Lapushner, Dvora, M. Pilowsky, Nehama Gilboa, W.H. Lindhout, A. Frankel

            More about susceptibility to Fenthion insecticides.

            Susceptibility of Pto/Pto and Pto/+ plants but not of +/+ plants to treatment by “Lebaycid” insecticide has been reported by Laterrot (TGC Report 35:6, 1985) and Laterrot and Philouze (TGC Report 36:23 1986). The phenomenon has been proposed to serve as a tool to indicate the presence of the Pto gene derived from “Ontario 7710”). Resistance to Pseudomonas syringae pv. tomato (Okabe) in Lycopersicon pimpinellifolium PI. 126430 has been found by Pilowsky and Zutra (TGC Report 32:42, 1982 and Phytoparasitica 14: 39-42. 1986) to be non allelic to Pto in “Ontario 7710”. Nevertheless a breeding line (Volcani 2671), deriving its resistance to bacterial speck from P.1. 126430 was found by us also to be sensitive to “Lebaycid” treatment.

            On the other hand the resistant cvs “Farthest North” and “Oregon Cherry” did not show the necrotic reaction to Fenthion treatment. The resistant cv. “Subartic Plenty” was sensitive to Fenthion (see table 1).

            The note by Laterrot and Philouze (TGC 36: 23, 1986) reporting susceptibility of the parthenocarpic line RP 75/59 and both its progenitors, “Atom” and “Bubjekosoko”, to “Lebaycid” led us to test parthenocarpic source material for susceptibility as a possible selection tool. All parthenocarpic material tested apart of “Bubjekosoko”, “Atom”, “RP 75/59”, “Subartic Plenty” and F₁ 4796 did not show significant necrotic reaction to Fenthion (see Table 1).

Table 1.            Necrotic reaction to Fenthion treatment of tomato leaflets.

1Treatment site

                                                            Wageningen                  Bet-Dagan

            Ontario 7710                                                                +++

            pat Soressi 70309                                -

            IVT-1 85009                                       -

            IVT-2 84094                                       -

            Volcani 2671 (Pto-2)                                                   +++

            Moneymaker (control)                          -

            Bubjekosoco                                        +++                 +++

            Atom                                                    ++                    ++

            RP 75/59                                             ++                    ++

            Farthest North                                      -                       -

            Sevérianin                                             -                       -

            Oregon T 5-4                                       -                       +?

            Oregon cherry                                      -                       -

            ²F₁ 4796 (Em Yahav 13)                      ++                    ++

            Heinemanns Jubilaum                                                    +

            Priora                                                                           -

            Oregon 11                                                                    +

            Subarctic plenty

            (Beaverlodge 6081)                                                      ++

- = no necrosis, +? = very few necrotic spots, + = necrotic spots, ++ = many spots, +++ = very many spots.

¹Wageningen - greenhouse grown plants, 1986 - Treatment Wageningen: dip into 4ml/l “Tiguvon” (2% Fenthion in parafin liqu.) + wetting agent

            Bet Dagan - Field grown plants, 1986 - Treatment Bet Dagan: dip into 300 µl/l of “Lebaycid 50%” + wetting agent

²Parthenocarpic F₁ cherry cv carrying genes of RP 75/59