Seedborne disease refers to the particular plant diseases that are
transmitted by seed. In some cases the transmission on seed is insignificant
compared to the population of disease organisms that exist in soil or on weed
species. In other cases, the transmission on seed is the primary means by which
a disease spreads. While we are cautious about any type of disease on seed, it
is this latter set of diseases that we must be most vigilant in controlling.
Planting infected seed may result in a widespread distribution of
disease within the crop, and an increased number of initial infection sites
from which the disease can spread. As an
example, consider the development of ascochyta blight in a chickpea crop. Since there is a high rate of
seed-to-seedling transmission of this disease, even a small percentage of
infected seed can result in significant seedling infection in the field. For a seed lot with 0.1 per cent ascochyta
infection (one infected seed in 1,000 seeds) and a planting density of three to
four plants/ft.2, 175 infected seedlings per acre could potentially result.
This is a substantial amount of early infection for such an aggressive disease.
The diseases that are caused by fungal pathogens which persist
(survive) in the soil matrix and in residues on the soil surface are defined as
soil borne diseases. Thus the soil is a reservoir of inoculums of these
pathogens, the majority of which are widely distributed in agricultural soils.
Diseases of plants are caused primarily by three types of pathogens: bacteria,
fungi, and viruses. Despite that fungi comprise the largest group of pathogens,
the bulk of seed-specific diseases are caused by bacteria or viruses. This is
due to the fact that bacteria and viruses are more adept at entering and then travelling
through the veins of the plant, a phenomenon known as ‘systemic infection,’ and
from the vascular system may make their way into the developing embryos of
seeds.
Read more on seedborne diseases and control: http://seedbuzz.com/knowledge-center/article/seedborne-disease-and-control
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