaves, rotting or mummified fruit, and other plant
debris left behind the previous Fall. Disease
pathogens can also survive in older mulching material laid out in previous
years. If a serious fungus infection exists, such as
Camellia Petal Blight, remove old mulch and replace with fresh material. Grab a rake and get out into the garden for a clean-up day
before first rainfall for best results. Dispose of any
suspect plant debris.
Removal of diseased plant tissues on the plant itself is your next line of
defense. Prune out diseased foliage, twigs or
branches, hand pick blighted camellia blossoms as they appear and dispose of
these in the trash. Avoid unnecessary pruning; pruning
causes wounds, which can be entry sites for decay and disease organisms. Sanitize pruning equipment to avoid transmitting disease
to healthy plants.
Avoid overhead irrigation – splashing water spreads fungal spores and wet
foliage promotes some foliar and fruit diseases such as leaf spots, rusts,
anthracnose, and brown rot.
Finally, follow up with preventative applications of a fungicidal spray. This is an especially critical step in the control of
peach leaf curl and other recurring diseases. Correct
identification of the pathogen is essential for selecting the proper control
method. Synthetic and organically acceptable spray
materials are available to control certain plant pathogens, primarily fungi. Products such as Bordeaux mixture, sulfur, fixed copper,
and fungicidal soap sprays protect plants from pathogen infection. These organically acceptable fungicides generally only
prevent the infection of healthy, spray-covered tissue and do not act
systemically to kill existing pathogens, therefore repeated applications may be
necessary during critical growing stages. Synthetic
fungicides are often more effective, easier to apply, and are less likely to
damage susceptible plants; some have systemic activity. Fungicides
require careful timing to be effective.
Consult a qualified nursery sales person to determine an appropriate spray
product for you. Wear protective gear such as goggles
and gloves use as directed on the product label.