No abstract

No abstract

The rhabdovirus causing maize mosaic in Shiraz, Iran, is transmitted by Ribautodelphax notabilis Logvinenko (Homoptera, Delphacidae). Average size of bullet‐shaped virus particles in negatively stained leaf‐dip preparations of naturally or experimentally infected plants was 81 × 179 nm. The virus is transmitted to wheat and barley causing mosaic and severe stunting. Similar virus particles have been observed in leaf‐dip preparations of naturally infected wheat, barley and Sudangrass. This is believed to be the first record of the involvement of R. notabilis in virus transmission. The relationship of the described isolate with similar viruses infecting gramineous plants is discussed.

No abstract

Russian wheat aphid (RWA), Diuraphis noxia is a serious pest of cereals in various regions of the world. Seventy-six barley genotypes collected from different areas in Iran were subjected to an initial mass screening test and six susceptible and 17 apparently resistant genotypes were identified. To determine resistance mechanisms, antixenosis, antibiosis and tolerance tests were conducted and selected genotypes were ranked according to their plant resistance indices.Four crosses were made between the two most resistant lines (Shz.B-106, and Shz.B-108) and two most susceptible lines (Shz.B-105 and Shz.B-107). F1, F2 and BCF1 (backcross to the resistant parent) seedlings were screened for RWA resistance in the greenhouse by artificial infection. Resistance in Shz.B-106 was apparently controlled by a semi-dominant gene, whereas resistance in Shz.B-108 was controlled by a dominant one.