Investigation of resistance and susceptibility of poplar spieces and clones to important poplar pests in North Khorasan province.

Resistance and susceptibility of poplar clones to important pests were evaluated during the years 2004-2006 in Northern-Khorasan province of Iran. For this purpose, 10 polar clones of the 4 species including Populus alba, P. nigra, P. deltoides and the hybrid poplar P. x. euramericana were planted in a randomized complete block design with 3 repetitions and each plot included 25 stands of each clone. Samplings were done on 5 poplar seedlings in nurseries and 9 poplar stands planted in the middle of each plot in the main field. During the research years, 8 pests were identified in the nurseries and main field as follow: 1- Paranthrene tabaniformis 2-Dicranura vinula 3-Diaspidiotus slavionicus 4-Zeugophora flavicollis 5-Monosteira unicostata 6-Chaitophorus populi 7-Pemphigus vesicalis 8-Melasoma populi Infection or damage rate of the above pests on each poplar clone were studied during 2005-2006 and the obtained data was statistically analyzed using SAS software. Based on the results of the analysis of variance compared with Duncan's test, the following results were obtained: Damage of Paranthrene tabaniformis was observed on all poplar clones. The highest damage level was observed on the clone P. nigra 63.135 in 2005 and the clones P. nigra dartoom, P. nigra 62.127, P.xe. 455 and P. x e.561.41 (in one single group) showed the maximum susceptibility in the year 2006. The lowest damage was seen on the two clones P. alba 44.9 and P. alba beshghardash in 2005, while the latest clone showed the lowest damage in 2006. Among the 10 poplar clones, P.xe. 561.41 showed the highest susceptibility to Dicranura vinula and the two clones P. alba 44.9 and P. alba beshghardash had the highest susceptibility to Diaspidiotus slavionicus. The highest infection rate of Zeugophora flavicollis was observed on the clones P. nigra 63.135, P. nigra 62.127, P. nigra 62.154 and P. nigra dartoom, while the other clones did not show any significant difference. Poplar lace bug, Monosteira unicostata showed the highest infection on P.alba 44.9 and P. alba beshghardash. The highest infection of Chaitophorus populi was observed on P. alba 44.9. The damage of Pemphigus vesicalis was on the clones P. nigra dartoom, P. nigra 62.127 and P. nigra 62.154. Based on the results of the antixenosis test of Melasoma populi, the two clones P. xe. 561.41 and P. n. 62.127 were the most susceptible clones to the pest compared to the other ones. Statistical analysis of data showed that in two years, the clones P. nigra 62.154 and P. n. 62.127, P. d. 69.55 and P. n. 63.135 had the highest stem diameter and height compared to the other clones.