Agriculture Reference
In-Depth Information
eliminates infection by diseases which require high moisture and humidity
levels.
Pathogen-Free Propagation
—Plant
disease pathogens are frequently
carried in or on vegetative propagation materials (such as roots, bulbs, tubers,
corms, and cuttings). Production of clean planting stock is especially impor-
tant in the culture of certain high-value agricultural and ornamental crops.
These plants must be grown in pathogen-free greenhouses or in sites isolated
from growing areas for these crops. When planning for isolation, consider
how far the pathogen may spread, how the pathogen is spread, and the distance
between potential growing sites.
Clean Planting Sites
—In some crops, certain plant disease pathogens
can be controlled or reduced by eliminating other nearby plants which are
hosts for the same disease organisms. These may be:
•
plants which harbor the pathogens, such as weeds around field bor-
ders, ditch banks, and hedgerows
•
plants which the organism requires for one stage of its life cycle. An
apple grower, for example, can control cedar apple rust by eliminat-
ing nearby cedar (juniper) trees.
Removing Infected Plants
—Diseases often can be controlled by sys-
tematically removing infected plants or plant parts before the disease pathogen
spreads to other "clean" plants. This method can be especially important for
the control of some viral and mycoplasma pathogens for which no other con-
trols are available.
Crop Residue Management
—Infected crop residues often provide an
ideal environment for carryover of many pathogens. In some cases the patho-
gens increase greatly in the residues. Three basic techniques are used in crop
residue management:
•
deep plowing buries pathogen-infested residues and surface soil and
replaces them with soil relatively free from pathogens
•
following reduces pathogen carry-over because their food source de-
cays and is no longer available
•
burning kills some pathogens and removes the residue on which they
live. This practice may not be legal in some areas
Disinfecting Equipment and Tools
—Some plant diseases can be
spread from plant to plant, field to field, and crop to crop by workers and their
equipment. Disinfecting equipment, tools, and clothing before moving from
an infected area to a disease-free area can prevent or delay disease spread. This
method of disease spread is especially important in high humidity and wet
