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Item Differential susceptibility of poplar hybrids to the aphid Chaitophorus leticomelas (Homoptera : Aphididae)Autores: Ramirez, C.C.; Zamudio, F.; Verdugo, J.V.; Nunez, M.E.After its recent introduction to Chile, the aphid Chaitophoris leucomelas Koch is becoming a serious pest affecting commercial poplar, Populus spp., plantations. The pattern of natural infestation of C. leucomelas among poplar hybrids with different pedigrees and the aphid intrinsic rate of increase (r(m)), of C. leucomelas were assessed in the field. In most of the hybrids, aphid abundance peaked in March (late summer). Among 12 types of poplar- crosses, [(P. trichocarpa Torr. & Gray x P. deltoides Bartram ex Marshall) x (P. trichocarpa x P. deltoides)] and [(P. trichocarpa x P. mowiczii Henry) x P, maximowiczii] showed the highest and lowest aphid densities: respectively. A trend to find more aphids in branch bases was apparent. The intrinsic rate of C. leucomelas increase was higher in [(P. trichocarpa x P. deltoides) x P. deltoides] hybrids. and lower in [(P. trichocarpa x P. maximmowiczii) x P. trichocarpa] hybrids. Aphid density and perfomance were higher in hybrids with P. deltoides parentage. whereas hybrids with P. maximowiczii parentage showed lower aphid densities and performance. Hybrids with P. nigra L. parentage, namelly, [P. trichocarpa x P. nigra] also had high aphid density, but aphid performance was lower compared with hybrids with P. deltoides parentage. These results suggest that among poplar hybrids studied. susceptibility to G. leucomelas is inherited through P. deltoides, whereas resistance seems to be inherited through P. maximowiczii. Thus, P. maximowiczii hybrids are recommended for commercial or ornamental planting programs in zones where there is a high risk of aphid infestation.Item Susceptibility of Populus spp. hybrids to aphids and rusts at three localities of ChileAutores: Rubio-Melendez, M.E.; Zamudio, F.; Ramirez, C.C.In the last few years an increasing interest on species and hybrids of the genus Populus has occurred in Chile. However, such plantations are strongly affected by pest and diseases. With the aim to identify potentially resistant (or less susceptible) hybrids of the genus Populus, the susceptibility of some poplar hybrids growing in experimental nurseries in Southern-Center Chile to the aphid Chaitophorus leucomelas Koch and to the rust Melampsora spp. was assessed. Results showed that aphid abundance was higher in the month of March, particularly in Coinco (O'Higgins Region) and lower in Pillanlelbun (Los Rios Regions) and Yumbel (Biobio Region). In Pillanlelbun the most susceptible hybrid to aphids was TDxTD [(P. trichocarpa x P. deltoides) x (P. trichocarpa x P. deltoides)], and the less susceptible ones were TDxD [(P. trichocarpa x P. deltoides) x P. deltoides], TxN (P. trichocarpa x P. nigra), TMxTM [(P. trichocarpa x P. maximowitzii) x (P. trichocarpa x P. maximowitzii)] and TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa]. Hybrid TxN (P. trichocarpa x P. nigra) was the most susceptible to rust in all testing sites, while the less susceptible hybrids were TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa], TDxD [(P. trichocarpa x P. deltoides) x P. trichocarpa] and TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa]. These susceptibilities varied among localities, particularly on aphids. Genetic and environmental factors accounting for by these results are discussed.
