Resistant and susceptible geraniums

Arthropod-Resistant and -Susceptible Geraniums Comparison of Chemistry... 

Plant Source. Geraniums were maintained in a greenhouse environment using standard cultural practices. The plant line 71-17-7 and its corresponding self-pollinated progeny, family 87-5, had been previously determined to be mite and aphid resistant, and plant line 71-10-1 and its corresponding self-pollinated progeny, families 85-26, 87-13 and 87-14, had previously been determined to be mite and aphid susceptible (Z)- Newly opened... 

Host plant resistance to the two-spotted spider mite, Tetranychus urtlcae, was observed In the geranium, Pelargonium x hortorum. Initial studies Indicated an association between leaf morphology and resistance later studies concluded that resistance was due largely to the presence of glandular trlchomes which produced a toxic exudate. The active components of this exudate have been Identified as anacardlc acids. Inheritance studies Indicated that resistance was dominant to susceptibility and that two dominant complementary genes conditioned resistance. 

We have shown that genetically controlled biochemical compounds in geraniums confer resistance to the two-spotted spider mite. Initial discovery of mite susceptibility among breeding materials led to an assessment of variation both at the genus and species levels. This... 

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