Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
bacterial pathogens (Pseudomonas savastanoi pv. phaseolicola and Xanthomonas axonopodis
pv. phaseoli on bean seeds) .The data obtained are conclusive enough to allow the use of D-
Genos kits for routine testing as an alternative to standard procedures.
Populations of two fungal pathogens of rice - Bipolaris oryzae (Cochliobolus miyabeanus),(
brown spot) and Saracladium oryzae, (sheath rot) - were used as model pathosystems.Methods
were developed to characterise these organisms using polymerase chain reaction (PCR) with both
random amplified polymorphic DNA (RAPD) and simple-sequence repeat SSR oligonucleotides as
primers.
Ustilago nuda infection of barley seed can be readily detected by PCR using primers Uh 1
and Uh 4 when the seed has a high level of infection. However, a better DNA extraction method is
needed in order to detect the required limit of 0.2%. The fungal pathogens which are difficult to be
distinguished on the basis of colony characters or on spore morphological characters owing to
their similarity, PCR based assays are the right answer in such cases.
Constraints in seed health testing on routine basis
To date there has been no systematic attempt to evaluate the large number of test
procedures for their appropriateness, whether in terms of cost, ease of use, but even more
importantly their scientific validity.
Challenges for seed health testing in Seed Industry
• Require greater emphasis by plant protection authorities on seed health testing
• Reliability of tests questioned
• Harmonisation of tests
• Use of protocols suitable to test seed.
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