Integrated control measures for sharka disease in Egypt

Maisa A. E. Awad1, Laila, M. Ibrahim1, F. Abo El- Abbas ²,M.H.El Hammady ² and

Amal Abou El-Ela1

1Virus and Phytoplasma Research Dept., Plant Pathology Res. Instit, Agricultural Research Center, Giza, Egypt. ² Dept. of Plant Pathology, Fac. of Agric., Ain Shams University, Cairo, Egypt

Received October 2007: accepted December2007

Abstract:

Sharka disease (Plum pox virus Potyvirus) was first recorded in 1986 in apricot orchards (cv.El- Amar ) grown in El-Fayium  Governorate, middle Egypt (Eg1- El- Amar  strain). In 1995 during survey work, different symptoms like sharka appeared on plum (Eg2 isolate) and peach (Eg3 isolate) on the other different orchards that used as source of virus isolates.

Cross protection experiments were using Eg2 and Eg3 isolates of PPV as protective isolates against the aggressive one (PPV-Eg1) on GF-305 peach seedlings. Some measures were recorded (height of seedlings, symptoms and Optical Density). Protected seedlings grew better than unprotected ones and showed less severe leaf symptoms.

The effect of mineral oil on the specific vector of PPV, i.e. M. persicae was studied. Apricot (cv. Hamawy) seedlings were sprayed 3, 5, 8 and 10 times with 3 different concentrations. The results showed that spraying young shoots with the mineral oil strongly reduced the PPV transmission by the aphid. Ten times sprays with 3 %oil during the spring and early summer gave protection with 100%.

Selected mother trees have healthy appearance, and good horticulture characters were marked. Then virus detection was done by DAS –ELISA technique using    polyclonal antibodies of viruses: PPV, PDV, PNRSV, PeRMV,  ArMV,  ToRSV  and ACLSV.Grafted seedlings were periodically tested for virus infection incidence using DAS- ELISA.

Different cultivars of apricot, peach and plum were used for production of virus –free plants by tissue culture. in this experiment and were treated with thermotherapy followed by chemotherapy using two concentrations of ribavirin (Virazol) 10 mg/ l and 20 mg/1 with modified two media. A higher percent of virus elimination was obtained in the apricot (cv. Canino) by 91.7 % and lower percent in the plum (cv. Beauty) by 88.6 %. Also combined cleaning method was used for elimination of the complex viruses (PPV,PNRSV and PDV)from apricot (cv.Canino),peach (Desert Red) and plum (Beauty).Thermotherapy of stone fruit in vivo , tip culture in vito connected with chemotherapy by adding ribavirn into media were used. The presence of the virus was proved by ELISA technique. The efficiency of combined cleaning method was 100% for PNRSV, 87.8% for PPV and 71.4% for PDV after more than one year.