KFRI Research Report No - Kerala Forest Research Institute

5. E. tereticornis clones developed from new Australian provenances had performedbetter than the average provenance yield and far better than local Eucalyptus‘hybrid’ plantations. Though many of the clones have remained resistant to pinkdisease, the clones, especially the coppice shoots are being attacked increasingly byseveral species of Cylindrocladium causing leaf blight. Hence, new clones of E.urophylla and E. pellita have to be developed for replacing the E. tereticornisclones. E. urophylla is tolerant to both the diseases while E. pellita is highlyresistant. Since hybrids are more productive, a better option will be hybridsbetween E. urophylla, E. grandis and E. pellita with E. urophylla and E. pellita asmother plants. Disease resistant seedlings from seeds of closely plantedprovenances of these three species can be screened for natural hybrids usingmolecular markers.6. Heart rot of A. mangium was not observed in young trees. But the disease occurs intrees above the age of 10 years. Hence, it may be better to extract mangiumplantations sufficiently earlier. Hybrid plants between A. mangium and A.auriculiformis with A. mangium as the mother plant are also more productive thaneither of the parents. Close planting of the two species as clonal seed orchard orseedling seed orchard will produce natural hybrids between the two species.Hybrids can be identified visually at the seedling stage itself and several suchhybrids can be tested for developing fast growing disease resistant clones.6. The provenance plots of eucalypts and acacias have to be maintained as they areprecious stock of original introduction of the popular exotics.41